Power conversion device

Abstract

A power conversion device includes an inverter that converts power output from a distributed power supply into alternating-current power and outputs the alternating-current power to an alternating-current system, and a control circuit (409) that controls the inverter. The control circuit (409) includes a virtual synchronous generator control circuit (83) that causes the inverter to have transient characteristics of a synchronous generator, a control parameter generation circuit (88) that generates a control parameter for controlling the virtual synchronous generator control circuit (83), an inverter voltage control circuit (85) that controls the inverter as a voltage source in accordance with alternating-current system voltage information input from the virtual synchronous generator control circuit (83), and a communication circuit that receives a power target value of the distributed power supply and information necessary for generation of the control parameter from a management device that manages the distributed power supply. The control parameter generation circuit (88) generates at least one of a speed adjustment rate and a damping coefficient used in the virtual synchronous generator control circuit (83) in accordance with the power target value and the information necessary for generation of the control parameter received by the communication circuit.

Description

Technical Field

[0001] This disclosure relates to power conversion devices. Background Technology

[0002] In recent years, to reduce environmental impact, the adoption of energy-generating devices (hereinafter referred to as "energy-generating devices") utilizing renewable energy sources such as solar cells has been accelerated. Furthermore, to address power shortages following the Great East Japan Earthquake, systems incorporating energy storage devices such as batteries (hereinafter referred to as "energy storage devices"), or systems combining energy-generating and energy storage devices, have been developed. In these systems, static inverters are used to connect the energy-generating and energy storage devices to the AC system.

[0003] On the other hand, in the power system, thermal power plants, which act as adjusters for changes in demand, are projected to gradually shut down in the future, based on the viewpoint of reducing generation costs, including management costs, as generation increases from renewable energy sources. However, synchronous generators in thermal power plants potentially play a role in suppressing system frequency fluctuations (inertial forces, synchronization forces, etc.). Therefore, as thermal power plants gradually shut down, the number of synchronous generators gradually decreases, raising concerns about ensuring the stability of the power system.

[0004] To address the aforementioned issues, development has been undertaken to advance control technology for virtual synchronous generators, enabling static inverters to function as synchronous generators. For example, Japanese Patent Application Publication No. 2019-176584 (Patent Document 1) discloses a method for setting control parameters of a distributed power source (static inverter) equipped with virtual synchronous generator control. Specifically, Patent Document 1 discloses a method for generating control parameters for setting the virtual inertia in the distributed power source based on either a required inertia value from the system user or a virtual inertia value calculated based on the specifications and operating state of the distributed power source.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-176584 Summary of the Invention

[0008] According to the method for generating control parameters described in the aforementioned Patent Document 1, although the system inertia force intended by the system manager is guaranteed, the distribution of power shared by each distributed power source cannot be guaranteed due to changes in load or changes in the power generation of the energy-generating equipment.

[0009] For example, consider a scenario where two batteries, each controlled by a virtual synchronous generator, are connected to the system as a distributed power source. The battery capacity is the same as the static inverter capacity, and the State of Charge (SOC) ratio at the current point in time is set to 2:1. In this case, the ratio of the target discharge power for each battery to the SOC ratio in the battery operation plan (charge / discharge plan) is also allocated at 2:1.

[0010] Here, when the overall system load increases, virtual synchronous generator control is implemented in each battery, and the increased power output is shared between the two batteries. At this time, with the control parameters of the virtual synchronous generator control for the two batteries being the same, each battery additionally outputs the same amount of power.

[0011] However, in the above-mentioned battery operation plan, it is preferable to plan the two batteries to output power according to the ratio of their respective SOCs, and the increased power is also distributed according to the ratio of this operation plan.

[0012] In the aforementioned patent document 1, the control parameters are determined solely by the system's inertia force as required by the system operator. Therefore, when multiple distributed power sources are used to share the excess or deficiency power during load fluctuations or power generation fluctuations from energy-generating devices, the distribution is based on the virtual inertia of each distributed power source. Consequently, there is a problem where the excess or deficiency power is distributed with a ratio different from that envisioned in the original operation plan.

[0013] Generally, the target power allocation (operational plan) for multiple power conversion devices is determined based on the capacity of each battery, its State of Charge (SOC), and the capacity of the static inverter. (For simplicity, this is assumed that a virtual synchronous generator control is installed in the static inverter of the battery system.) Specifically, during discharge, when the battery capacity and static inverter capacity are the same across multiple batteries, a larger amount of power is allocated to the battery with the higher SOC. This is because, for example, when the charging power of one of two batteries reaches zero (SOC = 0), the system's inertia is maintained by the remaining battery, so the apparent inertia force utilized by the static inverter is essentially halved. Therefore, when determining the power allocation for multiple batteries, it is necessary to allocate power in a way that ensures the SOC of each battery reaches approximately zero simultaneously (fully charged during charging).

[0014] In particular, when using multiple distributed power sources such as batteries equipped with virtual synchronous generator control to form a microgrid, there is a problem that the power supplied to the system cannot be distributed among the distributed power sources as intended when there are rapid changes in load or solar radiation.

[0015] This disclosure was made to solve the problems described above, and its purpose is to generate control parameters for the virtual synchronous generator control in a power system connected to multiple power conversion devices equipped with static inverters that have virtual synchronous generator control installed, so that even if the power consumption of the load changes or the power generated by the energy generation device changes, each power conversion device can distribute the insufficient power to the virtual synchronous generator control in a manner equal to the power target value notified from the upper-level EMS (Energy Management System).

[0016] In one embodiment of this disclosure, the power conversion device includes: an inverter that converts power output from a distributed power source into AC power and outputs it to an AC system; and a control circuit that controls the inverter. The control circuit includes: a virtual synchronous generator control circuit that enables the inverter to have the transient characteristics of a synchronous generator; a control parameter generation circuit that generates control parameters for controlling the virtual synchronous generator control circuit; an inverter voltage control circuit that controls the inverter as a voltage source based on AC system voltage information input from the virtual synchronous generator control circuit; and a communication circuit that receives power target values ​​of the distributed power source and information required for generating the control parameters from a management device that manages the distributed power source. The control parameter generation circuit generates at least one of a speed regulation rate and a damping coefficient used in the virtual synchronous generator control circuit based on the power target values ​​received from the communication circuit and the information required for generating the control parameters.

[0017] According to this disclosure, in a power system connected to multiple power conversion devices equipped with static inverters that control virtual synchronous generators, even if the power consumption of the load changes or the power generated by the energy generation equipment changes, each power conversion device can share the insufficient power in a manner equal to the ratio of the notified power target value. Attached Figure Description

[0018] Figure 1 This is a block diagram illustrating an example of the structure of a power distribution system.

[0019] Figure 2 This is for further explanation. Figure 1 The diagram shows the structure of the power distribution system.

[0020] Figure 3 It is shown Figure 1 The diagram shows the structure of CEMS.

[0021] Figure 4 It is shown Figure 3 The diagram shows the block diagram of the circuit structure for the operation plan.

[0022] Figure 5 It is shown Figure 3 The diagram shows the block diagram of the control parameter generation circuit.

[0023] Figure 6 It is shown Figure 1 The diagram shows a block diagram of the structure of a power conversion device for a megawatt-class solar power plant.

[0024] Figure 7 This is an explanation Figure 1 The diagram shown is a block diagram of the structure of a power conversion device for storage batteries.

[0025] Figure 8 This is an explanation Figure 6 The block diagram of the structure of the first control circuit is shown.

[0026] Figure 9 This is an explanation Figure 6 The block diagram of the structure of the second control circuit is shown.

[0027] Figure 10 This is an explanation Figure 7 The block diagram of the structure of the third control circuit is shown.

[0028] Figure 11 This is an explanation Figure 7 The block diagram of the structure of the fourth control circuit is shown.

[0029] Figure 12 This is an explanation Figure 11 The diagram shows the structure of the AC frequency detection circuit.

[0030] Figure 13 This is an explanation Figure 11 The diagram shows the structure of the inverter voltage control circuit.

[0031] Figure 14 This is an explanation Figure 11 The diagram shows the structure of the virtual synchronous generator control circuit.

[0032] Figure 15 This is an explanation Figure 14 The diagram shows the structure of the governor control circuit.

[0033] Figure 16 This is an explanation Figure 14 The diagram shows the block diagram of the structure of the operational circuit of the mass system.

[0034] Figure 17 This is a diagram showing the area covered by a virtual synchronous generator installed in the power conversion unit.

[0035] Figure 18 This is a diagram illustrating the control of a virtual synchronous generator installed in the power conversion device involved in Embodiment 1.

[0036] Figure 19 This is a diagram illustrating the control of a virtual synchronous generator installed in the power conversion device involved in Embodiment 1.

[0037] Figure 20 This is a graph illustrating an example of the ΔF / ΔP characteristics.

[0038] Figure 21 This is a diagram showing the frequency response waveform of the AC voltage output from the static inverter when the load changes drastically in the virtual synchronous generator control of the power conversion device installed in Embodiment 1.

[0039] Figure 22 This is a graph showing the response waveform of the effective value of the AC power output from the static inverters of two power conversion devices equipped with conventional virtual synchronous generator control.

[0040] Figure 23 The diagram shows the frequency response waveforms of the AC voltage output from each static inverter when two power conversion units equipped with conventional virtual synchronous generator control are activated.

[0041] Figure 24 This is a diagram illustrating an example of the ΔF / ΔP characteristics of a first power conversion unit equipped with conventional virtual synchronous generator control.

[0042] Figure 25 This is a diagram illustrating an example of the ΔF / ΔP characteristics of a second power conversion unit equipped with conventional virtual synchronous generator control.

[0043] Figure 26 This is a diagram illustrating an example of the ΔF / ΔP characteristics of a second power conversion device equipped with the virtual generator control according to Embodiment 1.

[0044] Figure 27 This is a diagram illustrating an example of the reference ΔF / ΔP characteristics in a power conversion device equipped with the virtual synchronous generator control according to Embodiment 1.

[0045] Figure 28 It is used to explain its use. Figure 27 The diagram shows the method for fabricating the baseline ΔF / ΔP characteristics and the ΔF / ΔP characteristics of each power conversion device.

[0046] Figure 29 This is a diagram illustrating the fabrication method of the reference ΔF / ΔP characteristics of a 4kW static inverter.

[0047] Figure 30This is a diagram illustrating an example of the baseline ΔF / ΔP characteristics and ΔF / ΔP characteristics of two power conversion devices with different capacities from a static inverter.

[0048] Figure 31 It shows from Figure 30 The diagram shows the waveforms of the effective values ​​of the AC power output from the two power conversion devices.

[0049] Figure 32 It is used for explanation Figure 1 The diagram shows the timing of typical operation of a distributed power system.

[0050] Figure 33 This is a flowchart illustrating the control process of CEMS.

[0051] Figure 34 This shows the process of manufacturing a storage battery. Figure 33 The flowchart of S05).

[0052] Figure 35 This is the processing of information required to generate the control parameters for virtual synchronous generator control. Figure 34 The flowchart of S056).

[0053] Figure 36 This illustrates the process for generating the baseline ΔF / ΔP characteristics. Figure 35 The flowchart of S0562).

[0054] Figure 37 This illustrates the process for generating the ΔF / ΔP characteristics. Figure 35 The flowchart of S0563).

[0055] Figure 38 This demonstrates the process of modifying the battery's operating plan. Figure 33 The flowchart of S09).

[0056] Figure 39 It is a flowchart used to explain the operation of a power conversion device.

[0057] Figure 40 This is a detailed description of the control processing of the second DC / AC converter. Figure 39 The flowchart of S204).

[0058] Figure 41 This illustrates the process of generating control parameters. Figure 39 The flowchart of S216).

[0059] Figure 42A This diagram illustrates the problem of controlling a power conversion device according to the control parameters for controlling a virtual synchronous generator generated in Embodiment 1.

[0060] Figure 42B This diagram illustrates the problem of controlling a power conversion device according to the control parameters for controlling a virtual synchronous generator generated in Embodiment 1.

[0061] Figure 43A This is a diagram illustrating an example of the ΔF / ΔP characteristic generated by changing the slope of the reference ΔF / ΔP characteristic of the first power conversion device.

[0062] Figure 43B This is a diagram illustrating an example of the ΔF / ΔP characteristic generated by changing the slope of the reference ΔF / ΔP characteristic of the second power conversion device.

[0063] Figure 44 This is a flowchart illustrating the generation process of the baseline ΔF / ΔP characteristics performed by CEMS.

[0064] Figure 45A This is a diagram illustrating an example of the reference ΔF / ΔP characteristics and ΔF / ΔP characteristics of the first power conversion device according to Embodiment 2.

[0065] Figure 45B This is a diagram illustrating an example of the reference ΔF / ΔP characteristics and ΔF / ΔP characteristics of the second power conversion unit according to Embodiment 2.

[0066] Figure 46 This is a flowchart used to explain the operation of the fourth control circuit.

[0067] Figure 47 This illustrates the process of generating control parameters. Figure 46 The flowchart of S220).

[0068] Figure 48 This illustrates the process for generating the baseline ΔF / ΔP characteristics. Figure 47 The flowchart of S2201).

[0069] Figure 49 This illustrates the process for generating the ΔF / ΔP characteristics. Figure 47 The flowchart of S2202).

[0070] Figure 50A This is a diagram used to illustrate the reference ΔF / ΔP characteristics and the method for manufacturing the ΔF / ΔP characteristics of the first power conversion device according to Embodiment 3.

[0071] Figure 50B This is a diagram used to illustrate the reference ΔF / ΔP characteristics and the method for manufacturing the ΔF / ΔP characteristics of the second power conversion device according to Embodiment 3.

[0072] Figure 51 This is a flowchart illustrating the generation process of the baseline ΔF / ΔP characteristics within CEMS.

[0073] Figure 52A This is a diagram used to illustrate the reference ΔF / ΔP characteristics and the method for manufacturing the ΔF / ΔP characteristics of the first power conversion device according to Embodiment 4.

[0074] Figure 52B This is a diagram used to illustrate the reference ΔF / ΔP characteristics and the method for manufacturing the ΔF / ΔP characteristics of the second power conversion device according to Embodiment 4.

[0075] Figure 53 This is a flowchart illustrating the generation process of the baseline ΔF / ΔP characteristics performed within CEMS.

[0076] Figure 54 This diagram illustrates the concept of virtual synchronous generator control technology.

[0077] (Symbol Explanation)

[0078] 11: Communication circuit; 12: Storage circuit; 13: Control parameter generation circuit; 14: Operation plan generation circuit; 15: Data transmission generation circuit; 16: Control circuit; 20: Substation; 21: Distribution automation system (DSO); 22, 201, 206, 210, 401, 406, 410: Voltmeter; 23: Automatic voltage regulator (SVR); 24: Power distribution system; 25: Communication line; 26: Megawatt-class solar power plant; 27: Power conversion device for megawatt-class solar power plant; 28: Switch; 29: Impedance; 30: Synchronous generator; 31: CEMS; 40, 40a~40c: System batteries; 41, 41a~40c: Power conversion device for batteries; 5 1: MPPT control circuit; 52: Voltage control circuit; 53: First switching circuit; 54: Fifth control circuit; 61: Phase detection circuit; 62: First sine wave generation circuit; 63, 66, 101, 832, 836, 852: Subtractors; 64: First PI control circuit; 65, 91, 103: Multipliers; 67: Sixth control circuit; 68: Second PI control circuit; 69: First PWM converter; 71: Charging control circuit; 72: Discharging control circuit; 73: Second switching circuit; 74: Seventh control circuit; 81: AC frequency detection circuit; 82: Effective power calculation circuit; 83: Virtual synchronous generator control circuit; 84: Inverter current control circuit; 85: Inverter current control circuit. 86: Voltage control circuit; 87: 3rd switching circuit; 88: 8th control circuit; 92: Control parameter generation circuit; 93: First-order delay system model; 104: Limiter circuit; 105: Integrator; 106: Divider; 107: Adder; 108: Phase calculation circuit; 100a~100d: Town; 110: Factory; 141: Battery operation plan generation circuit; 142: Power generation prediction circuit; 143: Power consumption prediction circuit; 144: Battery operation plan correction circuit; 135: 3rd management circuit; 146: 1st management circuit; 147: 2nd management circuit; 131: Reference ΔP / ΔF characteristic calculation circuit; 132: ΔP / ΔF characteristic calculation circuit; 138: Control circuit Circuits; 202, 207, 211, 402, 407, 411: Ammeters; 203: First DC / DC Converter; 204: First Control Circuit; 205, 405: DC Bus; 208: First DC / AC Converter; 209: Second Control Circuit; 212, 412: Communication I / F; 403: Second DC / DC Converter; 404: Third Control Circuit; 408: Second DC / AC Converter; 409: Fourth Control Circuit; 810: Phase Detection Circuit; 811: Frequency Detection Circuit; 812: Second Sine Wave Generator Circuit; 833: Speed ​​Controller Control Circuit; 837: Mass System Calculation Circuit; 851: Third Sine Wave Generator Circuit; 853: Third PI Control Circuit;854: Second PWM converter; 855: First current limiting circuit; 600: Load. Detailed Implementation

[0079] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be referred to by the same reference numerals, and their descriptions will generally not be repeated.

[0080] Implementation method 1.

[0081] (Example of a power distribution system structure)

[0082] First, a structural example of a power distribution system connected to the power conversion device according to Embodiment 1 will be described. Furthermore, while a three-phase system is illustrated in Embodiment 1, the power distribution system may also be a single-phase system.

[0083] Figure 1 This is a block diagram illustrating a structural example of the power distribution system 24. For example... Figure 1 As shown, the power distribution system 24 receives power from the substation 20. Multiple automatic voltage regulators (SVRs) 23a to 23c are installed in the power distribution system 24. The multiple SVRs 23a to 23c are connected in series relative to the flow of electricity. The multiple SVRs 23a to 23c are connected to buildings 112, apartments 113, towns A100a to D100d, factories 110, power conversion devices 27 for megawatt-class solar power plants, power conversion devices 41a to 41c for system batteries, and synchronous generators 30a and 30b. In the following description, SVRs 23a to 23c are collectively referred to as "SVR23". Furthermore, power conversion devices 41a to 41c are collectively referred to as "power conversion device 41".

[0084] In the power distribution system 24, multiple voltmeters 22a, 22e, 22f, 22i, 22j, and 22x are configured. Hereinafter, voltmeters 22a, 22e, 22f, 22i, 22j, and 22x will be collectively referred to as "voltmeter 22". The measured values ​​of each voltmeter 22 are sent to the power distribution automation system 21 (hereinafter referred to as "DSO21") at a predetermined period. DSO21 corresponds to one embodiment of a "system management device" that manages the power distribution system 24.

[0085] The tap position information, primary side voltage, and secondary side voltage information of SVR23 are sent to DSO21. In Embodiment 1, SVR23 notifies the tap position information, primary side voltage, and secondary side voltage information at a predetermined period, and notifies the tap position information, primary side voltage, and secondary side voltage information irregularly during tap switching.

[0086] The CEMS (Community Energy Management System) 31 collects various measurement values ​​and other information from consumers (townships 100a-100d, factories 110, buildings 112, apartments 113), power conversion devices 27, synchronous generators 30a and 30b, and power conversion devices 41a-41c at predetermined intervals. The CEMS 31 notifies the DSO 21 of the collected data in response to requests from the DSO 21. Furthermore, the power consumption of consumers within townships 100a-100d and the power generation of energy-generating devices are measured using smart meters (not shown) installed at each consumer. The CEMS 31 collects the smart meter measurements at predetermined intervals (e.g., 30-minute intervals). The CEMS 31 corresponds to one embodiment of a "management device".

[0087] A megawatt-class solar power station 26 is connected to power conversion device 27. System batteries 40a to 40c are connected to power conversion devices 41a to 41c respectively. Batteries 40a to 40c are large-capacity batteries capable of being connected to the power distribution system 24. In the following description, batteries 40a to 40c will be referred to collectively as "battery 40".

[0088] Figure 2 This is for further explanation. Figure 1 The diagram shows the structure of the power distribution system 24.

[0089] like Figure 2 As shown, the power distribution system 24 is connected to a load 600, a power conversion device 41, and a battery 40. Furthermore, for simplicity, in... Figure 2 In this paper, the impedance 29 of the power distribution system 24 is represented in a centralized system. It is assumed that the impedance 29 of the power distribution system 24 consists of a reactor component and a resistance component.

[0090] (1) CEMS31

[0091] Figure 3 It is shown Figure 1 The diagram shows the structure of CEMS31.

[0092] like Figure 3 As shown, the CEMS31 includes a communication circuit 11, a storage circuit 12, a control parameter generation circuit 13, an operation plan generation circuit 14, a data transmission generation circuit 15, and a control circuit 16.

[0093] The communication circuit 11 communicates with DSO21, various consumers (towns 100a-100d, factories 110, buildings 112, apartments 113), power conversion device 27, synchronous generators 30a and 30b, and power conversion devices 41a-41c via communication line 25.

[0094] The storage circuit 12 stores various information obtained via the communication circuit 11. Among these various information are measurement results and current status information of each distributed power source.

[0095] The control parameter generation circuit 13 generates control parameters for the virtual synchronous generators installed in the power conversion devices 41a to 41c.

[0096] The operation plan generation circuit 14 generates operation plans for the power conversion devices 41a to 41c based on control commands from DSO21. The operation plans for the power conversion devices 41a to 41c include the charging and discharging plans (target power values) for the corresponding batteries 40a to 40c. In Embodiment 1, the operation plan generation circuit 14 generates 24-hour operation plans at 30-minute intervals.

[0097] Furthermore, the operation plan generation circuit 14 determines whether the operation plan needs to be revised based on the measurement results of the power conversion devices 41a to 41c collected in 5-minute units and the SOC information of the batteries 40a to 40c. If it is determined that the operation plan needs to be revised, the operation plan generation circuit 14 revises the operation plan for the period until the next control command is notified from DSO21.

[0098] The data generation circuit 15 stores the control parameters generated by the control parameter generation circuit 13 and the control parameters of the virtual synchronous generator, as well as the operation plan output from the operation plan creation circuit 14. In response to a transmission command from the control circuit 16, the data generation circuit 15 outputs the stored data to the communication circuit 11. The communication circuit 11, according to the control signal output from the control circuit 16, transmits the data output from the data generation circuit 15 to the communication line 25.

[0099] Control circuit 16 is a control circuit used to manage the distributed power sources connected to power distribution system 24. Control circuit 16 manages the operation of communication circuit 11, storage circuit 12, control parameter generation circuit 13, operation plan creation circuit 14, and data transmission generation circuit 15.

[0100] (1-1) Operation plan production circuit 14

[0101] Figure 4 It is shown Figure 3 The diagram shows the structure of the operation plan manufacturing circuit 14.

[0102] like Figure 4 As shown, the operation plan generation circuit 14 includes a battery operation plan generation circuit 141, a power generation prediction circuit 142, a power consumption prediction circuit 143, a battery operation plan correction circuit 144, a first management circuit 145, and a second management circuit 146.

[0103] The battery operation planning circuit 141 generates operation plans (power target values) for the power conversion devices 41a, 41b, and 41c based on information related to control commands received from DSO21, the predicted power generation of the megawatt-class solar power plant 26 predicted by the power generation prediction circuit 142, and the predicted power consumption of consumers predicted by the power consumption prediction circuit 143. Furthermore, the control commands received from DSO21 to the battery operation planning circuit 141 include planned values ​​for the power consumed downstream of the substation 20 (power supplied to the distribution system 24). The planned power supply values ​​are composed of planned values ​​for 30-minute intervals and 24-hour periods.

[0104] The power generation prediction circuit 142 obtains 24-hour weather forecast information from a weather forecast server (not shown) via communication circuit 11. Based on the obtained weather forecast information and information from a database (not shown) prepared for predicting power generation, the power generation prediction circuit 142 predicts the power generation of the megawatt-class solar power plant 26.

[0105] The power consumption prediction circuit 143 predicts the total power consumption of each consumer based on the clock information (year, month, day, week, time) inside the CEMS31 and information from a database (not shown) prepared for power consumption prediction.

[0106] The battery operation plan correction circuit 144, via the communication circuit 11, determines whether the operation plan needs to be corrected based on the charging and discharging power and power target value information of the power conversion devices 41a-41c. If it is determined that correction is needed, the battery operation plan correction circuit 144 generates a corrected value for the operation plan.

[0107] The first management circuit 145 manages the creation of operation plans for the distributed power sources connected to the power distribution system 24. The first management circuit 145 stores the power target values ​​(charging power target value and discharging power target value) for each battery 40 generated by the battery operation plan creation circuit 141 and the battery operation plan correction circuit 144. Based on the control signal output from the second management circuit 146, the first management circuit 145 outputs the power target values ​​to the control parameter generation circuit 13 and the data transmission generation circuit 15.

[0108] The second management circuit 146 manages the operation of the battery operation plan generation circuit 141, the power generation prediction circuit 142, the power consumption prediction circuit 143, the battery operation plan correction circuit 144, and the first management circuit 145.

[0109] (1-2) Control parameter generation circuit 13

[0110] Figure 5 It is shown Figure 3 The block diagram shown is of the structure of the control parameter generation circuit 13.

[0111] like Figure 5 As shown, the control parameter generation circuit 13 includes a reference ΔF / ΔP characteristic calculation circuit 131, a ΔF / ΔP characteristic calculation circuit 132, a third management circuit 135, and a control circuit 136.

[0112] The reference ΔF / ΔP characteristic calculation circuit 131 calculates the reference ΔF / ΔP characteristic based on the capacity information of the static inverter (second DC / AC converter 408) of the power conversion devices 41a to 41c.

[0113] The ΔF / ΔP characteristic calculation circuit 132 calculates the ΔF / ΔP characteristic based on the above-mentioned baseline ΔF / ΔP characteristic and the operation plan production circuit 14 ( Figure 4 The power target value information is generated, and the ΔF / ΔP characteristic is calculated.

[0114] The third management circuit 135 manages the control parameters for the synchronous generator control. The third management circuit 135 stores and manages information such as the ΔF / ΔP characteristic calculated by the ΔF / ΔP characteristic calculation circuit 132 and the power target value Pref, etc., in a memory not shown.

[0115] The control circuit 136 manages the operation of the reference ΔF / ΔP characteristic calculation circuit 131, the ΔF / ΔP characteristic calculation circuit 132, and the third management circuit 135.

[0116] (2) Power conversion device 27

[0117] Figure 6 It is shown Figure 1 A block diagram of the structure of the power conversion device 27 shown.

[0118] like Figure 6 As shown, the power conversion device 27 includes voltmeters 201, 206, and 210, ammeters 202, 207, and 211, a first DC / DC converter 203, a first control circuit 204, a DC bus 205, a first DC / AC converter 208, a second control circuit 209, and a communication interface (I / F) 212.

[0119] Voltmeter 201 measures the DC voltage output from megawatt-class solar power plant 26. Ammeter 202 measures the DC current output from megawatt-class solar power plant 26.

[0120] The first DC / DC converter 203 converts the first DC voltage output from the megawatt-class solar power plant 26 into a second DC voltage. The first control circuit 204 controls the first DC / DC converter 203.

[0121] DC bus 205 supplies the second DC voltage output from the first DC / DC converter 203 to the first DC / AC converter 208. Voltmeter 206 measures the voltage of DC bus 205. Ammeter 207 measures the DC current output from the first DC / DC converter 203.

[0122] The first DC / AC converter 208 converts the DC power output from the first DC / DC converter 203 into AC power. The second control circuit 209 controls the first DC / AC converter 208.

[0123] Voltmeter 210 measures the AC voltage output from the first DC / AC converter 208. Ammeter 211 measures the AC current output from the first DC / AC converter 208. Communication I / F 212 enables communication between the power conversion unit 27 and CEMS 31.

[0124] (3) Power conversion device 41

[0125] Figure 7 This is an explanation Figure 1 The diagram shows the structure of the power conversion device 41.

[0126] like Figure 7 As shown, the power conversion device 41 includes voltmeters 401, 406, and 410, ammeters 402, 407, and 411, a second DC / DC converter 403, a third control circuit 404, a DC bus 405, a second DC / AC converter 408, a fourth control circuit 409, and a communication I / F 412.

[0127] Voltmeter 401 measures the DC voltage output from battery 40. Ammeter 402 measures the DC current output from battery 40.

[0128] The second DC / DC converter 403 converts the third DC voltage output from the battery 40 into a fourth DC voltage. The third control circuit 404 controls the second DC / DC converter 403.

[0129] DC bus 405 supplies the DC voltage output from the second DC / DC converter 403 to the second DC / AC converter 408. Voltmeter 406 measures the voltage of DC bus 405. Ammeter 407 measures the DC current output from the second DC / DC converter 403.

[0130] The second DC / AC converter 408 converts the DC power output from the second DC / DC converter 403 into AC power. The fourth control circuit 409 controls the second DC / AC converter 408.

[0131] Voltmeter 410 measures the AC voltage output from the second DC / AC converter 408. Ammeter 411 measures the AC current output from the second DC / AC converter 408. Communication I / F 412 enables communication between the power conversion unit 41 and CEMS 31.

[0132] Furthermore, in the first DC / DC converter 203 ( Figure 6 ) and the second DC / DC converter 403 ( Figure 7 In the first DC / AC converter 208, a known DC / DC converter can be appropriately used. Figure 6 ) and the second DC / AC converter 408 ( Figure 7 In this circuit, a known inverter can be used. The first DC / AC converter 208 and the second DC / AC converter 408 each correspond to an embodiment of a "static inverter". The second control circuit 209 and the fourth control circuit 409 correspond to an embodiment of a "control circuit".

[0133] (2-1) First control circuit 204

[0134] Figure 8 This is an explanation Figure 6 The block diagram of the structure of the first control circuit 204 shown is shown.

[0135] like Figure 8 As shown, the first control circuit 204 includes an MPPT (Maximum Power Point Tracking) control circuit 51, a voltage control circuit 52, a first switching circuit 53, and a fifth control circuit 54.

[0136] The MPPT control circuit 51 performs so-called Maximum Power Point Tracking (MPPT) control based on the measurements from voltmeter 201 and ammeter 202. To maximize the extraction of generated power from the megawatt-class solar power plant 26, the MPPT control circuit 51 searches for the maximum power point of the megawatt-class solar power plant 26. Specifically, the MPPT control circuit 51 generates control command values ​​for the first DC / DC converter 203 to control the DC voltage measured by voltmeter 201 to the voltage corresponding to the maximum power point.

[0137] The voltage control circuit 52 generates a control command value for the first DC / DC converter 203 to maintain the DC voltage (second DC voltage) of the DC bus 205 at a predetermined target voltage based on the measurement value of the voltmeter 206.

[0138] The fifth control circuit 54 outputs control parameters and target values ​​to the MPPT control circuit 51 and the voltage control circuit 52, and manages the power generation status of the megawatt-level solar power station 26. The fifth control circuit 54 also outputs control signals to the first switching circuit 53.

[0139] The first switching circuit 53 selectively outputs either the output of the MPPT control circuit 51 or the voltage control circuit 52 as the control command value of the first DC / DC converter 203 according to the control signal from the fifth control circuit 54.

[0140] The first DC / DC converter 203 is controlled in either MPPT mode or voltage control mode. In MPPT mode, the first switching circuit 53 outputs the control command value generated by the MPPT control circuit 51. In voltage control mode, the first switching circuit 53 outputs the control command value generated by the voltage control circuit 52.

[0141] (2-2) Second control circuit 209

[0142] Figure 9 This is an explanation Figure 6 The block diagram of the structure of the second control circuit 209 shown is shown.

[0143] like Figure 9 As shown, the second control circuit 209 includes a phase detection circuit 61, a first sine wave generation circuit 62, a current control circuit 60, and a sixth control circuit 67.

[0144] The current control circuit 60 includes a subtractor 63, a first PI control circuit 64, a multiplier 65, a subtractor 66, a second PI control circuit 68, and a first PWM converter 69. The current control circuit 60 executes a control mode that outputs power synchronously with the system voltage. This control mode is the control method used in typical solar power converters installed in homes.

[0145] Phase detection circuit 61 obtains data from voltmeter 210 ( Figure 6 The phase of the AC voltage is detected by measuring the waveform of the AC voltage.

[0146] The first sine wave generation circuit 62 generates a sine wave synchronized with the waveform of the AC voltage based on the amplitude of the AC voltage measured by the voltmeter 210 and the phase information detected by the phase detection circuit 61. Furthermore, in Embodiment 1, the phase detection circuit 61 detects the zero-crossing points of the AC voltage waveform and detects the frequency of the AC voltage from the zero-crossing point detection result. The phase detection circuit 61 outputs the detected frequency of the AC voltage along with the zero-crossing point information to the first sine wave generation circuit 62.

[0147] The current control circuit 60 is based on the voltage meter 206 ( Figure 6 The DC voltage of the DC bus 205 is measured and a control command value for controlling the first DC / DC converter 203 is generated. The subtractor 63 subtracts the DC voltage of the DC bus 205 measured by the voltmeter 206 from the target value of the DC bus voltage output by the sixth control circuit 67. The value after subtraction by the subtractor 63 is input to the first PI control circuit 64.

[0148] Multiplier 65 generates a current command value by multiplying the control command value output from the first PI control circuit 64 and the sine wave output from the first sine wave generation circuit 62.

[0149] Subtractor 66 calculates the current command value output from multiplier 65 and the current through ammeter 211. Figure 6 The deviation of the measured current value of the AC system is output to the second PI control circuit 68.

[0150] The second PI control circuit 68 generates a control command value based on the control parameters (proportional gain and integral time) provided by the sixth control circuit 67, in a manner that makes the deviation output from the subtractor 66 zero. The second PI control circuit 68 outputs the generated control command value to the first PWM converter 69.

[0151] The first PWM converter 69 performs PWM control based on the control command value input from the second PI control circuit 68, generates a control command value, and outputs the generated control command value to the first DC / AC converter 208.

[0152] The sixth control circuit 67 collects measurement results related to the DC bus 205 output from voltmeter 206 and ammeter 207, measurement results related to the AC system output from voltmeter 210 and ammeter 211, and status information of the first DC / DC converter 203 output from the first control circuit 204, and notifies the CEMS 31 and the like of the collected information via communication I / F 212.

[0153] Additionally, the sixth control circuit 67 notifies the first PI control circuit 64 and the second PI control circuit 68 of control parameters. The sixth control circuit 67 notifies the CEMS 31 of information related to active and reactive power measured by the AC system's effective voltage measurement unit (not shown) via communication I / F 212. The sixth control circuit 67 notifies the fifth control circuit 54 of the measured values ​​of the AC system's effective voltage and active power. For example, if the effective value of the system voltage exceeds a predetermined value, the fifth control circuit 54 switches the control of the megawatt-class solar power plant 26 from MPPT control to voltage control, thereby suppressing the rise in system voltage.

[0154] (3-1) Third control circuit 404

[0155] Figure 10 This is an explanation Figure 7 The block diagram of the structure of the third control circuit 404 is shown.

[0156] like Figure 10 As shown, the third control circuit 404 includes a charging control circuit 71, a discharging control circuit 72, a second switching circuit 73, and a seventh control circuit 74.

[0157] When the charging control circuit 71 performs charging control of the battery 40, it generates control command values ​​for the second DC / DC converter 403.

[0158] When the discharge control circuit 72 performs discharge control of the battery 40, it generates control command values ​​for the second DC / DC converter 403.

[0159] The 7th control circuit 74 outputs control parameters and target values ​​to the charging control circuit 71 and the discharging control circuit 72. The 7th control circuit 74 manages the state of charge (SOC), charging current, and discharging current of the battery 40. The 7th control circuit 74 outputs control signals to the 2nd switching circuit 73.

[0160] The second switching circuit 73 selectively outputs either the output of the charging control circuit 71 or the discharging control circuit 72 as a control command value for the second DC / DC converter 403, based on the control signal from the seventh control circuit 74. Specifically, when the battery 40 is instructed to charge, the second switching circuit 73 outputs the control command value generated by the charging control circuit 71. On the other hand, when the battery 40 is instructed to discharge, the second switching circuit 73 outputs the control command value generated by the discharging control circuit 72.

[0161] (3-2) Fourth control circuit 409

[0162] Figure 11 This is an explanation Figure 7 The block diagram of the structure of the fourth control circuit 409 is shown.

[0163] like Figure 11 As shown, the fourth control circuit 409 includes an AC frequency detection circuit 81, an effective power calculation circuit 82, a virtual synchronous generator control circuit 83, an inverter current control circuit 84, an inverter voltage control circuit 85, a third switching circuit 86, an eighth control circuit 87, and a control parameter generation circuit 88.

[0164] AC frequency detection circuit 81 is derived from voltmeter 410 ( Figure 7 The waveform of the measured AC voltage is used to detect the phase of the AC voltage. In Embodiment 1, zero-crossing points are detected from the AC voltage waveform, and the frequency is detected from the time interval between the detected zero-crossing points. Furthermore, the method for detecting the frequency of the AC voltage is not limited to using the detection results of zero-crossing points.

[0165] The effective power calculation circuit 82 uses a voltmeter 410 and a current meter 411. Figure 7 The effective power is calculated using the measured AC voltage and AC current information. In Embodiment 1, the effective power is calculated by accumulating the power of one cycle of the AC voltage waveform based on the zero-crossing detection information and AC frequency information output from the AC frequency detection circuit 81. Furthermore, the method for calculating the effective power is not limited to the above method; for example, in the case of a three-phase AC system, the effective power can also be calculated using methods such as DQ conversion.

[0166] The virtual synchronous generator control circuit 83, based on the frequency information of the AC voltage output from the AC frequency detection circuit 81 and the AC effective power information output from the effective power calculation circuit 82, enables the second DC / AC converter 408 (static inverter) to possess the inertial force, synchronization force, and damping force of a synchronous generator.

[0167] Virtual Synchronous Generator Control Technology

[0168] The following is a brief explanation of virtual synchronous generator control technology.

[0169] Synchronous generators, which are typically used in thermal power generation, have functions such as adjusting the output power according to the frequency (speed governor function), maintaining angular velocity (inertial force), synchronizing with the system voltage (synchronization force), regulating the voltage of the base system (AVR function: Automatic Voltage Regulation function), and continuing to operate even when the AC system voltage drops instantaneously during a system accident.

[0170] In virtual synchronous generator control technology, the transient response of a static inverter is controlled to enable the static inverter to simulate the functions of a synchronous generator. Specifically, this includes simulating three functions: speed governor function, simulating a mass system model based on the swing equation (dynamic characteristics of rotating machinery), and AVR function.

[0171] In Implementation 1, the case where the speed governor function and the function of simulating a mass system model based on the swing equation are specifically described are explained in the second DC / AC converter 408. Figure 54 The diagram shown illustrates a concept diagram for explaining virtual synchronous generator control technology. Furthermore, the AVR function of the synchronous generator, which is primarily based on output voltage or reactive power command values ​​notified from the host system (CEMS31 in Embodiment 1), is not implemented in Embodiment 1. The governor function and the function of simulating a mass system model based on the swing equation will be explained in detail below.

[0172] First, let me explain the function of the speed controller.

[0173] Speed ​​governors in power plants control the output power of generators by regulating the output of gas turbines or steam turbines in thermal and nuclear power plants, and / or the guide vanes of water turbines in hydroelectric power plants. In an AC power system, when power demand exceeds power supply, the system voltage frequency decreases. By incorporating a drooping characteristic in the speed governor of a controllable thermal or hydroelectric generator, the generator is controlled to increase power generation when the system voltage frequency decreases. Conversely, when the system voltage frequency rises due to power supply exceeding demand, the generator is controlled to decrease power generation.

[0174] Figure 54 This is a diagram schematically illustrating the function of the speed controller. For example... Figure 54As shown, when the angular velocity ω of the synchronous generator increases, the valve adjusting the energy inflow moves to the right, thereby reducing the energy supplied to the synchronous generator. Conversely, when the angular velocity ω of the synchronous generator decreases, the valve moves to the left, thereby increasing the energy supplied to the synchronous generator. Thus, the energy output from the synchronous generator can be controlled individually based on the frequency of the system voltage at this terminal (i.e., the angular velocity ω of the synchronous generator). Even when the synchronous generators perform the above operations individually, the load can be shared among multiple synchronous generators because the operation is managed according to the frequency of the system voltage. Regarding the speed governor, the Electrical Engineering Society provides a model consisting of a primary delay system as a standard model.

[0175] In Implementation 1, the operation of the speed governor is described using the model composed of the above-described single-delay system as shown in Equation (1).

[0176] -1 / {Kgd×(1+s×Tg)}…(1)

[0177] In equation (1), -1 / Kgd is the proportional gain of the speed controller (Kgd: speed regulation rate), and Tg is the time constant of the primary delay system (Tg: speed controller time constant).

[0178] Next, we will explain the functionality of simulating a mass system model based on the rocking equation.

[0179] like Figure 54 As shown, the synchronous generator has a rotor with a unit inertia constant M. For example, in the event of a sharp decrease in the power generation of a megawatt-class solar power plant 26 due to a rapid change in solar radiation, the insufficient power cannot be supplied instantaneously under the speed governor control described above. The synchronous generator converts the rotational energy stored in the rotor into electricity and outputs it to the AC system. At this time, when the angular velocity (speed) of the rotor decreases, the energy supplied by the speed governor increases, thereby balancing the demand for electricity and the supply of electricity. The swing equation of the simulated mass system model (generator rotor) is shown in the following equation (2). The swing equation is a formula that converts the energy P by the angular velocity ω into torque T.

[0180] Tin-Tout=M×dω / dt+Dg×ω…(2)

[0181] Where Dg is the damping coefficient and M is the inertial constant.

[0182] In Embodiment 1, it is explained that by incorporating Equations (1) and (2) into the control of the static inverter (second DC / AC converter 408), the inertial force, synchronization force and damping force of the synchronous generator are simulated.

[0183] Return to Figure 11The inverter current control circuit 84 generates control command values ​​for current control of the second DC / AC converter 408. Furthermore, compared to... Figure 9 The current control circuit 60 shown is identical in circuit structure and operation, only differing in control parameters, so detailed descriptions are omitted.

[0184] The inverter voltage control circuit 85 generates control command values ​​for voltage control of the second DC / AC converter 408.

[0185] The third switching circuit 86 switches the control command value from the inverter current control circuit 84 and the control command value from the inverter voltage control circuit 85 according to the output of the eighth control circuit 87.

[0186] The 8th control circuit 87 collects measurement results related to the DC bus 405 measured by the voltmeter 406 and the ammeter 407, as well as the status information of the 2nd DC / DC converter 403 output from the 3rd control circuit 404, and notifies the CEMS 31 and the others of the collected information via the communication I / F 412.

[0187] In addition, the 8th control circuit 87 notifies the virtual synchronous generator control circuit 83, the inverter current control circuit 84, and the inverter voltage control circuit 85 of their respective control parameters.

[0188] Furthermore, the 8th control circuit 87 notifies the CEMS 31 of the effective voltage of the AC system measured by the AC system effective voltage measurement unit (not shown) or the active power and reactive power measured by the AC system active power / reactive power measurement unit (not shown) via communication I / F 412. The 8th control circuit 87 notifies the 7th control circuit 74 of the measurement results of the AC system's effective voltage, active power, etc.

[0189] (3-2-1) AC Frequency Detection Circuit 81

[0190] Figure 12 This is an explanation Figure 11 The block diagram of the AC frequency detection circuit 81 shown is shown.

[0191] like Figure 12 As shown, the AC frequency detection circuit 81 includes a phase detection circuit 810, a frequency detection circuit 811, and a second sine wave generation circuit 812.

[0192] The phase detection circuit 810 detects zero-crossing points from the waveform of the system voltage output by the voltmeter 410. The phase detection method in the phase detection circuit 810 is not limited to zero-crossing point detection. Regarding zero-crossing point detection in actual operation, errors occur due to the zero-crossing point detection error of the voltmeter 410 (mainly offset error), the amplitude detection error of the voltmeter 410 (mainly linearity error), and errors in the sampling period when sampling the system voltage waveform. Furthermore, when sampling using a microcomputer, errors in the sampling period may occur due to the deviation in time from carrier interruption to actual sampling.

[0193] The frequency detection circuit 811 detects the system frequency from the period of the zero-crossing point output by the phase detection circuit 810. Furthermore, the method for detecting the system frequency is not limited to the method of detecting from the period of the zero-crossing point.

[0194] The second sine wave generation circuit 812 generates a sine wave synchronized with the system voltage based on the zero-crossing point detection result in the phase detection circuit 810, the frequency detection result in the frequency detection circuit 811, and the amplitude of the system voltage output from the CEMS31. The AC frequency detection circuit 81 outputs the zero-crossing point detection result (the detection time of the zero-crossing point), the frequency detection result, and the sine wave information.

[0195] (3-2-2) Inverter voltage control circuit 85

[0196] Figure 13 This is an explanation Figure 11 The block diagram shown is of the structure of the inverter voltage control circuit 85.

[0197] like Figure 13 As shown, the inverter voltage control circuit 85 includes a third sine wave generation circuit 851, a subtractor 852, a third PI control circuit 853, a first current limiting circuit 855, and a second PWM converter 854.

[0198] Inverter voltage control circuit 85 controls the voltage from virtual synchronous generator control circuit 83. Figure 11 The frequency and phase information output from the 8th control circuit 87 ( Figure 11 The amplitude information of the output system voltage is used to generate control command values ​​for controlling the second DC / AC converter 408. In addition, the amplitude information of the system voltage from the eighth control circuit 87 is input to the inverter voltage control circuit 85 via the second sine wave generation circuit 812.

[0199] From AC frequency detection circuit 81 ( Figure 11The sine wave information (frequency, phase, and amplitude information) is input to the third sine wave generation circuit 851. However, in Embodiment 1, QV control is not performed in the virtual synchronous generator control circuit 83, so the amplitude information is not controlled.

[0200] The third sine wave generation circuit 851 generates the target value of the AC voltage output from the second DC / AC converter 408 based on the input sine wave information.

[0201] Subtractor 852 calculates the target value of the AC voltage from the third sine wave generation circuit 851 and the deviation of the voltage measured by voltmeter 410, and outputs the calculated deviation to the third PI control circuit 853.

[0202] The third PI control circuit 853 generates a voltage command value by performing PI (proportional-integral) calculations in a manner that makes the input deviation zero. The third PI control circuit 853 outputs the generated voltage command value to the first current limiting circuit 855.

[0203] The first current limiting circuit 855 applies a limit to the voltage command value output from the third PI control circuit 853 based on the measurement result of the ammeter 411 input via the eighth control circuit 87. Specifically, the first current limiting circuit 855 limits the voltage command value when a current exceeding the current capacity of the second DC / AC converter 408 flows, thereby controlling the current flowing in the second DC / AC converter 408 to a predetermined current value (e.g., the current capacity of the second DC / AC converter 408). The output of the first current limiting circuit 855 is input to the second PWM converter 854. Furthermore, the control parameters (control gain and integral time) in the third PI control circuit 853 and the first current limiting circuit 855 are provided from the eighth control circuit 87.

[0204] The second PWM converter 854 generates a control signal by performing PWM (Pulse Width Modulation) control using the voltage command value output from the first current limiting circuit 855. The second PWM converter 854 outputs the generated control signal to the second DC / AC converter 408.

[0205] (3-2-3) Virtual Synchronous Generator Control Circuit 83

[0206] Figure 14 This is an explanation Figure 11 The diagram shows the structure of the virtual synchronous generator control circuit 83.

[0207] like Figure 14As shown, the virtual synchronous generator control circuit 83 includes a subtractor 832, a speed governor control circuit 833, an adder 835, a subtractor 836, and a mass system calculation circuit 837.

[0208] Subtractor 832 calculates the deviation between the measured frequency and the reference frequency Fref output from control circuit 87. The output of subtractor 832 is input to speed controller control circuit 833. Speed ​​controller control circuit 833 generates an offset value to be added to the target power value based on the output of subtractor 832. The detailed operation of speed controller control circuit 833 will be described later.

[0209] Adder 835 generates the control power target value of quality system calculation circuit 837 by adding the offset value output from speed controller control circuit 833 and the power target value Pref input from 8th control circuit 87.

[0210] Subtractor 836 calculates the deviation between the effective power input from effective power calculation circuit 82 and the control power target value input from adder 835. The output of subtractor 836 is input to quality system calculation circuit 837.

[0211] The mass system calculation circuit 837 calculates the frequency and phase of the system voltage output from the power conversion device 41 in such a way that the deviation output from the subtractor 836 is zero. Furthermore, in Embodiment 1, the control parameters (speed regulation rate Kgd, governor time constant Tg, inertia constant M, and damping coefficient Dg) of the speed governor control circuit 833 and the mass system calculation circuit 837 are provided by the control parameter generation circuit 88 via the eighth control circuit 87.

[0212] (3-2-3-1) Speed ​​Regulator Control Circuit 833

[0213] Figure 15 This is an explanation Figure 14 The diagram shows the structure of the speed controller control circuit 833.

[0214] like Figure 15 As shown, the speed controller circuit 833 has a multiplier 91, a first-order delay system model 92, and a limiter circuit 93.

[0215] Multiplier 91 multiplies the output of subtractor 832 and the proportional gain (-1 / Kgd) output from the 8th control circuit 87. The output of multiplier 91 is input to the primary delay system model 92. In embodiment 1, the primary delay system model 92 implements the standard model of a primary delay system (1 / (1+s×Tg)) suggested by the Institute of Electrical Engineering. Limiter circuit 93 performs limiting processing on the output of primary delay system model 92.

[0216] (3-2-3-2) Mass System Operation Circuit 837

[0217] Figure 16 This is an explanation Figure 14 The block diagram shown is of the structure of the mass system operation circuit 837.

[0218] like Figure 16 As shown, the mass system operation circuit 837 includes a subtractor 101, an integrator 102, a multiplier 103, a divider 104, an adder 105, and a phase calculation circuit 106.

[0219] Subtractor 101 calculates the deviation between the output of subtractor 836 and the output of multiplier 103. The output of subtractor 101 is input to integrator 102.

[0220] Integrator 102 generates the product by integrating the output of subtractor 101 by a factor of 1 / M. Figure 54 The target angular velocity of the generator rotor (2 × π × target frequency (e.g., 60 Hz)) and the difference Δω between the generator rotor's angular velocity are shown. The output of integrator 102 is input to multiplier 103.

[0221] Multiplier 103 multiplies the output of integrator 102 and the damping coefficient Dg input from the 8th control circuit 87.

[0222] The mass system operation circuit 837 is configured to control the second DC / AC converter 408 based on the deviation between the output of the subtractor 836 and the output of the multiplier 103, thereby simulating the damping force of the synchronous generator.

[0223] Divider 104 transforms the output Δω of integrator 102 into a frequency difference value Δf by dividing it by 2×π. Adder 105 transforms the frequency difference information Δf into the frequency (rotation frequency) of the generator rotor by adding the target frequency (60Hz) to the frequency difference information Δf. The output of adder 105 is input to phase calculation circuit 106. Phase calculation circuit 106 calculates the phase of the generator rotor.

[0224] Next, the transfer function of the swing equation of the mass system operation circuit 837 will be explained. The transfer function of the swing equation is shown in equation (3) below, and can be expressed using the proportional gain (1 / Dg) and time constant (M / Dg) of the first-order delay system.

[0225] (1 / M×s) / {1+Dg / M×(1 / s)}

[0226] =(1 / Dg)×[1 / {1+(M / Dg)×s}…(3)

[0227] Furthermore, based on the required response speed of the system, the time constant Tg of the governor in the virtual synchronous generator control and the time constant M / Dg of the mass system calculation unit are determined.

[0228] (Operating Summary of Power Conversion Device)

[0229] Next, a summary of the operation of the power conversion device according to Embodiment 1 will be described.

[0230] Figure 17 This is a diagram showing the area covered by the control of a virtual synchronous generator installed in the power conversion device 41. Figure 17 The horizontal axis represents response time, and the vertical axis represents the magnitude of demand fluctuations.

[0231] like Figure 17 As shown, the virtual synchronous generator control installed on the static inverter covers minute fluctuations ranging from tens of milliseconds to a few minutes, as well as short-cycle fluctuations. For fluctuations larger than a few minutes, load frequency control (LFC) or economic load sharing control (EDC) can be used to address them. Therefore, in Embodiment 1, the response performance of the virtual synchronous generator control is described as less than 1 second.

[0232] In the following instructions, the following uses Figure 2 The model shown consists of a battery 40 connected to the power distribution system 24, a power conversion device 41, an impedance 29 of the power distribution system, and a load 600. For simplicity, the inverter capacity of the power conversion device 41 is set to 4kW, and the capacity of the load 600 is set to a maximum of 4kW.

[0233] Figure 18 This diagram illustrates the control of the virtual synchronous generator installed in the power conversion device 41 according to Embodiment 1. Figure 18 The image shows an example of the relationship between the speed regulation rate Kgd and the system frequency when the power consumption of a load of 600 is changed without altering the target power value. Figure 18 Shown in Figure 2 The system frequency under steady-state conditions at various speed regulation rates Kgd is calculated when the load 600 changes from 2kW to 4kW after the power target value is set to 2kW by CEMS31. Furthermore, the governor time constant Tg, inertia constant M, and damping coefficient Dg are each fixed to constant values.

[0234] exist Figure 18 In the example, the system frequency decreases as Kgd increases until it reaches 0.343. On the other hand, it is confirmed that the system frequency converges when Kgd exceeds 0.343.

[0235] Figure 19This diagram illustrates the control of the virtual synchronous generator installed in the power conversion device 41 according to Embodiment 1. Figure 19 The image shows an example of the relationship between the damping coefficient Dg and the system frequency when the load changes drastically. Figure 19 Shown in Figure 2 The system frequency under various damping coefficients Dg when the load is varied from 2kW to 4kW under the condition that the power target value is set to 2kW by CEMS31. Furthermore, the governor time constant Tg, inertia constant M, and speed regulation rate Kgd (=0.343) are each fixed to constant values. Figure 19 In the example, it was confirmed that as the damping coefficient Dg decreases, the decrease in system frequency becomes greater.

[0236] Generally, the system frequency limits (upper and lower limits) are set at ±1 to 2% of the reference frequency (hereinafter referred to as Fref). Therefore, with a reference frequency Fref of 60Hz, the upper limit of the system frequency is approximately 61.2 to 60.6Hz, and the lower limit is approximately 59.4 to 58.8Hz. Thus, the speed regulation rate Kgd and damping coefficient Dg of the speed controller need to be set to ensure that the system frequency converges within the frequency range determined by the aforementioned limits.

[0237] Next, the ΔF / ΔP characteristics will be explained.

[0238] Figure 20 This is a graph illustrating an example of the ΔF / ΔP characteristics. Figure 20 The horizontal axis represents the deviation of the actual output power of the power conversion device 41 from the target power value, i.e., the differential power ΔP. Regarding the differential power ΔP, the case where the output power of the power conversion device 41 is greater than the target power value is defined as positive.

[0239] Figure 20 The vertical axis represents the deviation of the frequency of the AC voltage output by the power converter 41 from the reference frequency Fref of the AC system (e.g., 60Hz), i.e., the differential frequency ΔF. Regarding the differential frequency ΔF, the case where the frequency of the AC voltage output by the power converter 41 is higher than the reference frequency Fref is defined as positive. ΔFmax is the maximum value of the differential frequency ΔF.

[0240] In the virtual synchronous generator control circuit 83 involved in implementation method 1 ( Figure 8 )middle, Figure 20 The ΔF / ΔP characteristics shown are determined by the capacity, speed regulation rate Kgd, and damping coefficient Dg of the static inverter (second DC / AC converter 408). Furthermore, in Figure 20 Without considering the charging of battery 40, the power target value is set to half the capacity of the static inverter (second DC / AC converter 408). Figure 20 Showing will be Figure 2 The ΔF / ΔP characteristic is defined as follows: the system frequency when the power consumption of the medium load 600 is the same as the capacity of the static inverter (second DC / AC converter 408) is taken as the upper limit (Fref+ΔFmax), and the system frequency when the power consumption of the load 600 is zero is taken as the lower limit (Fref-ΔFmax).

[0241] In implementation method 1, Figure 20 The ΔF / ΔP characteristic shown is called the "reference ΔF / ΔP characteristic". As mentioned above, the reference ΔF / ΔP characteristic is the ΔF / ΔP characteristic under the following conditions in the discharge mode of battery 40: half the capacity of the static inverter is taken as the power target value; the system frequency reaches the upper limit (Fref + ΔFmax) when the output of the static inverter is consistent with the capacity; and the system frequency reaches the lower limit (Fref - ΔFmax) when the output of the static inverter is zero. Further details regarding the discharge mode will be described later.

[0242] Figure 21 This is a diagram showing the frequency response waveform of the AC voltage output from the static inverter when the load changes drastically in the virtual synchronous generator control of the power conversion device 41 installed in Embodiment 1.

[0243] As in Figure 17 The text explains that the virtual synchronous generator control installed on the static inverter covers minute vibrations and short-period variations ranging from tens of milliseconds to several minutes. Therefore, a response time of less than one second is required in the virtual synchronous generator control. Generally, reducing the time constant improves the response performance, but it also introduces vibrations into the response waveform. Furthermore, in the case of multiple distributed power sources operating collaboratively, problems such as unnecessary circulating currents may occur. Therefore, in Implementation 1, as... Figure 21 As shown, the speed controller control circuit 833 is determined in such a way that the system frequency converges in a 1-second manner. Figure 15 ) and the quality system operation circuit 837 ( Figure 16 The time constant in ).

[0244] (Previous Virtual Synchronous Generator Control and Its Problems)

[0245] Next, we will explain the problem of configuring two power conversion devices 41, which are equipped with conventional virtual synchronous generator control, into the power distribution system 24.

[0246] Figure 22 It is a diagram showing the response waveform of the effective value of the AC power output from the static inverters of two power conversion devices 41, each equipped with conventional virtual synchronous generator control. Figure 22The response waveforms shown indicate the actual values ​​of the AC power output from each static inverter when using two power conversion devices 41 to form an independent system and subjecting the load to rapid changes.

[0247] exist Figure 22 In this diagram, the inverter capacity of each power conversion device 41 is set to 4kW, and the load power consumption is set to 3.3kW. The target power value of the first battery (represented as "BAT1" in the diagram) corresponding to the first power conversion device 41 is set to 2.2kW, and the target power value of the second battery (represented as "BAT2" in the diagram) corresponding to the second power conversion device 41 is set to 1.1kW. The first and second power conversion devices 41 are controlled. It is envisioned that under these conditions, the load power consumption changes drastically by approximately half (1.65kW) in about 5 seconds.

[0248] like Figure 22 As shown, until the load changes drastically, the power output from the first power conversion device 41 is close to the target power value (2.2kW), and the power output from the second power conversion device 41 is close to the target power value (1.1kW), with the power ratio between the two being 2:1.

[0249] On the other hand, after a sharp change in load, the output power of the first power conversion device 41 becomes 1.35kW, and the output power of the second power conversion device 41 becomes 0.3kW, with a power ratio of 9:2. It can be seen that after such a sharp change in load, the two power conversion devices 41 output power at a ratio (9:2) that is different from the intended power sharing ratio (2:1).

[0250] Figure 23 The diagram shows the frequency response waveforms of the AC voltage output from each static inverter when two power conversion units 41, equipped with conventional virtual synchronous generator control, are operated under the above conditions. For example... Figure 23 As shown, even after a sharp change in load, the frequency of the AC voltage converges to approximately the same frequency through virtual synchronous generator control.

[0251] Next, use Figure 24 as well as Figure 25 This explains why the power allocation ratio changes when the load changes drastically.

[0252] Figure 24 This is a diagram illustrating an example of the ΔF / ΔP characteristics of a first power conversion device 41 equipped with conventional virtual synchronous generator control. Figure 25 This is a diagram illustrating an example of the ΔF / ΔP characteristics of a second power conversion device 41 equipped with conventional virtual synchronous generator control.

[0253] In previous virtual synchronous generator control, the ΔF / ΔP characteristics were not switched based on the target power value and the capacity of the static inverter. Figure 24 as well as Figure 25 In the example, the two power conversion devices 41 have the same static inverter capacity (4kW), so they provide the same ΔF / ΔP characteristics.

[0254] In such Figure 22 In the event of a sudden load change, the virtual synchronous generator control installed in each power conversion unit 41 operates to share the excess or insufficient power between the two power conversion units 41. At this time, as shown... Figure 23 As shown, two power conversion devices 41 are controlled in such a way that the frequencies of the AC voltages output from the static inverters are equal.

[0255] On the other hand, the differential power ΔP between the power output from each power conversion device 41 and the target power value is determined by... Figure 24 as well as Figure 25 The ΔF / ΔP characteristics shown indicate that the differential frequency ΔF is the same, and therefore the differential power ΔP will also be the same, as indicated by the diagram. Figure 22 As shown, after a sharp change in load, power is output from the two power conversion devices 41 at a different power sharing ratio than the intended power sharing ratio.

[0256] (Virtual synchronous generator control as described in Implementation Method 1)

[0257] Figure 26 This is a diagram illustrating an example of the ΔF / ΔP characteristics of a second power conversion device 41 equipped with the virtual generator control according to Embodiment 1. The solid line in the diagram represents the ΔF / ΔP characteristics of the second power conversion device 41, and the dashed line represents the ΔF / ΔP characteristics of the first power conversion device 41. Figure 24 ).

[0258] like Figure 22 As shown, when the power target value of the second power conversion device 41 (1.1kW) is half of the power target value of the first power conversion device 41 (2.2kW) (i.e., the power sharing ratio is 2:1), as follows: Figure 26 As shown, the ΔF / ΔP characteristic of the second power conversion device 41 is determined in such a way that the ratio of the differential power ΔP (ΔP1 in the figure) of the first power conversion device 41 to the differential power ΔP (ΔP2 in the figure) of the second power conversion device 41 is equal to the ratio (2:1) of the power target value at the same differential frequency ΔF.

[0259] It can be seen that through such Figure 26The diagram shows the ΔF / ΔP characteristics of the two power conversion devices 41. Even under load variations, the ratio of the power shared by each power conversion device 41 is equal to the ratio of the power target value notified from CEMS31 (2:1).

[0260] (Method for creating ΔF / ΔP characteristics)

[0261] Next, the method for fabricating the ΔF / ΔP characteristics of each power conversion device 41 in CEMS31 will be explained.

[0262] In Embodiment 1, when creating the ΔF / ΔP characteristics of each power conversion device 41, the CEMS 31 first creates a reference ΔF / ΔP characteristic for each power conversion device 41. In the following description, the method for creating the reference ΔF / ΔP characteristic is limited to the discharge of the battery 40.

[0263] The battery 40 has three operating modes: a discharge mode for discharging the battery 40, a charging mode for charging the battery 40, and a charge / discharge mode for charging and discharging the battery 40. When the battery 40 is operated in discharge mode or charging mode, a reference ΔF / ΔP characteristic is created such that the differential power ΔP corresponding to the differential power limit ΔFmax, which is the differential frequency ΔF, is half the capacity of the static inverter.

[0264] On the other hand, when the battery 40 operates in charge / discharge mode (especially when the power target value is close to zero), a reference ΔF / ΔP characteristic is created so that the differential power ΔP corresponding to ΔFmax is equal to the capacity of the static inverter.

[0265] Furthermore, CEMS31 needs to generate reference ΔF / ΔP characteristics for multiple power conversion devices 41 under the same strategy. Therefore, CEMS31 generates reference ΔF / ΔP characteristics in the first power conversion device 41 considering charging and discharging modes, while in the second power conversion device 41, reference ΔF / ΔP characteristics are generated without considering either charging or discharging modes.

[0266] Figure 27 This is a diagram illustrating an example of the reference ΔF / ΔP characteristics in a power conversion device 41 equipped with the virtual synchronous generator control according to Embodiment 1.

[0267] In Implementation 1, CEMS31 generates a reference ΔF / ΔP characteristic based on information from DSO21 relating to the system frequency limit (Fref±ΔFmax) and information relating to the capacity of the static inverter.

[0268] Specifically, considering only the discharge mode, the power target value Pref is set to half the capacity of the static inverter. The reference ΔF / ΔP characteristic is created so that the system frequency is at the lower limit (Fref-ΔFmax) when the power conversion device 41 outputs power equal to the capacity of the static inverter, and at the upper limit (Fref+ΔFmax) when the output of the static inverter is zero.

[0269] Furthermore, considering only the charging mode, if the charging power is treated as a negative value, and the system frequency is set to the lower limit (Fref-ΔFmax) when the charging power is zero, and the system frequency is set to the upper limit (Fref+Δfmax) when the charging power is equal to the capacity of the static inverter, the same effect can be achieved by creating a reference ΔF / ΔP characteristic.

[0270] Furthermore, considering the charging and discharging modes, if the power target value Pref is set to zero, and the system frequency is set to the lower limit (Fref-ΔFmax) when discharging with the same power as the static inverter, and the system frequency is set to the upper limit (Fref+ΔFmax) when charging with the same power as the static inverter, the same effect can be achieved by creating the reference ΔF / ΔP characteristic.

[0271] Next, use Figure 28 Instructions for use Figure 27 The method for manufacturing the reference ΔF / ΔP characteristics and the ΔF / ΔP characteristics of each power conversion device 41.

[0272] Furthermore, in the following description, the capacity of the static inverter in each power conversion device 41 is set to be the same. Figure 28 The middle section explains the use of Figure 27 The diagram illustrates the baseline ΔF / ΔP characteristic and the method for generating the ΔF / ΔP characteristic when the target power value differs from the baseline ΔF / ΔP characteristic (half the capacity of the static inverter). The dashed line in the diagram represents the baseline ΔF / ΔP characteristic (…). Figure 27 The solid line represents the ΔF / ΔP characteristic.

[0273] When the capacity of the static inverter is the same, in Embodiment 1, the slope of the ΔF / ΔP characteristic (solid line in the figure) is obtained by multiplying the slope of the reference ΔF / ΔP characteristic (dashed line in the figure) by dividing half (0.5 times) of the static inverter capacity by the power target value Pref of the power conversion device 41. For example, when the power target value Pref is 0.25 times the capacity of the static inverter, the slope of the ΔF / ΔP characteristic is obtained by multiplying the slope of the reference ΔF / ΔP characteristic by 0.5 / 0.25 (=2).

[0274] Next, we will explain the case where the capacities of the static inverters in each power conversion device 41 are different. In this case, the method for manufacturing the reference ΔF / ΔP characteristics of each power conversion device 41 is different from the method described above.

[0275] When the capacities of static inverters differ among multiple power conversion devices 41, a reference static inverter capacity is predetermined. For example, if the capacities of three static inverters are set to 10kW, 8kW, and 4kW, 8kW is used as the reference. Furthermore, it is generally acceptable to choose any capacity as the reference. Moreover, when used in… Figure 27 The manufacturing method described herein is used to produce a reference ΔF / ΔP characteristic for a static inverter with a reference capacity (8kW).

[0276] Next, using the reference ΔF / ΔP characteristics of a static inverter with a reference capacity of 8kW, the reference ΔF / ΔP characteristics of a static inverter with a capacity of 4kW are generated. Figure 29 This diagram illustrates the fabrication method of the reference ΔF / ΔP characteristics for a 4kW static inverter. The dashed line in the diagram represents the reference ΔF / ΔP characteristics of the static inverter with the reference capacity. Figure 27 The solid line represents the reference ΔF / ΔP characteristic of a 4kW static inverter.

[0277] like Figure 29 As shown, the slope of the reference ΔF / ΔP characteristic is obtained by multiplying the slope of the reference ΔF / ΔP characteristic for the reference capacity (8kW) by the value obtained by dividing the reference capacity (8kW) by the capacity of the static inverter (4kW). Specifically, the slope of the reference ΔF / ΔP characteristic for the 4kW static inverter is calculated by multiplying the slope of the reference ΔF / ΔP characteristic for the reference capacity (8kW) static inverter by 8 / 4 (=2). Similarly, the slope of the straight line of the reference ΔF / ΔP characteristic for the 10kW static inverter is calculated by multiplying the slope of the reference ΔF / ΔP characteristic for the reference capacity (8kW) static inverter by 8 / 10 (=0.8).

[0278] Figure 30 This is a diagram illustrating an example of the reference ΔF / ΔP characteristics and ΔF / ΔP characteristics of two power conversion units 41 with different capacities from a static inverter. Figure 30 In the diagram, dashed line L1 represents the reference ΔF / ΔP characteristic of the first power conversion device 41, and solid line L2 represents the ΔF / ΔP characteristic of the first power conversion device 41. Dashed line L3 represents the reference ΔF / ΔP characteristic of the second power conversion device 41, and solid line L4 represents the ΔF / ΔP characteristic of the second power conversion device 41.

[0279] exist Figure 30 In the example, in the first power conversion unit 41, the capacity of the static inverter is 8kW, and the target power value is 6kW. In the second power conversion unit 41, the capacity of the static inverter is 4kW, and the target power value is 1kW.

[0280] Figure 31 It shows from Figure 30 The diagram shows the waveforms of the actual AC power output from the two power conversion devices 41. Figure 31 The waveform is based on the virtual synchronous generator control circuit 83. Figure 30 The control parameters (Tg, Kgd, M, and Dg) generated by the ΔF / ΔP characteristics (solid lines L2 and L4 in the figure) of the two power conversion devices 41 shown cause the first and second power conversion devices 41 to operate.

[0281] exist Figure 31 The image shows the waveforms of the actual AC power output from each power conversion unit 41 when the load changes drastically from 3kW to 5.25kW. Figure 31 As shown, before and after a sudden change in load, the power sharing ratio of the first and second power conversion devices 41 is 2:1, operating as intended.

[0282] As explained above, when multiple power conversion devices 41 equipped with static inverters that control virtual synchronous generators are connected to the power distribution system 24, a ΔF / ΔP characteristic is generated for each power conversion device 41 based on the capacity of the static inverter and the target power value. Furthermore, for each power conversion device 41, a virtual synchronous generator control circuit 83 is generated using the ΔF / ΔP characteristic. Figure 11 ) control parameters.

[0283] By adopting such a structure, even under drastic changes in the power consumption of a load of 600 or the power generated by a megawatt-class solar power plant 26, the ratio of the power output from each power conversion device 41 can be equal to the ratio of the power target value notified from the CEMS 31. Thus, for example, it is possible to prevent the proportion of the discharge power of the battery 40, which has a low discharge power setting due to a low SOC, from increasing in the total discharge power.

[0284] Furthermore, in Embodiment 1, as a method for generating the ΔF / ΔP characteristics, a method for generating a reference ΔF / ΔP characteristic for each power conversion device 41 is described, and a method for generating the ΔF / ΔP characteristic based on the power target value using the generated reference ΔF / ΔP characteristic is described, but it is not limited to this. For example, it may also be configured to directly generate the control parameters (Tg, Kgd, M, Dg) of the virtual synchronous generator control circuit 83 based on the capacity of the static inverter, the power target value, and the SOC information of the battery 40.

[0285] (Operation of the power conversion device)

[0286] Next, use Figures 1 to 41 The operation of the power conversion device involved in Embodiment 1 is described in detail.

[0287] First refer to Figure 1 This describes the power distribution system 24 of the power conversion device involved in Implementation Method 1.

[0288] In Implementation 1, in the power distribution system 24, in order to control the system voltage supplied from the substation 20 to a predetermined voltage range, a plurality of SVR23 are connected in series between the substation 20 and the power conversion device 27 (or power conversion device 41a or town 100a).

[0289] The power conversion device 27 operates as a current source. A power conversion device 41a is installed near the power conversion device 27. In Embodiment 1, the power conversion device 41a operates as a voltage source. The power conversion device 41a can also smooth the generated power of the megawatt-class solar power plant 26 by performing virtual synchronous generator control.

[0290] The loads include towns 100a-100d, factories 110, buildings 112, and apartments 113. Power is supplied to the loads from substation 20, megawatt-class solar power station 26, and storage batteries 40. Emergency synchronous generators are installed in the factories and buildings.

[0291] Here, the operation of the distributed power system in the power distribution system 24, which receives power from the substation 20, the generated power from the megawatt-class solar power station 26, and the discharged power from the battery 40, is explained.

[0292] Figure 32 It is used to explain Figure 1 The diagram shows the typical operation of a distributed power system centered on CEMS31.

[0293] like Figure 32As shown, the steady-state processing consists of a process implemented at 30-minute intervals (hereinafter referred to as "process 1") and a process implemented at 5-minute intervals (hereinafter referred to as "process 2").

[0294] After the first processing (30-minute cycle processing) begins, DSO21 requests the output of measurement data collected by CEMS31 via communication line 25. Upon receiving the request from DSO21, CEMS31 sends measurement data to DSO21, including the power consumption of each consumer, the power generation of the megawatt-class solar power station 26, the charging and discharging power of the battery 40, and the SOC (State of Charge).

[0295] Upon receiving measurement data, DSO21 generates an operation plan for distribution system 24 based on the measurement data and notifies CEMS31 of the generated operation plan. The operation plan for distribution system 24 includes the power supply plan from substation 20 to distribution system 24, which is necessary for generating the operation plan (charge and discharge plan) for battery 40. DSO21 generates a 24-hour quantity for the 30-minute cycle power supply plan. The 30-minute cycle power supply plan represents the total power supplied from substation 20 to distribution system 24 over 30 minutes.

[0296] When CEMS31 receives the operation plan (power supply plan) from DSO21, it requests the power conversion unit 41 to send measurement data. The measurement data includes the charge / discharge capacity of the battery 40 over the most recent 5 minutes, as well as SOC information. Upon receiving the request from CEMS31, the power conversion unit 41 notifies CEMS31 of the measurement data.

[0297] CEMS31 receives measurement data from all power conversion devices 41a to 41c connected to the power distribution system 24. At this time, CEMS31 also collects measurement data such as the power consumption of each consumer over 30 minutes and the power generation of the megawatt-class solar power station 26.

[0298] After the measurement data is collected, CEMS31 generates the operation plan and control parameters for battery 40. The operation plan for battery 40 is the charging and discharging plan for battery 40, including the target values ​​of the charging and discharging power of battery 40 (power target values). The method for generating the operation plan and control parameters for battery 40 will be described later.

[0299] After the operation plan and control parameters of the storage battery 40 are completed, the CEMS31 notifies each power conversion device 41 of the corresponding operation plan and control parameters of the storage battery 40, and ends the first process.

[0300] Next, CEMS31 performs the second processing (5-minute cycle processing). CEMS31 collects measurement data from each power conversion device 41 every 5 minutes. Based on the collected measurement data, CEMS31 detects the deviation between the target power value and the actual charging and discharging power. If the deviation exceeds a predetermined threshold, CEMS31 recalculates the operating plan (target power value) for the battery 40 and notifies each power conversion device 41 of the recalculation result. The specific recalculation method will be described later.

[0301] (CEMS31's actions)

[0302] Next, use Figure 33 This section describes the detailed operation of CEMS31.

[0303] Figure 33 It is shown Figure 1 The flowchart shown is for the control processing of CEMS31. Figure 33 As shown, after processing begins, in step (hereinafter referred to as S)01, CEMS31 checks whether an output request for measurement data has been received from DSO21. If an output request is received ("Yes" in S01), CEMS31 collects measurement data from multiple power conversion devices 41 via S02. CEMS31 then notifies DSO21 of the measurement data stored in the storage circuit 12 via the communication circuit 11 via S03.

[0304] On the other hand, if no output request is received from DSO21 ("No" in S01) or if measurement data has been sent to DSO21 in S03, CEMS31 proceeds to S04 to confirm whether an operation plan (power supply plan) has been received from DSO21. If an operation plan has been received ("Yes" in S04), CEMS31 proceeds to S05 to create an operation plan (charge and discharge plan) for battery 40.

[0305] Figure 34 This illustrates the process of manufacturing the storage battery 40. Figure 33 The flowchart of S05).

[0306] like Figure 34 As shown, after the processing begins, the power generation capacity of the megawatt-class solar power plant 26 is predicted using S051CEMS31. Specifically, returning to... Figure 3 as well as Figure 4 Upon receiving the operation plan from DSO21, control circuit 16 ( Figure 3 The second management circuit 146 within the instruction operation plan production circuit 14 ( Figure 4The second management circuit 146, upon receiving an instruction from the control circuit 16, instructs the power generation prediction circuit 142 via the battery operation plan creation circuit 141 to predict the power generation of the megawatt-class solar power plant 26.

[0307] When the power generation forecasting circuit 142 receives an instruction from the second management circuit 146, it obtains a 24-hour weather forecast (from the present to 24 hours in advance) by accessing a weather forecast server configured on the Internet (not shown). Using the obtained 24-hour weather forecast and data stored in a power generation forecasting database (not shown) managed by the power generation forecasting circuit 142, the power generation forecasting circuit 142 forecasts the power generation capacity (from the present to 24 hours in advance). Furthermore, it constructs a power generation forecasting database based on actual power generation data of the megawatt-class solar power plant 26 collected at 30-minute intervals and weather data. The method for constructing the database is omitted.

[0308] After predicting the generated power in S051, CEMS31 predicts the consumer's power consumption via S052. Specifically, it returns to... Figure 4 When the second management circuit 146 receives the power generation prediction result of the megawatt-level solar power station 26 from the power generation prediction circuit 142, it instructs the power consumption prediction circuit 143 to predict the power consumption of consumers via the battery operation plan making circuit 141.

[0309] When the power consumption prediction circuit 143 receives an instruction from the second management circuit 146, it uses data from a power consumption prediction database (not shown) managed by the power consumption prediction circuit 143 to predict the power consumption of consumers for the next 24 hours, from the present to 24 hours later. Furthermore, the power consumption prediction database is constructed by processing consumer power consumption data collected in 30-minute cycles based on date, time, and weather information. The method for constructing the database is omitted.

[0310] After predicting the consumer's power consumption in S052, CEMS31 generates a demand plan via S053. Specifically, it returns to... Figure 4 When the power consumption prediction circuit 143 receives the predicted power consumption of the consumer, the battery operation plan making circuit 141 calculates the total charge and discharge power of batteries 40a to 40c for every 30 minutes based on the predicted power generation of the megawatt-class solar power station 26 predicted by the power generation prediction circuit 142, the predicted power consumption of the consumer predicted by the power consumption prediction circuit 143, and the operation plan (power supply plan for every 30 minutes) notified from DSO21.

[0311] After creating the demand plan in S053, CEMS31 specifies the charging and discharging power (target power value) of battery 40a to 40c in S054. Specifically, returning to... Figure 3 as well as Figure 4 The battery operation planning circuit 141 allocates the charging and discharging power of each battery 40 for every 30 minutes based on the SOC information of batteries 40a to 40c and the battery capacity collected by the storage circuit 12 via the communication circuit 11.

[0312] In Implementation 1, when making an operation plan for the 24-hour storage battery 40, CEMS 31 sets the charging and discharging power of each storage battery 40 in such a way that the SOC of the storage batteries 40a to 40c simultaneously becomes zero or that the storage batteries 40a to 40c are approximately simultaneously fully charged when they are in charging mode.

[0313] This is based on the following reasons. For example, it is conceivable that due to cloud cover above the megawatt-class solar power plant 26, the power generation of the megawatt-class solar power plant 26 decreases from 10MW to 4MW in 5 minutes. Furthermore, the capacities of the static inverters of the power conversion devices 41a to 41c are set to 8MW, 4MW, and 2MW, respectively.

[0314] Here, the SOC of battery 40a first reaches zero and stops discharging, thereby notifying the power conversion devices 41b and 41c of the battery operation plan by discharging 1MW and 0.5MW respectively from the remaining batteries 40b and 40c. In the event that the power generation of the megawatt-class solar power station 26 decreases by 6MW due to a sharp change in solar radiation, the discharge power from batteries 40b and 40c, controlled by the virtual synchronous generator, can only additionally output 3MW and 1.5MW respectively, thus failing to compensate for the insufficient 6MW.

[0315] On the other hand, when batteries 40a to 40c are operating, they can discharge up to a maximum of 14MW (=8MW+4MW+2MW), thus expanding the range of power compensation controlled by the virtual synchronous generator. Therefore, when creating an operation plan (charge and discharge plan) for battery 40 in CEMS31, the operation plan needs to be created in a way that makes the SOC of batteries 40a to 40c approximately zero or fully charged at the same time.

[0316] After setting the charging and discharging power (target power value) for batteries 40a to 40c in S054, CEMS31 confirms in S055 whether the information required for generating the control parameters for virtual generator control has been generated for all batteries 40a to 40c. If the generation of information for all batteries 40a to 40c has not yet been completed (in S055, "No"), CEMS31 proceeds to S056 to generate the information required for generating the control parameters for virtual generator control.

[0317] Figure 35 This describes the processing of information required to generate the control parameters for the virtual synchronous generator control. Figure 34 The flowchart of S056). The control parameter generation circuit 13 within CEMS31 ( Figure 5 ),implement Figure 35 The processing shown.

[0318] like Figure 35 As shown, after processing begins, control circuit 136 ( Figure 5 Collected via S0561 Figure 34 In S054, the battery operation plan generation circuit 141 generates the target power value of the battery 40 for the next 30 minutes, the capacity of the second DC / AC converter 408 (static inverter) within the power conversion device 41, and information related to the power distribution system 24. Furthermore, the information related to the power distribution system 24 includes the upper and lower limits of the system frequency and the virtual synchronous generator control circuit 83 (…). Figure 11 The upper limit of the system frequency is the reference frequency Fref (e.g., 60Hz) + ΔFmax, and the lower limit of the system frequency is Fref - ΔFmax.

[0319] After information collection is completed in S0561, the reference ΔF / ΔP characteristic calculation circuit 131 calculates the reference ΔF / ΔP characteristic for each power conversion device 41 in S0562. The reference ΔF / ΔP characteristic is explained below.

[0320] When generating control parameters for a power conversion device 41 equipped with virtual synchronous generator control, the reference ΔF / ΔP characteristic of the static inverter is first calculated. Furthermore, while the structure for generating control parameters for the power conversion device 41 is described in Embodiment 1, the same method can be used to generate control parameters for examples where virtual synchronous generator control is installed in power conversion devices capable of adjusting output, such as wind power generation devices.

[0321] Specifically, the reference ΔF / ΔP characteristic calculation circuit 131 ( Figure 5 )like Figure 27As shown, in the discharge mode of battery 40, half the capacity of the static inverter is used as the power target value so that the frequency of the AC voltage when the static inverter discharges to its maximum power is equal to the lower limit frequency (in Figure 27 The differential frequency ΔF = -ΔFmax), and the frequency of the AC voltage at which the discharge power of the static inverter is zero is equal to the upper limit frequency (in Figure 27 The baseline ΔF / ΔP characteristic is determined by the method of ΔF = ΔFmax.

[0322] On the other hand, in the charging mode of battery 40, half of the capacity of the static inverter is used as the power target value, so that the frequency of the AC voltage when the static inverter is charged to the maximum power is the upper limit frequency (ΔF=ΔFmax), and the frequency of the AC voltage when the static inverter is charged to zero is equal to the lower limit frequency (ΔF=-ΔFmax), thus determining the reference ΔF / ΔP characteristic.

[0323] In addition, during the charging and discharging mode of the battery 40, the power target value of the static inverter is set to zero, so that the frequency of the AC voltage when the static inverter discharges to its maximum power is equal to the lower limit frequency (ΔF=-ΔFmax) and the frequency of the AC voltage when the static inverter is charged to its maximum power is equal to the upper limit frequency (ΔF=ΔFmax), thus determining the reference ΔF / ΔP characteristic.

[0324] Figure 36 This illustrates the process for generating the baseline ΔF / ΔP characteristics. Figure 35 The flowchart of S0562).

[0325] like Figure 36 As shown, after the processing begins, the reference ΔF / ΔP characteristic calculation circuit 131 is used via S05621. Figure 5 The capacity information (Cinv) of the static inverter that is the target is collected from the control circuit 136.

[0326] When the capacity information of the static inverter is collected, the reference ΔF / ΔP characteristic calculation circuit 131 collects system information (ΔFmax) via S05622. Next, the reference ΔF / ΔP characteristic calculation circuit 131 calculates the slope of the reference ΔF / ΔP characteristic using the inverter capacity Cinv and ΔFmax via S05623.

[0327] Specifically, when the battery 40 is in charging or discharging mode, the reference ΔF / ΔP characteristic calculation circuit 131 sets the slope of the reference ΔF / ΔP characteristic to -ΔFmax / (Cinv×0.5). On the other hand, when the battery 40 is in charging or discharging mode, the slope of the reference ΔF / ΔP characteristic is set to -ΔFmax / Cinv.

[0328] Furthermore, regarding the reference ΔF / ΔP characteristics for which discharge mode (or charging mode) and charge / discharge mode are used, the battery operation planning circuit 141 ( Figure 4 According to Figure 34 The battery operation plan generation circuit 141 determines the charging and discharging power of the battery 40 in the demand plan generated in S053. Specifically, if the absolute value of the generated charging and discharging power is less than a predetermined value, the battery operation plan generation circuit 141 adopts a charging and discharging mode. Furthermore, the adopted mode is applied to all power conversion devices 41 connected to the power distribution system 24.

[0329] Return to Figure 35 After calculating the baseline ΔF / ΔP characteristic in S0562, the ΔF / ΔP characteristic calculation circuit 132 is then used in S0563. Figure 5 The ΔF / ΔP characteristic is generated. Specifically, the reference ΔF / ΔP characteristic calculation circuit 131 outputs the slope of the generated reference ΔF / ΔP characteristic to the control circuit 136 and the ΔF / ΔP characteristic calculation circuit 132.

[0330] The ΔF / ΔP characteristic calculation circuit 132 calculates the ΔF / ΔP characteristic based on the power target value provided by the control circuit 136. Figure 37 This illustrates the process for generating the ΔF / ΔP characteristics. Figure 35 The flowchart of S0563). Figure 37 As shown, after processing begins, the ΔF / ΔP characteristic calculation circuit 132 collects the power target value Pref from the control circuit 136 via S05631. The ΔF / ΔP characteristic calculation circuit 132 then determines via S05632 whether the collected power target value Pref does not exceed the static inverter capacity Cinv.

[0331] If the power target value Pref exceeds the static inverter capacity Cinv ("No" in S05632), the ΔF / ΔP characteristic calculation circuit 132 in S05633 limits the power target value Pref to the static inverter capacity Cinv through a limiter.

[0332] The ΔF / ΔP characteristic calculation circuit 132 calculates the slope of the ΔF / ΔP characteristic using the power target value Pref via S05634. Specifically, when the battery 40 is in discharge or charging mode, the slope of the ΔF / ΔP characteristic is set to the slope of the reference ΔF / ΔP characteristic × (Cinv × 0.5) / Pref. On the other hand, when the battery 40 is in charge / discharge mode, assuming the absorption of power fluctuations from a megawatt-level solar power plant 26 or renewable energy sources such as wind power (power target value is zero), the ΔF / ΔP characteristic, which depends only on the capacity of the static inverter, is used as is. Figure 35 The baseline ΔF / ΔP characteristic is obtained in S0562. In Implementation 1, the slope of the ΔF / ΔP characteristic, system information (±ΔFmax, etc.), and the power target value Pref are used to explain the information required for generating the control parameters for virtual synchronous generator control.

[0333] In passing Figure 35 After generating the ΔF / ΔP characteristics in S0563, return to Figure 34 In step S055, the control parameter generation circuit 13 checks whether the calculation of the information required for generating control parameters for all power conversion devices 41 connected to the power distribution system 24 has been completed. If the calculation of this information for all power conversion devices 41 has not been completed ("No" in S055), the circuit calculates the information required for generating control parameters for the next power conversion device 41. If the calculation of this information for all power conversion devices 41 has been completed ("Yes" in S055), the control parameter generation circuit 13 ends the process of creating the operation plan for the battery 40. Figure 33 (S05).

[0334] In passing Figure 33 After the processing of the operation plan of battery 40 is completed, the battery operation plan production circuit 141 (S05) Figure 4 The generated operation plan (power target value) is notified to the first management circuit 145 via the second management circuit 146. Figure 4 Upon receiving an operation plan, the first management circuit 145 stores the received operation plan in its memory and notifies the data generation circuit 15. Figure 3 The control parameter generation circuit 13 notifies the data transmission generation circuit 15 of the generated information.

[0335] After obtaining the operating plan (power target value) and control parameters required for the generation of the battery 40, the data generation circuit 15 processes them into a transmission format and outputs them to the communication circuit 11. Figure 3When the communication circuit 11 receives the transmission data from the transmission data generation circuit 15, it transmits the transmission data to the corresponding power conversion device 41 via the communication line 25.

[0336] exist Figure 33 In S10, after sending the information required for generating the operation plan and control parameters of all power conversion devices 41, in S11, it is checked whether to stop CEMS31. If CEMS31 is stopped ("Yes" in S11), the process ends. On the other hand, if CEMS31 is not stopped ("No" in S11), the process returns to S01.

[0337] In contrast, Figure 33 If no operation plan (power supply plan) is received from DSO21 in S04 ("No" in S04), CEMS31 proceeds to S06 to check whether the collection time for various measurement data has arrived. In Embodiment 1, as described above, CEMS31 collects measurement data in 5-minute cycles. If the collection time for measurement data has not arrived ("No" in S06), processing returns to S01. On the other hand, if the collection time for measurement data has arrived ("Yes" in S06), CEMS31 collects measurement data in S07. In Embodiment 1, CEMS31 collects 5 minutes each of charging / discharging power, current charging / discharging power, and SOC information of the battery 40 from power conversion devices 41a to 41c as measurement data.

[0338] When measurement data is collected in S07, CEMS31 confirms in S08 whether the operation plan of the battery 40 needs to be revised. In S07, CEMS31 compares the current charge / discharge power with the operation plan (power target value) for each of the multiple batteries 40. Specifically, CEMS31 confirms whether the power difference between the current charge / discharge power and the power target value exceeds a predetermined range and whether the SOC of the battery 40 exceeds a predetermined allowable range. If the power difference of any one of the multiple batteries 40 exceeds the predetermined range and / or the SOC exceeds the allowable range, CEMS31 re-examines the operation plan of all batteries 40. Furthermore, the operation plan of batteries 40 whose power difference exceeds the predetermined range and / or whose SOC exceeds the allowable range can also be re-examined.

[0339] Based on the above points, CEMS31 determines whether the operation plan of the battery 40 needs to be modified. If it determines that the operation plan of the battery 40 does not need to be modified ("No" in S08), it returns to S01 and continues processing. On the other hand, if it determines that the operation plan of the battery 40 needs to be modified ("Yes" in S08), CEMS31 proceeds to S09 and modifies the operation plans of all batteries 40.

[0340] Figure 38 This demonstrates the processing of the modified operation plan of the storage battery 40. Figure 33 The flowchart of S09). Circuit 14 is created by the operation plan within CEMS31. Figure 3 ),implement Figure 38 The processing shown.

[0341] like Figure 38 As shown, after processing begins, the second management circuit 146 ( Figure 4 ) via S091 for battery operation plan correction circuit 144 ( Figure 4 It indicates the modification of the operation plan and transmits the charging and discharging power and SOC information collected from each power conversion device 41.

[0342] In S092, the second management circuit 146 also outputs a value stored in the first management circuit 145 in response to the battery operation plan correction circuit 144. Figure 4 The operating plan (power target value) of the battery 40 and the capacity of the static inverter of the power conversion device 41 stored in the storage circuit 12.

[0343] The battery operation plan correction circuit 144 re-examines the operation plan of the battery 40 based on information provided from the second management circuit 146. For example, it is conceivable that because any value in the predicted power generation of the megawatt-class solar power plant 26 and the predicted power consumption of each consumer deviates from the actual value, the output power of the power conversion device 41 becomes twice the power target value.

[0344] In such a case, the system frequency is assumed to drop to near the lower limit (Fref-ΔFmax). When there is insufficient power above this level, the system frequency becomes the lower limit, and a situation may arise where power can no longer be supplied from the power conversion device 41.

[0345] Therefore, in Embodiment 1, when the target power value and the ratio of charge / discharge power are not within a predetermined range, the battery operation plan correction circuit 144 corrects the operation plan (target power value) of the battery 40 based on measurement data collected at 5-minute intervals. Specifically, the battery operation plan correction circuit 144 corrects the operation plan of the battery 40 based on the current charge / discharge power and SOC information.

[0346] The reason for using SOC in revising the operation plan of battery 40 is that, when using a lithium-ion battery as battery 40, the battery 40 sometimes malfunctions or deteriorates rapidly due to overcharging or over-discharging. Therefore, in normal battery control, when the SOC exceeds, for example, 90%, the battery charging mode is switched from constant current charging mode to constant voltage charging mode. In constant voltage charging mode, a large charging power cannot be obtained, so the power target value needs to be reduced in the virtual synchronous generator control. Similarly, since the battery 40 deteriorates when it becomes over-discharged, the discharge power needs to be reduced when the SOC falls below, for example, 5%. Therefore, SOC is used to create and revise the operation plan of battery 40.

[0347] Furthermore, when a lead-acid battery is used as the storage battery 40, although it is resistant to overcharging, it tends to deteriorate due to over-discharge. Therefore, in the case of a lead-acid battery, it is necessary to reduce the discharge power, for example, when the State of Charge (SOC) is below 20%. As described above, in order to suppress the deterioration of the battery in use, the SOC is used to adjust the power target value.

[0348] Specifically, the battery operation plan correction circuit 144 generates an operation plan for the battery 40 based on the current charging and discharging power. However, during charging when the State of Charge (SOC) is near its upper limit and during discharging when the SOC is near its lower limit, the battery operation plan is generated based on the current charging and discharging power and the SOC. Specifically, the target charging power is reduced when the SOC is close to its upper limit, and the target discharging power is reduced when the SOC is close to its lower limit.

[0349] After modifying the operating plan (power target value) of battery 40 in S093, the parameter generation circuit 13 is controlled via S094. Figure 3 The system confirms whether the calculation of the information required for generating all battery 40 control parameters is complete. If the calculation of the information required for generating all battery 40 control parameters is complete ("Yes" in S094), the battery operation plan correction circuit 144 ends the modification process of the battery 40 operation plan. On the other hand, if the modification of the operation plan of all batteries 40 has not been completed ("No" in S094), then in S095, the control parameter generation circuit 13 generates the information required for generating the control parameters of the virtual synchronous generator control. Furthermore, the method for generating the information required for the control parameters of the virtual synchronous generator control is the same as that in the above-mentioned battery 40 operation plan creation process (…). Figure 34 S056 and Figure 35 The generation method used in () is the same, so the explanation is omitted.

[0350] After generating the information required for the generation of control parameters in S095, the circuit returns to S094, where the control parameter generation circuit 13 confirms whether the calculation of the information required for the generation of control parameters for all power conversion devices 41 has been completed. If the calculation of the information required for the generation of control parameters for all power conversion devices 41 has not been completed (in S094, "No"), the control parameter generation circuit 13 generates the information required for the generation of control parameters for the next power conversion device 41 in S095.

[0351] On the other hand, after the calculation of the information required for generating the control parameters of all power conversion devices 41 is completed ("Yes" in S094), the battery operation plan correction circuit 144 ends the correction process of the operation plan of the battery 40 in S096.

[0352] Return to Figure 33 After the operation plan of the storage battery 40 is modified in S09, the storage battery operation plan creation circuit 141, in the same manner as when the operation plan is created, notifies the first management circuit 145 of the modified operation plan (power target value) via the second management circuit 146.

[0353] After obtaining the operation plan of the battery 40 from the battery operation plan generation circuit 141, the first management circuit 145 stores the obtained operation plan in a memory (not shown) and notifies the data transmission generation circuit 15. Similarly, the control parameter generation circuit 13 notifies the data transmission generation circuit 15 of the operation plan of the battery 40 and the information required for the generation of control parameters.

[0354] When the data generation circuit 15 receives the information required for the operation plan and control parameters of the battery 40, it processes them into a format for transmission and outputs them to the communication circuit 11.

[0355] When the communication circuit 11 receives transmission data from the transmission data generation circuit 15, it transmits the transmission data to the corresponding power conversion device 41 via the communication line 25. Figure 33 (S10).

[0356] exist Figure 33 In S10, after the operation plan for all power conversion devices 41 and batteries 40 is sent, S11 checks whether to stop CEMS31. If CEMS31 is stopped (Yes in S11), the process ends. On the other hand, if CEMS31 is not stopped, the process returns to S01 and continues.

[0357] As explained above, in Embodiment 1, when creating an operation plan (power target value) for the battery 40 for the power conversion device 41, information required for the control parameters of the virtual synchronous generator installed on the static inverter is generated based on the capacity of the static inverter of each power conversion device 41 and the power target value. Therefore, even if the power consumption of the load 600 or the power generated by energy-generating equipment such as the megawatt-class solar power plant 26 fluctuates during the period until the CEMS 31 notifies the next operation plan, excess or insufficient power can be distributed according to the same allocation ratio as the operation plan (power target value) of the battery 40.

[0358] Therefore, for example, if the power generation of the megawatt-class solar power plant 26 decreases by 50% due to changes in solar radiation immediately after the operation plan has been notified to all power conversion devices 41, the shortfall of 50% of the power is allocated according to the ratio of the power target value calculated when the operation plan was created. For example, if the power target value is controlled according to this ratio when the operation plan is created, and the charging and discharging power of each battery 40 is set in a way that makes the SOC of all batteries 40 approximately zero at the same time, even if the power generation of the megawatt-class solar power plant 26 decreases by 50%, the shortfall of power can be allocated according to the ratio of the power target value, so that the SOC of all batteries 40 can be controlled in a way that makes the SOC of all batteries 40 approximately zero at the same time.

[0359] Furthermore, in Embodiment 1, a structure was described that uses inverter capacity and power target value calculations when generating the information required for generating control parameters for virtual synchronous generator control in the static inverter of the power conversion device 41. However, this is not limited to this. For example, if the capacity of battery 40a is twice that of the inverter capacity of power conversion device 41a, and the capacity of battery 40b is three times that of the inverter capacity of power conversion device 41b, and the ratio of battery 40 capacity to inverter capacity differs among power conversion devices 41, the operating plan (power target value) for each battery 40 is generated considering the capacity ratio. Alternatively, the same effect can be obtained by considering the above-mentioned capacity ratio when generating control parameters.

[0360] (Operation of power conversion device 27 and power conversion device 41)

[0361] Next, use Figures 6 to 41 This explains the operation of the power conversion device 27 used in megawatt-class solar power plants and the power conversion device 41 used in storage batteries.

[0362] [Operation of power conversion device 27]

[0363] use Figure 6 This explains the operation of the power conversion device 27 used in a megawatt-class solar power plant.

[0364] After the megawatt-class solar power plant 26 begins generating electricity, the DC voltage input from the megawatt-class solar power plant 26 to the first DC / DC converter 203 within the power conversion device 27 rises. The first control circuit 204 monitors the DC voltage measured by the voltmeter 201. If the DC voltage exceeds a predetermined value, the first control circuit 204 causes the power conversion device 27 to transition from a standby state to normal operation.

[0365] After switching to normal operation, the second control circuit 209 within the power conversion unit 27 controls the first DC / AC converter 208. The control of the power conversion unit 27 during normal operation will be described below.

[0366] Reference Figure 6 The first control circuit 204 confirms whether the megawatt-class solar power station 26 is generating electricity. Specifically, the first control circuit 204 confirms whether the output voltage of the megawatt-class solar power station 26, measured by the voltmeter 201, exceeds a predetermined voltage. If the output voltage exceeds the predetermined voltage, the first control circuit 204 notifies the second control circuit 209 that the megawatt-class solar power station 26 is capable of generating electricity.

[0367] When the second control circuit 209 receives a notification from the first control circuit 204, it confirms whether to supply power to the power distribution system 24 from the substation 20 (whether the power distribution system 24 is not de-energized) based on the AC voltage of the power distribution system 24 measured by the voltmeter 10.

[0368] After confirming that the AC voltage measured by voltmeter 210 is above the predetermined voltage and that the power distribution system 24 is not powered down, the second control circuit 209 starts the DC / AC converter 208 and instructs the first control circuit 204 to start generating electricity in the megawatt-class solar power station 26.

[0369] Furthermore, in Embodiment 1, the case where the DC bus voltage of the DC bus 205 is managed by the first DC / AC converter 208 during normal operation is described. Additionally, in Embodiment 1, the distributed power management device is activated as a whole by managing the power regenerated from the power conversion device 27 to the power distribution system 24 using current control performed by the first DC / AC converter 208.

[0370] When the megawatt-class solar power station 26 is instructed to start generating electricity via the second control circuit 209, the fifth control circuit 54 of the first control circuit 204 ( Figure 8 ) Indicates MPPT control circuit 51 ( Figure 8 Start the maximum power point tracking control of the megawatt-class solar power plant 26.

[0371] A brief explanation of maximum power point tracking control. In maximum power point tracking control, the system manages whether the previous command value is greater than or less than the power command value from the period before last. Furthermore, it compares the generated power of the megawatt-class solar power plant 26 measured this time with the generated power of the megawatt-class solar power plant 26 measured last time. If the generated power increases, the command value is changed in the same direction as last time (either the direction of increase or decrease).

[0372] Specifically, if the measured power generation of the megawatt-class solar power plant 26 is higher than the previously measured power generation, the command value is increased if the previous command value was greater than the command value two years prior. Conversely, if the previous command value was less than the command value two years prior, the command value is decreased. Conversely, if the measured power generation of the megawatt-class solar power plant 26 is lower than the previously measured power generation, the command value is decreased if the previous command value was greater than the command value two years prior. Conversely, if the previous command value was less than the command value two years prior, the command value is increased. By controlling the command value in this way, the megawatt-class solar power plant 26 is controlled to maximize its power output.

[0373] The first DC / DC converter 203 activates its built-in boost circuit according to the command value output from the first control circuit 204, thereby converting the first DC voltage output from the megawatt-level solar power station 26 into a second DC voltage (the DC bus voltage of the DC bus 205) and outputting it.

[0374] After the first DC / DC converter 203 begins supplying power to the megawatt-class solar power plant 26, the second control circuit 209 controls the first DC / AC converter 208 to output (regenerate) the generated power from the megawatt-class solar power plant 26 to the power distribution system 24. Specifically, it monitors the DC bus voltage of the DC bus 205 and, if the DC bus voltage exceeds a control target value, outputs generated power synchronously with the AC voltage supplied from the power distribution system 24.

[0375] Next, use Figure 9 Explain the operation of the second control circuit 209.

[0376] In the second control circuit 209, the phase detection circuit 61 detects the phase through the voltmeter 210 ( Figure 1 The zero-crossing point of the waveform of the AC voltage of the power distribution system 24 is measured.

[0377] The first sine wave generation circuit 62 generates a reference sine wave synchronized with the waveform of the AC voltage of the power distribution system 24 based on information indicating the zero-crossing point detected by the phase detection circuit 61 and the waveform of the AC voltage measured by the voltmeter 210. The first sine wave generation circuit 62 outputs the generated reference sine wave to the multiplier 65.

[0378] Voltmeter 206 measures the voltage of DC bus 205 and outputs the measured value to subtractor 63 within current control circuit 60 and sixth control circuit 67. Furthermore, current control circuit 60 uses a control method (current control) that outputs power synchronously with the AC system voltage. This control method is typical of power conversion devices used in home solar power generation systems.

[0379] The sixth control circuit 67 stores the target voltage of the DC bus 205 and outputs the target voltage to the subtractor 63.

[0380] The current control circuit 60 controls the current output of the first DC / AC converter 208 in such a way that the DC bus voltage measured by the voltmeter 206 becomes the target voltage. The output of the subtractor 63 is input to the first PI control circuit 64. The first PI control circuit 64 performs PI control in such a way that the output of the subtractor 63 becomes zero. The output of the first PI control circuit 64 is input to the multiplier 65, which multiplies it with a reference sine wave from the first sine wave generation circuit 62, thereby converting it into a current command value.

[0381] The current command value output from multiplier 65 is input to subtractor 66. Subtractor 66 calculates the deviation between the current command value and the AC current value of the power distribution system 24 measured by ammeter 211, and inputs the calculated deviation to the second PI control circuit 68.

[0382] The second PI control circuit 68 performs PI control in a manner that makes the deviation output from the subtractor 66 zero. The first PWM converter 69 generates a command value for the first DC / AC converter 208 by executing PWM control on the output of the second PI control circuit 68. The first DC / AC converter 208 outputs AC current according to the command value provided by the first PWM converter 69.

[0383] Furthermore, if the AC voltage (AC effective voltage) measured by voltmeter 210 exceeds a predetermined voltage value, or if a request to suppress the power generation of the megawatt-class solar power plant 26 is notified from CEMS 31, the fifth control circuit 54 within the first control circuit 204 ( Figure 8The control of the megawatt-class solar power plant 26 is switched from MPPT control to voltage control. Specifically, the fifth control circuit 54 controls the DC voltage output from the megawatt-class solar power plant 26 in a manner that causes the AC voltage (AC effective voltage) measured by the voltmeter 210 to converge to a predetermined voltage range. Alternatively, the fifth control circuit 54 controls the output voltage of the megawatt-class solar power plant 26 in a manner that causes the generated power of the megawatt-class solar power plant 26 to converge to a power range notified from the CEMS 31.

[0384] In addition, the first switching circuit 53 ( Figure 8 According to the switching control signal provided by the fifth control circuit 54, the output of the MPPT control circuit 51 and the output of the voltage control circuit 52 are switched.

[0385] The sixth control circuit 67 collects measurement results related to the DC bus 205 measured by voltmeter 206 and ammeter 207, measurement results related to the power distribution system 24 measured by voltmeter 210 and ammeter 211, and status information of the first DC / DC converter 203 output from the first control circuit 204, and notifies the CEMS 31 of the collected information via communication I / F 212.

[0386] In addition, the sixth control circuit 67 also notifies the CEMS 31 of the effective voltage of the power distribution system 24 measured by the effective voltage measurement unit (not shown) or the information related to the active and reactive power of the AC system measured by the active / reactive power measurement unit (not shown), and also notifies the fifth control circuit 54 of the measurement results of the effective voltage, active power, etc. of the AC system.

[0387] As described above, when the actual value of the AC system voltage exceeds a predetermined value, the fifth control circuit 54 switches the control of the megawatt-class solar power station 26 from MPPT control to voltage control to suppress the rise of the AC system voltage.

[0388] [Operation of power conversion device 41]

[0389] Next, use Figures 7 to 41 This explains the operation of the power conversion device 41 used for the storage battery.

[0390] In embodiment 1, a virtual synchronous generator control is installed on the power conversion device 41, so the second DC / AC converter 408 operates as a voltage source by performing voltage control. That is, the third control circuit 404 ( Figure 7 This is controlled in a way that keeps the voltage of the DC bus 405 constant. The following uses... Figure 10 Explain the operation of the third control circuit 404.

[0391] The voltage of DC bus 405 is measured by voltmeter 406. The measured value of voltmeter 406 is input to charging control circuit 71, discharging control circuit 72 and the seventh control circuit 74.

[0392] When the voltage of the DC bus 405 is greater than the target voltage output from the 7th control circuit 74, the charging control circuit 71 controls the charging power of the battery 40 to be the target voltage. On the other hand, when the voltage of the DC bus 405 is less than the target voltage, the discharging control circuit 72 increases the discharging power of the battery 40.

[0393] Furthermore, the output of the charging control circuit 71 and the output of the discharging control circuit 72 are switched by the second switching circuit 73. The seventh control circuit 74 outputs a switching control signal to the second switching circuit 73 based on the voltage value of the DC bus 405 measured by the voltmeter 406.

[0394] Next, the fourth control circuit 409 will be described. Figure 7 (The action of ).

[0395] Figure 39 This is a flowchart used to explain the operation of the power conversion device 41.

[0396] like Figure 39 As shown, after processing begins, the fourth control circuit 409 initializes various control parameters via S200. Next, via S201, the fourth control circuit 409 collects voltage values ​​measured by voltmeters 401, 406, and 410, current values ​​measured by ammeters 402, 407, and 411, and current status information of the battery 40. Furthermore, the voltmeter 410 measures AC voltage, so the eighth control circuit 87... Figure 11 The effective value of the AC voltage is calculated in the control circuit 87 and used as the voltage value. The ammeter 411 measures the AC current, so the effective value of the AC current is calculated in the control circuit 87 and used as the current value. The charging and discharging power calculation circuit (not shown) in the control circuit 74 calculates the charging and discharging power and charging and discharging force of the battery based on the collected data.

[0397] The AC voltage of the power distribution system 24 measured by voltmeter 410 is input to the AC frequency detection circuit 81. Figure 11 The AC frequency detection circuit 81 detects the zero-crossing point of the AC voltage waveform via S202.

[0398] Figure 12 It is shown Figure 11 The block diagram shown illustrates the structure of the AC frequency detection circuit 81. Figure 12As shown, the measured value from voltmeter 410 is input to phase detection circuit 810. Through... Figure 39 In step S202, the phase detection circuit 810 detects the zero-crossing point of the AC voltage. Furthermore, in embodiment 1, the zero-crossing point represents the point and time at which the waveform of the AC voltage measured by the voltmeter 410 switches from negative to positive. The phase detection circuit 810 outputs information indicating the detected zero-crossing point to the frequency detection circuit 811.

[0399] The frequency detection circuit 811 calculates the period of the AC voltage based on the time of the zero-crossing point detected by the phase detection circuit 810 in the previous step and the time of the zero-crossing point detected in the current step. The frequency detection circuit 811 then calculates the frequency of the AC voltage based on the calculated period.

[0400] The second sine wave generation circuit 812 outputs sine wave information as zero-crossing point information detected by the phase detection circuit 810 and AC voltage frequency information detected by the frequency detection circuit 811. The zero-crossing point information and frequency information are output to the inverter current control circuit 84, the inverter voltage control circuit 85, the virtual synchronous generator control circuit 83, and the eighth control circuit 87.

[0401] Return to Figure 39 If a zero-crossing point is detected in S202 ("Yes" in S202), the phase detection circuit 810 sets the zero-crossing point detection flag in S203. If the processing in S203 ends or if no zero-crossing point is detected in S202 ("No" in S202), the fourth control circuit 409 controls the second DC / AC converter 408 in S204.

[0402] The following uses Figure 11 as well as Figure 40 This explains the control of the second DC / AC converter 408.

[0403] As described above, the power conversion device 41 is equipped with virtual synchronous generator control, so the second DC / AC converter 408 is controlled as a voltage source. That is, the second DC / AC converter 408 is voltage-controlled. Therefore, when the power supplied to the power distribution system 24 is insufficient, the second DC / AC converter 408 is controlled to increase the output power. On the other hand, when the power supplied to the power distribution system 24 becomes excessive, the second DC / AC converter 408 is controlled to decrease the output power.

[0404] Figure 40 This is a flowchart illustrating the detailed control processing of the second DC / AC converter 408.

[0405] like Figure 40As shown, through S2041, the effective power calculation circuit 82 ( Figure 11 After calculating the power value based on the measurements from voltmeter 410 and ammeter 411, the calculated power value is integrated in S2042. If the zero-crossing detection flag is set ("Yes" in S2043), the effective power calculation circuit 82 proceeds to S2044, stores the integrated value of the effective power value for one cycle of AC voltage in the storage circuit (not shown) within the 8th control circuit 87, and initializes the integrated value to zero in S2045.

[0406] If the processing of S2045 ends or the zero-crossing detection flag is not set ("No" in S2043), the inverter voltage control circuit 85 generates the command value for the second DC / AC converter 408 via S2046.

[0407] Next, refer to Figure 13 This indicates the operation of the inverter voltage control circuit 85.

[0408] like Figure 13 As shown, the inverter voltage control circuit 85 controls the voltage according to the virtual synchronous generator control circuit 83. Figure 11 The frequency and phase information output by the second DC / AC converter 408 (input via the second sine wave generation circuit 812) and the amplitude information of the AC system voltage input from the eighth control circuit 87 via the second sine wave generation circuit 812 are used to generate control command values ​​for controlling the second DC / AC converter 408.

[0409] Specifically, the third sine wave generation circuit 851 receives sine wave information (frequency, phase, and amplitude information, as well as frequency and phase information calculated by the virtual synchronous generator control circuit 83) from the AC frequency detection circuit 81. Based on the input information, the third sine wave generation circuit 851 generates a target value for the AC system voltage output from the second DC / AC converter 408.

[0410] Subtractor 852 subtracts the voltage measured by voltmeter 410 from the output of the third sine wave generation circuit 851, and outputs the subtraction result to the third PI control circuit 853.

[0411] The third PI control circuit 853 generates a voltage command value by executing PI control to make the input subtraction result zero, and outputs the generated voltage command value to the first current limiting circuit 855.

[0412] The first current limiting circuit 855 applies a limit based on the voltage command value provided from the third PI control circuit 853, according to the measurement result in the ammeter 411 input via the eighth control circuit 87. For example, consider a case where the power target value notified from the CEMS 31 is 90% of the inverter capacity, and the load power consumption has increased. In this case, in the ΔF / ΔP characteristic described in Embodiment 1, the output power exceeding the inverter capacity within the power conversion device 41 is required before the frequency deviation (differential frequency ΔF) of the AC system voltage reaches -ΔFmax. Therefore, it is necessary to limit the output power (output current) of the power conversion device 41 in a way that prevents exceeding the inverter capacity. Therefore, in Embodiment 1, in the case of a current flowing through the second DC / AC converter 408 exceeding its current capacity, current limiting is implemented to control the current flowing through the second DC / AC converter 408 to a predetermined current value (e.g., the current capacity of the second DC / AC converter 408).

[0413] Specifically, the first current limiting circuit 855 monitors the current flowing through the second DC / AC converter 408 and controls (limits) the current value to prevent the current from exceeding the current capacity of the second DC / AC converter 408. The output of the first current limiting circuit 855 is input to the second PWM converter 854. Furthermore, the control parameters (control gain and integral time) of the third PI control circuit 853 and the first current limiting circuit 855 are set to be output from the eighth control circuit 87.

[0414] The second PWM converter 854 uses the voltage command value output from the first current limiting circuit 855 to perform PWM control, thereby generating a control command value. The second PWM converter 854 outputs the generated control command value to the second DC / AC converter 408.

[0415] Return to Figure 39 After generating the control command value for the second DC / AC converter 408 in S204, the virtual synchronous generator control circuit 83 is activated via S205. Figure 11 The virtual synchronous generator control is executed. In Implementation 1, one cycle of the AC voltage is set as the control cycle. Alternatively, the control cycle can be set to an integer multiple of one cycle of the AC voltage or a predetermined cycle such as one second.

[0416] Figure 14 This is a block diagram showing the structure of the virtual synchronous generator control circuit 83.

[0417] 8th control circuit 87 ( Figure 11Upon determining that the control timing has been reached, the virtual synchronous generator control circuit 83 is instructed to generate information related to the frequency and phase used in voltage control. In Embodiment 1, at the zero-crossing point, the third sine wave generation circuit 851 within the inverter voltage control circuit 85 is updated. Figure 13 The frequency and phase of the generated sine wave. Therefore, in Embodiment 1, the control period becomes the period of the zero-crossing point detected by the AC frequency detection circuit 81.

[0418] like Figure 14 As shown, in the virtual synchronous generator control circuit 83, the subtractor 832 receives input from the AC frequency detection circuit 81 (…). Figure 11 The measured value of the frequency of the input AC voltage is subtracted from the reference frequency Fref (e.g., 60Hz) input from the 8th control circuit 87, and the subtraction result is output to the speed controller control circuit 833. Figure 15 It is shown Figure 14 The diagram shows a detailed structural block diagram of the speed controller control circuit 833.

[0419] like Figure 15 As shown, in the speed controller control circuit 833, multiplier 91 controls subtractor 832. Figure 14 The output of the multiplier 91 is multiplied by the control parameter (-1 / Kgd) notified from the 8th control circuit 87. The multiplier 91 inputs the multiplication result to the first-order delay system model 92.

[0420] Furthermore, the speed regulation rate Kgd and the speed governor time constant Tg used in the speed governor control circuit 833 are set to a register (not shown) via the 8th control circuit 87, using parameters notified from CEMS31 and parameters generated by the control parameter generation circuit 88.

[0421] As described above, the first-order delay system model 92 performs a calculation using the time constant Tg notified from the 8th control circuit 87 to simulate the first-order delay system (1 / (1+s×Tg)), and outputs the calculation result to the limiter circuit 93.

[0422] The limiter circuit 93 imposes a limit on the input data. Specifically, the limiter circuit 93 limits the output power of the second DC / AC converter 408 in such a way that it does not exceed the power capacity of the second DC / AC converter 408.

[0423] Return to Figure 14 Adder 835 adds the output of speed controller control circuit 833 and the power target value Pref output from 8th control circuit 87. Furthermore, regarding the power target value Pref, 8th control circuit 87 outputs parameters notified from CEMS 31.

[0424] Subtractor 836 subtracts from the output of adder 835 the output of effective power calculation circuit 82. Figure 11 The effective power output is calculated and the subtraction result is output to the quality system operation circuit 837. Figure 16 It is shown Figure 14 The block diagram showing the detailed structure of the mass system operation circuit 837 is shown.

[0425] like Figure 16 As shown, subtractor 101 is derived from subtractor 836 ( Figure 14 The output of the multiplier 103 is subtracted from the output of the multiplier 103, and the subtracted value is output to the integrator 102.

[0426] Integrator 102 divides the subtraction result of subtractor 101 by the inertia constant M output from control circuit 87, and integrates the division result. The output Δω of integrator 102 is equivalent to the difference between the angular velocity (2×π×60Hz) relative to the frequency of the AC voltage. The output Δω of integrator 102 is input to multiplier 103 and divider 104.

[0427] Multiplier 103 multiplies the output Δω of integrator 102 and the damping coefficient Dg provided from the 8th control circuit 87, and outputs the multiplication result to subtractor 101.

[0428] Divider 104 transforms the output Δω of integrator 102 into a difference value Δf with the reference frequency Fref (60Hz) by dividing Δω by 2×π. Adder 105 adds the output Δf of divider 104 and the reference frequency Fref (60Hz) to generate a value used in inverter voltage control circuit 85. Figure 11 The frequency (Fref+Δf) used for voltage control in )

[0429] Furthermore, regarding the inertia constant M and damping coefficient Dg used in the mass system operation circuit 837, the control parameter generation circuit 88 uses the information required for generating virtual synchronous generator control parameters generated and notified by CEMS31 to generate parameters, sets the parameters to a register (not shown) via the 8th control circuit 87, and uses the parameters set to the register.

[0430] The frequency information (Fref+Δf) output from adder 105 is input to phase calculation circuit 106. The operation of phase calculation circuit 106 will be described below.

[0431] In implementation 1, the phase calculation circuit 106 is used to calculate the phase of the adder 105 ( Figure 16 The frequency information output is integrated and used as the phase information output when the inverter voltage control circuit 85 performs voltage control.

[0432] From the quality system operation circuit 837 ( Figure 16 The phase and frequency information output are processed by the second sine wave generation circuit 812 within the AC frequency detection circuit 81. Figure 12 The input is given to the third sine wave generation circuit 851 within the inverter voltage control circuit 85. Figure 13 The third sine wave generation circuit 851 generates the target value of the AC voltage output from the power conversion device 41 based on the input information.

[0433] Return to Figure 39 After the virtual synchronous generator control process in S205 is completed, the fourth control circuit 409 checks in S206 whether a transmission request for measurement data has been received from CEMS31. If a transmission request has been received from CEMS31 ("Yes" in S206), the eighth control circuit 87 ( Figure 11 The measurement data is transmitted via communication I / F412 through S207. Figure 7 Notify CEMS31.

[0434] On the other hand, if the measurement data is notified in S207 or if no transmission request is received from CEMS31 ("No" in S206), the 8th control circuit 87 enters S208 to confirm whether control information has been received from CEMS31.

[0435] If control information is received from CEMS31 (Yes in S208), the 8th control circuit 87 sets the control information reception flag in S209. If the processing in S209 ends or if no control information is received from CEMS31 (No in S208), the 8th control circuit 87 checks in S210 whether a zero-crossing detection flag is set. If the zero-crossing detection flag is not set (No in S210), the processing returns to S201.

[0436] On the other hand, when a zero-crossing point detection flag is set ("Yes" in S210), the second sine wave generation circuit 812 (…) is activated via S211. Figure 12 The system voltage frequency and phase information are acquired, and the zero-crossing detection flag is reset in S212.

[0437] After resetting the zero-crossing detection flag in S212, the second sine wave generation circuit 812 updates the information of the frequency and phase of the system voltage (the zero-crossing time information in Implementation 1) to the information taken in S211 via S213.

[0438] After processing in S213 is completed, the 8th control circuit 87 checks in S214 whether control information has been received from CEMS31 (whether a control information reception flag is set). If the reception flag is not set ("No" in S214), the processing returns to S201.

[0439] On the other hand, when the receiving flag is set ("Yes" in S214), the 8th control circuit 87 replaces the frequency target value (reference frequency Fref) and the power target value Pref with the received data in S215.

[0440] The control parameter generation circuit 88 generates control parameters (speed regulation rate Kgd, damping coefficient Dg, and inertia constant M) for the virtual synchronous generator control via S216. Figure 41 This illustrates the process of generating control parameters. Figure 39 The flowchart of S216 is described. In Embodiment 1, the case where the information required for generating the control parameters for virtual synchronous generator control from CEMS31 is input as the ΔF / ΔP characteristic is explained. In addition to the ΔF / ΔP characteristic, the control parameter generation circuit 88 uses system information (reference frequency Fref, power target value Pref, ΔFmax information) and inverter capacity Cinv to generate control parameters.

[0441] like Figure 41 As shown, after the generation of control parameters begins, the control parameter generation circuit 88 initializes the speed adjustment rate Kgd and the damping coefficient Dg by setting them to predetermined initial values ​​through S2161.

[0442] After initializing the speed regulation rate Kgd and damping coefficient Dg in S2161, the control parameter generation circuit 88 proceeds to S2162, using the speed regulation rate Kgd and damping coefficient Dg to calculate the slope of the ΔF / ΔP characteristic. In Embodiment 1, the control parameter generation circuit 88 ( Figure 11 ) Install simulated virtual synchronous generator control circuit 83 ( Figure 11 The virtual synchronous generator model of the operation is used to generate control parameters.

[0443] Furthermore, the method for generating control parameters is not limited to this; for example, it can also be configured to... Figure 18 The relationship between the speed regulation rate Kgd and the system frequency shown is stored as corresponding table data for each damping coefficient Dg, and... Figure 19 The relationship between the damping coefficient Dg and the system frequency is shown in the table data for each speed regulation rate Kgd. Using this table data, the appropriate speed regulation rate Kgd and damping coefficient Dg are determined.

[0444] In implementation method 1, a virtual synchronous generator model is used... Figures 14 to 16 The block diagram shown is a model derived from a formula model, but it is not limited to this. For example, it can also be a virtual synchronous generator control circuit 83 generated based on the transfer function of the governor control unit shown in equation (1) and the swing equation shown in equation (2). Figure 11 The transfer function is used to generate the structure of control parameters.

[0445] In S2162, by inputting the set speed regulation rate Kgd and damping coefficient Dg into the virtual synchronous generator model, for example, calculations are performed from the quality system calculation circuit 837 when a load variation of 25% of the inverter capacity is input. Figure 14 The system frequency output is calculated. The differential frequency ΔF is calculated by subtracting the reference frequency Fref from this calculation result. Furthermore, the slope of the ΔF / ΔP characteristic is calculated by dividing the calculated differential frequency ΔF by the load variation (0.25 times the inverter capacity in this example).

[0446] After calculating the slope of the ΔF / ΔP characteristic in S2162, the control parameter generation circuit 88 compares the calculated slope of the ΔF / ΔP characteristic with the value obtained through S2163. Figure 35 S0563 ( Figure 37 The slope of the generated ΔF / ΔP characteristic. Specifically, the control parameter generation circuit 88 confirms whether the deviation of the slopes of these two ΔF / ΔP characteristics falls within a predetermined allowable range.

[0447] If the slope deviation falls within the above-mentioned allowable range, the control parameter generation circuit 88 determines that the slopes of the two ΔF / ΔP characteristics are consistent ("Yes" in S2163), and causes the processing to proceed to S2169.

[0448] On the other hand, if the slope deviation does not fall within the aforementioned allowable range, the control parameter generation circuit 88 determines that the slopes of the two ΔF / ΔP characteristics are inconsistent ("No" in S2163). In this case, the control parameter generation circuit 88 proceeds to S2164 and changes the damping coefficient Dg. In Embodiment 1, the control parameter generation circuit 88 adds a predetermined value to the current damping coefficient Dg.

[0449] After changing the damping coefficient Dg in S2164, the control parameter generation circuit 88 confirms in S2165 whether the damping coefficient Dg has entered a predetermined range. If the damping coefficient Dg enters the predetermined range ("yes" in S2165), the control parameter generation circuit 88 returns to S2162 and uses the changed damping coefficient Dg to calculate the slope of the ΔF / ΔP characteristic.

[0450] On the other hand, if the damping coefficient Dg exceeds the predetermined range ("No" in S2165), the control parameter generation circuit 88 determines that an appropriate characteristic cannot be obtained under the current speed adjustment rate Kgd, and returns the damping coefficient Dg to its initial value in S2166, and changes the speed adjustment rate Kgd. Specifically, the control parameter generation circuit 88 adds a predetermined value to the current speed adjustment rate Kgd (initial value).

[0451] After changing the speed adjustment rate Kgd in S2166, the control parameter generation circuit 88 confirms in S2167 whether the speed adjustment rate Kgd has entered a predetermined range. If the speed adjustment rate Kgd deviates from the predetermined range ("No" in S2167), the control parameter generation circuit 88 proceeds to S2168, considering that an appropriate speed adjustment rate Kgd and damping coefficient Dg have not been determined, and sets the speed adjustment rate Kgd and damping coefficient Dg to their respective pre-prepared default values, causing the process to proceed to S2169.

[0452] On the other hand, if the speed regulation rate Kgd is within the predetermined range in S2167 ("Yes" in S2167), the control parameter generation circuit 88 returns to S2162 and calculates the slope of the ΔF / ΔP characteristic using the modified speed regulation rate Kgd and the damping coefficient Dg. The control parameter generation circuit 88 repeatedly executes the processing of S2162 to S2167 until it determines "Yes" in S2163 or "No" in S2167.

[0453] Furthermore, if the speed regulation rate Kgd and damping coefficient Dg are set to default values ​​in S2168, even if load changes occur, the insufficient power cannot be distributed according to the power ratio based on the operation plan.

[0454] In implementation method 1, according to Figure 19 The relationship between the damping coefficient Dg and the frequency of the AC system voltage is shown. The damping coefficient Dg and the speed regulation rate Kgd can be calculated. Alternatively, based on... Figure 18 The relationship between the speed regulation rate Kgd and the frequency of the AC system voltage is shown. Calculate the damping coefficient Dg and the speed regulation rate Kgd.

[0455] After setting the speed regulation rate Kgd and the damping coefficient Dg, the control parameter generation circuit 88 calculates the inertia constant M via S2169. In Implementation 1, the inertia constant M is calculated based on the response time required in the virtual synchronous generator control. Specifically, the response performance of the virtual synchronous generator control is determined by the governor control circuit 833 ( Figure 14 The governor time constant Tg and the mass system calculation circuit 837 derived from the swing equation. Figure 14The time constant M / Dg is determined by the speed governor. In Embodiment 1, the default value of the speed governor time constant Tg is used, and the speed governor time constant Tg is not generated, so only the time constant of the mass system operation circuit 837 is controlled. According to the above formula (3), the time constant of the mass system operation circuit 837 is obtained by M / Dg. Therefore, in Embodiment 1, the inertia constant M is calculated by multiplying the time constant of the mass system operation circuit 837, which is determined by the default value, by the damping coefficient Dg.

[0456] Return to Figure 39 After the control parameters (speed adjustment rate Kgd, damping coefficient Dg, and inertia constant M) are calculated in S216, the control parameter generation circuit 88 notifies the 8th control circuit 87 of this information and outputs the calculated control parameters.

[0457] When the eighth control circuit 87 receives the calculated control parameters, it outputs the calculated control parameters to the virtual synchronous generator control circuit 83 to update the control parameters. After the control parameters are updated, the eighth control circuit 87 clears (resets) the register (not shown) with the receive flag set via S217, causing the processing to return to S201.

[0458] As explained above, according to the distributed power system of Embodiment 1, even if the demand balance changes significantly after the operation plan (power target value) of the batteries 40a to 40c made by CEMS31 is immediately notified to the corresponding power conversion devices 41a to 41c, the distribution ratio of the output power of the power conversion devices 41a to 41c can be approximately equal to the ratio of the power target value when the operation plan was made.

[0459] Therefore, in cases where an operation plan (discharge plan) is created to make the SOC of batteries 40a to 40c approximately zero simultaneously after a few hours, or in cases where an operation plan (charging plan) is created to make batteries 40a to 40c approximately fully charged simultaneously, even if the power consumption of the load 600 or the power generated by the megawatt-class solar power plant 26 deviates significantly from the intended power at the time the operation plan was created, although the time deviates from the intended time, it is still possible to make the SOC of batteries 40a to 40c approximately zero simultaneously or to make batteries 40a to 40c approximately fully charged simultaneously, thus adhering to the intended operation plan.

[0460] Furthermore, in conventional virtual synchronous generator control technology, power conversion devices 41a to 41c equally share the insufficient power. Therefore, sometimes the power sharing ratio of power conversion device 41 with a relatively small power target value becomes high, and the corresponding battery 40 reaches zero SOC before the other batteries 40. In contrast, according to Embodiment 1, the insufficient power can be shared according to the power target value set in the operation plan, so the power sharing ratio of the battery 40 with a low SOC (i.e., a small power target value) can be suppressed to be low.

[0461] Implementation method 2.

[0462] In Implementation 1, the control circuit 83 (executed by CEMS31) for generating a virtual synchronous generator installed on the power conversion device 41 is described. Figure 11 The method for generating the information required for the control parameters of the power conversion device 41 and the control parameter generation circuit 88 ( Figure 11 The method for generating control parameters for execution.

[0463] In Embodiment 2, the problem of the control parameters generated in Embodiment 1 and its solution will be explained. Furthermore, in Embodiment 2, the operation of setting the slope of the reference ΔF / ΔP characteristic as the information generated by CEMS31 required for generating the control parameters will be explained.

[0464] Therefore, the structure of the CEMS31 involved in Embodiment 2 is the same as that of the CEMS31 involved in Embodiment 1, except that the control parameter generation circuit 13 ( Figure 5 ) and control parameter generation circuit 88 ( Figure 11 The processing differs. Hereinafter, the distributed power management device according to Implementation Method 2 will be described focusing on the operation of different parts.

[0465] Figure 42A as well as Figure 42B This is a diagram used to illustrate the problem of controlling the power conversion device 41 according to the control parameters for controlling the virtual synchronous generator, as described in Embodiment 1 above.

[0466] The following uses Figure 42A as well as Figure 42B This section explains the issue of the control parameters generated in Implementation Method 1. To simplify the explanation, we assume the case of using two power conversion devices 41 with equal inverter capacities Cinv.

[0467] The CEMS31 provides a power target value equivalent to 12.5% ​​of the inverter capacity for the first power conversion device 41, and the CEMS31 provides a power target value equivalent to 25% of the inverter capacity for the second power conversion device 41.

[0468] Furthermore, in Embodiment 1, the reference ΔF / ΔP characteristic and the horizontal axis of the ΔF / ΔP characteristic were described with the actual power (kW). However, in the following description, the horizontal axis is the result obtained by standardizing the charging and discharging power output from the power conversion device 41 with the inverter capacity of the power conversion device 41 (i.e., the capacity of the second DC / AC converter 408).

[0469] Figure 42A as well as Figure 42B The figures show the baseline ΔF / ΔP characteristics and the ΔF / ΔP characteristics of the power conversion device 41 manufactured under the above conditions. In each figure, the dashed line represents the baseline ΔF / ΔP characteristics, and the solid line represents the ΔF / ΔP characteristics.

[0470] exist Figure 42A The diagram shows the ΔF / ΔP characteristics of the first power conversion unit 41 when the power target value is 12.5% ​​of the inverter capacity. Figure 42B The diagram shows the ΔF / ΔP characteristics of the second power conversion device 41 when the power target value is 25% of the inverter capacity.

[0471] exist Figure 42A In the case where the frequency of the virtual synchronous generator control system decreases to Fref (reference frequency) - ΔFmax due to load fluctuations, the power that can be increased by the first power conversion device 41 becomes 12.5% ​​of the inverter capacity. That is, the power that can be covered by the first power conversion device 41 becomes up to 25% of the inverter capacity.

[0472] Similarly, in Figure 42B In this process, the power that can be increased by the second power conversion device 41 becomes up to 25% of the inverter capacity. That is, the power that can be covered by the second power conversion device 41 becomes up to 50% of the inverter capacity.

[0473] As described above, when the power target value notified to each power conversion device 41 is small, the power range that can cover load fluctuations or power generation fluctuations becomes narrower. Figure 42A as well as Figure 42B In the example, by changing the ΔF / ΔP characteristics of the first and second power conversion devices 41, it is possible, similar to Embodiment 1, to expand the range of power that can be covered when load or power generation changes occur while allocating power at a 2:1 ratio. Figure 43A as well as Figure 43B An example of this is shown in the figure.

[0474] Figure 43A as well as Figure 43B This example illustrates the case where the slope of the reference ΔF / ΔP characteristic of each power conversion device 41 is changed to generate the ΔF / ΔP characteristic. Figure 43A In the diagram, the dashed line represents the modified reference ΔF / ΔP characteristic of the first power conversion device 41. Figure 43B In the diagram, the dashed line represents the reference ΔF / ΔP characteristic of the modified second power conversion device 41. Figure 43A as well as Figure 43B Compared to Figure 42A as well as Figure 42B The slope of the baseline ΔF / ΔP characteristic becomes 1 / 2 times.

[0475] With this configuration, when the system frequency drops to Fref-ΔFmax, the first power conversion device 41 can control the increased power through a virtual synchronous generator to reach 25% of the inverter capacity. The increased power through the second power conversion device 41 can reach up to 50% of the inverter capacity. Thus, it can cope with load changes or power generation changes of up to 2 times.

[0476] Based on the above concepts, the operation of the distributed power system according to Embodiment 2 will be explained. In Embodiment 2, the information required for generating control parameters for virtual synchronous generator control will be explained, using the slope of the reference ΔF / ΔP characteristic.

[0477] Figure 44 This is a flowchart illustrating the process of generating the reference ΔF / ΔP characteristic performed by CEMS31. Furthermore, in Embodiment 2, in CEMS31, only the reference ΔF / ΔP characteristic calculation circuit 131 ( Figure 5 The ΔF / ΔP characteristic calculation circuit 132 does not operate. Therefore, a notification is sent to the data generation circuit 15. Figure 3 The information becomes the slope representing the reference ΔF / ΔP characteristic and the reference power command value used when generating the slope. Apart from this, the operation of CEMS31 is the same as that of CEMS31 according to Embodiment 1, so only the generation process of the reference ΔF / ΔP characteristic will be described below.

[0478] like Figure 44 As shown, after the start of processing, the reference ΔF / ΔP characteristic calculation circuit 131 ( Figure 5 The initial value is set via S056201. Specifically, the value of the register storing the maximum value of the power target value Pref output to the power conversion device 41 connected to the power distribution system 24, Pref_max, is cleared (Pref_max = 0). In addition, the number i of the power conversion device 41 connected to the power distribution system 24 is set to zero (i = 0).

[0479] exist Figure 44In the process, n (n≥2) power conversion devices 41 are connected to and operated by the power distribution system 24. In addition, the Pcs_no of the power conversion device 41 whose maximum value Pref_max of the power target value is stored is set to 0 (Pcs_no=0).

[0480] After initialization in S056201, the reference ΔF / ΔP characteristic calculation circuit 131 obtains the inverter capacity Cinv_i and the power target value Pref_i of the i-th power conversion device 41 through S056202.

[0481] In S056203, the reference ΔF / ΔP characteristic calculation circuit 131 compares the absolute values ​​of the inverter capacity Cinv obtained in S056202 and the power target value Pref_i. If the absolute value of the power target value Pref_i is greater than the inverter capacity Cinv_i ("Yes" in S056203), the reference ΔF / ΔP characteristic calculation circuit 131 changes the power target value Pref_i to the inverter capacity Cinv_i in S056204.

[0482] When the absolute value of the power target value Pref_i is less than or equal to the inverter capacity Cinv (as stated in S056203), or after the power target value Pref_i is changed to the inverter capacity Cinv, the reference ΔF / ΔP characteristic calculation circuit 131 divides the power target value Pref_i by the inverter capacity Cinv via S056205, thereby standardizing the power target value Pref_i using the inverter capacity Cinv. In the following description, the standardized power target value Pref_i will be referred to as Pref_temp.

[0483] After the standardization process is completed in S056205, the reference ΔF / ΔP characteristic calculation circuit 131 compares the absolute value of the standardized power target value Pref_temp with the maximum value of the power target value Pref_max in S056206. If the absolute value of Pref_temp is greater than or equal to Pref_max ("No" in S056206), in S056207, Pref_max is set to the absolute value of Pref_temp. Furthermore, Pcs_no is set to the current power conversion device 41 number i.

[0484] If the absolute value of Pref_temp is less than Pref_max ("Yes" in S056206) or after processing in S056207, the reference ΔF / ΔP characteristic calculation circuit 131 increments the number i of the power conversion device 41 by 1 (i = i + 1) via S056208.

[0485] In S056209, the reference ΔF / ΔP characteristic calculation circuit 131 determines whether the verification for all power conversion devices 41 of distributed power sources has been completed via S056202 to S056207. In S056209, it verifies whether i ≥ n. If the verification for all power conversion devices 41 of distributed power sources has not been completed ("No" in S056209), the process returns to S056202.

[0486] On the other hand, if the confirmation of the power conversion device 41 for all distributed power sources is completed ("Yes" in S056209), the reference ΔF / ΔP characteristic calculation circuit 131 determines in S056210 whether Pref_max is less than 0.5.

[0487] When Pref_max ≥ 0.5 ("No" in S056210), the reference ΔF / ΔP characteristic calculation circuit 131 sets the power target value (the command value normalized with inverter capacity) used when generating the reference ΔF / ΔP characteristic to 0.5. Therefore, the control parameters used in the virtual synchronous generator control circuit 83 are essentially the same as those described in Embodiment 1.

[0488] On the other hand, when Pref_max < 0.5 ("Yes" in S056210), the reference ΔF / ΔP characteristic calculation circuit 131 sets the power target value (the command value normalized with inverter capacity) used when generating the reference ΔF / ΔP characteristic to Pref_max via S056212.

[0489] Next, we will explain the case where the power target value (the command value normalized with inverter capacity) used when generating the baseline ΔF / ΔP characteristics is set to Pref_max. Figure 44 Method for generating the baseline ΔF / ΔP characteristics under (S056212).

[0490] The following uses Figure 45A as well as Figure 45B This section explains the baseline ΔF / ΔP characteristics and the method for generating the ΔF / ΔP characteristics involved in Implementation Method 2. Figure 45A as well as Figure 45B In this context, we envision the first power conversion device 41 and the second power conversion device 41 being connected to the power distribution system 24.

[0491] In the first power conversion unit 41, Cinv = 8kW, Pref = 2kW (command value normalized to inverter capacity = 0.25). In the second power conversion unit 41, Cinv = 4kW, Pref = 0.5kW (command value normalized to inverter capacity = 0.125). Therefore, according to Figure 44As shown in the process, Pref_max (the maximum value of the instruction value after normalization with inverter capacity) becomes the instruction value 0.25 in the first power conversion device 41.

[0492] In Embodiment 1 described above, the command value for generating the reference ΔF / ΔP characteristic is set to 0.5. Therefore, when the system frequency decreases by ΔFmax, the output power of the power conversion device 41 becomes the inverter capacity Cinv × 0.5. In contrast, in Embodiment 2, the command value for generating the reference ΔF / ΔP characteristic is 0.25.

[0493] exist Figure 45A The diagram shows the reference ΔF / ΔP characteristics (dashed line) and ΔF / ΔP characteristics (solid line) of the first power conversion device 41 according to Embodiment 2. Figure 45A The diagram also shows the ΔF / ΔP characteristics (single-dot dashed line) involved in Implementation 1. Figure 45A The horizontal axis represents the result of inverter capacity normalization, and the vertical axis represents the differential frequency ΔF with respect to the reference frequency Fref.

[0494] exist Figure 45A In the example, the command value for generating the baseline ΔF / ΔP characteristic is set to 0.25. This means that, compared to the case of Implementation 1, the slope of the baseline ΔF / ΔP characteristic is made 0.5 times (0.25 (command value for generating the baseline ΔF / ΔP characteristic) / 0.5 (command value for generating the original baseline ΔF / ΔP characteristic (Implementation 1)) times). Therefore, in Figure 45A In the case of a decrease in system frequency ΔFmax, the reference ΔF / ΔP characteristic is determined in such a way that the output power of the first power conversion device 41 becomes the inverter capacity Cinv.

[0495] Next, we will explain how to determine the slope of the ΔF / ΔP characteristic.

[0496] There are various methods for generating ΔF / ΔP characteristics. For example, one method describes the generation of ΔF / ΔP characteristics using the slope of the baseline ΔF / ΔP characteristic (or the command value used when generating the baseline ΔF / ΔP characteristic (0.25 in this example)), inverter capacity Cinv, system association information (system frequency, ΔFmax), and power target value Pref as control parameters for virtual synchronous generator control.

[0497] When the slope of the reference ΔF / ΔP characteristic is received as a control parameter, firstly, the slope of the reference ΔF / ΔP characteristic with an instruction value of 0.5, as described in Embodiment 1, is calculated. Furthermore, the slope of the received reference ΔF / ΔP characteristic is divided by the slope of the reference ΔF / ΔP characteristic with an instruction value of 0.5, and based on the division result, the instruction value used when determining the reference ΔF / ΔP characteristic using CEMS31 (0.25 in this example) is calculated.

[0498] Next, based on the baseline ΔF / ΔP characteristic when the instruction value is set to 0.5, the slope of the ΔF / ΔP characteristic is calculated using the generation method described in Implementation Method 1. For example, in Figure 45A In the example, the slope becomes twice that of the baseline ΔF / ΔP characteristic when the command value is set to 0.5. This slope is equivalent to 0.5 (the command value used to generate the baseline ΔF / ΔP characteristic) / 0.25 (the result of normalizing by dividing the power target value notified from CEMS31 by the inverter capacity). Moreover, the slope of the baseline ΔF / ΔP characteristic is calculated by making this slope half of (0.25 (the command value used to generate the baseline ΔF / ΔP characteristic) / 0.5 (the command value used to generate the baseline ΔF / ΔP characteristic)). Regarding the slope of the ΔF / ΔP characteristic obtained from its calculation result, when the system frequency decreases by ΔFmax, half of the output inverter capacity Cinv (4kW) is achieved. Furthermore, in the generation method of Embodiment 1, the output of the first power conversion device 41 becomes 2kW.

[0499] exist Figure 45B The reference ΔF / ΔP characteristic (dashed line) and the ΔF / ΔP characteristic (solid line) of the second power conversion device 41 are shown in the figure. Figure 45B The diagram also shows the ΔF / ΔP characteristics (single-dot dashed line) involved in Implementation 1. Figure 45B The horizontal axis represents the result of inverter capacity normalization, and the vertical axis represents the differential frequency ΔF with respect to the reference frequency Fref.

[0500] exist Figure 45B In the example, the ΔF / ΔP characteristic of the second power conversion device 41 is generated by dividing the power target value Pref notified from CEMS31 by the inverter capacity Cinv, resulting in a value of 0.25. Specifically, with Figure 45A Similarly, based on the baseline ΔF / ΔP characteristic generated by setting the instruction value to 0.5, the slope of the ΔF / ΔP characteristic is calculated using the generation method described in Implementation 1.

[0501] More specifically, the slope becomes 4 times the baseline ΔF / ΔP characteristic when the command value is set to 0.5 (0.5 (the command value used when generating the baseline ΔF / ΔP characteristic) / 0.125 (the result of normalizing the power target value notified from CEMS31 by the inverter capacity)). Furthermore, the slope of the baseline ΔF / ΔP characteristic is calculated by making this slope 1 / 2 times (0.25 (the command value used when determining the baseline ΔF / ΔP characteristic) / 0.5 (the command value when generating the baseline ΔF / ΔP characteristic)).

[0502] Regarding the slope of the ΔF / ΔP characteristic calculated from the results, when the system frequency decreases by ΔFmax, the output inverter capacity (4kW) is 1 / 4 (1kW). Furthermore, in the generation method described in Embodiment 1, the output power of the second power conversion device 41 becomes 0.5kW. Therefore, by generating the baseline ΔF / ΔP characteristic using the generation method described in Embodiment 2, it is possible to double the output power of the second power conversion device 41 (from 2.5kW to 5.0kW) in response to load variations or power generation variations.

[0503] Next, use Figure 46 as well as Figure 47 This describes the operation of the fourth control circuit 409 using the method for generating the reference ΔF / ΔP characteristics according to Embodiment 2.

[0504] Figure 46 This is a flowchart centered on the operation of the fourth control circuit 409.

[0505] like Figure 46 As shown, after the operation of the power conversion device 41 begins, the fourth control circuit 409 initializes various control parameters in S200 by setting various control parameters to predetermined initial values.

[0506] After initialization is completed via S200, the 8th control circuit 87, in S201, similarly to Embodiment 1, collects the measured voltages of voltmeters 401, 406, and 410, the measured currents of ammeters 402, 407, and 411, and the current status information (SOC, etc.) of the battery 40. Based on the collected data, the 7th control circuit 74 ( Figure 10 The charging and discharging power calculation circuit (not shown) within the battery 40 calculates the charging and discharging power and the charging and discharging force. The waveform of the AC system voltage of the power distribution system 24, measured by the voltmeter 410, is input to the AC frequency detection circuit 81.

[0507] In S202, the AC frequency detection circuit 81 detects the zero-crossing point of the AC system voltage. The method for detecting the zero-crossing point is the same as that described in Embodiment 1, so it is omitted. If a zero-crossing point of the AC system voltage is detected ("Yes" in S202), the AC frequency detection circuit 81 sets a zero-crossing point detection flag in S203.

[0508] If no zero-crossing point is detected ("No" in S202) or if a zero-crossing point detection flag is set (S203), the fourth control circuit 409 controls the second DC / AC converter 408 via S204. Furthermore, the control operation of the second DC / AC converter 408 is the same as the control operation in Embodiment 1 (see...). Figure 40 Since they are the same, the explanation is omitted.

[0509] Next, refer to Figure 13 This indicates the operation of the inverter voltage control circuit 85.

[0510] Inverter voltage control circuit 85 controls the voltage from virtual synchronous generator control circuit 83. Figure 11 The frequency and phase information output from the 8th control circuit 87 ( Figure 11 The amplitude information of the output system voltage is used to generate control command values ​​for controlling the second DC / AC converter 408. In addition, the amplitude information of the AC system voltage from the eighth control circuit 87 is input to the inverter voltage control circuit 85 via the second sine wave generation circuit 812.

[0511] From AC frequency detection circuit 81 ( Figure 11 The sine wave information (frequency, phase, and amplitude information) is input to the third sine wave generation circuit 851. However, in embodiment 2, QV control is not performed in the control circuit 83, so the amplitude information is not controlled.

[0512] The third sine wave generation circuit 851 generates the target value of the AC voltage output from the second DC / AC converter 408 based on the input sine wave information.

[0513] Subtractor 852 calculates the target value of the AC voltage from the third sine wave generation circuit 851 and the deviation of the voltage measured by voltmeter 410, and outputs the calculated deviation to the third PI control circuit 853.

[0514] The third PI control circuit 853 generates a voltage command value by performing PI (proportional-integral) calculations in a manner that makes the input deviation zero. The third PI control circuit 853 outputs the generated voltage command value to the first current limiting circuit 855.

[0515] As described in Embodiment 1, the first current limiting circuit 855 applies a limit to the voltage command value output from the third PI control circuit 853 based on the measurement result of the ammeter 411 input via the eighth control circuit 87. Specifically, the first current limiting circuit 855 limits the voltage command value when a current exceeding the current capacity of the second DC / AC converter 408 flows, thereby controlling the current flowing through the second DC / AC converter 408 to be below a predetermined current value (e.g., the current capacity of the second DC / AC converter 408). The output of the first current limiting circuit 855 is input to the second PWM converter 854.

[0516] The second PWM converter 854 generates a control signal by performing PWM control using the voltage command value output from the first current limiting circuit 855. The second PWM converter 854 outputs the generated control signal to the second DC / AC converter 408.

[0517] Return to Figure 46 After S204, virtual synchronous generator control is performed in S205. In Embodiment 2, similarly to Embodiment 1, one cycle of the AC system voltage is set as the control cycle. Furthermore, the control cycle can be an integer multiple of the AC system voltage cycle or a predetermined cycle such as 1 second.

[0518] use Figure 14 The block diagram of the virtual synchronous generator control circuit 83 shown illustrates the virtual synchronous generator control (…). Figure 46 (S205).

[0519] 8th control circuit 87 ( Figure 11 Upon determining that the control timing has been reached, the virtual synchronous generator control circuit 83 is instructed to generate information related to the frequency and phase used in voltage control. In embodiment 2, at the zero-crossing point, the third sine wave generation circuit 851 within the inverter voltage control circuit 85 is updated. Figure 13 The frequency and phase of the generated sine wave. Therefore, in Embodiment 2, the control period becomes the period of the zero-crossing point detected by the AC frequency detection circuit 81.

[0520] Subtractor 832 is derived from AC frequency detection circuit 81 ( Figure 11 The measured value of the frequency of the input AC system voltage is subtracted from the reference frequency Fref (e.g., 60Hz) input from the 8th control circuit 87, and the subtraction result is output to the speed controller control circuit 833. Figure 15 ).

[0521] In the speed controller control circuit 833, multiplier 91 corresponds to subtractor 832. Figure 14The output of the multiplier 91 is multiplied by the control parameter (-1 / Kgd) notified from the 8th control circuit 87. The multiplier 91 inputs the multiplication result to the first-order delay system model 92.

[0522] Furthermore, the speed regulation rate Kgd and the speed governor time constant Tg used in the speed governor control circuit 833 are set into a register (not shown) by the control parameter generation circuit 88 based on the information required for generating control parameters notified from CEMS31 (the slope of the reference ΔF / ΔP characteristic), inverter capacity, power target value, and system information.

[0523] As described above, the single-delay system model 92 performs a calculation using the time constant Tg notified from the 8th control circuit 87 to simulate the single-delay system (1 / (1+s×Tg)), and outputs the calculation result to the limiter circuit 93. The limiter circuit 93 imposes a limit on the input data.

[0524] Adder 835 ( Figure 14 The output of the speed governor control circuit 833 and the power target value Pref output from the 8th control circuit 87 are added together. Furthermore, regarding the power target value Pref, the 8th control circuit 87 outputs parameters notified from CEMS31.

[0525] Subtractor 836 subtracts from the output of adder 835 the output of effective power calculation circuit 82. Figure 11 The effective power output is calculated, and the subtraction result is output to the quality system arithmetic circuit 837. Figure 16 ).

[0526] In the quality system operation circuit 837 ( Figure 16 In subtractor 101, subtractor 836 ( Figure 14 The output of the multiplier 103 is subtracted from the output of the multiplier 103, and the subtracted value is output to the integrator 102.

[0527] Integrator 102 divides the subtraction result of subtractor 101 by the inertia constant M output from control circuit 87, and integrates the division result. The output Δω of integrator 102 is equivalent to the difference between the angular velocity (2×π×60Hz) relative to the frequency of the AC voltage. The output Δω of integrator 102 is input to multiplier 103 and divider 104.

[0528] Multiplier 103 multiplies the output Δω of integrator 102 and the damping coefficient Dg provided from the 8th control circuit 87, and outputs the multiplication result to subtractor 101.

[0529] Divider 104 transforms Δω, the output of integrator 102, into a differential frequency Δf with the reference frequency Fref (60Hz) by dividing Δω by 2×π. Adder 105 adds the output Δf of divider 104 to the reference frequency Fref (60Hz) to generate a frequency for use in inverter voltage control circuit 85. Figure 11 The frequency (Fref+Δf) used for voltage control in )

[0530] Furthermore, regarding the inertia constant M and damping coefficient Dg used in the mass system operation circuit 837, the parameters generated by the control parameter generation circuit 88 based on the information required for generating the control parameters (the slope of the reference ΔF / ΔP characteristic) generated by the control parameter generation circuit 88 through CEMS31 according to the above points are set to a register (not shown) via the 8th control circuit 87, and the parameters set to the register are used.

[0531] The frequency information (Fref+Δf) output from adder 105 is input to phase calculation circuit 106. The phase calculation circuit 106 integrates this frequency information and outputs it as the phase information when the inverter voltage control circuit 85 performs voltage control.

[0532] From the quality system operation circuit 837 ( Figure 16 The phase and frequency information output are processed by the second sine wave generation circuit 812 within the AC frequency detection circuit 81. Figure 12 The input is given to the third sine wave generation circuit 851 within the inverter voltage control circuit 85. Figure 13 The third sine wave generation circuit 851 generates the target value of the AC voltage output from the power conversion device 41 based on the input information.

[0533] Return to Figure 46 After the virtual synchronous generator control process in S205 is completed, the fourth control circuit 409 confirms in S206 whether a transmission request for measurement data has been received from CEMS31. If a transmission request has been received from CEMS31 ("Yes" in S206), the eighth control circuit 87 ( Figure 11 The measurement data is transmitted via communication I / F412 through S207. Figure 7 Notify CEMS31.

[0534] On the other hand, if the measurement data is notified in S207 or if no transmission request is received from CEMS31 ("No" in S206), the 8th control circuit 87 enters S208 to confirm whether control information has been received from CEMS31.

[0535] If control information is received from CEMS31 (Yes in S208), the 8th control circuit 87 sets the control information reception flag in S209. If the process in S209 ends or if no control information is received from CEMS31 (No in S208), the 8th control circuit 87 checks in S210 whether a zero-crossing detection flag is set. If the zero-crossing detection flag is not set (No in S210), the process returns to S201.

[0536] On the other hand, when a zero-crossing point detection flag is set ("Yes" in S210), the second sine wave generation circuit 812 (…) is activated via S211. Figure 12 The frequency and phase information of the AC system voltage are acquired, and the zero-crossing detection flag is reset in S212.

[0537] After resetting the zero-crossing detection flag in S212, the second sine wave generation circuit 812 updates the frequency and phase information of the AC system voltage (zero-crossing time information in Implementation 2) to the information taken in S211 via S213.

[0538] After the processing in S213 is completed, the 8th control circuit 87 checks in S214 whether control information has been received from CEMS31 (whether a control information reception flag is set). If the reception flag is not set ("No" in S214), the processing returns to S201.

[0539] On the other hand, when the receiving flag is set ("Yes" in S214), the 8th control circuit 87 replaces the frequency target value (reference frequency Fref) and the power target value Pref with the received data in S215. The control parameter generation circuit 88 generates the control parameters (speed regulation rate Kgd, damping coefficient Dg, and inertia constant M) for the virtual synchronous generator control in S220.

[0540] Figure 47 This illustrates the process of generating control parameters. Figure 46 The flowchart of S220 is described below. In Embodiment 2, the slope of the reference ΔF / ΔP characteristic is described as the information required for generating control parameters for virtual synchronous generator control from CEMS31. Furthermore, in Embodiment 2, in addition to the slope of the reference ΔF / ΔP characteristic, the system information (reference frequency Fref, power target value Pref, ΔFmax information) and inverter capacity Cinv are used to generate the control parameters as the information required for generating the control parameters.

[0541] After the processing begins, the control parameter generation circuit 88 within the fourth control circuit 409 generates the reference ΔF / ΔP characteristic in S2201. Figure 48 This illustrates the process for generating the baseline ΔF / ΔP characteristics. Figure 47 The flowchart of S2201).

[0542] like Figure 48 As shown, after the processing begins, the control parameter generation circuit 88 collects the capacity information (Cinv) of the static inverter of the second DC / AC converter 408 from the eighth control circuit 87 via S05621.

[0543] After collecting the capacity information (Cinv) of the static inverter, the control parameter generation circuit 88 collects system information (ΔFmax) from the eighth control circuit 87 via S05622. Next, the control parameter generation circuit 88 uses the generation method described in Embodiment 1 via S05623 to calculate the slope of the reference ΔF / ΔP characteristic based on the inverter capacity Cinv and ΔFmax. In Embodiment 2, the slope of the reference ΔF / ΔP characteristic generated using the method described in Embodiment 1 is referred to as "the slope of the reference ΔF / ΔP characteristic that becomes the reference".

[0544] Specifically, when the battery 40 is in charging or discharging mode, the slope of the reference ΔF / ΔP characteristic, which will serve as the reference, is set to -ΔFmax / (Cinv×0.5). On the other hand, when the battery 40 is in charging or discharging mode, the slope of the reference ΔF / ΔP characteristic, which will serve as the reference, is set to -ΔFmax / Cinv.

[0545] Furthermore, regarding the reference ΔF / ΔP characteristic for which discharge mode (or charging mode) and charge / discharge mode to adopt, the 8th control circuit 87 determines this based on the power target value notified from the CEMS 31 and notifies the control parameter generation circuit 88. Specifically, if the absolute value of the set power target value is less than a predetermined value, the 8th control circuit 87 adopts the charge / discharge mode.

[0546] After calculating the slope of the reference ΔF / ΔP characteristic as a reference in S05623, the control parameter generation circuit 88 obtains the slope of the reference ΔF / ΔP characteristic notified from CEMS31 from the 8th control circuit 87 via S056231.

[0547] The control parameter generation circuit 88 calculates the command value used by CEMS31 when generating the reference ΔF / ΔP characteristic according to the above points, based on the slope of the obtained reference ΔF / ΔP characteristic and the slope of the reference ΔF / ΔP characteristic generated as a reference in S05623. Specifically, it is calculated by (command value used by CEMS31 when generating the reference ΔF / ΔP characteristic) = (slope of the reference ΔF / ΔP characteristic received from CEMS31) / (slope of the reference ΔF / ΔP characteristic calculated as a reference in S05623) × (command value used when calculating the slope of the reference ΔF / ΔP characteristic as a reference (0.5 in embodiment 2)).

[0548] Return to Figure 47 After the generation of the reference ΔF / ΔP characteristic in S2201 (the generation of the instruction value used when generating the reference ΔF / ΔP characteristic from CEMS31) is completed, the control parameter generation circuit 88 generates the ΔF / ΔP characteristic through S2202. Figure 49 This illustrates the process for generating the ΔF / ΔP characteristics. Figure 47 The flowchart of S2202).

[0549] like Figure 49 As shown, after the processing begins, the control parameter generation circuit 88 obtains the parameters in S05630. Figure 47 The command values ​​calculated in S2201 and used by CEMS31 when generating the baseline ΔF / ΔP characteristics.

[0550] In S05631, the control parameter generation circuit 88 obtains the control command value (power target value) notified from CEMS31 via the 8th control circuit 87. In S05632, the control parameter generation circuit 88 determines whether the collected power target value does not exceed the inverter capacity Cinv. If the power target value exceeds the inverter capacity Cinv ("No" in S05632), the ΔF / ΔP characteristic calculation circuit 132 limits the power target value to the inverter capacity Cinv via a limiter in S05633.

[0551] The control parameter generation circuit 88 calculates the slope of the ΔF / ΔP characteristic using S05634. Specifically, firstly, based on the slope of the reference ΔF / ΔF characteristic (the command value when generating the reference ΔF / ΔP characteristic is 0.5), the slope of the same ΔF / ΔP characteristic as in Embodiment 1 is calculated. In the following description, for ease of explanation, the ΔF / ΔP characteristic identical to that in Embodiment 1 will be referred to as the "intermediate ΔF / ΔP characteristic".

[0552] Next, the slope of the ΔF / ΔP characteristic is calculated using the instruction value used in generating the baseline ΔF / ΔP characteristic in CEMS31 obtained in S05631, the instruction value used in calculating the baseline ΔF / ΔP characteristic that becomes the baseline (0.5 in Implementation 2), and the slope of the intermediate ΔF / ΔP characteristic.

[0553] The slope of the ΔF / ΔP characteristic is calculated as follows: (slope of the intermediate ΔF / ΔP characteristic) × (instruction value used when generating the baseline ΔF / ΔP characteristic in CEMS31) / (instruction value used when calculating the baseline ΔF / ΔP characteristic that becomes the baseline (0.5 in Implementation 2)).

[0554] Return to Figure 47 After generating the ΔF / ΔP characteristic in S2202, initial values ​​are set for the speed regulation rate Kgd and the damping coefficient Dg in S2203. Furthermore, in S2204, the slope of the ΔF / ΔP characteristic is calculated based on the speed regulation rate Kgd and the damping coefficient Dg. In Embodiment 2, the control parameter generation circuit 88 (…) is described similarly to Embodiment 1. Figure 11 ) Install simulated virtual synchronous generator control circuit 83 ( Figure 11 The virtual synchronous generator model of the operation is used to generate control parameters. However, the method for generating control parameters is not limited to this.

[0555] In S2204, a virtual synchronous generator model is used to generate the speed regulation rate Kgd and damping coefficient Dg, which determine the slope of the ΔF / ΔP characteristics. Specifically, by inputting the set speed regulation rate Kgd and damping coefficient Dg into the virtual synchronous generator model, for example, calculations are performed from the quality system calculation circuit 837 when a load variation of 25% of the inverter capacity is input. Figure 14 The system frequency is output. The differential frequency ΔF is calculated by subtracting the reference frequency Fref from this calculation result. Furthermore, the slope of the ΔF / ΔP characteristic is calculated by dividing the calculated ΔF by the load variation.

[0556] After calculating the slope of the ΔF / ΔP characteristic in S2204, the control parameter generation circuit 88 compares the calculated slope of the ΔF / ΔP characteristic with the slope of the ΔF / ΔP characteristic generated in S2202 in S2205. Specifically, the control parameter generation circuit 88 confirms whether the deviation between the slopes of these two ΔF / ΔP characteristics falls within a predetermined allowable range.

[0557] If the slope deviation falls within the above-mentioned allowable range, the control parameter generation circuit 88 determines that the slopes of the two ΔF / ΔP characteristics are consistent ("Yes" in S2205), and causes the process to proceed to S2211.

[0558] On the other hand, if the slope deviation does not fall within the aforementioned allowable range, the control parameter generation circuit 88 determines that the slopes of the two ΔF / ΔP characteristics are inconsistent ("No" in S2205). In this case, the control parameter generation circuit 88 proceeds to S2206 and changes the damping coefficient Dg. In Embodiment 2, the control parameter generation circuit 88 adds a predetermined value to the current damping coefficient Dg.

[0559] After changing the damping coefficient Dg in S2206, the control parameter generation circuit 88 confirms in S2207 whether the damping coefficient Dg has entered a predetermined range. If the damping coefficient Dg enters the predetermined range ("Yes" in S2207), the control parameter generation circuit 88 returns to S2204 and uses the changed damping coefficient Dg to calculate the slope of the ΔF / ΔP characteristic.

[0560] On the other hand, if the damping coefficient Dg exceeds the predetermined range ("No" in S2208), the control parameter generation circuit 88 determines that an appropriate characteristic cannot be obtained under the current speed adjustment rate Kgd, and returns the damping coefficient Dg to its initial value through S2208, and changes the speed adjustment rate Kgd. Specifically, the control parameter generation circuit 88 adds a predetermined value to the current speed adjustment rate Kgd (initial value).

[0561] After changing the speed adjustment rate Kgd in S2208, the control parameter generation circuit 88 checks in S2209 whether the speed adjustment rate Kgd has entered a predetermined range. If the speed adjustment rate Kgd is outside the predetermined range ("No" in S2209), the control parameter generation circuit 88 proceeds to S2210, considering that an appropriate speed adjustment rate Kgd and damping coefficient Dg have not been determined, and sets the speed adjustment rate Kgd and damping coefficient Dg to their respective pre-prepared default values, causing the process to proceed to S2211.

[0562] On the other hand, if the speed regulation rate Kgd is within the predetermined range in S2209 ("Yes" in S2209), the control parameter generation circuit 88 returns to S2204 and calculates the slope of the ΔF / ΔP characteristic using the changed speed regulation rate Kgd and damping coefficient Dg. The control parameter generation circuit 88 repeatedly executes the processing of S2204 to S2209 until it determines "Yes" in S2205 or "No" in S2209.

[0563] Furthermore, if the speed regulation rate Kgd and damping coefficient Dg are set to default values ​​in S2210, even if load changes occur, the insufficient power cannot be amortized according to the power ratio based on the operation plan.

[0564] In Implementation 2, similarly to Implementation 1, according to Figure 19 The relationship between the damping coefficient Dg and the frequency of the AC system voltage is shown. The damping coefficient Dg and the speed regulation rate Kgd can be calculated. Alternatively, based on... Figure 18 The relationship between the speed regulation rate Kgd and the frequency of the AC system voltage is shown. Calculate the damping coefficient Dg and the speed regulation rate Kgd.

[0565] After setting the speed regulation rate Kgd and the damping coefficient Dg, the control parameter generation circuit 88 calculates the inertia constant M via S2211. The inertia constant M is calculated based on the required response time in the virtual synchronous generator control. Specifically, the response performance of the virtual synchronous generator control is determined by the governor control circuit 833 (…). Figure 14 The governor time constant Tg and the mass system calculation circuit 837 derived from the swing equation. Figure 14 The time constant M / Dg is determined by the speed governor. In Embodiment 1, the default value of the speed governor time constant Tg is used, and the speed governor time constant Tg is not generated, so only the time constant of the mass system operation circuit 837 is controlled. According to the above formula (3), the time constant of the mass system operation circuit 837 is obtained by M / Dg. Therefore, in Embodiment 1, the inertia constant M is calculated by multiplying the time constant of the mass system operation circuit 837, which is determined by the default value, by the damping coefficient Dg.

[0566] Return to Figure 46 After the control parameters (speed adjustment rate Kgd, damping coefficient Dg, and inertia constant M) are calculated in S220, the control parameter generation circuit 88 notifies the 8th control circuit 87 of this information and outputs the calculated control parameters.

[0567] After receiving the calculated control parameters, the 8th control circuit 87 updates the control parameters by outputting them to the virtual synchronous generator control circuit 83 via S216. After the control parameters are updated, the 8th control circuit 87 clears (resets) the register (not shown) with the receive flag set via S217, causing the processing to return to S201.

[0568] As explained above, the distributed power system according to Embodiment 2 has the effect of making the power distribution ratio of each power conversion device 41a to 41c approximately equal to the power target value at the time the operation plan created by CEMS31 was just notified to the power conversion devices 41a to 41c. This is even in cases where the demand balance changes significantly after the operation plan created by CEMS31 has just been notified to the power conversion devices 41a to 41c.

[0569] For example, in the case of an operation plan in which the SOC of the batteries 40a to 40c in the operation plan is approximately zero (during the discharge plan) or approximately fully charged at the same time after a few hours, although the time changes, the SOC can be approximately zero or fully charged at the same time, which has the effect of maintaining the intended operation plan.

[0570] Furthermore, it goes without saying that since each power conversion device 41 equally shares the differential power, the power sharing ratio of the power conversion device 41 with a small power target value becomes higher, and the SOC of the battery 40 becomes zero first. However, by applying this method, the insufficient power can be shared according to the original power target value ratio. Therefore, for example, with the battery 40 with a low SOC (small power target value), the power sharing can be suppressed to a low level.

[0571] Furthermore, the CEMS31 is configured to control the reference ΔF / ΔP characteristics based on the power target value notified to each power conversion device 41. Therefore, for example, when the power target value notified to each power conversion device 41 is small, in Embodiment 1, when there is a large load change or power generation change, the deviation of the system frequency becomes -Δfmax. The inverter capacity of the second DC / AC converter 408 is still insufficient to supply power but cannot output it. However, by controlling as described above, it has the effect of increasing the power that can be output from the second DC / AC converter 408 (see Figure 45).

[0572] Implementation method 3.

[0573] In Embodiment 2, the problem of control parameters for controlling the virtual synchronous generator generated in Embodiment 1 and the solution to this problem are explained. As a solution, a method for calculating the slope of the reference ΔF / ΔP characteristic generated by CEMS31, which is the information required for generating control parameters for controlling the virtual synchronous generator, is explained.

[0574] In Embodiment 3, other methods for determining the slope of the reference ΔF / ΔP characteristic and a method for calculating the slope of the reference ΔF / ΔP characteristic based thereon are explained. Therefore, the structure of CEMS31 in Embodiment 3 is basically the same as that of CEMS31 in Embodiment 2, except that the control parameter generation circuit 13 ( Figure 5 ) and control parameter generation circuit 88 ( Figure 11 The processing differs from that in the previous method. Hereinafter, implementation method 3 will be described focusing on the actions of the different parts.

[0575] Implementation 3 differs from Implementation 2 in that it determines whether to use a different numerical value than Implementation 1 to calculate the slope of the baseline ΔF / ΔP characteristic, and in the method of generating the instruction value used when generating the slope of the baseline ΔF / ΔP characteristic.

[0576] Specifically, in implementation 3, the calculation is performed by using the operation plan manufacturing circuit 14 ( Figure 3 The output notification to each power conversion device 41 is the average of the command values ​​that are normalized by dividing the power target value by the inverter capacity of the corresponding power conversion device 41. Furthermore, if the calculated average value is below a predetermined value, the command value used to calculate the slope of the reference ΔF / ΔP characteristic is generated as the average of the command values ​​that are normalized by dividing the power target value by the inverter capacity of each power conversion device 41.

[0577] Figure 50A as well as Figure 50B This is a diagram illustrating the reference ΔF / ΔP characteristics and the method for generating the ΔF / ΔP characteristics of the two power conversion devices 41 equipped with virtual synchronous generator control according to Embodiment 3. Hereinafter, the method for generating the control parameters for virtual synchronous generator control according to Embodiment 3 will be explained using FIG. 50.

[0578] exist Figure 50A In the first power conversion device 41, the inverter capacity is 8kW, and the power target value standardized using the inverter capacity is 0.6. Figure 50B In the second power conversion device 41, the inverter capacity is 4kW, and the power target value standardized using the inverter capacity is 0.1. Figure 50A In the diagram, a single-dotted line represents the ΔF / ΔP characteristic produced using the manufacturing method described in Embodiment 1. Figure 50B In the figure, the ΔF / ΔP characteristics produced by the manufacturing method according to Embodiment 1 are represented by a single-dot dash.

[0579] Next, the average of the command values ​​standardized by dividing the power target values ​​of the first and second power conversion devices 41 by the capacity of each inverter is (0.6 + 0.1) / 2 = 0.35. Therefore, in Embodiment 3, the command value generated when calculating the slope of the reference ΔF / ΔP characteristic is 0.35. Furthermore, the method for calculating the slope of the reference ΔF / ΔP characteristic is the same as in Embodiment 2, so the explanation is omitted.

[0580] exist Figure 50A In the diagram, the reference ΔF / ΔP characteristic of the first power conversion device 41 is represented by a dashed line. Figure 50BIn the figures, the reference ΔF / ΔP characteristics of the second power conversion device 41 are represented by dashed lines. Additionally, in each figure, the ΔF / ΔP characteristics are represented by solid lines when generating the control parameters of the virtual synchronous generator control circuit 83.

[0581] In addition, regarding Figure 50A The ΔF / ΔP characteristic shown imposes a limit when the differential power ΔP becomes more than 0.4 times the inverter capacity. This occurs because, since the original command value is 0.6, no more output power (output current) can be output at the point when the inverter has output a power less than 0.4 times its capacity.

[0582] Furthermore, in Embodiment 3, for convenience, the ΔF / ΔP characteristic is represented as a limit output of ΔP = 0.4, as shown by solid lines. However, in actual control, the first current limiting circuit 855 within the inverter voltage control circuit 85 (see reference 855) is used. Figure 11 as well as Figure 14 Output restrictions are implemented. Therefore, output from CEMS31 is not... Figure 50A The characteristics shown by the solid line are output as the slope of the baseline ΔF / ΔP characteristic or the information used to generate that slope, which is the information required to generate the slope of the ΔF / ΔP characteristic.

[0583] Here, I will briefly explain Figure 14 The operation of the first current limiting circuit 855 shown.

[0584] The first current limiting circuit 855 monitors the output of the ammeter 411 input via the eighth control circuit 87. If the AC current output from the second DC / AC converter 408 exceeds its current capacity, the first current limiting circuit 855 reduces the output current by limiting the current command value output to the second PWM converter 854. Through this control, the power output from the power conversion device 41 becomes as follows: Figure 50A The ΔF / ΔP characteristic is represented by solid lines.

[0585] Based on the above, a method for generating information required for the operation of the distributed power system involved in Embodiment 3, namely, the generation of control parameters for the virtual synchronous generator control in CEMS31, will be explained. In Embodiment 3, the slope of the reference ΔF / ΔP characteristic will be used as the information required for generating control parameters, similar to Embodiment 2.

[0586] Figure 51This is a flowchart illustrating the process for generating the baseline ΔF / ΔP characteristic within CEMS31. Furthermore, the operation of CEMS31 is the same as in Embodiment 2, except for the calculation of the baseline ΔF / ΔP characteristic; therefore, only the process for generating the baseline ΔF / ΔP characteristic will be described.

[0587] like Figure 51 As shown, after the start of processing, the reference ΔF / ΔP characteristic calculation circuit 131 ( Figure 5 In S056221, initial values ​​are set during generation. Specifically, Pref_avg, used when calculating the average of the command values ​​normalized to the inverter capacity of each of the second DC / AC converters 408, is initialized to zero when calculating the target power value output to the power conversion device 41 operating connected to the power distribution system 24. Furthermore, the number i of the power conversion device 41 operating connected to the power distribution system 24 is set to zero. Figure 51 In the process, n (n≥2) power conversion devices 41 are connected to the power distribution system 24 and operate.

[0588] After initialization is completed in S056221, in S056202, the inverter capacity Cinv_i and the power target value Pref_i of the i-th power conversion device 41 are obtained.

[0589] In S056203, the absolute values ​​of the inverter capacity Cinv_i obtained in S056202 and the power target value Pref_i are compared. If the absolute value of the power target value Pref_i exceeds the inverter capacity Cinv_i, then in S056204, the power target value Pref_i is changed to the inverter capacity Cinv_i.

[0590] If the absolute value of the power target value Pref_i is less than or equal to the inverter capacity Cinv_i (as indicated by "Yes" in S056203) or after processing in S056204, in S056222, the power target value Pref_i is standardized using the inverter capacity Cinv_i by dividing it by the inverter capacity Cinv_i. Hereinafter, the standardized power target value (Pref_i / Cinv_i) will be referred to as the "standardized command value". Furthermore, the absolute value of the standardized command value is added (integrated) to Pref_avg.

[0591] After the addition (integration) of the absolute value of the standardized instruction value is completed in S056222, in S056208, the number i of the power conversion device 41 is increased by 1 (i = i + 1).

[0592] In S056209, it is confirmed whether the power conversion device 41 of the distributed power source has been confirmed for all actions (i≥n). If the confirmation of the power conversion device 41 of the distributed power source has not been completed ("No" in S056209), return to S056202 and continue the process.

[0593] On the other hand, if the confirmation regarding all power conversion devices 41 of distributed power sources has been completed in S056209 ("Yes" in S056209), in S056223, the integral result (Pref_avg) is divided by the number of connected power conversion devices 41 n, and the division result is compared with 0.5. Furthermore, in Embodiment 3, the case of comparing the division result with 0.5 is described, but it is not limited to this; other values ​​are also possible. Additionally, this value (0.5) can, of course, be controlled by changing the number of connected power conversion devices 41 n.

[0594] If "No" is selected in S056223, in S056224, the instruction value used when generating the reference ΔF / ΔP characteristic is set to 0.5 in the same way as in Implementation 1, the reference ΔF / ΔP characteristic of the power conversion device 41 is generated, and the process ends.

[0595] On the other hand, if "yes" is indicated in S056223, in S056225, the instruction value used when generating the reference ΔF / ΔP characteristic will be set to Pref_avg / n, the reference ΔF / ΔP characteristic of the power conversion device 41 will be generated, and the process will end.

[0596] As explained above, according to the distributed power management device of Embodiment 3, even in cases where the demand balance changes significantly after the operation plan created by CEMS31 has just been notified to the power conversion devices 41a-41c (for example, a significant change in load power consumption or a significant change in the power generated by the megawatt-class solar power plant 26, resulting in a large change in demand and supply compared to the power expected when the operation plan was created), it has the effect of making the power distribution ratio of each power conversion device 41a-41c approximately equal to the power target value when the operation plan was created. For example, in the case where the operation plan is carried out in a manner that the SOC of the batteries 40a-40c in the operation plan is approximately zero (during the discharge plan) or approximately fully charged at the same time after a few hours, although the time varies, the SOC can be approximately zero or fully charged at the same time, thus maintaining the intended operation plan.

[0597] Furthermore, although it goes without saying that since each power conversion device 41 equally shares the differential power, the power sharing ratio of the power conversion device 41 with a small power target value becomes higher, and the state of charge (SOC) of the battery 40 becomes zero first, by applying this method, the insufficient power can be shared according to the original power target value ratio. Therefore, for example, with the battery 40 with a low SOC (small power target value), the power sharing can be suppressed to a low level.

[0598] Furthermore, the CEMS31 is configured to control the reference ΔF / ΔP characteristics based on the average value of the power target value standardized by the capacity of each inverter of each power conversion device 41. Therefore, for example, when the power target value notified to each power conversion device 41 is small, in Embodiment 1, even if the differential frequency ΔF becomes -ΔFmax, the inverter capacity of the second DC / AC converter 408 can still supply insufficient power but cannot output it. However, by controlling as described above, it has the effect of increasing the power that can be output from the second DC / AC converter 408.

[0599] Furthermore, regarding the effectiveness of Implementation Method 3, the more power conversion devices 41 operating in the power distribution system 24, the better the effect. For example, when the standardized power target values ​​are 0.6, 0.2, 0.1, 0.15, 0.25, and 0.3, the average value Pref_avg becomes 0.27, and the power range that can cope with load changes can be expanded by about 2 times (0.5 times / 0.27 times) when all the power conversion devices 41 have the same inverter capacity.

[0600] Implementation method 4.

[0601] In Embodiments 2 and 3, as a problem of control parameters for controlling the virtual synchronous generator generated in Embodiment 1 and its solution, a method for calculating the slope of the reference ΔF / ΔP characteristic generated by CEMS31 as information for generating control parameters for controlling the virtual synchronous generator is explained.

[0602] In Embodiment 4, other methods for determining the slope of the reference ΔF / ΔP characteristic and a method for calculating the slope of the reference ΔF / ΔP characteristic based thereon are explained. Therefore, the structure of the CEMS31 in Embodiment 4 is basically the same as that of the CEMS31 in Embodiment 3, except for the control parameter generation circuit 13 ( Figure 5 The processing and control parameter generation circuit 88 ( Figure 11 The processing is the same. Hereinafter, implementation method 4 will be described focusing on the actions of different parts.

[0603] Compared to embodiments 2 and 3, embodiment 4 differs in the conditions for determining whether to calculate the slope of the baseline ΔF / ΔP characteristic using a different value than that in embodiment 1, and in the method for generating the instruction value used when generating the slope of the baseline ΔF / ΔP characteristic.

[0604] Specifically, in implementation 4, circuit 14 is manufactured according to the operation plan. Figure 3 The output notifies each power conversion device 41 of the target power value, calculates the power fluctuation range that can be covered when the control parameters of the virtual synchronous generator control circuit 83 are generated according to the key points of Embodiment 1, and generates a reference ΔF / ΔP characteristic based on the calculation results. More specifically, the reference ΔF / ΔP characteristic is determined in a way that ensures the power fluctuation range that can be covered by the CEMS31. Hereinafter, using Figure 52A as well as Figure 52B An overview of implementation method 4 is provided.

[0605] Figure 52A as well as Figure 52B This diagram illustrates the reference ΔF / ΔP characteristics and the creation process of the ΔF / ΔP characteristics for the two power conversion devices 41 equipped with virtual synchronous generator control according to Embodiment 4. Hereinafter, using... Figure 52A as well as Figure 52B This describes the method for creating the control parameters used to control the virtual synchronous generator generated in Implementation Method 4.

[0606] exist Figure 52A In the first power conversion device 41, the inverter capacity is 8kW, and the power target value after standardization using the inverter capacity is 0.25. Figure 52B In the second power conversion device 41, the inverter capacity is 4kW, and the power target value after standardization using the inverter capacity is 0.125. Figure 52A In the diagram, a single-dotted line represents the ΔF / ΔP characteristic produced using the manufacturing method described in Embodiment 1. Figure 52B In the figure, the ΔF / ΔP characteristics produced by the manufacturing method according to Embodiment 1 are represented by a single-dot dash.

[0607] Next, based on the ΔF / ΔP characteristics calculated according to Embodiment 1 from the power target values ​​of the two power conversion devices 41, the reference ΔF / ΔP characteristics of Embodiment 4 are generated. Figure 52A As shown, the first power conversion device 41 can supply 2.0kW (8.0kW (inverter capacity) × 0.25 (target power value)) of insufficient power to accommodate load fluctuations and power generation fluctuations from the energy generation equipment. Figure 52BIn this configuration, the second power conversion device 41 can supply 0.5kW (4.0kW (inverter capacity) × 0.125 (target power value)) of insufficient power. Therefore, it can supply insufficient power up to a maximum of 2.5kW.

[0608] That is, the first and second power conversion devices 41 discharge 4kW and 1kW respectively, resulting in a system frequency of 60Hz-ΔFmax, which cannot be further reduced. Therefore, in embodiment 4, for load fluctuations and fluctuations in the generated power of the energy-generating equipment, the operation plan creation circuit 14 in CEMS31 (see reference) is used during operation plan creation to handle these fluctuations. Figure 3 The electrical force that needs to be covered in the virtual synchronous generator control is calculated. Furthermore, the control parameters of the virtual synchronous generator control circuit 83 are created based on this calculation result. More specifically, the configuration determines the reference ΔF / ΔP characteristics.

[0609] For example, an instruction is output from the operation planning circuit 14 in a manner that allows the two power conversion devices 41 to handle variations up to 4.0 kW.

[0610] In this case, the power coverage area calculated according to Embodiment 1 is increased by 1.6 times (4.0 / 2.5 times). Therefore, the slope of the reference ΔF / ΔP characteristic becomes 1 / 1.6 times. Thus, the command value for calculating the reference ΔF / ΔP characteristic becomes 0.3125 (=0.5 / 1.6).

[0611] exist Figure 52A as well as Figure 52B In the figures, the reference ΔF / ΔP characteristic involved in Embodiment 4 is represented by a dashed line. Furthermore, the method for calculating the slope of the reference ΔF / ΔP characteristic is the same as that in Embodiment 2, so its explanation is omitted. Additionally, in each figure, the solid line represents the ΔF / ΔP characteristic when generating the control parameters of the virtual synchronous generator control circuit 83.

[0612] Based on the above, the operation of the distributed power system in Implementation Method 4 will be explained. Hereinafter, a method for generating the information required to generate the control parameters for controlling the virtual synchronous generator generated by CEMS31 will be described.

[0613] In Embodiment 4, the slope of the baseline ΔF / ΔP characteristic is used as the information required for generating the control parameters, similar to Embodiments 2 and 3.

[0614] Figure 53This is a flowchart illustrating the process of generating the baseline ΔF / ΔP characteristic performed within CEMS31. Furthermore, the operation of CEMS31 is the same as in Embodiments 2 and 3, except for the calculation of the baseline ΔF / ΔP characteristic; therefore, only the process of generating the baseline ΔF / ΔP characteristic will be described.

[0615] like Figure 53 As shown, after the start of processing, the reference ΔF / ΔP characteristic calculation circuit 131 ( Figure 5 The initial values ​​for generation are set (S056241). Specifically, W_conver_sum, which is used to calculate the sum of the power target values ​​output to the power conversion devices 41 connected to and operating with the power distribution system 24, is initialized to zero. Additionally, the reference ΔF / ΔP characteristic calculation circuit 131 sets the number i of the power conversion devices 41 connected to and operating with the power distribution system 24 to zero. In this process, it is assumed that n (n≥2) power conversion devices 41 are connected to and operating with the power distribution system 24.

[0616] After initialization is completed in S056241, in S056202, the inverter capacity Cinv_i and the power target value Pref_i of the i-th power conversion device 41 are obtained.

[0617] In S056242, the absolute value of the power target value Pref_i obtained in S056202 is divided by the inverter capacity Cinv_i, and the result of this division is compared with 0.5. If the result of the comparison is greater than 0.5 ("No" in S056242), Temp is set to the inverter capacity Cinv_i - |Pref_i| by S056243.

[0618] On the other hand, if the division result is less than or equal to 0.5 ("Yes" in S056242), the absolute value of the power target value Pref_i is substituted into Temp in S056244. This is because, when using the reference ΔF / ΔP characteristic generated in Embodiment 1, when the power target value exceeds 0.5, when the virtual synchronous generator control circuit 83 controls the power conversion device 41 using the ΔF / ΔP characteristic generated based on the aforementioned power target value, the power output as a shortfall exceeds half the inverter capacity before the differential frequency ΔF becomes -ΔFmax. Therefore, Temp is substituted in such a way that the sum of |Pref_i| becomes the maximum value (i.e., the inverter capacity) of the power that can be output from the power conversion device 41.

[0619] In S056245, W_conver_sum = W_conver_sum + Temp is calculated. Then, in S056208, the number i of the power conversion device 41 is increased by 1 (i = i + 1).

[0620] After S056208 is completed, S056209 confirms whether all distributed power source power conversion devices 41 (i≥n) have been verified. If the verification of all distributed power source power conversion devices 41 has not been completed ("No" in S056209), return to S056202 and continue the process.

[0621] If, in S056209, the power conversion device 41 of the distributed power source completes the verification of all operations ("Yes" in S056209), in S056246, the addition result (W_conver_sum) is compared with that from the operation plan production circuit 14 (see reference). Figure 3 The predetermined value for notification. Furthermore, although the method for generating the predetermined value in the operation plan generation circuit 14 is not described in detail, it is configured, for example, in the power generation prediction circuit 142 (see reference). Figure 4 The database (not shown) within the system stores predicted values ​​for the power fluctuations of the megawatt-class solar power plant 26 caused by variations in solar radiation, and also stores predictions for the power consumption prediction circuit 143 (see reference). Figure 4 The predicted values ​​of load fluctuations are also pre-stored in a database (not shown), and the aforementioned predetermined values ​​can be generated based on these two predicted values.

[0622] If W_cover_sum is above a predetermined value ("No" in S056246), it is determined that the range of power fluctuations predicted by the operation plan generation circuit 14 can be covered. In S056247, the instruction value for calculating the slope of the reference ΔF / ΔP characteristic is set to 0.5 in the same way as in Implementation 1, and the generation process of the reference ΔF / ΔP characteristic ends.

[0623] On the other hand, if W_cover_sum is less than a predetermined value ("Yes" in S056246), the range of power fluctuations predicted by the operation plan generation circuit 14 cannot be covered, so an instruction value used when generating the reference ΔF / ΔP characteristic is generated (S056248). In embodiment 4, as in Figure 52A as well as Figure 52B The example illustrates that the generation process of the baseline ΔF / ΔP characteristic is completed by calculating the command value according to the following formula.

[0624] Command value = 0.5 / (Predetermined value notified from operation plan generation circuit 14 / W_conver_sum)

[0625] As explained above, the distributed power management device according to Embodiment 4 has the effect of making the power distribution ratio of each power conversion device 41a to 41c approximately equal to the power target value at the time the operation plan created by CEMS31 was just notified to the power conversion devices 41a to 41c. This is even in cases where the demand balance changes significantly after the operation plan created by CEMS31 has just been notified to the power conversion devices 41a to 41c.

[0626] For example, if an operation plan is carried out in such a way that the SOC of the batteries 40a to 40c in the operation plan becomes approximately zero (during the discharge plan) or approximately fully charged at the same time after a few hours, the SOC can become approximately zero or fully charged at the same time, even though the time changes, thus maintaining the intended operation plan.

[0627] Furthermore, it goes without saying that since each power conversion device 41 equally shares the differential power, the power sharing ratio of the power conversion device 41 with a small power target value becomes higher, and the SOC of the battery 40 becomes zero first. However, by applying this method, the insufficient power can be shared according to the original power target value ratio. Therefore, for example, with the battery 40 with a low SOC (small power target value), the power sharing can be suppressed to a low level.

[0628] Furthermore, the control uses CEMS31 to generate a reference ΔF / ΔP characteristic based on the over- or under-powered power when the differential frequency ΔF of the power target value notified to each power conversion device 41 becomes -ΔFmax. Therefore, the power range that can cover load variations and power generation variations can be specified by the operation planning circuit 14. This has the effect of generating control parameters within the virtual synchronous generator control circuit 83 in a way that covers the variation range predicted based on power generation prediction results and power consumption prediction results. Figure 52A as well as Figure 52B In the example, it can cover load variations of approximately 1.6 times.

[0629] As explained above, in the distributed power system according to embodiments 1 to 4, in a power distribution system 24 equipped with multiple power conversion devices 41 controlled by virtual synchronous generators, even if there are fluctuations in load power consumption or power generation fluctuations from energy-generating equipment such as the megawatt-level solar power station 26, the insufficient power can be covered by the power sharing ratio generated by the CEMS 31. For example, it has the effect of suppressing the imbalance of the power target value during operation planning when the load power consumption increases, and increasing the power sharing ratio of the power output of the power conversion device 41 with the smaller power target value compared to the power of other power conversion devices 41.

[0630] Furthermore, in embodiments 1 to 4, a portion of the functions installed in the CEMS31 are configured to be located on the power conversion device 41 side. For example, in the case where a virtual synchronous generator control is installed in a household battery installed in a general consumer, in embodiment 1, it is necessary to use the CEMS31 to generate control parameters for the virtual synchronous generator control of hundreds to thousands of household batteries. However, by installing a portion of the functions on the household battery side, it is possible to reduce the processing load on the CEMS31 side.

[0631] Furthermore, when the structures of the virtual synchronous generator control unit installed in the power conversion device 41 and the household storage battery differ, and when the control parameters are configured to be generated on the CEMS31 side, for example, multiple types need to be prepared. Figure 5 The virtual synchronous generator model shown, or when using the table data shown in Embodiment 2, requires multiple types of table data, and the number of control parameters generated also varies. Even in such cases, by configuring the control parameters to be generated on the power conversion device 41 or the household battery side, the processing on the CEMS 31 side can simplify this process.

[0632] Furthermore, in embodiments 1 to 4, the information required for generating control parameters of the virtual synchronous generator control circuit 83 within the power conversion device 41 includes information required for generating the reference ΔF / ΔP characteristic (slope information of the reference ΔF / ΔP characteristic, command value information used when generating the reference ΔF / ΔP characteristic, power target value, etc.), information required for generating the ΔF / ΔP characteristic (slope of the ΔF / ΔP characteristic, power target value), and system information (reference frequency, ΔFmax value, response time required in virtual synchronous generator control, etc.), but is not limited to these. For example, even if the configuration is to notify the value of the deviation (ΔFcalc) of the system frequency when the output of the power conversion device 41 changes by a predetermined value (ΔP_fix) or the excess or deficiency (ΔPcalc) of the power output from the power conversion device 41 when the deviation of the system frequency changes to a predetermined value (ΔF_fix), the slope of the ΔF / ΔP characteristic is calculated based on the notified information, and the control parameters of the virtual synchronous generator control circuit 83 are generated based on the calculation result, the same effect is achieved.

[0633] Furthermore, in embodiments 1 to 4, when an operation plan (power target value) is created for the power conversion device 41, control parameters for controlling the virtual synchronous generator installed in the static inverter are generated based on the capacity of the static inverter in each power conversion device 41 and the power target value. Therefore, even if the power consumption of the load changes (or changes drastically) or the power generation of energy-generating equipment such as the megawatt-class solar power plant 26 changes (or changes drastically) during the period until the CEMS31 notifies the next operation plan, the insufficient power can be shared with a sharing ratio that is approximately the same as the operation plan (power target value).

[0634] Therefore, even if, for example, solar radiation changes immediately after the operation plan is announced, and the power generation of the megawatt-class solar power plant 26 decreases by 50%, the shortfall of 50% of the power is shared according to the ratio of the target power value calculated when the operation plan was made. Thus, for example, if the plan is designed to make the State of Charge (SOC) approximately zero simultaneously by controlling the target power value when the operation plan is made according to this ratio, even if the power generation of the megawatt-class solar power plant 26 decreases by 50% due to changes in solar radiation, the shortfall of power is shared according to the ratio of the target power value, thus achieving the effect of controlling the SOC to approximately zero simultaneously.

[0635] Furthermore, while embodiments 1 to 4 describe the case where the virtual synchronous generator control is installed on the power conversion device 41, the method is not limited thereto. For example, the same effect is achieved even when the virtual synchronous generator control is installed on an energy-generating device such as a wind turbine. In particular, since a wind turbine uses a propeller to rotate a motor, it has inertial force on the generator side, thus achieving the same effect.

[0636] Furthermore, in embodiments 1-4, the case of installing several large-capacity batteries such as battery 40 in the power distribution system 24 was described. However, it is also possible to install virtual synchronous generator control in power conversion devices for household batteries or electric vehicles, implementing the same control as CEMS 31. In this case, the number of power conversion devices connected to the power distribution system 24 reaches several hundred. Therefore, even if the battery capacity is configured as large-capacity batteries such as battery 40 (e.g., several hundred kW to several mW) and household batteries (several kW), the same effect is achieved.

[0637] Furthermore, while the power conversion device 41 has been described in embodiments 1-4, it is not limited thereto. Similarly, in the case of installing a virtual synchronous generator control system to a system that uses a static inverter as a voltage source, such as one that supplies power from solar cells (not limited to megawatt-level solar power plants, but also residential solar cells), wind turbines, or fuel cells, the same effect can be obtained simply by configuring the control parameters for generating the virtual synchronous generator control. Furthermore, on-board batteries from electric vehicles (EVs), plug-in hybrid electric vehicles (PHEVs), or fuel cell vehicles (FCVs) can also be used.

[0638] Furthermore, in embodiments 1 to 4, for the sake of simplicity, the operation was explained using a power conversion device 41 of several kW, but it is not limited to this. Also, although the application to the power distribution system 24 was described, it is not limited to this; the same effect will certainly be achieved even when this technology is applied to power transmission systems or microgrids of independent systems.

[0639] Furthermore, implementation methods 1 to 4 are illustrated using three-phase AC as an example, but are not limited to this; of course, single-phase AC or single-phase three-wire AC can also be used.

[0640] Furthermore, even when a system-use battery power conversion device (three-phase AC) and a household battery system (single-phase AC) coexist, the same effect can be achieved as long as the control parameters are configured to generate the virtual synchronous generator control.

[0641] Furthermore, in embodiments 1 to 4, the case where the capacity of the static inverter and the power target value are used to calculate the control parameters for virtual synchronous generator control when generating control parameters for the static inverter in the power conversion device 41 is described. However, this is not limited to this. For example, even if the battery capacity of the battery 40a is twice that of the static inverter in the power conversion device 41a, and the battery capacity of the battery 40b is three times that of the static inverter in the power conversion device 41b, and the ratio of the battery capacity to the static inverter capacity is different, the same effect can be obtained by considering the above capacity ratio to generate the operation plan (power target value) or when generating the information required for generating control parameters for virtual synchronous generator control.

[0642] In embodiments 1 to 4, two scenarios were described: when the control parameters for virtual synchronous generator control are generated by the CEMS31, the information generated and sent by the CEMS31 is added to the power target value, and system information, information needed to generate the slope of the ΔF / ΔP characteristic, and information needed to generate the slope of the reference ΔF / ΔP characteristic are sent. However, it is not limited to these scenarios. As long as the configuration is such that the CEMS31 sends information that can generate control parameters in the power conversion device with the virtual synchronous generator control unit connected to the power distribution system 24, the same effect can be obtained.

[0643] In embodiments 1 to 4, the case where a virtual synchronous generator model is built in when determining the control parameters of the virtual synchronous generator control unit is described, or the case where a virtual synchronous generator model is built in. Figure 19 The relationship between the damping coefficient Dg and frequency is shown in a table, where multiple speed regulation values ​​Kgd are stored as data. Based on the ΔFmax information, a combination of speed regulation Kgd and damping coefficient Dg that approximately matches the slope of the ΔF / ΔP characteristic is retrieved. Figure 18 The relationship between the speed regulation rate Kgd and the frequency is shown as table data with the values ​​of multiple damping coefficients Dg. The combination of speed regulation rate Kgd and damping coefficient Dg that is approximately consistent with the slope of the ΔF / ΔP characteristic can be retrieved based on the ΔFmax information, but it is not limited to this. For example, it can also be done in other ways, such as by using a virtual synchronous generator control unit built into the formula model.

[0644] Furthermore, in embodiments 1 to 4, the case where the control parameters of the virtual synchronous generator control unit are determined by generating the ΔF / ΔP characteristics is described. However, this is not the only possibility. For example, it is also possible to install a power distribution system model (digital twin) of substation 20 or less within the CEMS31, and use this power distribution system model to generate the information needed to calculate each control parameter in a manner that allows it to operate optimally in the envisioned use case. Furthermore, it is also possible to install AI or similar devices to calculate the control parameters.

[0645] In embodiments 1 to 4, the communication cycle between CEMS31 and DSO21 is set to 30 minutes, and the communication cycle between CEMS31 and each power conversion device 41 is set to 5 minutes. However, it is not limited to this. For example, the communication cycle between CEMS31 and each power conversion device 41 can be set to 1 minute or further shortened.

[0646] In addition, in embodiments 1 to 4, the speed controller model in the speed controller control circuit 833 is modeled as a primary delay system, but it is not limited to this. Even if it is composed of a secondary delay system and an LPF (Low Pass Filter), it will achieve the same effect.

[0647] Furthermore, in embodiments 1 to 4, using Figure 16 The integrator and feedback loop shown are used to model the operational circuit of the mass system, but are not limited to this. For example, it can also be modeled using a first-order delay system, a second-order delay system, an LPF, etc.

[0648] Furthermore, in embodiments 1 to 4, for the sake of simplicity, VQ control, which is frequently implemented in virtual synchronous generator control, has been omitted. However, even if this method is applied to a power conversion device that is also equipped with VQ control as a virtual synchronous generator control, the same effect can certainly be obtained. Furthermore, the structure of the quality system calculation circuit 837 is not limited to... Figure 16 The structure shown.

[0649] Explanation of variations.

[0650] Furthermore, in embodiments 1 to 4, for ease of understanding, the control circuits for the power conversion device 27 for megawatt-class solar power plants and the power conversion device 41 for batteries are described as follows: Figures 6 to 16 The structure shown is as follows: Figures 3-5 The diagram shows the structure of CEMS31 constructed using hardware (H / W). However, even if the functions of each module or a portion of the modules described in each module are implemented using software (S / W) installed on the CPU (Central Processing Unit), the same control functions can still be achieved. Alternatively, the same control functions can be achieved by functionally dividing at least a portion of the modules through both software and hardware.

[0651] The embodiments disclosed herein should be considered illustrative and not restrictive in all respects. The scope of this disclosure is set forth in the claims, not in the foregoing description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A power conversion device, comprising: An inverter converts the electricity output from a distributed power source into AC power and outputs it to an AC system. as well as The control circuit controls the inverter. The control circuit includes: A virtual synchronous generator control circuit enables the inverter to possess the transient characteristics of a synchronous generator; A control parameter generation circuit generates control parameters for controlling the virtual synchronous generator control circuit. The inverter voltage control circuit controls the inverter as a voltage source based on the AC system voltage information input from the virtual synchronous generator control circuit; and The communication circuit receives the power target value of the distributed power source and the information required for generating the control parameters from the management device that manages the distributed power source. The control parameter generation circuit generates at least one of the speed regulation rate and damping coefficient used in the virtual synchronous generator control circuit, based on the power target value received by the communication circuit and the information required for generating the control parameters.

2. The power conversion device according to claim 1, wherein, The virtual synchronous generator control circuit includes: The speed governor control circuit simulates the speed governor function of the synchronous generator; and The mass system calculation circuit simulates the swing equation of the synchronous generator. The control parameters used to control the governor control circuit include the governor time constant, which determines the response performance of the synchronous generator, and the speed regulation rate. The control parameters used to control the operational circuit of the mass system include the inertial constant simulating the inertia of the mechanical rotor and the damping coefficient applying a damping force to the mechanical rotor.

3. The power conversion device according to claim 1, wherein, It also includes a voltmeter for measuring the AC system voltage of the AC system. The inverter voltage control circuit generates an AC voltage target value based on the AC system voltage information input from the virtual synchronous generator control circuit, and controls the inverter as the voltage source based on the generated AC voltage target value and the measured value of the voltmeter.

4. The power conversion device according to claim 2, wherein, It also includes a voltmeter for measuring the AC system voltage of the AC system. The inverter voltage control circuit generates an AC voltage target value based on the AC system voltage information input from the virtual synchronous generator control circuit, and controls the inverter as the voltage source based on the generated AC voltage target value and the measured value of the voltmeter.

5. The power conversion device according to claim 2, wherein, It also has: A voltmeter is used to measure the AC system voltage of the AC system. A galvanometer is used to measure the alternating current of the AC system. An effective power calculation circuit calculates the AC effective power based on the measurements from the voltmeter and the ammeter. as well as An AC frequency detection circuit detects the frequency and zero-crossing point or phase of the AC system voltage based on the voltmeter readings. The speed controller control circuit calculates the offset value applied to the target power value based on the reference frequency of the AC system voltage and the frequency of the AC system voltage detected by the AC frequency detection circuit, and outputs the calculation result to the quality system calculation circuit. The quality system calculation circuit generates the frequency and phase of the AC system voltage, which is output to the inverter voltage control circuit as AC system voltage information, based on the sum of the power target value and the offset value and the effective AC power.

6. The power conversion device according to claim 4, wherein, It also has: A galvanometer is used to measure the alternating current of the AC system. An effective power calculation circuit calculates the AC effective power based on the measurements from the voltmeter and the ammeter. as well as An AC frequency detection circuit detects the frequency and zero-crossing point or phase of the AC system voltage based on the voltmeter readings. The speed controller control circuit calculates the offset value applied to the target power value based on the reference frequency of the AC system voltage and the frequency of the AC system voltage detected by the AC frequency detection circuit, and outputs the calculation result to the quality system calculation circuit. The quality system calculation circuit generates the frequency and phase of the AC system voltage, which is output to the inverter voltage control circuit as AC system voltage information, based on the sum of the power target value and the offset value and the effective AC power.

7. The power conversion device according to claim 5 or 6, wherein, The inverter voltage control circuit includes a current limiting circuit that limits the AC current output by the inverter. The current limiting circuit limits the AC current output by the inverter when the measured value of the ammeter deviates from the preset current range.

8. The power conversion device according to any one of claims 1 to 6, wherein, The control parameter generation circuit generates the control parameters based on the inverter's capacity, specified information for connection to the AC system, the target power value received by the communication circuit, and the information required for generating the control parameters.

9. The power conversion device according to claim 8, wherein, The control parameter generation circuit generates a reference ΔF / ΔP characteristic, which represents the relationship between the deviation of the system frequency relative to the reference frequency of the AC system voltage (i.e., the differential frequency) and the deviation of the inverter's output power relative to the target power value (i.e., the differential power) when the multiplication value obtained by multiplying the inverter's capacity by a predetermined ratio is used as the target power value. Based on the generated baseline ΔF / ΔP characteristics and the power target value notified from the management device, ΔF / ΔP characteristics for controlling the inverter are generated. The control parameters are generated using the generated ΔF / ΔP characteristics.

10. The power conversion device according to any one of claims 1 to 6, wherein, The information required to generate the control parameters includes a baseline ΔF / ΔP characteristic or information required to generate the baseline ΔF / ΔP characteristic, or the ΔF / ΔP characteristic or information required to generate the ΔF / ΔP characteristic. The reference ΔF / ΔP characteristic represents the relationship between the deviation of the system frequency relative to the reference frequency of the AC system voltage (i.e., the differential frequency) and the deviation of the inverter's output power relative to the power target value (i.e., the differential power) when the multiplication value obtained by multiplying the inverter's capacity by a predetermined ratio is used as the power target value. The ΔF / ΔP characteristic represents the relationship between the deviation of the system frequency relative to the reference frequency (i.e., the differential frequency) and the deviation of the inverter's output power relative to the power target value notified from the management device (i.e., the differential power). The control parameter generation circuit generates the control parameters based on the power target value notified from the management device, the information required for generating the control parameters, and the capacity of the inverter.

11. The power conversion device according to claim 9, wherein, The control parameter generation circuit: Calculate the differential power of the inverter's output power relative to the target power value notified from the management device. Calculate the differential frequency relative to the differential frequency based on the ΔF / ΔP characteristic or the information required to generate the ΔF / ΔP characteristic. The control parameters are generated based on the calculated differential power and differential frequency.

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