Power supply system

Abstract

To provide a technique for suppressing and stabilizing voltage fluctuations when a power generation system and a storage battery system are interconnected to supply power to a load during stand-alone operation.SOLUTION: A power supply system includes a power generation system and a storage battery system in its configuration and is interconnected with a power grid and supplies power to a load. The power supply system is capable of supplying first AC power generated from power generated by the power generation system and second AC power generated from power stored in the storage battery system to the load during stand-alone operation. The power generation system is connected to the storage battery system via a power feeding path to which the load is connected, is interconnected with respect to an AC voltage output from the storage battery system, and outputs the first AC power on which a predetermined amount of reactive power is applied to the power feeding path. The storage battery system transmits an instruction signal to suppress the application of reactive power to the power generation system when the second AC power is output to the power feeding path connected to the load.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a power supply system including a power generation system and a battery system, and capable of supplying power from the power generation system and the battery system to a load during independent operation.

Background Art

[0002] Conventionally, a distributed power supply system including a power generation system using a solar power generation module or the like and a battery system, and operating in connection with a power grid to which commercial power is supplied is known (see, for example, Patent Document 1). The distributed power supply system is configured to store, for example, the generated power generated by the power generation system or the power supplied from the power grid during a time period such as at night when the cost is low, and supply the stored power to a load when necessary. The battery system includes, for example, a stationary battery device incorporating a battery module, and by adopting a portable battery mounted on an EV (Electric Vehicle), HV (Hybrid Vehicle), PHV (Plug-in Hybrid Vehicle), etc., a so-called V2H (Vehicle to Home) system or V2L (Vehicle to Load) system can be constructed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in distributed power systems, including power generation systems and battery storage systems, flicker may occur during independent operation in the event of a power outage. For example, this can occur when power generated by a power generation system and power stored in a battery storage system are connected and supplied to loads within a consumer's premises. When flicker occurs, for example, lighting may flicker, and there is a risk that home appliances installed in the consumer's premises may malfunction or break down.

[0005] This invention has been made in view of the above circumstances, and its purpose is to provide a technology that suppresses and stabilizes voltage fluctuations when a power generation system and a battery storage system are interconnected and supply power to a load during independent operation. [Means for solving the problem]

[0006] One form of disclosure technology to solve the above problems is, A power supply system comprising a power generation system and a battery storage system, which is connected to a power grid and supplies power to a load, wherein during independent operation, the power supply system is capable of supplying to the load a first AC power generated from the power generation system and a second AC power generated from the power stored in the battery storage system, The power generation system is connected to the battery system via a power supply path to which the load is connected, and is linked to the AC voltage output from the battery system, and outputs a first AC power to the power supply path to which a predetermined amount of reactive power is applied, When the battery storage system outputs the second AC power to the power supply path to which the load is connected, it transmits an instruction signal to the power generation system to suppress the application of the reactive power. It is characterized by the following:

[0007] As a result, in the distributed power system 300a, the power generation system 100 and the battery storage system 200 work together in conjunction to supply AC power to the load 350 during independent operation. In the power system 100, it becomes possible to suppress the amount of reactive power applied to determine the grid connection status. As a result, in the AC power supplied to the power supply path to which the load 350 is connected, disturbance currents caused by the amount of reactive power adjustment (applied amount) can be suppressed. In the distributed power system 300a, during standalone operation, voltage fluctuations when the power generation system 100 and the battery storage system 200 are connected and supply power to the load 350 can be suppressed and stabilized.

[0008] In one embodiment of the disclosed technology, the battery system may transmit an instruction signal to the power generation system to stop applying the reactive power. Upon receiving notification from the battery system 200, the power generation system 100 performs current control by setting the frequency deviation-based adjustment gain of the reactive power applied to determine the interconnection state with the second AC power output from the battery system 200 to the power supply path to "0", thereby generating the first AC power. Since no reactive power injection adjustment is performed on the first AC power output from the power generation system 100 to the power supply path, no disturbance current is generated.

[0009] In one embodiment of the disclosed technology, the battery system may transmit instruction signals to the power generation system that limit the upper and lower limits of the applied reactive power and suppress the degree of increase or decrease of the applied reactive power. Upon notification from the battery system 200, the power generation system 100 applies a gently sloping gain to the reactive power adjustment gain based on the frequency deviation, and current control is performed to limit the upper and lower limits of the injected reactive power to generate the first AC power. By making the slope of the reactive power gentler and limiting the upper and lower limits, changes in disturbance current in the first AC power output from the power generation system 100 to the power supply path can be suppressed to a certain extent, and changes in the tracking lag amount in the battery system 200 can be suppressed to a certain extent.

[0010] In one embodiment of the disclosed technology, the power generation system and the battery storage system are equipped with a control device connected via a communication network, the control device detecting a power outage or voltage fluctuation using physical quantities obtained from the power supply path to which the load is connected, and transmitting an instruction signal to the power generation system to suppress the application of reactive power. Even in such an embodiment, the power generation system 100 can suppress the amount of reactive power applied to determine the interconnection state with the second AC power output from the battery storage system 200 to the power supply path, in accordance with the instruction signal generated by the controller 340, which is a control device. In the distributed power supply system 300b, which is a power supply system, it becomes possible to relatively reduce the costs associated with adding or modifying the existing power generation system 100 and battery storage system 200.

[0011] In one embodiment of the disclosed technology, the physical quantities may include at least one of the following physical quantities in the power supply path: voltage, current, frequency, reactive power, or active power. Based on these physical quantities, the controller 340 can detect voltage fluctuations occurring in the power supply path and notify the power generation system 100 of an instruction to suppress the application of reactive power so that lighting installed in the customer's facilities does not flicker. The controller 340 can generate an instruction to suppress the application of reactive power that appropriately reflects the characteristics of the power supply path, such as voltage drop and frequency deviation due to wiring impedance, in which these physical quantities are detected.

[0012] In one embodiment of the disclosed technology, the instructions may include an instruction to stop the application of the reactive power or an instruction to limit the upper and lower limits of the amount of reactive power applied. In a distributed power system 300b, which is a power system, the power generation system 100 can output to the power supply path a first AC power that is current-controlled with an adjustment gain based on the frequency deviation of the reactive power set to "0", or a first AC power that is current-controlled with a gently sloping gain applied to the adjustment gain of the reactive power based on the frequency deviation, thereby limiting the upper and lower limits of the amount of reactive power injected. In the power generation system 100, changes in disturbance current in the first AC power are suppressed to "0" or to a certain extent.

[0013] Another form of disclosure technology is, A power supply system comprising a power generation system and a battery storage system, which is connected to a power grid and supplies power to a load, wherein during independent operation, the power supply system is capable of supplying to the load a first AC power generated from the power generation system and a second AC power generated from the power stored in the battery storage system, The power generation system is connected to the battery storage system via a power supply path to which the load is connected, and when the AC power in the power supply path satisfies predetermined conditions, the system stops the applied reactive power or limits the upper and lower limits of the applied reactive power amount, and suppresses the degree of increase or decrease of the applied reactive power amount. It is characterized by the following:

[0014] Even in this configuration, in the distributed power system 300a, when the power generation system 100 and the battery storage system 200 are interconnected and cooperate to supply AC power to the load 350 in independent operation, it becomes possible to suppress the amount of reactive power applied in the power generation system 100 to determine the interconnection status. In the AC power supplied to the power supply path to which the load 350 is connected, disturbance currents caused by the amount of reactive power adjustment (applied amount) can be suppressed, and voltage fluctuations when the power generation system 100 and the battery storage system 200 are interconnected and supply power to the load in independent operation can be suppressed and stabilized. [Effects of the Invention]

[0015] According to the present invention, a technology is provided to suppress and stabilize voltage fluctuations when a power generation system and a battery storage system are interconnected and supply power to a load during independent operation. [Brief explanation of the drawing]

[0016] [Figure 1] This is a block diagram showing the schematic configuration of a distributed power supply system according to the premise of the present invention. [Figure 2]A diagram showing the fluctuation of alternating current power due to flicker on the premise of the present invention. [Figure 3] A diagram explaining the voltage fluctuation due to follow-up delay on the premise of the present invention. [Figure 4] A block diagram showing the schematic configuration of a distributed power system according to an embodiment of the present invention. [Figure 5] A diagram showing an example of the hardware configuration of a control unit of a power storage PCS according to the present embodiment of the present invention. [Figure 6] A flowchart showing an example of a process for suppressing reactive power of a power storage PCS according to an embodiment of the present invention. [Figure 7] A flowchart showing an example of a process for suppressing reactive power injection of a PV_PCS according to an embodiment of the present invention. [Figure 8] A block diagram showing the schematic configuration of a distributed power system according to Modification 1 of the present invention. [Figure 9] A block diagram showing the schematic configuration of a distributed power system according to Modification 2 of the present invention. [Figure 10] A block diagram showing the schematic configuration of a distributed power system according to Modification 3 of the present invention. [Figure 11] A flowchart showing an example of a process for suppressing reactive power of a controller according to Modification 3 of the present invention.

Mode for Carrying Out the Invention

[0017] 〔Application Example〕 Hereinafter, application examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the schematic configuration of a distributed power system 300 that is a premise of an application example of the present invention. This is a diagram. The distributed power system 300 includes a power generation system 100 and a battery storage system 200. In the power generation system 100, the power generated by PV 110 is converted to AC power via PV_PCS 120 (power conditioner) which has an inverter (INV) 130 and a control unit 140, and output to the power supply path to which the load 350 is connected. The battery storage system 200 includes a battery 210 and a battery storage PCS 220 which has a bidirectional inverter (bidirectional INV) 230 and a control unit 240. In the event of independent operation due to a power outage, etc., if the power generated by PV 110 exceeds the load power, the battery 210 is charged via the battery storage PCS 220, and if the generated power is less than the load power, the power stored in the battery 210 is discharged, and AC power based on the discharged power is supplied to the load 350 to supplement the generated power.

[0018] As shown in Figures 2 and 3, during standalone operation, when the power generation system 100 and the battery storage system 200 work together to supply AC power to the power supply path to which the load 350 is connected, flicker may occur, causing fluctuations in the voltage of the AC power. One possible cause of the flicker is the mutual interference between the current control of the PV_PCS120, which generates the AC power supplied to the power supply path, and the voltage control of the battery storage PCS220.

[0019] For example, in the PV_PCS120 of the distributed power system 300 that has started independent operation, islanding detection is performed using the AC power output from the energy storage PCS220 as the connection target. In islanding detection, when the PV_PCS120 generates AC power, a predetermined amount of reactive power is injected into it, as shown in Figure 3(2). The PV_PCS120 then measures the frequency of the AC power with the injected reactive power, and if the frequency deviation from a predetermined reference frequency (50Hz, 60Hz, etc.) exceeds a predetermined threshold, it determines that there is no connection target and stops the operation of the PV_PCS120 due to islanding factors.

[0020] During independent operation, the injected reactive power is output to the power supply path to which the energy storage PCS220 is connected as a disturbance current generated in the AC power. The energy storage PCS220 measures the voltage value of the power supply path to which the AC power (active power + reactive power) with disturbance current is supplied, and voltage control is performed to follow a certain voltage command. In the bidirectional INV230 of the energy storage PCS220, AC power is generated so that the voltage value becomes the desired voltage value according to the control command and output to the power supply path. As a result, there is a tracking delay from the voltage command value in the AC power output from the energy storage PCS220 to the power supply path, and as the above process is repeated, reactive power injection to synchronize ⇒ tracking delay occurs repeatedly, which becomes a cause of flicker where the voltage fluctuates at low frequency. In the following, reactive power as a disturbance current is explained as a cause of voltage fluctuation, but voltage fluctuations in the power supply path can also occur if there is a fluctuation in active power.

[0021] As shown in Figures 4 and 5, in the distributed power supply system 300a according to this application example, the control unit 140a of PV_PCS120a and the control unit 240a of energy storage PCS220a are equipped with communication functions and are interconnected via a communication line N. The communication line N is a communication network including wired and wireless connections such as CAN (Controller Area Network) and RS-485, PV_PC The system includes connecting wiring that allows for the exchange of input / output signals (e.g., relay contact signals) such as I / O between the control unit 140a of S120a and the control unit 240a of the energy storage PCS220a.

[0022] As shown in Figures 6 and 7, during the standalone operation of the distributed power supply system 300a according to this application example, the control unit 240a of the energy storage PCS 220a instructs the control unit 140a of the PV_PCS 120a via the communication line N to prevent the injection of reactive power when supplying AC power to the power supply path to which the load 350 is connected. Upon receiving notification of the instruction from the energy storage PCS 220a, the control unit 140a of the PV_PCS 120a performs current control by setting the reactive power adjustment gain based on the frequency deviation, as explained in Figure 3(2), to a value of "0". In the AC power output from S120a to the power supply path, no reactive power injection adjustment is performed according to the frequency deviation, so no disturbance current caused by reactive power injection adjustment is generated. Furthermore, in the control unit 140a of PV_PCS120a, for example, a gain with a gentle slope is used for the reactive power adjustment gain based on the frequency deviation, thereby performing current control to limit the upper and lower limits of the amount of reactive power injected. By making the slope of the amount of reactive power injected gentle and limiting the upper and lower limits, it becomes possible to suppress changes in disturbance current in the AC power output from PV_PCS120a to the power supply path to a certain extent, and to suppress changes in the tracking delay amount in the energy storage PCS220a to a certain extent.

[0023] In the distributed power system 300a related to this application example, collaborative control between the energy storage PCS220a and PV_PCS120a via the communication line N makes it possible to suppress and stabilize voltage fluctuations when the power generation system and the battery storage system are interconnected and supply power to the load during independent operation.

[0024] [Example 1] In the following section, specific embodiments of the present invention will be described in more detail with reference to the drawings.

[0025] <System Configuration> Figure 1 is a block diagram illustrating the schematic configuration of a distributed power supply system 300 according to the premise of an embodiment of the present invention. The distributed power supply system 300 according to the premise of this embodiment is a power supply system comprising a power generation system 100 and a battery storage system 200. The distributed power supply system 300 is operated in conjunction with a power grid 310 to which commercial power is supplied, and is configured to store, for example, the generated power generated by the power generation system 100 or the power supplied from the power grid 310 during off-peak hours such as nighttime when rates are low, and to supply it to a load 350 installed at a customer's facility. In the configuration shown in Figure 1, for example, the power supply mode to the load 350, i.e., the operating mode of interconnected operation when the grid is functioning normally and independent operation when there is a power outage, is switched via a switch 320 installed at the customer's facility. When the grid is functioning normally, commercial power supplied from the interconnected power grid 310 is supplied to the battery storage system 200 and the load 350, and when there is a power outage, the power stored in the battery 210 is supplied to the load 350. The power generated by the power generation system 100 can be supplied to the load 350 and the power grid 310 when the grid is functioning normally, and can be supplied to the load 350 and the battery storage system 200 during a power outage. Power sensors (voltage sensors, current sensors) 330 are provided in the wiring path connecting the power generation system 100 and the load 350.

[0026] The power generation system 100 comprises a photovoltaic solar cell (e.g., a solar power generation module) PV110 and a power conditioner 120 such as a PV_PCS (hereinafter also referred to as PV_PCS120), which is a power generation device. A power sensor (current sensor, voltage sensor) 121 is provided between PV110 and PV_PCS120. In this embodiment, the power generation system 100 is described as a solar power generation system, but other forms of power generation systems may be adopted. Examples of other forms of power generation systems include power generation systems using natural energy such as wind power and hydropower, and self-generation systems using fuel. In the power generation system 100, the generated power (DC power) produced by the photovoltaic solar cell PV110 is output to PV_PCS120. The PV_PCS120 comprises an inverter (INV) 130 and a control unit 140. Based on control commands from the control unit, it converts the power generated from the PV110 into DC power of a predetermined voltage value (DC-DC conversion), and the INV130 converts the converted DC power into AC power synchronized with the commercial power supply (DC-AC conversion), generating power that can be supplied to the load 350, etc. The control unit 140 is connected to various sensors, including power sensor 121 and power sensor 330, and based on the power values ​​(current value, voltage value) detected by power sensor 121, it controls the power supply so that, for example, power can be supplied at the maximum power (current × voltage value) point or the optimal operating point where the output power of the PV_PCS120 is maximum. A command for Maximum Power Point Tracking (MPPT) is generated.

[0027] The battery storage system 200 comprises a battery storage system 210 and a battery storage PCS 220 connected to the battery storage system 210. The battery storage system 210 is, for example, a stationary battery storage device that incorporates a battery storage module of a predetermined capacity. However, the battery storage system 210 may include portable batteries installed in EVs (Electric Vehicles), HVs (Hybrid Vehicles), PHVs (Plug-in Hybrid Vehicles), etc. By providing portable batteries, a V2H (Vehicle to Home) system or a system installed within the customer's facility can be established. A V2L (Vehicle to Load) system can be constructed that enables power supply to loads such as electrical appliances in ordinary households.

[0028] The energy storage PCS220 comprises a bidirectional inverter (bidirectional INV)230 and a control unit 240. Based on control commands from the control unit, it converts the DC energy discharged from the battery 210 into DC power of a predetermined voltage value (DC-DC conversion). The bidirectional INV230 then converts the converted DC power into AC power usable by a load 350, etc. (DC-AC conversion) and outputs it to the wiring path to which the load is connected. As an example of DC-AC conversion, the generation of AC power by PWM control can be used. The energy storage PCS220 also converts AC power output from the interconnected power grid 350 or power generation system 100 into DC power (AC-DC conversion) via the bidirectional INV230, and then converts the voltage value of the converted DC power to a predetermined voltage value (DC-DC conversion) to charge the battery 210.

[0029] In the event of a power outage, the power supply path to the load 350 via the switch 320 is switched from the power grid 310 side to the battery system 200 side. The battery storage PCS 220 of the battery system 200 starts independent operation, and voltage control is performed by a control command from the control unit 240 to control the voltage value at the output terminal of the device of the AC power output to the power supply path to which the load 350 is connected to a constant value. The PV_PCS 120 of the power generation system 100 is linked to the power value of the AC power output from the battery storage PCS 220, for example, detected via the power sensor 330, and controlled so that the power generated by PV 110 can be supplied to the power supply path at the optimal operating point. In the distributed power system 300, for example, if the power generated by PV110 exceeds the load power, the battery 210 is charged via the energy storage PCS220. If the generated power is less than the load power, the power stored in the battery 210 is discharged, and AC power based on the discharged power is supplied to the load 350 to supplement the generated power. In this way, the distributed power system 300 enables a stable power supply through the cooperation of the power generation system 100 and the battery storage system 200, even when the generated power is less than the power consumed by the load 350.

[0030] In a distributed power system 300 including a power generation system 100 and a battery storage system 200, during standalone operation, AC power controlled by current based on generated power and AC power controlled by voltage based on stored power discharged from the battery 210 are supplied to the load 350. When the power generation system 100 and the battery storage system 200 work together to supply AC power to the power supply path to which the load 350 is connected, flicker may occur, causing fluctuations in the voltage of the AC power.

[0031] Figure 2 shows the fluctuation of AC power due to flicker. In Figure 2, the vertical axis represents voltage value, and the horizontal axis represents time. The thick solid line graph g1 shows the change in the voltage value of the AC power supplied to load 350. Note that the AC power exemplified in Figure 2 is an example with a frequency of 60 Hz (system frequency).

[0032] As shown in graph g1, when flicker occurs, voltage fluctuations g2, which vary at a low frequency, are superimposed on the power supplied to load 350. Pressure fluctuations g2 may cause, for example, flickering in lighting installed in a customer's facility, and may cause malfunctions or failures in household electrical appliances. Therefore, during independent operation, there is a risk that the power generated by the cooperative power generation system 100 and the power stored in the battery storage system 200 may not be able to be used effectively.

[0033] One possible cause of this flicker is the mutual interference between the current control of the PV_PCS120, which generates the AC power supplied to the power supply path, and the voltage control of the energy storage PCS220. In other words, before a power outage occurs, the power generation system 100 is connected to the power grid 310, so the PV_PCS120 is controlled so that the power generated by PV110 can be supplied at the optimal operating point based on the power values ​​(current and voltage values) detected by power sensors 121, 330, etc. In the PV_PCS120, in order to determine islanding operation with respect to commercial power supplied from the power grid 310, control is performed to generate reactive power in addition to the AC power generated based on the power generation power.

[0034] In the event of a power outage or other issue, the power supply path to the load 350 via the switch 320 is switched to the battery system 200 side, and the power supply path to the load 350 is connected to the power storage PCS 220, which has started independent operation. The power storage PCS 220 controls charging and discharging based on the voltage value at the output terminal of its own device, and when the stored power discharged from the battery 210 is output to the power supply path, the power storage PCS 220 outputs AC power that is voltage-controlled based on the voltage value at the output terminal of its own device.

[0035] When AC power is supplied from the energy storage PCS220 to the power supply path to which the load 350 is connected, the PV_PCS120 determines whether it is operating independently based on the AC voltage output from the energy storage PCS220 to the power supply path. In other words, the PV_PCS120 injects reactive power into the AC power generated based on the generated power and outputs AC power to the power supply path to which the load 350 is connected. In the power supply path to which the load 350 is connected, disturbances (disturbance currents) will occur due to the change in reactive power injected by the PV_PCS120.

[0036] During independent operation, the PCS220 energy storage unit measures the AC voltage in the power supply path where disturbance currents occur and performs voltage control to follow a constant voltage command (control command). The bidirectional INV230 of the PCS220 converts the power discharged from the battery 210 into AC power and outputs it to the power supply path according to the control command. In the PCS220, a control delay occurs between the generation of the control command and the generation of AC power by the bidirectional INV230, resulting in a delay in the AC voltage output from the PCS220 to the power supply path in response to disturbance currents.

[0037] In PV_PCS120, frequency changes in the AC voltage that have a tracking delay are detected. Then, PV_PCS120 injects reactive power into the AC power for which a frequency change has been detected. As the above process is repeated, fluctuations occur in the frequency of the AC power supplied to the power supply path, resulting in flicker of voltage fluctuations g2 that vary with a low frequency period.

[0038] Figure 3 illustrates voltage fluctuations due to tracking lag. Figure 3(1) shows an example of the relative control relationship between voltage control in the energy storage PCS220 and reactive power control in the PV_PCS120, and Figure 3(2) shows an example of the reactive power control characteristics in the PV_PCS120. Note that the reactive power control characteristics in Figure 3(2) are an example where the apparent power of the AC power output from the PV_PCS120 to the power supply path connected to load 350 is 4 kVA.

[0039] In Figure 3(1), the vertical axis represents the relative magnitudes of the voltage command value, measured voltage value, and reactive power (disturbance current) in the PV_PCS120 at the energy storage PCS220, while the horizontal axis represents the passage of time. The graph shown by the thin dashed line represents the voltage measured at the energy storage PCS220 (voltmeter The graphs, shown with solid lines, represent the changes in the voltage command. The graphs shown with dashed lines represent the changes in reactive power output from PV_PCS120. The periods shown with dashed lines (Frequency Circle 1, Frequency Circle 2) represent, respectively, the frequency (Circled 1) due to phase lag (Circled 1) and the frequency (Circled 2) due to phase lag (Circled 1), as will be explained later.

[0040] As shown in the circled area 1 enclosed in a rectangular frame, in the distributed power supply system 300 when independent operation has begun, the PV_PCS120 uses the AC voltage output from the energy storage PCS220 as the connection target and performs reactive power injection to determine island operation. As shown in Figure 3(2), the PV_PCS120 adjusts the reactive power in the range of -1kVar to +1kVar according to the frequency deviation. For example, when the frequency deviation with respect to the AC voltage of the connection target is ±0.01Hz or less, the reactive power generated using the first-stage gain with a relatively gentle slope is injected into the AC power generated by INV130. For other frequency deviations, the reactive power generated using the second-stage gain with a relatively steep slope, whose slope is defined with an upper limit of +1kVar and a lower limit of -1kVar, is injected into the AC power generated by INV130. The AC power into which reactive power is injected according to the frequency deviation is measured by the energy storage PCS220 as an AC voltage with disturbance current (circled in a rectangular frame, 2).

[0041] In the energy storage PCS220, voltage control is performed so that the measured voltage value follows a certain voltage command value, and AC power with a voltage controlled according to the control command, resulting in the desired voltage value, is output from the bidirectional INV230 to the power supply path. As previously described, a tracking delay occurs in the AC power output to the power supply path from the voltage command value, resulting in a phase delay (circled 1) between the voltage value of the AC power output from the energy storage PCS220 (measured voltage value) and the voltage command value (circled 2 enclosed in a rectangular frame).

[0042] In PV_PCS120, reactive power is injected to determine islanding operation based on the AC voltage output from the energy storage PCS220. As a result, a tracking delay is superimposed between the voltage value (measured voltage) and the voltage command value of the AC power output from the energy storage PCS220, resulting in a phase delay (circled 2). As shown in circled 3 enclosed in a rectangular frame, in the distributed power supply system 300 during independent operation, changes in disturbance current cause changes in phase delay, and these changes in phase delay further cause changes in frequency. As shown in circled 4 enclosed in a rectangular frame, changes in frequency cause changes in disturbance current (changes in the amount of reactive power injected), and as the above process is repeated between PV_PCS120 and the energy storage PCS220, the AC power supplied to the power supply path experiences fluctuations in voltage at low frequencies.

[0043] Figure 4 is a block diagram showing the schematic configuration of the distributed power system 300a according to this embodiment. The distributed power system 300a according to this embodiment has the same configuration as the distributed power system 300 described using Figure 1, etc. However, in the distributed power system 300a according to this embodiment, the PV_PCS120a constituting the power generation system 100 is equipped with a control unit 140a, and the energy storage PCS220a constituting the battery storage system 200 is equipped with a control unit 240a, which differs from the energy storage PCS220 in the distributed power system 300. Note that the distributed power system 300a according to this embodiment corresponds to an example of a "power system", and the power generation system 100 corresponds to an example of a "power generation system". Also, the battery storage system 200 according to this embodiment corresponds to an example of a "battery storage system". Furthermore, the AC power output from the inverter (INV) 130 of the PV_PCS120a constituting the power generation system 100 corresponds to an example of "first AC power," and the AC power output from the bidirectional inverter (bidirectional INV) 230 of the energy storage PCS220a constituting the battery storage system 200 corresponds to an example of "second AC power."

[0044] The control unit 140a of PV_PCS120a and the control unit 240a of the energy storage PCS220a in this embodiment are equipped with communication functions and are interconnected via a communication line N. Examples of such a communication line N include CAN (Controller Area Network) and RS-485. However, Furthermore, the communication line N may include public networks such as the Internet, wireless networks such as mobile phone networks, dedicated networks such as VPNs (Virtual Private Networks), and networks such as LANs (Local Area Networks). The communication line N includes wired and wireless connections. It may include a communication network. Furthermore, the communication line N may be a connection wiring between the control unit 140a of PV_PCS120a and the control unit 240a of the energy storage PCS220a, capable of sending and receiving I / O and other input / output signals (e.g., relay contact signals).

[0045] In this embodiment, the control unit 240a of the energy storage PCS220a instructs the control unit 140a of the PV_PCS120a via the communication line N to prevent the injection of reactive power when supplying AC power to the power supply path to which the load 350 is connected during standalone operation. Upon receiving notification of the instruction from the energy storage PCS220a, the control unit 140a of the PV_PCS120a performs current control by setting the reactive power adjustment gain based on the frequency deviation, as explained in Figure 3(2), to a value of "0". In the INV130 of the PV_PCS120a in this embodiment, AC power is generated based on the current control command from the control unit 140a and output to the power supply path to which the load 350 is connected. Since the AC power output from the PV_PCS120a to the power supply path does not undergo reactive power injection adjustment according to the frequency deviation, no disturbance current caused by reactive power injection adjustment occurs. In the distributed power supply system 300a according to this embodiment, cooperative control by the energy storage PCS220a and PV_PCS120a via the communication line N makes it possible to suppress and stabilize voltage fluctuations when the power generation system and the battery storage system are interconnected and supply power to the load during independent operation.

[0046] Furthermore, when the above notification is received from the energy storage PCS220a, the control unit 140a of PV_PCS120a may, for example, inject reactive power using a first-stage gain with a gentle slope as the adjustment gain for reactive power based on the frequency deviation, and perform current control. That is, in the reactive power control characteristics shown in Figure 3(2), by using a gain with a gentle slope, such as the first-stage gain, it becomes possible to limit the upper and lower limits of the amount of reactive power injected when generating AC power. By limiting the upper and lower limits of the amount of reactive power injected, it becomes possible to suppress changes in disturbance current in the AC power output from PV_PCS120a to the power supply path to a certain extent, and to suppress changes in the tracking delay amount in the energy storage PCS220a to a certain extent. Even with such a control configuration, it becomes possible to suppress and stabilize voltage fluctuations when the power generation system and the battery storage system are interconnected and supply power to the load during independent operation.

[0047] <Control Unit Configuration> Figure 5 shows an example of the hardware configuration of the control unit 240a of the energy storage PCS220a according to this embodiment. As shown in Figure 5, the control unit 240a is a computer whose components include a processor 241, main memory 242, auxiliary storage 243, communication IF 244, and input / output IF 245, which are interconnected by a connection bus 246. The main memory 242 and auxiliary storage 243 are recording media that can be read by the control unit 240a. The main memory 242 and auxiliary storage 243 constitute the memory of the control unit 240a. Multiple instances of each of the above components may be provided, or some components may be omitted. Furthermore, the control unit 140a in PV_PCS120a is configured in the same manner as the hardware configuration shown in Figure 5. The following description will focus on the control unit 240a.

[0048] The processor 241 is a central processing unit that controls the entire control unit 240a. The processor 241 is, for example, a CPU (Central Processing Unit), an MPU (Micro Processor Unit), or a DSP (Digital Signal Processor). Then, the program stored in the auxiliary storage device 243 is deployed in an executable format to the working area of ​​the main memory device 242, and peripheral devices are controlled through the execution of the program, thereby providing a function that matches the predetermined purpose. Note that some or all of the functions are provided by an ASIC (Application Specific Integrated Circuit), GPU (Graphics Processing Unit), etc. Similarly, some or all of the functions may be handled by dedicated LSIs such as FPGAs (Field-Programmable Gate Arrays), numerical processors, vector processors, and image processing processors. (Large-scale integration) may be implemented using other hardware circuits. It may also be a System on a Chip (SoC) configured by integrating the above-mentioned processor (MPU, etc.) and storage media such as memory onto a single chip.

[0049] The main memory 242 stores programs executed by the processor 241, data processed by the processor, etc. The main memory 242 includes flash memory, RAM (Random Access Memory), and ROM (Read Only Memory). The auxiliary storage device 243 stores various programs and various data on a recording medium that can be read and written freely. The auxiliary storage device 243 is also called an external storage device. The auxiliary storage device 243 is used as a storage area that assists the main memory 242 and stores programs executed by the processor 241, data processed by the processor 241, etc. The auxiliary storage device 243 stores, for example, the OS (Operating System), various programs, various tables, etc. The OS includes, for example, a communication interface program that exchanges data with external devices connected via the communication IF 244. External devices include, for example, the control unit 140a and controller computers of the PV_PCS120a connected to the communication line N. The auxiliary storage device 243 includes non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)). These include recon disks, solid-state drives, and hard disk drives (HDDs).

[0050] The communication IF244 is an interface for connecting the control unit 240a to the communication line N. The communication IF244 can be configured appropriately depending on the connection method with the communication line N. The input / output IF245 is an interface for inputting and outputting data between the control unit 240a and the connected equipment. Input devices such as a touch panel or operation buttons on the housing of the energy storage PCS220a are connected to the input / output IF245. Operation instructions from the operator operating the input device are received via the input / output IF245. Furthermore, input / output IF245 can be connected to, for example, an LCD (Liquid Crystal Display) or an EL (Electroluminescence) display. Display devices such as panels, and output devices such as printers and speakers are connected to them.

[0051] <Processing flow> Next, with reference to Figures 6 and 7, the control configuration of the distributed power supply system 300a according to this embodiment will be described. Figure 6 is a flowchart showing an example of a process that generates instructions for suppressing reactive power, which is executed by the control unit 240a of the energy storage PCS 220a according to this embodiment. The process shown in Figure 6 is performed during independent operation when PV_PCS 120a and energy storage PCS 220a cooperate to connect and supply AC power to the power supply path to which the load 350 is connected.

[0052] After processing begins, in the energy storage PCS220a, which generates AC power based on the stored energy, an instruction is generated to suppress the injection of reactive power to PV_PCS120a (step S101). When the control unit 240a of the energy storage PCS220a generates an instruction to suppress the injection of reactive power, for example, an instruction to stop the injection of reactive power or an instruction to suppress the amount of reactive power injected, the process proceeds to step S102. In step S102, when the generated suppression instruction is notified to PV_PCS120a via the communication line N, the process proceeds to step S103. In step S103, the energy storage PCS220a generates AC power with a desired voltage value that follows the voltage control command value based on the stored energy continuously stored (charged) in the battery 210, and outputs it to the power supply path to which the load 350 is connected. After the processing of S103 is completed, this routine will be terminated.

[0053] Figure 7 is a flowchart showing an example of a process for suppressing reactive power injection, which is performed by the control unit 140a of the PV_PCS120a according to this embodiment. The process shown in Figure 7 is performed when the PV_PCS120a and the energy storage PCS220a cooperate in interconnection and supply AC power to the power supply path to which the load 350 is connected during independent operation, and when an instruction to suppress the injection of reactive power is received from the energy storage PCS220a via the communication line N.

[0054] After processing begins, the PV_PCS120a, which generates AC power based on the generated power, performs a control to suppress the amount of reactive power injected in order to determine island operation, targeting the AC voltage output from the energy storage PCS220a to the power supply path (step S111). The control unit 140a generates a control command for current control by setting the reactive power adjustment gain based on frequency deviation to "0" when, for example, the instruction from the energy storage PCS220a indicates stopping the injection of reactive power. Also, when the instruction from the energy storage PCS220a indicates suppressing the amount of reactive power injected, the control unit 140a adjusts the slope of the adjustment gain to limit the upper and lower limits of the amount of reactive power injected based on frequency deviation, for example. For example, as shown in the reactive power control characteristics of Figure 3(2), by limiting the reactive power adjustment gain to the first stage gain, the slope of the adjustment gain of the amount of reactive power injected based on frequency deviation becomes gentler, and the change in disturbance current in the AC power generated by PV_PCS120a is suppressed to a certain extent.

[0055] Returning to Figure 7, in step S112, a current control command generated to suppress reactive power injection is output to INV130. In PV_PCS120a, power conversion is performed to convert the generated power into AC power according to the current control command value, stopping the injection of reactive power, or generating AC power with the amount of reactive power injected suppressed, which is then output to the power supply path. After the processing in step S112 is completed, this routine is terminated.

[0056] As explained above, in the distributed power supply system 300a according to this embodiment, when PV_PCS120a and energy storage PCS220a are operating independently, they cooperate to connect to the grid and when AC power is supplied to the power supply path to which the load 350 is connected, the system is controlled so that reactive power is not injected via the communication line N. For example, when the injection of reactive power is stopped, the reactive power adjustment gain based on the frequency deviation is set to "0" and current control is performed, generating AC power based on the generated power. Since the injection of reactive power is not adjusted according to the frequency deviation, no disturbance current caused by such injection adjustment occurs in the AC power. Furthermore, when the amount of reactive power injected is suppressed, the slope of the increase and decrease of the adjustment gain is gradually adjusted to limit the upper and lower limits of the amount of reactive power injected based on the frequency deviation, and changes in disturbance current in the AC power are suppressed to a certain extent. According to the distributed power supply system 300a of this embodiment, cooperative control by the energy storage PCS220a and PV_PCS120a via the communication line N makes it possible to suppress and stabilize voltage fluctuations when the power generation system and the battery storage system are interconnected and supply power to the load during independent operation.

[0057] [Variation 1] In the embodiment of Example 1, instructions to suppress the injection of reactive power generated by the energy storage PCS220a are transmitted to the control unit 140a of PV_PCS120a via the communication line N. Instructions to suppress the injection of reactive power to PV_PCS120a may also be configured to be notified to PV_PCS120a via a controller 340a provided in the distributed power supply system 300a, as shown in Figure 8(1). The controller 340a is an information processing device that manages, for example, the power generation status and operation history of the power generation system 100, the charge / discharge status and operation history of the battery storage system 200, etc. The controller 340a in Figure 8(1) controls the energy storage PCS220a via the communication line N. It is connected to the control unit 240a and the control unit 140a of PV_PCS120a, respectively. In the modified example 1, the control unit 240a of the energy storage PCS220a should send an instruction to the controller 340a to suppress reactive power injection in step S102 of Figure 6. The controller 340a should receive the instruction to suppress reactive power injection sent from the energy storage PCS220a and send the suppression instruction to the control unit 140a of PV_PCS120a. In PV_PCS120a, the control unit 140a should execute the processing flow shown in Figure 7 upon receiving the suppression instruction sent from the controller 340a.

[0058] The instruction to suppress reactive power injection may be configured to be notified to PV_PCS120a via a controller 250 provided in the battery storage system 200 and a controller 150 provided in the power generation system 100, as shown in Figure 8(2). Controller 250 is an information processing device that manages the charge / discharge status, setting parameters, operation history, maintenance history, etc., in the battery storage system 200, while controller 150 is an information processing device that manages the power generation status, operation history, maintenance history, etc., in the power generation system 100. Controller 250 is connected to the control unit 240a of the battery storage PCS220a, and controller 150 is connected to the control unit 140a of PV_PCS120a. Controller 250 provided in the battery storage system 200 and controller 150 provided in the power generation system 100 are connected via a communication line N. In the modified example shown in Figure 8(2), the control unit 240a of the energy storage PCS 220a should transmit an instruction to the controller 250 to suppress reactive power injection in step S102 of Figure 6. The controller 250 transmits the instruction to suppress reactive power injection to the controller 150, which is connected via the communication line N, and the controller 150 transmits the received instruction to the control unit 140a of the PV_PCS 120a. The control unit 140a of the PV_PCS 120a should receive the instruction to suppress reactive power injection transmitted from the controller 150 and execute the processing flow shown in Figure 7.

[0059] [Variation 2] Figure 9 is a block diagram showing the schematic configuration of a distributed power supply system 300a according to Modification 2. In Example 1 and Modification 1, the main component of the reactive power injection suppression instruction was described as the energy storage PCS 220a. However, as shown in Figure 9(1), the controller 150a of the power generation system 100 may generate the reactive power injection suppression instruction. The controller 150a detects, for example, a power outage in the power system 310 or voltage fluctuations in the power supply path during independent operation, based on the detection values ​​of power sensors (voltage sensors, current sensors) 330 provided in the wiring path connecting the power generation system 100 and the load 350, and power sensors 331 provided in the wiring path connecting the power system 310 and the switch 320. For example, with the power system 310 connected, the power outage and power recovery may be determined by comparing the detected value of the power sensor 331 with a predetermined threshold. Alternatively, the power outage and power recovery may be determined by acquiring signals associated with the switching of the switch 320 to the power outage side (e.g., relay contact switching signals) and signals associated with the switching to the normal system side. Similarly, after independent operation has started, the controller 150a may acquire the detected value of the power sensor 330 and determine if flicker has occurred in the power supply path, as shown in Figure 2, on the condition that the range of voltage fluctuations within a predetermined period exceeds a threshold.

[0060] Then, the controller 150a, triggered by a power outage in the power grid 310 or voltage fluctuations (flicker occurrence) in the power supply path during independent operation, executes steps S101 to S102 in Figure 6 and sends an instruction to the control unit 140a of PV_PCS120a to suppress reactive power injection. The control unit 140a of PV_PCS120a receives the suppression instruction to suppress reactive power injection sent from the controller 150a and executes the processing flow shown in Figure 7. In the distributed power supply system 300a of Modification 2, the power generation system is performed without the involvement of the battery system 200. The 100 unit alone can suppress reactive power injection.

[0061] Furthermore, as shown in Figure 9(2), the PV_PCS120a of the power generation system 100 may be equipped with a control unit 140b that generates a reactive power injection suppression instruction. That is, in Figure 9(2), the control unit 140b detects a power outage in the power system 310 or voltage fluctuations in the power supply path during independent operation based on the detection values ​​of the power sensors 330 and 331. For example, the control unit 140b may determine a power outage and power recovery by comparing the detection value of the power sensor 331 with a predetermined threshold while the power system 310 is connected. The control unit 140b may also determine a power outage and power recovery by acquiring signals associated with the switching of the switch 320 to the power outage side (e.g., relay contact switching signal), signals associated with the switching to the normal system side, etc. Furthermore, after independent operation has started, the control unit 140b may acquire the detection value of the power sensor 330 and determine flicker occurring in the power supply path based on the condition that the voltage fluctuation range within a predetermined period exceeds a threshold, as shown in Figure 2.

[0062] Then, the control unit 140b can determine whether to suppress reactive power injection in the event of a power outage in the power system 310 or voltage fluctuations in the power supply path (flicker occurrence) during independent operation, and execute the processing flow shown in Figure 7. In the modified example 2 shown in Figure 9(2), it becomes possible to suppress reactive power injection by controlling the PV_PCS120a.

[0063] In the modified form 2, the decision to suppress reactive power injection may be based on either a power outage in the power grid 310 or the detection of voltage fluctuations in the power supply path during independent operation. This can be appropriately selected depending on the scale and size of the distributed power supply system 300a, the amount of power generated by the power generation system 100, the amount of power consumed by the load 350, and the amount of power stored in the battery system 200.

[0064] [Example 3] Figure 10 is a block diagram illustrating the schematic configuration of the distributed power supply system 300b according to Modification 3. The distributed power supply system 300b according to Modification 3 has the same configuration as the distributed power supply system 300 described using Figure 1, etc. However, the configuration of the distributed power supply system 300b according to Modification 3 differs from the distributed power supply system 300 in that it includes a controller 340 that monitors the state of AC power supplied to the power supply path, and the controller, the control unit 140b of PV_PCS120b, and the control unit 240b of energy storage PCS220b are connected via a communication network N1. In addition, a sensor (one of the sensors S1 to S5) for measuring a physical quantity that identifies the state of AC power in the power supply path is provided in the power supply path to which the load 350 is connected, and the measured physical quantity is output to the controller 340 connected to the sensor. In Modification 3, the communication network N1 is substantially equivalent to the communication line N, and the hardware configurations of the controller 340, control unit 140b, and control unit 240b are substantially equivalent to the hardware configuration of the control unit 240a in the embodiment, so their explanation is omitted. The distributed power supply system 300b in Modification 3 corresponds to an example of a "power supply system," and the power generation system 100 corresponds to an example of a "power generation system." Furthermore, the battery storage system 200 in Modification 3 corresponds to an example of a "battery storage system," and the controller 340 corresponds to an example of a "control device." The AC power output from the inverter (INV) 130 of the PV_PCS 120b constituting the power generation system 100 corresponds to an example of "first AC power," and the AC power output from the bidirectional inverter (bidirectional INV) 230 of the battery storage PCS 220b constituting the battery storage system 200 corresponds to an example of "second AC power." The differences from the embodiment will be explained below.

[0065] In the distributed power supply system 300b according to Modification 3, the controller 340 identifies the state of the AC power supplied to the power supply path when the PV_PCS120b and the energy storage PCS220b cooperate in interconnection during standalone operation, based on the physical quantity measured by the sensor (any one of the sensors S1 to S5). The controller 340 then identifies Depending on the state of the AC power, the control unit 140b of PV_PCS120b is notified of an instruction to suppress the injection of reactive power. In the modified form, as in the embodiment, the distributed power supply system 300b can suppress and stabilize voltage fluctuations when the power generation system and the battery storage system are interconnected and supply power to the load during independent operation.

[0066] In Figure 10, Z1 to Z3 represent the line impedances in the power supply path to which the load 350 is connected. Line impedance Z1 represents the line impedance in the wiring path between PV_PCS120b and the connection point to which the load 350 is connected, line impedance Z2 represents the line impedance in the wiring path between the switch 320 and the connection point to which the load 350 is connected, and line impedance Z3 represents the line impedance in the wiring path between the energy storage PCS220b and the switch 320. Furthermore, S1 to S5 represent the installation locations where sensors are installed to detect physical quantities (e.g., electromagnetic information such as voltage, current, frequency, active power, and reactive power) that indicate the state of AC power in the power supply path to which the load 350 is connected, as will be described later.

[0067] <Processing flow> Figure 11 is a flowchart showing an example of a process for suppressing reactive power, which is performed by the controller 340 according to Modification 3. The process shown in Figure 11 is performed during standalone operation when the PV_PCS120b and the energy storage PCS220b work together to connect to the grid and supply AC power to the power supply path to which the load 350 is connected.

[0068] After the start of processing, in step S121, the controller 340 obtains control command values ​​related to the AC power supplied to the power supply path from the energy storage PCS 220b via the communication network N1, and the process proceeds to step S122. Examples of such control command values ​​include voltage command values ​​and frequency command values ​​(50Hz, 60Hz, etc.). In step S122, the controller 340 obtains physical quantities (e.g., voltage, current, frequency, active power, reactive power, etc.) indicating the state of the AC power over a predetermined period from a sensor (any one of the sensors from S1 to S5) installed in the power supply path, and the process proceeds to step S123. In step S123, the average value of the physical quantities measured over the predetermined period is compared with the control command values ​​(average value of voltage command values, frequency command value) obtained from the energy storage PCS 220b, and voltage fluctuations in the power supply path are identified. For example, voltage deviations (voltage fluctuations) are identified by comparing the voltage command values ​​obtained as control command values ​​with the measured voltage values ​​in the power supply path. Furthermore, voltage fluctuations are identified based on the frequency deviation between the frequency command value acquired as a control command value and the measured frequency in the power supply path. For other physical quantities (current, active power, reactive power), the fluctuation values ​​(deviation between the maximum and minimum values) within a predetermined period can be used to identify them instead of voltage fluctuations. Note that the controller 340 may determine the voltage fluctuations in the power supply path to which the load 350 is connected based only on the physical quantities acquired from the power supply path. In this case, the processing in step S121 can be omitted. After the completion of step S123, the process proceeds to step S124.

[0069] In step S124, a comparison is made with a determination threshold to determine whether the identified voltage fluctuation suppresses reactive power injection. Such determination thresholds can be determined experimentally in advance. For example, the voltage fluctuation value in the power supply path when flickering occurs in lighting, etc., during independent operation can be measured in advance. Then, the measured voltage fluctuation value can be multiplied by a correction coefficient (for example, a real number greater than 0 and less than or equal to 1) to obtain the determination threshold. The correction coefficient can be appropriately adjusted according to the system configuration of the distributed power supply system 300b to be controlled, the amount of power supplied during independent operation, etc. Alternatively, an index value that defines the degree of flickering in lighting, etc., may be used. For other physical quantities (current, active power, reactive power), instead of the voltage fluctuation value, a comparison is made between the fluctuation value (deviation between the maximum and minimum value) within a specified period and the determination threshold corresponding to that physical quantity. Step S1 In step 24, if the voltage fluctuation range measured in the power supply path is greater than or equal to the determination threshold (step S124, "Yes"), it is determined that flicker is occurring and the process proceeds to step S125; otherwise (step S124, "No"), this routine is terminated.

[0070] In step S125, a suppression instruction (an instruction to stop the injection of reactive power or to suppress the amount of reactive power injected) is generated to suppress the injection of reactive power to PV_PCS120b in the same manner as S101 to S102 in the flow shown in Figure 6, and this suppression instruction is notified to PV_PCS120b via the communication network N1. In PV_PCS120b, the processing shown in the flow shown in Figure 7 is performed according to the suppression instruction notified from controller 340. When the suppression instruction indicates stopping the injection of reactive power, PV_PCS120b generates a control command for current control by setting the reactive power adjustment gain based on the frequency deviation to "0", and outputs AC power with the injection of reactive power stopped to the power supply path. When the suppression instruction indicates suppressing the amount of reactive power injected, the slope of the adjustment gain is gently adjusted so that the upper and lower limits of the amount of reactive power injected are restricted based on the frequency deviation, and AC power with changes in disturbance current suppressed to a certain extent is output to the power supply path. After the processing in step S125 is completed, this routine is terminated.

[0071] As explained above, in the distributed power supply system 300b according to Modification 3, when AC power is supplied to the power supply path to which the PV_PCS120b and the energy storage PCS220b work together to connect during standalone operation and the load 350 is connected, the controller 340 controls the system so that reactive power is not injected. For example, when the injection of reactive power is stopped, the reactive power adjustment gain based on the frequency deviation is set to "0" and current control is performed, generating AC power based on the generated power. Since the injection of reactive power is not adjusted according to the frequency deviation, no disturbance current caused by such injection adjustment occurs in the AC power. Furthermore, when the amount of reactive power injected is suppressed, the slope of the increase and decrease of the adjustment gain is gradually adjusted to limit the upper and lower limits of the amount of reactive power injected based on the frequency deviation, and changes in disturbance current in the AC power are suppressed to a certain extent. According to the distributed power supply system 300b of modified example 3, the controller 340 controls the voltage fluctuations that occur when the power generation system and the battery storage system are interconnected and supply power to the load during independent operation, thereby stabilizing the system.

[0072] Furthermore, in the modified example 3, the controller 340 can obtain a physical quantity that identifies the state of AC power in the power supply path from any one of the sensor installation locations S1 to S5 shown in Figure 10. For example, by detecting the physical quantity related to control from the target location specified in S4, it becomes possible to suppress reactive power injection, appropriately reflecting the voltage drop and frequency deviation due to the wiring impedance Z3 between the energy storage PCS 220b and the switch 320. For example, it is expected that the accuracy of suppressing voltage fluctuations that occur due to modifications accompanying changes in the energy storage capacity of the battery system 200, or additional modifications such as V2H or V2L, can be improved.

[0073] The same applies to other parts. In S3, it becomes possible to further control the suppression of reactive power injection, reflecting the voltage drop and frequency deviation due to the impedance of the switch 320. Also, in S2, the voltage drop and frequency deviation due to the wiring impedance Z2 between the switch 320 and the connection terminal to which the load 350 is connected can be reflected, and in S1, the voltage drop and frequency deviation due to the wiring impedance Z1 between the PV_PCS120b and the connection terminal to which the load 350 is connected can be reflected. In the modified distributed power system 300b, it becomes possible to suppress voltage fluctuations by appropriately reflecting changes in wiring impedance due to the expansion or modification of the power generation system 100 and the battery storage system 200, thereby stabilizing the AC power output to the power supply path.

[0074] (others) The embodiments described above are merely examples, and the disclosure of these embodiments may be modified as appropriate without departing from its essence. The processes and means described in this disclosure can be freely combined and implemented as long as no technical inconsistencies arise.

[0075] Furthermore, processes described as being performed by a single device may be divided and executed by multiple devices. Conversely, processes described as being performed by different devices may be executed by a single device. The hardware configuration used to implement each function can be flexibly changed.

[0076] Computer-readable recording media A program that enables any of the above functions to be implemented in an information processing device or other machine or device (hereinafter referred to as a computer, etc.) can be recorded on a recording medium that the computer, etc. can read. Then, by having the computer, etc. read and execute the program on this recording medium, the function can be provided.

[0077] Here, a recording medium that can be read by a computer refers to a recording medium that stores information such as data and programs through electrical, magnetic, optical, mechanical, or chemical means and can be read by a computer. Examples of such recording media that can be removed from a computer include flexible disks, magneto-optical disks, CD-ROMs, CD-R / Ws, DVDs, Blu-ray discs, DATs, 8mm tapes, and memory cards such as flash memory. Recording media that are fixed to a computer include hard disks and ROMs.

[0078] For the purpose of comparing the constituent elements of this disclosure with the configurations of the embodiments, the constituent elements of this disclosure are listed below with reference numerals in the drawings. <Note 1> A power supply system (300a) comprising a power generation system (100) and a battery storage system (200), which is connected to a power grid (310) to supply power to a load (350), wherein during independent operation, the power supply system (300a) is capable of supplying to the load (350) a first AC power generated from the power generated by the power generation system (100) and a second AC power generated from the power stored in the battery storage system (200), The power generation system (100) is connected to the battery system (200) via a power supply path to which the load (350) is connected, and is connected to the AC voltage output from the battery system (200), and outputs a first AC power to which a predetermined amount of reactive power is applied to the power supply path to which the load (350) is connected, When the battery system (200) outputs the second AC power to the power supply path to which the load (350) is connected, it transmits an instruction signal to the power generation system (100) to suppress the application of the reactive power. A power supply system (300A) characterized by the following.

[0079] <Note 2> The system comprises a power generation system (100) and a battery storage system (200), and a control device (340) connected to the power generation system (100) and the battery storage system (200) via a communication network (N1). The power supply system (300b) according to Invention 1, characterized in that the control device (340) detects a power outage or voltage fluctuation using a physical quantity obtained from the power supply path to which the load (350) is connected, generates an instruction signal to suppress the application of the reactive power, and transmits it to the power generation system (100).

[0080] <Note 3> A power supply system (300a) comprising a power generation system (100) and a battery storage system (200), which is connected to a power grid (310) to supply power to a load (350), wherein during independent operation, the power supply system (300a) is capable of supplying to the load (350) a first AC power generated from the power generated by the power generation system (100) and a second AC power generated from the power stored in the battery storage system (200), The power generation system (100) is connected to the battery storage system (200) via a power supply path to which the load (350) is connected, and when the AC power in the power supply path satisfies predetermined conditions, the system stops the applied reactive power or limits the upper and lower limits of the amount of reactive power applied, and suppresses the degree of increase or decrease of the amount of reactive power applied. A power supply system (300A) characterized by the following. [Explanation of Symbols]

[0081] 100 power generation systems 110 PV 120, 120a, 120b PV_PCS 121 Power Sensor 130 INV 140, 140a, 140b control unit 150, 150a controller 200 Battery Storage System 210 Battery 220, 220a, 220b Energy storage PCS 230 Bidirectional INV 240, 240a, 240b control unit 250 Controllers 300, 300a, 300b Distributed Power Systems 310 Power system 320 Switch 330, 331 Power Sensors 340, 340a, Controller 350 load Z1, Z2, Z3 line impedance S1, S2, S3, S4, S5 Sensor installation locations

Claims

1. A power supply system comprising a power generation system and a battery storage system, which is connected to a power grid and supplies power to a load, wherein during independent operation, the power supply system is capable of supplying to the load a first AC power generated from the power generation system and a second AC power generated from the power stored in the battery storage system, The power generation system is connected to the battery system via a power supply path to which the load is connected, and is linked to the AC voltage output from the battery system. It outputs a first AC power to the power supply path to which a predetermined amount of reactive power is applied, and when it receives an instruction signal to suppress the application of the reactive power, it suppresses the application of the reactive power. The battery storage system detects voltage fluctuations in the power supply path during independent operation using physical quantities obtained from the power supply path to which the load is connected, and when it detects voltage fluctuations, it generates the instruction signal and transmits the instruction signal to the power generation system when outputting the second AC power to the power supply path to which the load is connected. A power supply system characterized by the following features.

2. The power supply system according to claim 1, characterized in that the battery storage system transmits the instruction signal to the power generation system to stop applying the reactive power.

3. The power supply system according to claim 1, characterized in that the battery storage system transmits instruction signals to the power generation system that limit the upper and lower limits of the amount of reactive power applied, and suppress the degree of increase or decrease of the amount of reactive power applied.

4. The system includes a control device connected to the power generation system and the battery storage system via a communication network, The power supply system according to claim 1, characterized in that the control device detects voltage fluctuations in the power supply path during the independent operation using physical quantities obtained from the power supply path to which the load is connected, generates an instruction signal to suppress the application of reactive power, and transmits it to the power generation system.

5. The power supply system according to claim 4, characterized in that the physical quantity includes at least one of the following physical quantities in the power supply path: voltage value, current value, frequency, reactive power, and active power.

6. The power supply system according to claim 4 or 5, characterized in that the instructions for suppressing the application of reactive power include instructions for stopping the application of the reactive power or instructions for limiting the upper and lower limits of the amount of reactive power applied.

7. A power supply system comprising a power generation system and a battery storage system, and a control device connected to the power generation system and the battery storage system via a communication network, wherein the power supply system is connected to a power grid and supplies power to a load, and in the case of independent operation, the power supply system is capable of supplying to the load a first AC power generated from the power generated by the power generation system and a second AC power generated from the power stored in the battery storage system, The power generation system is connected to the battery system via a power supply path to which the load is connected, and is linked to the AC voltage output from the battery system. It outputs a first AC power to the power supply path to which a predetermined amount of reactive power is applied, and when it receives an instruction signal to suppress the application of the reactive power, it suppresses the application of the reactive power. The control device detects voltage fluctuations in the power supply path during independent operation using physical quantities obtained from the power supply path to which the load is connected, generates an instruction signal to suppress the application of reactive power, and transmits it to the power generation system. A power supply system characterized by the following features.

8. A first sensor is provided at the output terminal of the power conditioner of the power generation system, A second sensor is provided at the connection end to which the load is connected, A third sensor is provided at the power generation system side end of a switch that switches the destination to which the power generation system is connected to the power grid or the battery storage system, A fourth sensor is provided at the battery system side end of the switch, The battery storage system further includes a fifth sensor provided at the output terminal of the power conditioner, The first sensor, the second sensor, the third sensor, the fourth sensor, and the fifth sensor are configured to measure at least one of the following physical quantities: voltage, current, frequency, reactive power, and active power. The control device detects voltage fluctuations in the power supply path during autonomous operation based on the measured value of at least one of the first to fifth sensors. The power supply system according to claim 7, characterized in that

Images