Distributed power supply control system, distributed power supply control device, central processing unit, distributed power supply control method, system stabilization control method, and control parameter setting method

Abstract

The distributed power supply control system (4) includes a central processing unit (5) that sets control parameters for power control on power supplied from the distributed power supplies (7-1 to 7-4) performed by a plurality of distributed power supply control devices (6-1 to 6-4), each connected to a different distributed power supply (7-1 to 7-4), and a plurality of distributed power supply control devices (6-1 to 6-4) that measure a system state, which is the state of power at a point of the connected transmission and distribution system (1), and use the measurement information of the system state and the control parameters to calculate an emergency control amount according to the type of system disturbance when a system disturbance occurs in the transmission and distribution system (1), thereby performing power control.

Description

[Technical field]

[0001] The present disclosure relates to a distributed power supply control system to which distributed power supplies are connected, a distributed power supply control device, a central processing unit, a distributed power supply control method, a system stabilization control method, and a control parameter setting method. [Background technology]

[0002] Conventionally, when a system disturbance occurs in a power system due to an earthquake, lightning strike, or the like, the power system becomes unstable and there is a risk of a large-scale blackout. In recent years, the introduction of renewable energy sources, i.e., renewable energy sources, has been progressing, but since renewable energy sources are connected to the power system via inverters, they do not have the inertia of conventional synchronous generators. Therefore, in a power system where a large number of renewable energy sources are connected and the number of synchronous generators is reduced, it is feared that the power system is easily unstable and the risk of a large-scale blackout increases. For this reason, technology is being developed to equip distributed power sources such as renewable energy sources and storage battery systems with a system stabilization function. In general, when a system disturbance occurs, the voltage, power flow, frequency, etc. change in a complex manner, and further, the state of change differs depending on the type of system disturbance that occurs, so the control that the distributed power source should perform to stabilize the system differs. Therefore, the distributed power source needs to properly detect and identify the system disturbance that occurs and perform appropriate stabilization control.

[0003] For example, Patent Document 1 discloses a technology related to a power system control device including a power conversion device, which determines the type of system disturbance from the system voltage and frequency deviation based on measurement data such as voltage and frequency measured by the power conversion device, and selects a control method for controlling the active power and reactive power output by the power conversion device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-182815 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional technology only deals with system disturbances that cause voltage drops, and therefore has a problem in that it is not possible to appropriately control system disturbances that do not cause voltage drops.

[0006] The present disclosure has been made in consideration of the above, and has an object to provide a distributed power supply control system that can improve the stability of a power grid. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the distributed power supply control system of the present disclosure includes a central processing unit that sets control parameters for power control on power supplied from the distributed power supplies, which is performed by a plurality of distributed power supply control devices each connected to a different distributed power supply, and a plurality of distributed power supply control devices that measure a system state, which is the state of power at a point in the connected power transmission and distribution system, and use the measurement information of the system state and the control parameters to calculate an emergency control amount according to the type of system disturbance when a system disturbance occurs in the power transmission and distribution system, thereby performing power control. The distributed power supply control device measures, as the system state, the system voltage, system frequency, and frequency change rate of the system frequency at a point of the power transmission and distribution system to which it is connected, and determines whether or not a system disturbance has occurred in the power transmission and distribution system and the type of the system disturbance when a system disturbance has occurred in the power transmission and distribution system using at least one of the system voltage, the system frequency, and the frequency change rate of the system frequency from the measurement information of the system state, and the control parameters, and determines whether or not emergency control at the time of the occurrence of a system disturbance is likely to adversely affect the system voltage and the system frequency from the measurement information of the system state, and the control parameters. It is characterized by: Effect of the Invention

[0008] The distributed power supply control system according to the present disclosure has an effect of improving the stability of the power grid. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a configuration example of a power system according to a first embodiment. [Diagram 2] FIG. 1 is a block diagram showing a configuration example of a central processing unit according to a first embodiment. [Diagram 3] FIG. 1 is a block diagram showing a configuration example of a distributed power supply control device according to a first embodiment; [Figure 4]FIG. 13 shows an example of a generator phase angle when a ground fault or short circuit fault occurs in the power transmission and distribution system according to the first embodiment, and an example of a change over time in active power and reactive power output by emergency control implemented by the distributed power supply control device when a ground fault or short circuit fault occurs. [Diagram 5] FIG. 13 shows an example of a system frequency when a power source tripping or a power line route cutoff accident occurs in the power transmission and distribution system according to the first embodiment, and an example of a time change in active power and reactive power output by emergency control implemented by a distributed power supply control device when a power source tripping or a power line route cutoff accident occurs. [Figure 6] FIG. 13 shows an example of a system frequency when a load drop or load line route breakage accident occurs in the power transmission and distribution system according to the first embodiment, and an example of a time change in active power and reactive power output by emergency control implemented by the distributed power supply control device when a load drop or load line route breakage accident occurs. [Figure 7] FIG. 1 is a diagram showing an example of normal control logic executed in a distributed power supply control device according to a first embodiment; [Figure 8] A flowchart showing an operation of an emergency control amount calculation unit of the distributed power supply control device according to the first embodiment for determining whether a system disturbance occurs and the type of the system disturbance when the system disturbance occurs and selecting an emergency control to be performed. [Figure 9] 1 is a flowchart showing the operation of the distributed power supply control system according to the first embodiment. [Figure 10] 1 is a flowchart showing the operation of a distributed power supply control device according to a first embodiment. [Figure 11] 1 is a flowchart showing the operation of a central processing unit according to the first embodiment. [Figure 12] FIG. 1 is a diagram showing an example of the configuration of a processing circuit that realizes a distributed power supply control device according to a first embodiment when the processing circuit is realized by a processor and a memory. [Figure 13] FIG. 1 is a diagram showing an example of the configuration of a processing circuit that realizes a distributed power supply control device according to a first embodiment when the processing circuit is realized by dedicated hardware. [Figure 14]10 is a first flowchart showing an operation of an emergency control amount calculation unit of a distributed power supply control device according to a second embodiment for determining whether a system disturbance occurs and the type of the system disturbance when the system disturbance occurs and selecting an emergency control to be performed. [Figure 15] 2 is a second flowchart showing an operation of the emergency control amount calculation unit of the distributed power supply control device according to the second embodiment for determining whether or not a system disturbance has occurred and the type of the system disturbance when the system disturbance has occurred and selecting the emergency control to be performed. [Figure 16] 3 is a third flowchart showing an operation of the emergency control amount calculation unit of the distributed power supply control device according to the second embodiment for determining whether or not a system disturbance has occurred and the type of the system disturbance when the system disturbance has occurred and selecting the emergency control to be performed. [Figure 17] 4 is a fourth flowchart showing an operation of the emergency control amount calculation unit of the distributed power supply control device according to the second embodiment for determining whether or not a system disturbance has occurred and the type of the system disturbance when the system disturbance has occurred and selecting the emergency control to be performed. [Figure 18] FIG. 11 is a block diagram showing a configuration example of a central processing unit according to a third embodiment. [Figure 19] FIG. 11 is a block diagram showing a configuration example of a distributed power supply control device according to a third embodiment. [Figure 20] FIG. 13 is a block diagram showing a configuration example of a distributed power supply control device according to a fourth embodiment. [Figure 21] 11 is a flowchart showing an operation of a voltage / current control mode setting unit for changing the control mode of the power converter when a system disturbance occurs during normal operation in a distributed power supply control device according to a fourth embodiment. [Figure 22] A flowchart showing an operation of a voltage / current control mode setting unit for changing the control mode of the power converter when a grid disturbance occurs and then converges in a distributed power supply control device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A distributed power supply control system, a distributed power supply control device, a central processing unit, a distributed power supply control method, a system stabilization control method, and a control parameter setting method according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0011] Embodiment 1 FIG. 1 is a diagram showing a configuration example of a power system 100 according to a first embodiment. As shown in FIG. 1, the power system 100 includes a power transmission and distribution system 1, large-scale power supply facilities 2-1 to 2-3, loads 3-1 to 3-3, a distributed power supply control system 4, a plurality of distributed power supplies 7-1 to 7-4, and a measuring device 8 for the power transmission and distribution system 1. The distributed power supply control system 4 includes a central processing unit 5 and distributed power supply control devices 6-1 to 6-4. In the example of FIG. 1, there are three large-scale power supply facilities 2-1 to 2-3 and three loads 3-1 to 3-3, and four distributed power supply control devices 6-1 to 6-4 and four distributed power supplies 7-1 to 7-4, but the number is not limited to this. In the example of FIG. 1, there is only one measuring device 8, but there may be a plurality of measuring devices 8. Hereinafter, when there is no need to distinguish between the large-scale power supply facilities 2-1 to 2-3, the distributed power supply control devices 6-1 to 6-4, and the distributed power sources 7-1 to 7-4, they will be referred to as the large-scale power supply facility 2, the load 3, the distributed power supply control device 6, and the distributed power source 7, respectively. The distributed power supply control system 4 is a system including a plurality of distributed power supply control devices 6 and a central processing unit 5 that controls the operation of the plurality of distributed power supply control devices 6.

[0012] The large-scale power source facility 2 is a power source such as a thermal power plant. The loads 3 are consumers such as companies and individual homes. The distributed power sources 7 are power sources based on renewable energy such as photovoltaics (PV) and wind power. The distributed power sources 7 may be power sources including power storage devices such as storage batteries.

[0013] The distributed power supply control device 6 is a device that controls the power generated by the distributed power supply 7. The distributed power supply control device 6 includes a power converter such as an inverter circuit for transferring power between the distributed power supply 7 and the power transmission and distribution system 1.

[0014] The central processing unit 5 is connected to the distributed power supply control device 6 and the measurement device 8 via a communication network. The communication network may be the Internet, a dedicated network, or a network using both. The central processing unit 5 receives measurement information indicating the system state, which is the state of power in the power transmission and distribution system 1 measured by the measurement device 8, via the communication network, grasps the status of the power transmission and distribution system 1, and utilizes it for calculations performed by the central processing unit 5. The central processing unit 5 also receives distributed power supply information including the operating state of the distributed power supply 7 from the distributed power supply control device 6 via the communication network. The distributed power supply information includes, for example, the installation capacity of the distributed power supply 7, the current output state from the distributed power supply 7, and the amount of charged power when the distributed power supply 7 has a storage capacity. The central processing unit 5 sets control parameters for power control for the distributed power supply 7 performed by the distributed power supply control device 6, and transmits the control parameters to the distributed power supply control device 6 via the communication network.

[0015] Fig. 2 is a block diagram showing an example of the configuration of the central processing unit 5 according to embodiment 1. As shown in Fig. 2, the central processing unit 5 includes a communication unit 51, a recording unit 52, a system information setting unit 53, a system disturbance setting unit 54, a system response calculation unit 55, and a control parameter setting unit 56.

[0016] The communication unit 51 communicates with the measuring device 8 installed in the power transmission and distribution system 1 and the distributed power supply control device 6 via the communication network. The communication unit 51 receives measurement information indicating a system state, which is a state of power in the power transmission and distribution system 1 measured by the measuring device 8, from the measuring device 8 connected to the power transmission and distribution system 1. The measurement information received from the measuring device 8 includes, for example, at least one of an operating state of a generator, a demand, a voltage flow state, and a power flow state. The communication unit 51 also receives, from a plurality of distributed power supply control devices 6 each connected to a different distributed power source 7, distributed power supply information including an operating state of the distributed power source 7, and measurement information indicating a system state, which is a state of power at a point in the power transmission and distribution system 1 to which the distributed power supply control device 6 is connected. The communication unit 51 transmits the control parameters of the power control performed by the distributed power supply control device 6 set by the control parameter setting unit 56 to the distributed power supply control device 6. In the following description, the measurement information that the communication unit 51 receives from the measuring device 8 may be referred to as first measurement information, and the measurement information that the communication unit 51 receives from the distributed power supply control device 6 may be referred to as second measurement information.

[0017] The recording unit 52 records equipment information indicating equipment included in the power transmission and distribution system 1, the first measurement information received by the communication unit 51, the second measurement information received by the communication unit 51, the distributed power source information received by the communication unit 51, etc. The recording unit 52 also records settings, calculation results, etc. used by the system information setting unit 53, the system disturbance setting unit 54, the system response calculation unit 55, and the control parameter setting unit 56.

[0018] Based on the first measurement information, the second measurement information, the distributed power source information, and the facility information, the system information setting unit 53 sets a current state indicating a current operating state of the power transmission and distribution system 1. The current state is, for example, an operating state of the power transmission and distribution system 1 that changes from moment to moment, such as a voltage flow state or a power flow state of the power transmission and distribution system 1.

[0019] The system disturbance setting unit 54 sets at least one system disturbance that may occur in the power transmission / distribution system 1 for the current state of the power transmission / distribution system 1 set by the system information setting unit 53. The system disturbance includes, for example, a system accident such as one or more ground faults or short circuits occurring at any position of the power transmission / distribution system 1, a power source drop which is the drop of one or more of the large-scale power source facilities 2, a load drop which is the drop of one or more of the loads 3, a power line route break which is the disconnection of the transmission line through which power is transmitted, i.e., the power line in which multiple large-scale power source facilities 2 are interconnected, and a load line route break which is the disconnection of the transmission line through which power is transmitted, i.e., the load line. The system disturbance also includes a multiple system disturbance consisting of a combination of two or more of the above-mentioned system disturbances.

[0020] The system response calculation unit 55 calculates, i.e., simulates, the response of the power transmission / distribution system 1 before a system disturbance occurs in the power transmission / distribution system 1 and when a system disturbance set by the system disturbance setting unit 54 occurs in the power transmission / distribution system 1, and compiles the results of the simulation. The response of the power transmission / distribution system 1 refers to the states of the system frequency F, the center of inertia frequency, the system voltage V, the tidal current, the generator phase angle, frequency, output, load power, etc., at one or more points in the power transmission / distribution system 1 before and when a system disturbance occurs.

[0021] The control parameter setting unit 56 sets control parameters for controlling the power control on the distributed power sources 7 performed by the multiple distributed power source control devices 6, based on the response of the power transmission and distribution system 1 when no system disturbance occurs in the power transmission and distribution system 1 and the response of the power transmission and distribution system 1 when a system disturbance occurs in the power transmission and distribution system 1. Details of the power control of the distributed power sources 7 performed by the distributed power source control device 6 will be described later. In the central processing unit 5, as described above, the communication unit 51 transmits the control parameters set by the control parameter setting unit 56 to the distributed power source control device 6.

[0022] Fig. 3 is a block diagram showing a configuration example of the distributed power supply control device 6 according to embodiment 1. As shown in Fig. 3, the distributed power supply control device 6 includes a power converter 601, a communication unit 602, a recording unit 603, a measurement unit 604, an emergency control amount calculation unit 605, and a normal control amount calculation unit 606.

[0023] The power converter 601 is a device that performs power control for interchange of power between the distributed power source 7 and the power transmission and distribution system 1. The power converter 601 performs power control for converting the power supplied from the distributed power source 7 into a form of power that can be handled by the power transmission and distribution system 1. Examples of the power converter 601 include a PV, which is a DC power source, a converter that converts DC power from a storage battery into AC power, a BTB (Back-To-Back) converter for connecting a variable speed wind power generator to a system, and a CYCLO (registered trademark) converter included in a doubly-fed induction generator.

[0024] The communication unit 602 communicates with the central processing unit 5 via the communication network. The communication unit 602 transmits to the central processing unit 5 measurement information indicating a system state, which is a state of power at a point in the power transmission and distribution system 1 to which the distributed power supply control device 6 is connected, measured by a measurement unit 604 described later. The communication unit 602 also transmits to the central processing unit 5 distributed power supply information including the operating state of the distributed power source 7 recorded in a recording unit 603 described later. The communication unit 602 receives control parameters for power control performed by the distributed power supply control device 6, which have been set by the central processing unit 5.

[0025] The recording unit 603 records control parameters for power control of the distributed power source 7 performed by the distributed power source control device 6, which are transmitted from the central processing unit 5 and received by the communication unit 602. The recording unit 603 also stores distributed power source information including the operating state of the distributed power source 7. The distributed power source information includes, for example, the installed capacity of the distributed power source 7, the current output state from the distributed power source 7, and the amount of charged power when the distributed power source 7 has a power storage capacity.

[0026] The measurement unit 604 measures the system state, which is the state of power at the point in the power transmission and distribution system 1 to which the distributed power supply control device 6 is connected. The measurement unit 604 measures, as the system state, the system voltage V, the system frequency F, and the rate of change of frequency RoCoF (Rate of Change of Frequency) of the system frequency F at the point in the power transmission and distribution system 1 to which the distributed power supply control device 6 is connected. The measurement unit 604 may also measure, as the system state, the system current at the point in the power transmission and distribution system 1 to which the distributed power supply control device 6 is connected.

[0027] The emergency control amount calculation unit 605 uses the measurement information measured by the measurement unit 604 and the control parameters recorded in the recording unit 603 to determine whether or not a system disturbance has occurred in the power transmission and distribution system 1 and the type of system disturbance when a system disturbance has occurred in the power transmission and distribution system 1, according to a system state determination flow described later. The emergency control amount calculation unit 605 uses the control parameters to calculate an emergency control amount that is an emergency control amount when the power converter 601 performs power control, depending on the type of system disturbance when a system disturbance has occurred. An emergency is when a system disturbance has occurred in the power transmission and distribution system 1. Details of the emergency control by the emergency control amount calculation unit 605 will be described later.

[0028] The normal state control amount calculation unit 606 uses the measurement information measured by the measurement unit 604 and the control parameters recorded in the recording unit 603 to calculate a normal state control amount, which is a control amount when the power converter 601 performs power control in a state where no system disturbance occurs in the power transmission and distribution system 1. The normal state refers to a state where no system disturbance occurs in the power transmission and distribution system 1. Details of the normal state control by the normal state control amount calculation unit 606 will be described later.

[0029] In the distributed power supply control device 6 , a power converter 601 performs power control using an emergency control amount calculated by an emergency control amount calculation unit 605 and a normal control amount calculated by a normal control amount calculation unit 606 .

[0030] FIG. 4 is a diagram showing an example of the generator phase angle when a ground fault or short circuit fault occurs in the power transmission and distribution system 1 according to the first embodiment, and the time variation of the active power and reactive power output by the emergency control performed by the distributed power supply control device 6 when a ground fault or short circuit fault occurs. A ground fault, a short circuit fault, etc. are sometimes called a system fault. As shown in FIG. 4, at a time T 0 A system disturbance occurs due to a ground fault or a short circuit fault in the distributed power supply control device 6. The distributed power supply control device 6 measures the system state when the system disturbance occurs, and outputs active power and reactive power as active power P Emg FLT , reactive power Q Emg FLT The distributed power control device 6 changes the active power P Emg FLT and reactive power Q Emg FLT Output duration T out FLT After the output continues for a period of time, the output is reduced by T dec FLT The control amount is reduced by applying the active power P Emg FLT , reactive power Q Emg FLT , output duration T out FLT , and output reduction time T dec FLT These control parameters are set by the control parameter setting unit 56 of the central processing unit 5.

[0031] The distributed power control device 6 controls the effective power P Emg FLT and reactive power Q Emg FLT Regarding the above, the following function is determined by the central processing unit 5, and the voltage drop amount ΔV when a system disturbance occurs is measured by the measurement unit 604. FLT In this case, the coefficient AP FLT and coefficient AQ FLT These are the control parameters set by the control parameter setting unit 56 of the central processing unit 5.

[0032] P Emg FLT (ΔV FLT )=AP FLT ×ΔV FLT Q Emg FLT (ΔV FLT )=AQ FLT ×ΔV FLT

[0033] In general, distributed power supply control that feeds back the measured voltage and the voltage deviation ΔV from the voltage reference value is stable but is slow to detect system disturbances, while distributed power supply control that feeds back the differential amount of the voltage deviation ΔV has the characteristic that it can detect system disturbances quickly but the control is prone to become unstable. By implementing distributed power supply control that outputs constant values ​​of active power and reactive power as shown in Fig. 4, the distributed power supply control device 6 can implement control that detects system disturbances quickly and is stable, and can contribute to improving the stability of the power transmission and distribution system 1.

[0034] It is generally known that, when a system fault occurs, the stability of the power transmission and distribution system 1 can be improved by increasing the active power output of the generator, which tends to accelerate, and by maintaining the system voltage V at a high level. Therefore, it is desirable for the distributed power control device 6 to absorb active power from the power transmission and distribution system 1 and inject reactive power into the power transmission and distribution system 1 in emergency control when a system fault occurs. Therefore, the active power P Emg FLT and reactive power Q Emg FLT It is desirable to set it so as to satisfy the above.

[0035] FIG. 5 is a diagram showing an example of the system frequency F when a power source trip or a power line route disconnection accident occurs in the power transmission and distribution system 1 according to the first embodiment, and an example of the time change of the active power and the reactive power output by the emergency control performed by the distributed power control device 6 when a power source trip or a power line route disconnection accident occurs. The target power sources are, for example, the large-scale power supply facilities 2-1 to 2-3. As shown in FIG. 5, at a time T0 A power system disturbance occurs due to a power supply failure or a power line route cut accident. The distributed power control device 6 measures the system state when the system disturbance occurs, and outputs active power and reactive power as active power P Emg GD , reactive power Q Emg GD The distributed power control device 6 changes the active power P Emg GD and reactive power Q Emg GD Output duration T out GD After the output continues for a period of time, the output is reduced by T dec GD The control amount is reduced by applying the active power P Emg GD , reactive power Q Emg GD , output duration T out GD , and output reduction time T dec GD These control parameters are set by the control parameter setting unit 56 of the central processing unit 5.

[0036] The distributed power control device 6 controls the effective power P Emg GD and reactive power Q Emg GD Regarding the frequency change rate RoCoF at the time of the occurrence of the system disturbance, the following function is determined by the central processing unit 5, and the frequency change rate RoCoF at the time of the occurrence of the system disturbance is measured by the measurement unit 604. GD In this case, the coefficient AP GD and coefficient AQ GD These are the control parameters set by the control parameter setting unit 56 of the central processing unit 5.

[0037] P Emg GD (RoCoF GD )=AP GD ×RoCoF GD Q Emg GD (RoCoFGD )=AQ GD ×RoCoF GD

[0038] The distributed power supply control device 6 performs distributed power supply control such as outputting a constant value of active power or reactive power as shown in FIG. 5, thereby enabling the implementation of rapid and stable control for detecting system disturbances, similar to the case of a system fault as described in FIG. 4, and contributing to improving the stability of the power transmission and distribution system 1.

[0039] It is also generally known that in the event of a power source trip or power line route breakage accident, the frequency stability of the power transmission and distribution system 1 can be improved by compensating for the insufficient amount of active power supply, keeping the system voltage V low, and suppressing the power consumption of the load 3. This is because the load 3 has voltage characteristics, and the lower the voltage, the less power it consumes. Therefore, it is desirable for the distributed power control device 6 to inject active power into the power transmission and distribution system 1 and absorb reactive power from the power transmission and distribution system 1 in emergency control in the event of a power source trip or power line route breakage accident. Therefore, the active power P Emg GD and reactive power Q Emg GD is desirably set so as to satisfy the above. In the following description, a power supply drop or a power line route cut accident may be referred to as a drop in a power supply or a cut in a power line, which is a transmission line connected to a power supply.

[0040] FIG. 6 is a diagram showing an example of the system frequency F when a load drop or load line route breakage accident occurs in the power transmission and distribution system 1 according to the first embodiment, and an example of the time change of the active power and the reactive power output by the emergency control performed by the distributed power supply control device 6 when a load drop or load line route breakage accident occurs. The target loads are, for example, the loads 3-1 to 3-3. As shown in FIG. 6, at a time T 0 A system disturbance occurs due to a load drop or a load line route breakage accident. The distributed power control device 6 measures the system state when the system disturbance occurs, and outputs active power and reactive power as active power P Emg LD , reactive power QEmg LD The distributed power control device 6 changes the active power P Emg LD and reactive power Q Emg LD Output duration T out LD After the output continues for a period of time, the output is reduced by T dec LD The control amount is reduced by applying the active power P Emg LD , reactive power Q Emg LD , output duration T out LD , and output reduction time T dec LD These control parameters are set by the control parameter setting unit 56 of the central processing unit 5.

[0041] The distributed power control device 6 controls the effective power P Emg LD and reactive power Q Emg LD Regarding the frequency change rate RoCoF at the time of the occurrence of the system disturbance, the following function is determined by the central processing unit 5, and the frequency change rate RoCoF at the time of the occurrence of the system disturbance is measured by the measurement unit 604. LD In this case, the coefficient AP LD and coefficient AQ LD These are the control parameters set by the control parameter setting unit 56 of the central processing unit 5.

[0042] P Emg LD (RoCoF LD )=AP LD ×RoCoF LD Q Emg LD (RoCoF LD )=AQ LD ×RoCoF LD

[0043] The distributed power supply control device 6 performs distributed power supply control such as outputting a constant value of active power or reactive power as shown in FIG. 6, thereby enabling the implementation of rapid and stable control for detecting system disturbances, similar to the case of a system fault as described in FIG. 4, and contributing to improving the stability of the power transmission and distribution system 1.

[0044] It is also generally known that in the event of a load drop or load line route breakage accident, the frequency stability of the power transmission and distribution system 1 can be improved by compensating for the excess active power supply, keeping the system voltage V high, and increasing the power consumption of the load 3. This is because the load 3 has voltage characteristics, and the higher the voltage, the greater the power consumption. Therefore, it is desirable for the distributed power control device 6 to absorb active power from the power transmission and distribution system 1 and inject reactive power into the power transmission and distribution system 1 in emergency control in the event of a load drop or load line route breakage accident. Therefore, the active power P Emg LD and reactive power Q Emg LD is desirably set so as to satisfy the above. In the following description, a load drop or load line route breakage accident may be referred to as a drop of the load 3 or a break in the load line, which is a transmission line connected to the load 3.

[0045] As shown in Fig. 4 to Fig. 6, the control parameter setting unit 56 of the central processing unit 5 sets control parameters for the distributed power supply control device 6 to output a specified first magnitude of active power and a specified second magnitude of reactive power for a specified first period, i.e., step control, and then change the magnitude of the active power and the reactive power at a constant rate so that the output becomes zero after a specified second period, i.e., control in a ramp shape, as the power control using the emergency control amount performed by the distributed power supply control device 6. This allows the emergency control amount calculation unit 605 to control the output of active power and the output of reactive power as shown in Fig. 4 to Fig. 6 based on the control parameters set by the control parameter setting unit 56 of the central processing unit 5. Note that in each of Figs. 4 to 6, the intervals on the time axis may be the same in the upper and lower figures, or may be different.

[0046] 7 is a diagram showing an example of normal control logic implemented in the distributed power supply control device 6 according to the first embodiment. Immediately after the occurrence of a system disturbance, the distributed power supply control device 6 needs to output large active power and reactive power at high speed, but the control amounts of the active power and reactive power may not be optimal control amounts for stabilizing the power transmission and distribution system 1. Therefore, in the distributed power supply control device 6, the normal control amount calculation unit 606 feeds back current information of the power transmission and distribution system 1 measured by the measurement unit 604, and determines the output of active power and reactive power to be output by the distributed power supply control device 6.

[0047] The normal control amount calculation unit 606 performs proportional control, integral control, or both of them as normal control based on the frequency deviation ΔF of the power transmission and distribution system 1, and calculates the base output P 0 By adding this to the active power output during normal control, the active power control output during normal control, P Nor The normal control amount calculation unit 606 may apply a dead band to the frequency deviation ΔF. 0 For example, when the distributed power source 7 is a PV, the base output P may be a PV power generation amount determined by maximum power point tracking control, i.e., MPPT (Maximum Power Point Tracking). 0 It is also possible to eliminate the base output P 0 may be input from a component other than the normal control amount calculation unit 606.

[0048] Furthermore, the normal control amount calculation unit 606 performs proportional control or integral control or both as normal control based on the voltage deviation ΔV of the system voltage V of the power transmission and distribution system 1 from the reference value, and calculates the base output Q 0 By adding this to the reactive power output during normal control, the normal reactive power control output Q Nor The normal control amount calculation unit 606 may apply a dead band to the voltage deviation ΔV. 0For example, when the distributed power source 7 is a PV, the base output Q may be a reactive power value determined by constant power factor operation. 0 It is also possible to eliminate the base output Q 0 may be input from a component other than the normal control amount calculation unit 606.

[0049] In the normal control shown in FIG. 7 , the proportional gain, the integral gain, the size of the dead band, the reference value of the system voltage V, etc. are control parameters for the normal control, and these control parameters are set by the control parameter setting unit 56 of the central processing unit 5.

[0050] The emergency control shown in Fig. 4 to Fig. 6 is a control in which the distributed power supply control device 6 outputs large active power and reactive power at high speed for a certain time immediately after the occurrence of a system disturbance, and the normal control shown in Fig. 7 is a control in which the distributed power supply control device 6 outputs active power and reactive power while feeding back the system state, although not at high speed, after a short time has passed since the occurrence of the system disturbance. As shown in Fig. 7, the sum of the command value of the emergency control and the command value of the normal control finally becomes the command value of the control of active power and reactive power performed by the power converter 601. In this way, the distributed power supply control device 6 can improve the stability of the power transmission and distribution system 1 quickly and stably by combining the emergency control and the normal control.

[0051] In addition, if the distributed power source 7 is not a system such as a power storage device, it may be possible that active power cannot be absorbed, in which case the active power may be set to 0 and the reactive power may be controlled as described above. Furthermore, since MPPT is generally implemented for renewable energy sources such as PV and wind power generation, if there is no power storage device, it may be possible that the injected active power cannot be increased, in which case the active power may be outputted to the maximum, i.e., at the current level, and the reactive power may be controlled as described above.

[0052] Fig. 8 is a flowchart showing an operation of the emergency control amount calculation unit 605 of the distributed power supply control device 6 according to the first embodiment for determining whether or not a system disturbance has occurred and the type of system disturbance when a system disturbance has occurred, and selecting emergency control to be performed. The flowchart shown in Fig. 8 is the system state determination flow described above. The emergency control amount calculation unit 605 determines the system voltage V of the power transmission and distribution system 1 and the system voltage threshold value V th FLT The system voltage threshold V is compared with the threshold V and the occurrence or non-occurrence of a system fault is determined based on the degree of decrease in the system voltage V of the power transmission and distribution system 1 (step S101). th FLT is a system fault detection threshold value for the system voltage V for detecting a system fault as a system disturbance, which is set as a control parameter by the control parameter setting unit 56 of the central processing unit 5. That is, the control parameter setting unit 56 of the central processing unit 5 sets the system voltage threshold value V th FLT The emergency control amount calculation unit 605 sets the system voltage V of the power transmission and distribution system 1<system voltage threshold V th FLT In the case where (step S101: Yes), that is, the system voltage V of the power transmission and distribution system 1 is equal to or lower than the system voltage threshold V th FLT If the difference is less than the threshold voltage V, it is determined that a grid fault has occurred, and the process proceeds to step S104. th FLT If so (step S101: No), it is determined that no grid accident has occurred, and the process proceeds to step S102.

[0053] The emergency control amount calculation unit 605 calculates the frequency change rate RoCoF and the frequency change rate threshold RoCoF Lth The frequency change rate threshold RoCoF is compared with the frequency change rate threshold RoCoF to determine whether or not a power supply loss or a power line route cut accident has occurred (step S102). Lthis a first power supply loss detection threshold for the frequency change rate RoCoF, which is set as a control parameter by the control parameter setting unit 56 of the central processing unit 5, for detecting a power supply loss or a power line disconnection, which is a transmission line connected to a power supply, as a system disturbance. That is, the control parameter setting unit 56 of the central processing unit 5 sets the frequency change rate threshold RoCoF Lth The emergency control amount calculation unit 605 sets the frequency change rate RoCoF<frequency change rate threshold value RoCoF Lth (step S102: Yes), that is, the frequency change rate RoCoF is equal to or lower than the frequency change rate threshold RoCoF Lth If the frequency change rate RoCoF is less than the threshold value RoCoF, it is determined that a power supply loss or power line route interruption accident has occurred, and the process proceeds to step S105. Lth If so (step S102: No), it is determined that a power supply loss or power line route disconnection accident has not occurred, and the process proceeds to step S103.

[0054] The emergency control amount calculation unit 605 calculates the frequency change rate RoCoF and the frequency change rate threshold RoCoF Uth The frequency change rate threshold RoCoF is compared with the frequency change rate threshold RoCoF to determine whether a load drop or load line route breakage has occurred (step S103). Uth is a first load drop detection threshold for the frequency change rate RoCoF, which is set as a control parameter by the control parameter setting unit 56 of the central processing unit 5, for detecting a drop of the load 3 or a disconnection of a load line, which is a transmission line connected to the load 3, as a system disturbance. That is, the control parameter setting unit 56 of the central processing unit 5 sets the frequency change rate threshold RoCoF Uth The emergency control amount calculation unit 605 sets the frequency change rate RoCoF>frequency change rate threshold value RoCoF Uth (step S103: Yes), that is, the frequency change rate RoCoF is equal to or lower than the frequency change rate threshold RoCoF Uth If it is greater than the frequency change rate RoCoF, it is determined that a load drop or load line route breakage accident has occurred, and the process proceeds to step S106. UthIf so (step S103: No), it is determined that no load drop or load line route breakage accident has occurred, and the process proceeds to step S113.

[0055] The emergency control amount calculation unit 605 calculates the system frequency F and the system frequency threshold F Lth The emergency control amount calculation unit 605 compares the system frequency threshold F with the system frequency threshold F to determine whether or not the emergency control in the event of a grid accident may have an adverse effect on the grid frequency F, and if there is a possibility of an adverse effect, makes a determination not to start the emergency control in the event of a grid accident (step S104). Lth If the grid frequency is F (step S104: Yes), it is determined that the emergency control in the event of a grid accident will not adversely affect the grid frequency F, and the process proceeds to step S107. Lth If ≧system frequency F (step S104: No), it is possible that emergency control in the event of a system accident may adversely affect the system frequency F, and the process proceeds to step S113.

[0056] The emergency control amount calculation unit 605 calculates the system frequency F and the system frequency threshold F Uth and compare the system voltage V with the system voltage threshold V Lth and judge whether or not emergency control in the event of a power source trip or power line route cutoff accident may adversely affect the system frequency F and system voltage V, and if there is a possibility of adverse effect, judge not to start emergency control in the event of a power source trip or power line route cutoff accident (step S105). The emergency control amount calculation unit 605 compares system frequency F<system frequency threshold F Uth And the grid voltage threshold V Lth If the grid voltage is V (step S105: Yes), it is determined that the emergency control in the event of a power source drop or a power line route cut accident will not adversely affect the grid frequency F and the grid voltage V, and the process proceeds to step S108. Uth and grid voltage threshold V Lth≧system voltage V is satisfied (step S105: No), the process proceeds to step S113 since emergency control in the event of a power source loss or power line route cutoff accident may adversely affect the system frequency F and system voltage V.

[0057] The emergency control amount calculation unit 605 calculates the system frequency F and the system frequency threshold F Lth and compare the system voltage V with the system voltage threshold V Uth and judges whether or not emergency control at the time of load drop or load line route breakage accident may adversely affect the system frequency F and system voltage V, and if there is a possibility of adverse effect, judges not to start emergency control at the time of load drop or load line route breakage accident (step S106). Lth < System frequency F and system voltage V < System voltage threshold V Uth If so (step S106: Yes), it is determined that the emergency control at the time of load drop or load line route breakage accident will not adversely affect the grid frequency F and the grid voltage V, and the process proceeds to step S109. Lth ≧ System frequency F and system voltage V ≧ System voltage threshold V Uth If at least one of the above is true (step S106: No), the process proceeds to step S113 since emergency control in the event of a load drop or load line route breakage accident may adversely affect the system frequency F and the system voltage V.

[0058] The emergency control amount calculation unit 605 judges whether an accident control flag, which is set by the central processing unit 5 for each distributed power supply control device 6 and indicates whether emergency control is to be performed in the event of a grid accident, is ON or not (step S107). If the accident control flag is ON (step S107: Yes), the emergency control amount calculation unit 605 starts accident control as an emergency control to be performed in the event of a grid accident (step S110). If the accident control flag is OFF (step S107: No), the emergency control amount calculation unit 605 proceeds to step S113 as an emergency control is not to be performed in the event of a grid accident.

[0059] The emergency control amount calculation unit 605 judges whether a power supply drop control flag, which is set for each distributed power supply control device 6 by the central processing unit 5 and indicates whether emergency control is to be performed in the event of a power supply drop or a power line route cut accident, is ON or not (step S108). If the power supply drop control flag is ON (step S108: Yes), the emergency control amount calculation unit 605 starts the power supply drop control as the emergency control is to be performed in the event of a power supply drop or a power line route cut accident (step S111). If the power supply drop control flag is OFF (step S108: No), the emergency control amount calculation unit 605 proceeds to step S113 as the emergency control is not to be performed in the event of a power supply drop or a power line route cut accident.

[0060] The emergency control amount calculation unit 605 judges whether a load drop control flag, which is set for each distributed power supply control device 6 by the central processing unit 5 and indicates whether emergency control is to be performed in the event of a load drop or a load line route breakage accident, is ON (step S109). If the load drop control flag is ON (step S109: Yes), the emergency control amount calculation unit 605 starts the load drop control as the emergency control is to be performed in the event of a load drop or a load line route breakage accident (step S112). If the load drop control flag is OFF (step S109: No), the emergency control amount calculation unit 605 proceeds to step S113 as the emergency control is not to be performed in the event of a load drop or a load line route breakage accident.

[0061] If step S103: No, or step S104: No, or step S105: No, or step S106: No, or step S107: No, or step S108: No, or step S109: No, the emergency control amount calculation unit 605 does not start emergency control (step S113).

[0062] In the following description, the accident control flag, the power supply drop control flag, and the load drop control flag may be collectively referred to as the control flag. In this way, the control parameter setting unit 56 of the central processing unit 5 sets a control flag as a control parameter for controlling whether or not the distributed power supply control device 6 performs power control using the emergency control amount. The control parameter setting unit 56 of the central processing unit 5 can set the control flag according to the positions of the distributed power supply control device 6 and the distributed power source 7 connected to the power transmission and distribution system 1, the operating state of the distributed power source 7, the positional relationship between adjacent distributed power supply control devices 6 or between the distributed power sources 7, and the like. This allows the emergency control amount calculation unit 605 to perform power control using the emergency control amount when the control flag is ON, and not to perform power control using the emergency control amount when the control flag is OFF.

[0063] The emergency control amount calculation unit 605 can appropriately determine the occurrence or non-occurrence of a system disturbance and the type of the system disturbance even in a complicated system state such as when multiple faults occur in the power transmission and distribution system 1 by repeatedly executing the flowchart shown in FIG. 8, and can start emergency control. th FLT ,V Lth ,V Uth , frequency change rate threshold RoCoF Lth ,RoCoF Uth , grid frequency threshold F Lth ,F Uth , and the start flag of the emergency control corresponding to each type of system disturbance are control parameters set by the central processing unit 5.

[0064] In general, when controlling the active power and reactive power of the distributed power source 7 in an emergency, the impact on the stability of the power transmission and distribution system 1 changes depending on the installation positions of the distributed power source 7, the distributed power source control device 6, etc. For example, when a system accident occurs, stability is improved by increasing the active power of a generator with an accelerating tendency, keeping the voltage of the power transmission and distribution system 1 high, reducing the current flowing through the transmission line, etc. Therefore, system stability is improved by the distributed power source 7 near the accelerating generator absorbing or reducing the active power, or the distributed power source 7 located on the transmitting side of the power transmission and distribution system 1 absorbing or reducing the active power, etc. On the other hand, system stability is deteriorated by the distributed power source 7 near the decelerating generator absorbing or reducing the active power, or the distributed power source 7 located on the receiving side of the power transmission and distribution system 1 absorbing or reducing the active power, etc.

[0065] Furthermore, in the event of a power source trip or power line route cut accident, frequency stability is improved by making up for the insufficient supply of active power and by keeping the voltage of the power transmission and distribution system 1 low to suppress power consumption by the load 3. Therefore, when the distributed power source 7 located on the receiving side of the power transmission and distribution system 1 absorbs or reduces active power, the power flow through the transmission line increases and the system voltage V becomes lower, which is effective in improving frequency stability. On the other hand, when the distributed power source 7 located on the transmitting side of the power transmission and distribution system 1 absorbs or reduces active power, the power flow through the transmission line decreases and the system voltage V becomes higher, which is less effective in improving frequency stability.

[0066] Furthermore, in the event of a load drop or load line route breakage accident, frequency stability can be improved by reducing the supply of excess active power, keeping the system voltage V high and increasing the power consumption of the load 3, etc. Therefore, when the distributed power source 7 located on the receiving side of the power transmission and distribution system 1 injects or increases active power, the power flow through the transmission line decreases and the system voltage V becomes higher, which is effective in improving frequency stability. On the other hand, when the distributed power source 7 located on the transmitting side of the power transmission and distribution system 1 injects or increases active power, the power flow through the transmission line increases and the system voltage V becomes lower, which is less effective in improving frequency stability.

[0067] Therefore, the control parameter setting unit 56 of the central processing unit 5 sets an emergency control startup flag for each distributed power supply control device 6 according to the installation location of the distributed power supply control device 6, and executes emergency control only on the distributed power sources 7 that are effective for improving the stability of the system. This enables the central processing unit 5 to more effectively contribute to improving the stability of the system.

[0068] Active power P Emg FLT , reactive power Q Emg FLT , output duration T out FLT , output reduction time T dec FLT , coefficient AP FLT , coefficient AQ FLT , active power P Emg GD , reactive power Q Emg GD , output duration T out GD , output reduction time T dec GD , coefficient AP GD , coefficient AQ GD , active power P Emg LD , reactive power Q Emg LD , output duration T out LD , output reduction time T dec LD , coefficient AP LD , coefficient AQ LD , proportional gain in normal control, integral gain in normal control, size of dead band, reference value of grid voltage V, grid voltage threshold V th FLT , frequency change rate threshold RoCoF Lth , frequency change rate threshold RoCoF Uth , grid frequency threshold F Lth , grid frequency threshold F Uth , grid voltage threshold V Lth , grid voltage threshold V Uth, and the emergency control start flag are control parameters that are set by the control parameter setting unit 56 of the central processing unit 5.

[0069] These control parameters may be set arbitrarily by the system operator, or may be set by the control parameter setting unit 56 so as to be effective for improving the stability of the power transmission and distribution system 1 as described above based on the response of the power transmission and distribution system 1 before and at the time of a system disturbance calculated by the system response calculation unit 55, or the control parameter setting unit 56 may set the control parameters by performing optimization calculations, or the control parameter setting unit 56 may set the control parameters using a machine learning technique.

[0070] The operation of the distributed power supply control system 4 will be described. FIG. 9 is a flowchart showing the operation of the distributed power supply control system 4 according to the first embodiment. In the distributed power supply control system 4, the central processing unit 5 sets control parameters for power control on power supplied from the distributed power supplies 7, which is performed by a plurality of distributed power supply control devices 6 each connected to a different distributed power supply 7 (step S11). The distributed power supply control device 6 measures the system state, which is the state of power at a point of the power transmission and distribution system 1 to which it is connected, and uses the measurement information of the system state and the control parameters to calculate an emergency control amount according to the type of system disturbance when a system disturbance occurs in the power transmission and distribution system 1 (step S12), and performs power control (step S13). Note that the above-mentioned operation of the distributed power supply control system 4 is a basic operation, and the distributed power supply control system 4 can also perform operations other than the operation shown in FIG. 9. For example, in the distributed power supply control system 4, when the control parameters are set by default, the distributed power supply control device 6 can calculate the emergency control amount and perform power control even if the control parameters are not set by the central processing unit 5.

[0071] The operation of the distributed power supply control device 6 will be described. FIG. 10 is a flowchart showing the operation of the distributed power supply control device 6 according to the first embodiment. In the distributed power supply control device 6, the measurement unit 604 measures the system state, which is the state of power at the point of the power transmission and distribution system 1 to which the distributed power supply control device 6 is connected (step S21). The communication unit 602 transmits to the central processing unit 5 the distributed power supply information including the operation state of the distributed power source 7 and the measurement information indicating the system state measured by the measurement unit 604 (step S22), and receives from the central processing unit 5 the control parameters of the power control set by the central processing unit 5 (step S23). The emergency control amount calculation unit 605 uses the measurement information and the control parameters to determine whether or not a system disturbance has occurred in the power transmission and distribution system 1 and the type of the system disturbance when the system disturbance has occurred in the power transmission and distribution system 1, and calculates an emergency control amount, which is the control amount when the power converter 601 performs power control according to the type of the system disturbance when the system disturbance has occurred (step S24). The power converter 601 uses the emergency control amount to perform power control to convert the power supplied from the distributed power source 7 into a form of power that can be handled by the power transmission and distribution system 1 (step S25). Note that the above-described operation of the distributed power source control device 6 is a basic operation, and the distributed power source control device 6 is also capable of performing operations other than the operation shown in Fig. 10. For example, in a case where control parameters are set by default as in the case of Fig. 9, the distributed power source control device 6 can calculate the emergency control amount and perform power control even if the control parameters are not set by the central processing unit 5.

[0072] The operation of the central processing unit 5 will be described. FIG. 11 is a flowchart showing the operation of the central processing unit 5 according to the first embodiment. In the central processing unit 5, the communication unit 51 receives, from the measurement device 8 connected to the power transmission and distribution system 1, first measurement information indicating a system state, which is a state of power in the power transmission and distribution system 1 measured by the measurement device 8, and receives, from a plurality of distributed power source control devices 6 each connected to a different distributed power source 7, distributed power source information including an operation state of the distributed power source 7, and second measurement information indicating a system state, which is a state of power at a point in the power transmission and distribution system 1 to which the distributed power source control device 6 is connected (step S31). The system information setting unit 53 sets a current state indicating a current operation state of the power transmission and distribution system 1 based on the first measurement information, the second measurement information, the distributed power source information, and the equipment information indicating the equipment included in the power transmission and distribution system 1 (step S32). The system disturbance setting unit 54 sets a system disturbance that may occur in the power transmission and distribution system 1 for the current state of the power transmission and distribution system 1 (step S33). The system response calculation unit 55 simulates the response of the power transmission / distribution system 1 before a system disturbance occurs in the power transmission / distribution system 1 and when the system disturbance set by the system disturbance setting unit 54 occurs in the power transmission / distribution system 1 (step S34). The control parameter setting unit 56 sets control parameters for controlling power control on the distributed power sources 7 performed by the multiple distributed power source control devices 6, based on the response of the power transmission / distribution system 1 in a state in which no system disturbance occurs in the power transmission / distribution system 1 and the response of the power transmission / distribution system 1 when a system disturbance occurs in the power transmission / distribution system 1 (step S35).

[0073] Next, a hardware configuration of the distributed power supply control device 6 according to the first embodiment will be described. In the distributed power supply control device 6, the power converter 601 is a device such as a converter. The communication unit 602 is a communication device. The recording unit 603 is a memory. The measurement unit 604 is a sensor. The emergency control amount calculation unit 605 and the normal control amount calculation unit 606 are realized by processing circuits. The processing circuit may be a memory that stores a program and a processor that executes the program stored in the memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0074] FIG. 12 is a diagram showing an example of the configuration of a processing circuit 90 in the case where the processing circuit for realizing the distributed power supply control device 6 according to the first embodiment is realized by a processor 91 and a memory 92. The processing circuit 90 shown in FIG. 12 is a control circuit and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is realized by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 92. In the processing circuit 90, each function is realized by the processor 91 reading and executing the program stored in the memory 92. That is, the processing circuit 90 includes a memory 92 for storing a program that results in the processing of the distributed power supply control device 6 being executed. This program can also be said to be a program for causing the distributed power supply control device 6 realized by the processing circuit 90 to execute it. This program may be provided by a storage medium in which the program is stored, or may be provided by other means such as a communication medium.

[0075] Here, the processor 91 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc. Also, the memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc), etc.

[0076] Fig. 13 is a diagram showing an example of the configuration of a processing circuit 93 when the processing circuit for realizing the distributed power supply control device 6 according to the first embodiment is realized by dedicated hardware. The processing circuit 93 shown in Fig. 13 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. The processing circuit 93 may be partially realized by dedicated hardware and partially realized by software or firmware. In this way, the processing circuit 93 can realize each of the above-mentioned functions by dedicated hardware, software, firmware, or a combination of these.

[0077] Although the hardware configuration of the distributed power supply control device 6 has been described, the central processing unit 5 has a similar hardware configuration. In the central processing unit 5, the communication unit 51 is a communication device. The recording unit 52 is a memory. The system information setting unit 53, the system disturbance setting unit 54, the system response calculation unit 55, and the control parameter setting unit 56 are realized by processing circuits. The processing circuit may be a memory that stores a program and a processor that executes the program stored in the memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0078] As described above, according to this embodiment, the distributed power supply control system 4 quickly detects the occurrence of a system disturbance and the type of the system disturbance at the installation position of the distributed power supply control device 6, and performs a high-speed and highly stable emergency control and a normal control that is not fast but can feed back the system state. As a result, the distributed power supply control system 4 can improve the stability of the power transmission and distribution system 1, i.e., the power system 100, when a system disturbance occurs, and contribute to avoiding large-scale blackouts. Furthermore, the central processing unit 5 can enhance the effect of improving the stability of the power transmission and distribution system 1, i.e., the power system 100, by setting a start flag for emergency control and parameters for emergency control and normal control according to the installation position of the distributed power supply control device 6.

[0079] The distributed power supply control system 4 can also appropriately control system disturbances that do not involve voltage drops, such as frequency fluctuations caused by power supply drop or load drop, and can also appropriately control complex system disturbances consisting of system accidents, power supply drop, load drop, and combinations of these. When a system disturbance occurs, the distributed power supply control system 4 can perform different power controls using the distributed power supply control device 6, taking into consideration the impact and contribution to system stability depending on the installation positions of the distributed power supply control device 6, the distributed power sources 7, and the like in the power transmission and distribution system 1.

[0080] Embodiment 2 In the second embodiment, a modified example of the operation of the emergency control amount calculator 605 of the distributed power supply control device 6 shown in FIG. 8 and described in the first embodiment will be described.

[0081] The first modified example will be described. Fig. 14 is a first flowchart showing the operation of the emergency control amount calculation unit 605 of the distributed power supply control device 6 according to the second embodiment for determining whether or not a system disturbance has occurred and the type of system disturbance when a system disturbance has occurred and selecting emergency control to be performed. In the flowchart shown in Fig. 14, the operation of step S101 is the same as the operation of step S101 in the flowchart shown in Fig. 8. However, in the flowchart shown in Fig. 14, if step S101: No, the process proceeds to step S121.

[0082] The emergency control amount calculation unit 605 calculates the system frequency F and the system frequency threshold F Lth GD The system frequency threshold F is compared with the system frequency threshold F to determine whether or not a power supply loss or a power line route cut accident has occurred (step S121). Lth GD is a second power supply failure detection threshold value for the system frequency F, which is set as a control parameter by the control parameter setting unit 56 of the central processing unit 5, for detecting a power supply failure or a power line break, which is a transmission line connected to a power supply, as a system disturbance. That is, the control parameter setting unit 56 of the central processing unit 5 sets the system frequency threshold value F Lth GD The emergency control amount calculation unit 605 sets the system frequency F<system frequency threshold F Lth GD In the case of (step S121: Yes), that is, the grid frequency F is equal to or greater than the grid frequency threshold F Lth GD If the power supply frequency F is less than the power supply frequency threshold F, the system determines that a power supply loss or power line route cut accident has occurred, and proceeds to step S105. Lth GD If so (step S121: No), it is determined that a power supply loss or power line route disconnection accident has not occurred, and the process proceeds to step S122.

[0083] The emergency control amount calculation unit 605 calculates the system frequency F and the system frequency threshold F Uth LD The system frequency threshold F is compared with the system frequency threshold F to determine whether a load drop or a load line route breakage has occurred (step S122). Uth LD is a second load drop detection threshold value for the system frequency F, which is set as a control parameter by the control parameter setting unit 56 of the central processing unit 5, for detecting a drop of the load 3 or a break in a load line, which is a transmission line connected to the load 3, as a system disturbance. That is, the control parameter setting unit 56 of the central processing unit 5 sets the system frequency threshold value F Uth LDThe emergency control amount calculation unit 605 sets the system frequency F>system frequency threshold F Uth LD In the case of (step S122: Yes), that is, the grid frequency F is equal to or greater than the grid frequency threshold F Uth LD If F is greater than F, it is determined that a load drop or load line route breakage accident has occurred, and the process proceeds to step S106. Uth LD If so (step S122: No), it is determined that no load drop or load line route breakage accident has occurred, and the process proceeds to step S113.

[0084] The subsequent operations are the same as those in steps S104 to S113 in the flowchart shown in Fig. 8. In this way, the emergency control amount calculation unit 605 can obtain the same effects as those in the first embodiment even when using the system frequency F instead of the frequency change rate RoCoF in the first embodiment.

[0085] A second modified example will be described. Fig. 15 is a second flowchart showing the operation of the emergency control amount calculation unit 605 of the distributed power supply control device 6 according to the second embodiment for determining whether or not a system disturbance has occurred and the type of system disturbance when a system disturbance has occurred, and selecting emergency control to be performed. In the flowchart shown in Fig. 15, the operation of step S101 is the same as the operation of step S101 in the flowchart shown in Fig. 8. However, in the flowchart shown in Fig. 15, if step S101: No, the process proceeds to step S131.

[0086] The emergency control amount calculation unit 605 calculates the frequency change rate RoCoF and the frequency change rate threshold RoCoF Lth and compare the grid frequency F with the grid frequency threshold F Lth GD The emergency control amount calculation unit 605 compares the frequency change rate RoCoF with the frequency change rate threshold RoCoF to determine whether a power supply loss or a power line route interruption accident has occurred (step S131). Lth and grid frequency F< grid frequency threshold F LthGD If at least one of the above is true (step S131: Yes), it is determined that a power supply loss or a power line route cut accident has occurred, and the process proceeds to step S105. Lth and grid frequency F< grid frequency threshold F Lth GD If at least one of the above is not satisfied (step S131: No), it is determined that a power supply loss or a power line route cut accident has not occurred, and the process proceeds to step S132. Lth and grid frequency threshold F Lth GD In this way, the emergency control amount calculation unit 605 determines whether the frequency change rate RoCoF is equal to or smaller than the frequency change rate threshold RoCoF. Lth and grid frequency F is less than grid frequency threshold F Lth GD If at least one of the following conditions is met, it can be determined that a power supply failure or a power line breakage has occurred.

[0087] The emergency control amount calculation unit 605 calculates the frequency change rate RoCoF and the frequency change rate threshold RoCoF Uth and compare the grid frequency F with the grid frequency threshold F Uth LD The emergency control amount calculation unit 605 compares the frequency change rate RoCoF with the frequency change rate threshold RoCoF to determine whether a load drop or a load line route breakage accident has occurred (step S132). Uth and grid frequency F > grid frequency threshold F Uth LD If at least one of the above is true (step S132: Yes), it is determined that a load drop or load line route breakage accident has occurred, and the process proceeds to step S106. Uth and grid frequency F > grid frequency threshold F Uth LDIf at least one of the above is not satisfied (step S132: No), it is determined that no load drop or load line route breakage accident has occurred, and the process proceeds to step S113. Uth and grid frequency threshold F Uth LD In this way, the emergency control amount calculation unit 605 determines whether the frequency change rate RoCoF is equal to or smaller than the frequency change rate threshold RoCoF. Uth and grid frequency F is greater than grid frequency threshold F Uth LD If at least one of the above is true, it can be determined that the load 3 has fallen off or the load line has been broken.

[0088] The subsequent operations are similar to steps S104 to S113 in the flowchart shown in Fig. 8. In this manner, the emergency control amount calculation unit 605 uses the system frequency F in addition to the frequency change rate RoCoF of the first embodiment, thereby being able to more accurately determine whether or not a system disturbance has occurred and to more accurately determine the type of system disturbance when a system disturbance has occurred than in the first embodiment.

[0089] A third modified example will be described. Even if no power drop or load drop occurs and only a grid accident occurs, if a large frequency fluctuation occurs, there is a possibility that either the power drop control or the load drop control will be activated. For this reason, a process may be added in which the power drop control and the load drop control are not activated for a certain period of time after the grid accident occurs, or a detection threshold for activating the power drop control and the load drop control is adjusted. Hereinafter, the power drop control and the load drop control are collectively referred to as the power supply load drop control.

[0090] In the distributed power supply control device 6, an adjustment flag for the control when the load drops is provided, and the adjustment flag for the control when the load drops is set to OFF under normal conditions, and the adjustment flag for the control when the load drops is set to ON when a certain condition is satisfied. The adjustment flag is set to ON when, for example, the central processing unit 5 detects the occurrence of an accident from wide-area measurement information, operation information of a protective relay, etc., and in that case, the central processing unit 5 transmits a signal to the distributed power supply control device 6 to set the adjustment flag to ON, and the distributed power supply control device 6 sets the adjustment flag to ON for a certain period of time after receiving the signal from the central processing unit 5. As for other conditions, for example, the distributed power supply control device 6 may set the adjustment flag for the control when the load drops to ON for a certain period of time after starting the accident control, or may set the adjustment flag for the control when the load drops to ON for a certain period of time when the voltage phase angle of the measurement information of the device itself, the system frequency F of the power transmission and distribution system 1, the frequency change rate RoCoF of the power transmission and distribution system 1, etc. are fluctuating up and down. When a system accident occurs far from the position of a certain distributed power supply control device 6, even if the voltage of the power transmission and distribution system 1 does not drop significantly, the voltage phase angle, the system frequency F of the power transmission and distribution system 1, the frequency change rate RoCoF of the power transmission and distribution system 1, etc. may oscillate up and down significantly. Therefore, when the distributed power supply control device 6 detects up and down oscillations in the voltage phase angle, the system frequency F of the power transmission and distribution system 1, the frequency change rate RoCoF of the power transmission and distribution system 1, etc., it sets an adjustment flag for the control at the time of load drop of the power supply 6 to ON for a certain period of time. That is, the control parameter setting unit 56 of the central processing unit 5 or the emergency control amount calculation unit 605 of the distributed power supply control device 6 sets, as a control parameter, an adjustment flag for the control at the time of load drop of the power supply to ON, which prevents the distributed power supply control device 6 from detecting types other than the system accident as a system disturbance for a specified period of time after the system accident occurs in the power transmission and distribution system 1. In the following description, the adjustment flag for the control at the time of load drop of the power supply may be simply referred to as an adjustment flag.

[0091] Fig. 16 is a third flowchart showing an operation of the emergency control amount calculation unit 605 of the distributed power supply control device 6 according to the second embodiment for determining whether a system disturbance has occurred and the type of the system disturbance when the system disturbance has occurred and selecting an emergency control to be performed. In the flowchart shown in Fig. 16, the operation of step S101 is the same as the operation of step S101 in the flowchart shown in Fig. 8. However, in the flowchart shown in Fig. 16, if step S101: No, the process proceeds to step S141.

[0092] The emergency control amount calculation unit 605 determines whether or not to execute the power drop control and the load drop control depending on whether the adjustment flag for the power load drop control is ON or OFF (step S141). When the adjustment flag for the power load drop control is OFF (step S141: Yes), the emergency control amount calculation unit 605 proceeds to step S102, assuming that the power drop control or the load drop control will be executed if the above-mentioned condition is met. When the adjustment flag for the power load drop control is ON (step S141: No), the emergency control amount calculation unit 605 proceeds to step S113, assuming that the power drop control and the load drop control will not be started regardless of the above-mentioned condition. In this way, when the adjustment flag for the power load drop control is ON, the emergency control amount calculation unit 605 does not detect types of system disturbance other than the system fault as the system disturbance.

[0093] The subsequent operations are similar to steps S104 to S113 in the flowchart shown in Fig. 8. In this manner, the emergency control amount calculation unit 605 can perform emergency control in accordance with the system state of the power transmission and distribution system 1 by using the adjustment flag for control when a power source load drops.

[0094] The third modified example can be applied to the first and second modified examples. That is, steps S102 and S103 shown in Fig. 16 may be replaced with steps S121 and S122 shown in Fig. 14, or steps S131 and S132 shown in Fig. 15.

[0095] A fourth modified example will be described. Fig. 17 is a fourth flowchart showing an operation of the emergency control amount calculation unit 605 of the distributed power supply control device 6 according to the second embodiment for determining whether a system disturbance occurs and the type of system disturbance when the system disturbance occurs and selecting the emergency control to be performed. In the flowchart shown in Fig. 17, the operation of step S141 is the same as the operation of step S141 in the flowchart shown in Fig. 16. However, in the flowchart shown in Fig. 17, if step S141: No, the process proceeds to step S142. The operation of step S141 in the flowchart shown in Fig. 17 corresponds to an operation of changing the start determination threshold of the power supply drop control and the load drop control depending on whether the adjustment flag of the power supply load drop control is ON or OFF.

[0096] The emergency control amount calculation unit 605 calculates the frequency change rate RoCoF and the frequency change rate threshold RoCoF Lth2 The frequency change rate threshold RoCoF is compared with the frequency change rate threshold RoCoF to determine whether a power supply loss or a power line route interruption has occurred (step S142). Lth2 is the frequency change rate threshold RoCoF Lth The emergency control amount calculation unit 605 determines whether the frequency change rate RoCoF<frequency change rate threshold value RoCoF Lth2 If (step S142: Yes), it is determined that a power supply loss or power line route cut accident has occurred, and the process proceeds to step S105. Lth2 If so (step S142: No), it is determined that a power supply loss or power line route disconnection accident has not occurred, and the process proceeds to step S143.

[0097] The emergency control amount calculation unit 605 calculates the frequency change rate RoCoF and the frequency change rate threshold RoCoF Uth2 The frequency change rate threshold RoCoF is compared with the frequency change rate threshold RoCoF to determine whether a load drop or load line route breakage has occurred (step S143). Uth2 is the frequency change rate threshold RoCoF UthThe emergency control amount calculation unit 605 determines whether the frequency change rate RoCoF>frequency change rate threshold value RoCoF Uth2 If (step S143: Yes), it is determined that a load drop or load line route breakage accident has occurred, and the process proceeds to step S106. Uth2 If so (step S143: No), it is determined that no load drop or load line route breakage accident has occurred, and the process proceeds to step S113.

[0098] The subsequent operations are similar to steps S104 to S113 in the flowchart shown in Fig. 8. In this manner, the emergency control amount calculation unit 605 can change the activation determination thresholds for the power supply drop control and the load drop control by using the adjustment flag for the power supply load drop control, and can perform emergency control according to the system state of the power transmission and distribution system 1.

[0099] The fourth modified example can also be applied to the first modified example and the second modified example. That is, the parts of step S102 and step S103 shown in Fig. 17 may be replaced with step S121 and step S122 shown in Fig. 14, or may be replaced with step S131 and step S132 shown in Fig. 15. Furthermore, the parts of step S142 and step S143 may be changed to a content of comparing the grid frequency F with a threshold value for the grid frequency F, or may be changed to a content of combining the current content of step S142 and step S143 with a content of comparing the grid frequency F with a threshold value for the grid frequency F.

[0100] For example, the control parameter setting unit 56 of the central processing unit 5 or the emergency control amount calculation unit 605 of the distributed power control device 6 sets, as a control parameter, an adjustment flag for control at load drop of power supply to ON, which causes the distributed power control device 6 not to use the first power supply drop detection threshold and the second power supply drop detection threshold for a specified period after a system accident occurs in the power transmission and distribution system 1. In addition, the control parameter setting unit 56 of the central processing unit 5 sets, as a control parameter, at least one of a third power supply drop detection threshold for the frequency change rate RoCoF and a fourth power supply drop detection threshold for the system frequency F, for detecting a power supply drop or a power line disconnection. In this case, when the adjustment flag for control at load drop of power supply is ON, the emergency control amount calculation unit 605 can determine that a power supply drop or a power line disconnection has occurred when at least one of the frequency change rate RoCoF being less than the third power supply drop detection threshold and the system frequency F being less than the fourth power supply drop detection threshold is satisfied.

[0101] Furthermore, the control parameter setting unit 56 of the central processing unit 5 or the emergency control amount calculation unit 605 of the distributed power supply control device 6 sets, as a control parameter, an adjustment flag for power supply load drop control to ON, which prevents the distributed power supply control device 6 from using the first load drop detection threshold and the second load drop detection threshold for a specified period after a system accident occurs in the power transmission and distribution system 1. Furthermore, the control parameter setting unit 56 of the central processing unit 5 sets, as a control parameter, at least one of a third load drop detection threshold for the frequency change rate RoCoF and a fourth load drop detection threshold for the system frequency F, for detecting a drop of the load 3 or a disconnection of the load line. In this case, when the adjustment flag for power supply load drop control is ON, the emergency control amount calculation unit 605 can determine that a drop of the load 3 or a disconnection of the load line has occurred when at least one of the frequency change rate RoCoF is greater than the third load drop detection threshold and the system frequency F is greater than the fourth load drop detection threshold is satisfied.

[0102] In the second embodiment, the flowcharts shown in Figs. 14 to 17 are the above-mentioned system state determination flows.

[0103] Embodiment 3 In the third embodiment, a case will be described in which the control amount for the power converter 601 of the distributed power supply control device is corrected.

[0104] The configuration of the power system 100 in the third embodiment is similar to the configuration of the power system 100 in the first embodiment shown in Fig. 1. However, in the third embodiment, the central processing unit 5 shown in Fig. 1 will be described as a central processing unit 5a, and the distributed power supply control device 6 will be described as a distributed power supply control device 6a, as described later.

[0105] Fig. 18 is a block diagram showing a configuration example of a central processing unit 5a according to the third embodiment. As shown in Fig. 18, the central processing unit 5a is obtained by adding a correction control amount calculation unit 57 to the central processing unit 5 of the first embodiment shown in Fig. 2. When a system disturbance occurs in the power transmission and distribution system 1, the central processing unit 5a receives information about the system disturbance via the communication unit 51. Based on the system disturbance information received by the communication unit 51, the correction control amount calculation unit 57 calculates a correction control amount for each distributed power supply control device 6a when the distributed power supply control device 6a performs power control, and outputs the correction control amount to the distributed power supply control device 6a via the communication unit 51.

[0106] The correction control amount calculation unit 57 calculates the active power and reactive power of the distributed power source 7 required for stabilizing the power transmission and distribution system 1 by calculating the system response at the time of occurrence of a system disturbance by gradually changing the active power and reactive power of the distributed power source 7 for the system disturbance set by the system disturbance setting unit 54, for example, for the calculation method of the correction control amount for each distributed power source control device 6a. The correction control amount calculation unit 57 may set the calculation method of the correction control amount for each distributed power source control device 6a by performing an optimization calculation, may set using a machine learning method, or may set by accepting a manual operation from the operator of the distributed power source control system 4. In addition, the correction control amount calculation unit 57 may create a table showing the correspondence between the system disturbance assumed before the system disturbance occurs and the correction control amount of the distributed power source control device 6a for the system disturbance by the above-mentioned method, and may select the correction control amount calculated in advance for the system disturbance from the above-mentioned table when the system disturbance occurs.

[0107] FIG. 19 is a block diagram showing a configuration example of a distributed power supply control device 6a according to a third embodiment. As shown in FIG. 19, the distributed power supply control device 6a is obtained by adding a correction control amount setting unit 607 to the distributed power supply control device 6 according to the first embodiment shown in FIG. 3. The correction control amount setting unit 607 acquires the correction control amount determined by the central processing unit 5a via the communication unit 602. The correction control amount setting unit 607 sets the acquired correction control amount in the power converter 601 as active power and reactive power command values, that is, outputs the acquired correction control amount to the power converter 601. The power converter 601 performs power control by using the sum of the active power and reactive power command values ​​from the emergency control amount calculation unit 605, the normal control amount calculation unit 606, and the correction control amount setting unit 607 as the final active power and reactive power control command values, as in FIG. 7 described in the first embodiment. That is, in the third embodiment, the power converter 601 performs power control by using the correction control amount. In addition, the power converter 601 may give priority to the active power and reactive power command values ​​from the correction control amount setting unit 607 and ignore the active power and reactive power command values ​​from the emergency control amount calculation unit 605 and the normal control amount calculation unit 606.

[0108] The output of the corrected control amount, i.e., the command values ​​of active power and reactive power, from the corrected control amount setting unit 607 continues for a certain period of time and then decreases. The duration of the output of the corrected control amount, i.e., the command values ​​of active power and reactive power, from the corrected control amount setting unit 607 may be several minutes, for example, since it is sufficient that the output is output until the output of the large-scale power-source facility 2 is sufficiently controlled by the frequency control function of the power transmission and distribution system 1, such as governor-free operation of the large-scale power-source facility 2 and LFC (Load Frequency Control), i.e., load frequency control.

[0109] Generally, when the central processing unit 5a detects a system disturbance, determines the control amount of the distributed power supply control device 6a, and transmits the control amount from the central processing unit 5a to the distributed power supply control device 6a via a communication network, it takes a certain amount of time from the detection of the system disturbance to the implementation of control of the distributed power supply 7. Furthermore, since the central processing unit 5a determines control parameters in advance for emergency control of the distributed power supply control device 6a, there may be cases where the emergency control amount becomes excessive or insufficient due to measurement errors, the occurrence of unexpected system disturbances, differences in response between the model system used in the calculation and the actual system, and the like.

[0110] Therefore, according to this embodiment, the distributed power supply control device 6a can combine emergency control performed using its own measurement information and correction control performed upon receiving instructions from the central processing unit 5a, thereby enabling high-speed control through emergency control and correction of the control amount through correction control, thereby contributing to improving the stability of the power transmission and distribution system 1.

[0111] Embodiment 4 In the fourth embodiment, a case will be described in which the control mode for the power converter 601 of the distributed power supply control device is controlled.

[0112] The configuration of the power system 100 in the fourth embodiment is similar to the configuration of the power system 100 in the first embodiment shown in Fig. 1. However, in the fourth embodiment, the distributed power supply control device 6 shown in Fig. 1 will be described as a distributed power supply control device 6b, as described later.

[0113] FIG. 20 is a block diagram showing a configuration example of a distributed power supply control device 6b according to a fourth embodiment. As shown in FIG. 20, the distributed power supply control device 6b is obtained by adding a voltage / current control mode setting unit 608 to the distributed power supply control device 6 according to the first embodiment shown in FIG. 3. The voltage / current control mode setting unit 608 sets the control mode of the power converter 601 based on the measurement information acquired from the measurement unit 604 and the start-up information of emergency control acquired from the emergency control amount calculation unit 605. Specifically, the voltage / current control mode setting unit 608 sets the control mode of the power converter 601 so that the power converter 601 operates in a voltage control type, i.e., GFM (Grid Forming), in which the inverter operates as a voltage source during normal times when no grid disturbance occurs, and operates in a current control type, i.e., GFL (Grid-Following), in which the inverter operates as a current source during grid disturbance. That is, the voltage / current control mode setting unit 608 operates the power converter 601 in a voltage controlled manner when no system disturbance is occurring in the power transmission / distribution system 1, and operates the power converter 601 in a current controlled manner when a system disturbance is occurring in the power transmission / distribution system 1.

[0114] 21 is a flowchart showing an operation of the voltage / current control mode setting unit 608 changing the control mode of the power converter 601 when a system disturbance occurs during normal operation in the distributed power supply control device 6b according to the fourth embodiment. When emergency control is activated in the emergency control amount calculation unit 605 (step S201: Yes), the voltage / current control mode setting unit 608 changes the control mode of the power converter 601 from the voltage control type to the current control type (step S202). When emergency control is not activated in the emergency control amount calculation unit 605 (step S201: No), the voltage / current control mode setting unit 608 operates the power converter 601 with the control mode of the voltage control type maintained (step S203).

[0115] 22 is a flowchart showing an operation of the voltage / current control mode setting unit 608 changing the control mode of the power converter 601 when a grid disturbance occurs and the grid disturbance converges in the distributed power supply control device 6b according to the fourth embodiment. The voltage / current control mode setting unit 608 determines whether the grid disturbance has converged or not from the measurement information acquired from the measurement unit 604 (step S204). The voltage / current control mode setting unit 608 determines whether the grid disturbance has converged or not from the measurement information acquired from the measurement unit 604, for example, when grid voltage V≧grid voltage threshold V th Nor And the grid frequency threshold F Lth Nor ≦Grid frequency F ≦ Grid frequency threshold F Uth Nor If the above conditions are not satisfied, the voltage / current control mode setting unit 608 determines that the grid disturbance has converged. If the voltage / current control mode setting unit 608 determines that the grid disturbance has converged (step S204: Yes), it changes the control mode of the power converter 601 to the voltage control type (step S205). If the voltage / current control mode setting unit 608 determines that the grid disturbance has not converged (step S204: No), it operates the power converter 601 with the control mode of the current control type (step S206).

[0116] The method of determining whether the grid disturbance has converged in the voltage / current control mode setting unit 608 is not limited to the above example. In the example of FIG. 22, th Nor , grid frequency threshold F Lth Nor , and the grid frequency threshold F Uth Nor are control parameters, and the values ​​set by the central processing unit 5 may be used as these control parameters.

[0117] Generally, current-controlled inverters have high tracking ability to command values ​​of active power and reactive power, but they need to change the command values ​​using measurement information such as voltage, current, and frequency, and cannot respond quickly to the inertia of a synchronous generator. On the other hand, voltage-controlled inverters have poor tracking ability to command values ​​of active power and reactive power, but can simulate the response of a synchronous generator and perform high-speed response to the inertia, such as virtual synchronous generator control.

[0118] Therefore, according to this embodiment, the distributed power supply control device 6b operates the power converter 601 as a voltage control type during normal operation, and operates the power converter 601 as a current control type when a grid disturbance occurs. This allows the distributed power supply control device 6b to achieve both a high-speed response equivalent to the inertia of a synchronous generator immediately after the occurrence of a grid disturbance, and good follow-up to the emergency control performed during the grid disturbance and the stabilization control by the normal control, and can further contribute to improving the stability of the power transmission and distribution grid 1.

[0119] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0120] 1 Power transmission and distribution system, 2-1 to 2-3 Large-scale power supply equipment, 3-1 to 3-3 Load, 4 Distributed power supply control system, 5, 5a Central processing unit, 6, 6-1 to 6-4, 6a, 6b Distributed power supply control device, 7, 7-1 to 7-4 Distributed power supply, 8 Measurement device, 51, 602 Communication unit, 52, 603 Recording unit, 53 System information setting unit, 54 System disturbance setting unit, 55 System response calculation unit, 56 Control parameter setting unit, 57 Correction control amount calculation unit, 90, 93 Processing circuit, 91 Processor, 92 Memory, 100 Power system, 601 Power converter, 604 Measurement unit, 605 Emergency control amount calculation unit, 606 Normal control amount calculation unit, 607 Correction control amount setting unit, 608 Voltage and current control mode setting unit.

Claims

1. a central processing unit that sets control parameters for power control on power supplied from a plurality of distributed power sources, the control parameters being implemented by a plurality of distributed power source control devices each connected to a different distributed power source; a plurality of the distributed power control devices that measure a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power control devices are connected, and that, when a system disturbance occurs in the power transmission and distribution system, calculates an emergency control amount according to a type of the system disturbance using measurement information of the system state and the control parameters, thereby performing the power control; Equipped with The distributed power supply control device measures, as the system state, a system voltage, a system frequency, and a frequency change rate of the system frequency at a point of the power transmission and distribution system to which it is connected, and determines whether or not the system disturbance has occurred in the power transmission and distribution system and the type of the system disturbance when the system disturbance has occurred in the power transmission and distribution system using the system voltage, the system frequency, or at least one of the frequency change rate of the system frequency among the measurement information of the system state, and the control parameters, and determines whether or not emergency control at the time of the occurrence of the system disturbance is likely to adversely affect the system voltage and the system frequency, using the system voltage and the system frequency among the measurement information of the system state, and the control parameters. A distributed power supply control system comprising:

2. the central processing unit sets, as the control parameter, a system fault detection threshold for the system voltage in order to detect a system fault as the system disturbance; The distributed power supply control device determines that the grid fault has occurred when the grid voltage is less than the grid fault detection threshold.

2. The distributed power supply control system according to claim 1 .

3. the central processing unit sets, as the control parameter, at least one of a first power supply disconnection detection threshold value for the frequency change rate and a second power supply disconnection detection threshold value for the system frequency, in order to detect a power supply disconnection or a disconnection of a power line that is a transmission line connected to the power supply as the system disturbance; the distributed power supply control device determines that a power supply drop or a break in the power line has occurred when at least one of the rate of frequency change being less than the first power supply drop detection threshold and the system frequency being less than the second power supply drop detection threshold is satisfied; 2. The distributed power supply control system according to claim 1 .

4. the central processing unit sets, as the control parameter, at least one of a first load drop detection threshold value for the frequency change rate and a second load drop detection threshold value for the system frequency, in order to detect a load drop or a break in a load line, which is a transmission line connected to the load, as the system disturbance; the distributed power supply control device determines that a drop in the load or a break in the load line has occurred when at least one of the rate of frequency change is greater than the first load drop detection threshold and the system frequency is greater than the second load drop detection threshold is satisfied; 2. The distributed power supply control system according to claim 1 .

5. the central processing unit or the distributed power control device sets, as the control parameter, an adjustment flag to ON, which causes the distributed power control device not to use the first power supply loss detection threshold and the second power supply loss detection threshold for a specified period after a system accident occurs in the power transmission and distribution system; the central processing unit sets, as the control parameter, at least one of a third power supply loss detection threshold value for the frequency change rate and a fourth power supply loss detection threshold value for the system frequency, for detecting the loss of the power supply or the breakage of the power line; When the adjustment flag is on, the distributed power supply control device determines that a power supply drop or a break in the power line has occurred when at least one of the rate of frequency change is less than the third power supply drop detection threshold and the system frequency is less than the fourth power supply drop detection threshold is satisfied.

4. The distributed power supply control system according to claim 3.

6. the central processing unit or the distributed power supply control device sets, as the control parameter, an adjustment flag to ON, which causes the distributed power supply control device not to use the first load drop detection threshold and the second load drop detection threshold for a specified period after a system fault occurs in the power transmission and distribution system; the central processing unit sets, as the control parameter, at least one of a third load drop detection threshold value for the frequency change rate and a fourth load drop detection threshold value for the system frequency, for detecting a drop of the load or a break in the load line; When the adjustment flag is on, the distributed power supply control device determines that a drop in the load or a break in the load line has occurred when at least one of the frequency change rate being greater than the third load drop detection threshold and the system frequency being greater than the fourth load drop detection threshold is satisfied.

5. The distributed power supply control system according to claim 4.

7. the distributed power supply control device calculates a normal control amount in a state in which the system disturbance is not occurring in the power transmission and distribution system, and performs the power control using the emergency control amount and the normal control amount.

2. The distributed power supply control system according to claim 1 .

8. the central processing unit sets, as the control parameter, a control flag for controlling whether or not the distributed power supply control device performs the power control using the emergency control amount, the distributed power supply control device performs the power control using the emergency control amount when the control flag is on, and does not perform the power control using the emergency control amount when the control flag is off; 2. The distributed power supply control system according to claim 1 .

9. the central processing unit calculates a correction control amount when the distributed power supply control device performs the power control, The distributed power supply control device performs the power control using the correction control amount.

9. A distributed power supply control system according to claim 1, wherein the distributed power supply control system comprises:

10. A distributed power supply control device in a distributed power supply control system including a plurality of distributed power supply control devices and a central processing unit that controls operations of the plurality of distributed power supply control devices, A measurement unit that measures a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power source control device is connected; a communication unit that transmits, to the central processing unit, distributed power source information including an operating state of the distributed power source and measurement information indicating a system state measured by the measurement unit, and receives, from the central processing unit, control parameters for power control set by the central processing unit; an emergency control amount calculation unit that uses the measurement information and the control parameters to determine whether or not a system disturbance has occurred in the power transmission / distribution system and a type of the system disturbance when the system disturbance has occurred in the power transmission / distribution system, and calculates an emergency control amount that is a control amount when a power converter performs the power control according to the type of the system disturbance when the system disturbance has occurred; the power converter performing the power control to convert the power supplied from the distributed power source into a form of power that can be handled in the power transmission and distribution system by using the emergency control amount; Equipped with the measurement unit measures, as the system state, a system voltage, a system frequency, and a frequency change rate of the system frequency at a point in the power transmission and distribution system to which the distributed power supply control device is connected; the emergency control amount calculation unit uses the system voltage, at least one of the system frequency and a frequency change rate of the system frequency, among the measurement information of the system state, and the control parameter to determine whether or not the system disturbance has occurred in the power transmission / distribution system, and a type of the system disturbance when the system disturbance has occurred in the power transmission / distribution system, and uses the system voltage and the system frequency, among the measurement information of the system state, and the control parameter to determine whether or not emergency control at the time of the occurrence of the system disturbance is likely to adversely affect the system voltage and the system frequency. A distributed power supply control device comprising:

11. a normal-state control amount calculation unit that calculates a normal-state control amount, which is a control amount when the power converter performs the power control in a state in which the system disturbance is not occurring in the power transmission and distribution system, by using the measurement information and the control parameters; Equipped with The power converter performs the power control using the emergency control amount and the normal control amount. The distributed power supply control device according to claim 10 .

12. a control flag for controlling whether or not the distributed power control device performs the power control using the emergency control amount is set in the central processing unit as the control parameter; the emergency control amount calculation unit performs the power control using the emergency control amount when the control flag is on, and does not perform the power control using the emergency control amount when the control flag is off; The distributed power supply control device according to claim 10 .

13. a correction control amount for when the distributed power supply control device performs the power control is calculated in the central processing unit, moreover, a correction control amount setting unit that sets the correction control amount to the power converter; Equipped with The power converter performs the power control using the correction control amount. The distributed power supply control device according to claim 10 .

14. a voltage / current control mode setting unit that operates the power converter in a voltage controlled manner when the system disturbance is not occurring in the power transmission / distribution system, and operates the power converter in a current controlled manner when the system disturbance is occurring in the power transmission / distribution system; The distributed power supply control device according to any one of claims 10 to 13, further comprising:

15. a communication unit that receives, from a measuring device connected to the power transmission and distribution system, first measurement information indicating a system state, which is a state of power in the power transmission and distribution system measured by the measuring device, and receives, from a plurality of distributed power supply control devices each connected to a different distributed power supply, distributed power supply information including an operating state of the distributed power supply, and second measurement information indicating a system state, which is a state of power at a point in the power transmission and distribution system to which the distributed power supply control device is connected; a system information setting unit that sets a current state indicating a current operating state of the power transmission and distribution system based on the first measurement information, the second measurement information, the distributed power source information, and equipment information indicating equipment included in the power transmission and distribution system; a system disturbance setting unit that sets a system disturbance that may occur in the power transmission and distribution system with respect to the current state of the power transmission and distribution system; a system response calculation unit that simulates a response of the power transmission / distribution system before the system disturbance occurs in the power transmission / distribution system and a response of the power transmission / distribution system when the system disturbance set by the system disturbance setting unit occurs in the power transmission / distribution system; a control parameter setting unit that sets control parameters for controlling power control over the distributed power sources performed by a plurality of the distributed power source control devices, based on a response of the power transmission and distribution system in a state in which the power transmission and distribution system is not disturbed and a response of the power transmission and distribution system when the power transmission and distribution system is disturbed; A central processing unit comprising:

16. The control parameter setting unit sets, as the control parameter, a system fault detection threshold for detecting a system fault as the system disturbance with respect to a system voltage of the power transmission and distribution system.

16. The central processing unit according to claim 15.

17. the control parameter setting unit sets, as the control parameter, at least one of a first power supply disconnection detection threshold value for a frequency change rate of the power transmission and distribution system and a second power supply disconnection detection threshold value for a system frequency, in order to detect a power supply disconnection or a disconnection of a power line that is a transmission line connected to the power supply as the system disturbance; 16. The central processing unit according to claim 15.

18. the control parameter setting unit sets, as the control parameter, at least one of a first load drop detection threshold value for a frequency change rate of the power transmission and distribution system and a second load drop detection threshold value for a system frequency, in order to detect a load drop or a break in a load line, which is a transmission line connected to the load, as the system disturbance; 16. The central processing unit according to claim 15.

19. the control parameter setting unit sets, as the control parameter, an adjustment flag to ON, which causes the distributed power supply control device not to detect types of the system disturbance other than the system fault for a specified period after a system fault occurs in the power transmission and distribution system; 16. The central processing unit according to claim 15.

20. the control parameter setting unit sets, as the control parameter, a control flag for controlling whether or not the distributed power supply control device performs the power control using an emergency control amount corresponding to a type of the grid disturbance; 16. The central processing unit according to claim 15.

21. the control parameter setting unit sets the control parameters as the power control using an emergency control amount according to the type of the system disturbance performed by the distributed power supply control device, such that the distributed power supply control device outputs active power of a specified first magnitude and reactive power of a specified second magnitude for a specified first period, and then changes the magnitude of the active power and the magnitude of the reactive power at a constant rate so that the output becomes zero after a specified second period.

16. The central processing unit according to claim 15.

22. a correction control amount calculation unit that calculates a correction control amount when the distributed power supply control device performs the power control; 22. A central processing unit according to claim 15, comprising:

23. a first step in which a central processing unit sets control parameters for power control on power supplied from different distributed power sources, the control parameters being implemented by a plurality of distributed power source control devices each connected to a different distributed power source; a second step in which a plurality of the distributed power control devices measure a system voltage, a system frequency, and a frequency change rate of the system frequency at a point of the power transmission and distribution system to which they are connected as a system state, which is a state of power at the point of the power transmission and distribution system, and determine whether or not a system disturbance has occurred in the power transmission and distribution system and a type of the system disturbance when the system disturbance has occurred in the power transmission and distribution system using the system voltage, the system frequency, or at least one of the frequency change rate of the system frequency among the measurement information of the system state, and the control parameter, and determine whether or not emergency control at the time of the occurrence of the system disturbance is likely to adversely affect the system voltage and the system frequency among the measurement information of the system state, and the control parameter; a third step of calculating an emergency control amount according to a type of the system disturbance when the system disturbance occurs in the power transmission and distribution system by using the measurement information of the system state and the control parameters, and performing the power control; A distributed power supply control method comprising:

24. A method for controlling system stabilization of a distributed power supply control device in a distributed power supply control system including a plurality of distributed power supply control devices and a central processing unit that controls operation of the plurality of distributed power supply control devices, comprising: a measurement step in which a measurement unit measures a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power supply control device is connected; a communication step in which a communication unit transmits to the central processing unit distributed power source information including an operating state of the distributed power source and measurement information indicating a system state measured by the measurement unit, and receives from the central processing unit control parameters for power control set by the central processing unit; an emergency control amount calculation step in which an emergency control amount calculation unit uses the measurement information and the control parameters to determine whether or not a system disturbance has occurred in the power transmission / distribution system and a type of the system disturbance when the system disturbance has occurred in the power transmission / distribution system, and calculates an emergency control amount that is a control amount when a power converter performs the power control according to the type of the system disturbance when the system disturbance has occurred; a power conversion step in which the power converter performs the power control to convert the power supplied from the distributed power source into a form of power that can be handled in the power transmission and distribution system, using the emergency control amount; Including, In the measuring step, the measurement unit measures, as the system state, a system voltage, a system frequency, and a frequency change rate of the system frequency at a point in the power transmission and distribution system to which the distributed power supply control device is connected; In the emergency control amount calculation step, the emergency control amount calculation unit determines whether or not the system disturbance has occurred in the power transmission / distribution system and a type of the system disturbance when the system disturbance has occurred in the power transmission / distribution system, using the system voltage, the system frequency or at least one of a frequency change rate of the system frequency, and the control parameter, among the measurement information of the system state, and determines whether or not emergency control at the time of the occurrence of the system disturbance is likely to adversely affect the system voltage and the system frequency, using the system voltage and the system frequency, and the control parameter, among the measurement information of the system state. A power system stabilization control method comprising:

25. a communication step in which a communication unit receives, from a measuring device connected to the power transmission and distribution system, first measurement information indicating a system state, which is a state of power in the power transmission and distribution system measured by the measuring device, and receives, from a plurality of distributed power supply control devices each connected to a different distributed power supply, distributed power supply information including an operating state of the distributed power supply, and second measurement information indicating a system state, which is a state of power at a point in the power transmission and distribution system to which the distributed power supply control device is connected; a system information setting step in which a system information setting unit sets a current state indicating a current operating state of the power transmission and distribution system based on the first measurement information, the second measurement information, the distributed power source information, and equipment information indicating equipment included in the power transmission and distribution system; a system disturbance setting step in which a system disturbance setting unit sets a system disturbance that may occur in the power transmission and distribution system for the current state of the power transmission and distribution system; a system response calculation step in which a system response calculation unit simulates a response of the power transmission / distribution system before the system disturbance occurs in the power transmission / distribution system and a response of the power transmission / distribution system when the system disturbance set by the system disturbance setting unit occurs in the power transmission / distribution system; a control parameter setting step in which a control parameter setting unit sets control parameters for controlling power control over the distributed power sources performed by a plurality of the distributed power source control devices, based on a response of the power transmission / distribution system in a state in which the power transmission / distribution system is not disturbed and a response of the power transmission / distribution system when the power transmission / distribution system is disturbed; A control parameter setting method comprising:

26. A central processing unit that sets control parameters for power control on power supplied from a plurality of distributed power sources, the control parameters being implemented by a plurality of distributed power source control devices each connected to a different distributed power source; a plurality of the distributed power control devices that measure a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power control devices are connected, and that, when a system disturbance occurs in the power transmission and distribution system, calculates an emergency control amount according to a type of the system disturbance using measurement information of the system state and the control parameters, thereby performing the power control; Equipped with the central processing unit or the distributed power supply control device sets, as the control parameter, an adjustment flag on that prevents the distributed power supply control device from detecting a type of the system disturbance other than the system fault for a specified period after a system fault occurs in the power transmission and distribution system; the distributed power supply control device measures, as the system state, a system voltage, a system frequency, and a frequency change rate of the system frequency at a point of the power transmission and distribution system to which the distributed power supply control device is connected, and determines, using the measurement information of the system state and the control parameters, whether or not the system disturbance has occurred in the power transmission and distribution system, and a type of the system disturbance when the system disturbance has occurred in the power transmission and distribution system, and when the adjustment flag is on, does not detect a type of the system disturbance other than the system fault as the system disturbance; A distributed power supply control system comprising:

27. ​​A central processing unit that sets control parameters for power control on power supplied from a plurality of distributed power sources, the control parameters being implemented by a plurality of distributed power source control devices each connected to a different distributed power source; a plurality of the distributed power control devices that measure a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power control devices are connected, and that, when a system disturbance occurs in the power transmission and distribution system, calculates an emergency control amount according to a type of the system disturbance using measurement information of the system state and the control parameters, thereby performing the power control; Equipped with the central processing unit sets the control parameters as the power control using the emergency control amount performed by the distributed power supply control device, such that the distributed power supply control device outputs active power of a specified first magnitude and reactive power of a specified second magnitude for a specified first period, and then changes the magnitude of the active power and the magnitude of the reactive power at a constant rate so that the output becomes zero after a specified second period; the distributed power supply control device controls the output of the active power and the output of the reactive power based on the control parameters set by the central processing unit. A distributed power supply control system comprising:

28. A central processing unit that sets control parameters for power control on power supplied from a plurality of distributed power sources, the control parameters being implemented by a plurality of distributed power source control devices each connected to a different distributed power source; a plurality of the distributed power control devices that measure a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power control devices are connected, and that, when a system disturbance occurs in the power transmission and distribution system, calculates an emergency control amount according to a type of the system disturbance using measurement information of the system state and the control parameters, thereby performing the power control; Equipped with the distributed power supply control device includes a power converter for performing the power control, and operates the power converter as a voltage control type when the system disturbance is not occurring in the power transmission and distribution system, and operates the power converter as a current control type when the system disturbance is occurring in the power transmission and distribution system. A distributed power supply control system comprising:

29. The distributed power supply control device measures the system voltage and system frequency at the point of the power transmission and distribution system to which it is connected as the system state, and determines whether the system disturbance has converged or not using the measurement information of the system state and the control parameters, and if it is determined that the system disturbance has converged, operates the power converter in a voltage controlled type.

29. The distributed power supply control system according to claim 28.

30. A distributed power control device in a distributed power control system including a plurality of distributed power control devices and a central processing unit that controls operation of the plurality of distributed power control devices, A measurement unit that measures a system state, which is a state of power at a point of a power transmission and distribution system to which the distributed power supply control device is connected; a communication unit that transmits, to the central processing unit, distributed power source information including an operating state of the distributed power source and measurement information indicating a system state measured by the measurement unit, and receives, from the central processing unit, control parameters for power control set by the central processing unit; an emergency control amount calculation unit that uses the measurement information and the control parameters to determine whether or not a system disturbance has occurred in the power transmission / distribution system and a type of the system disturbance when the system disturbance has occurred in the power transmission / distribution system, and calculates an emergency control amount that is a control amount when a power converter performs the power control according to the type of the system disturbance when the system disturbance has occurred; the power converter performing the power control to convert the power supplied from the distributed power source into a form of power that can be handled in the power transmission and distribution system by using the emergency control amount; Equipped with In the central processing unit, as the power control using the emergency control amount performed by the distributed power supply control device, the control parameters are set such that the distributed power supply control device outputs active power of a specified first magnitude and reactive power of a specified second magnitude for a specified first period, and then changes the magnitude of the active power and the magnitude of the reactive power at a constant rate so that the output becomes zero after a specified second period; the emergency control amount calculation unit controls the output of the active power and the output of the reactive power based on the control parameters set by the central processing unit. A distributed power supply control device comprising:

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