System operation schedule control device and system operation schedule control method

Abstract

To suppress system instability regarding control of a system interlocked inverter corresponding to a situation of a system short-circuit capacity.SOLUTION: A system operation schedule control device comprises a comparison section, a determination section and a generation section. The comparison section compares a system short-circuit capacity in operation scheduling regarding a power system, to which a plurality of power conversion apparatuses is connected, with a system short-circuit capacity in actual operation. In a case where the system short-circuit capacity in operation scheduling is different from the system short-circuit capacity in actual operation, the determination section determines that system instability of the power system is predicted and determines to change an operation mode of any power conversion apparatus of a control target in the plurality of power conversion apparatuses. In the case where the system instability of the power system is predicted, the generation section generates a signal instructing the change of the operation mode of the power conversion apparatus of the control target and transmits the signal to the power conversion apparatus of the control target.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a system operation plan control device and a system operation plan control method. [Background technology]

[0002] In recent years, as renewable energy sources such as solar and wind power have become the mainstream power source, the operation of generators has decreased and instead, grid-connected inverter power sources are being introduced into the power grid more and more. Grid-connected inverter power sources (grid-connected inverters) are often equipped with GFL (Grid Following) control, which follows the grid with current control due to the high responsiveness of PQ control, for example.

[0003] In this situation, problems have been pointed out with GFL control, such as a decrease in grid inertia, a decrease in grid short-circuit capacity, and a decrease in synchronizing power. In response to these problems, for example, a method has been proposed in which the inverter power supply is voltage-controlled by GFM (Grid Forming) control, and the inertia constant and damping constant are changed according to changes in the grid short-circuit capacity (Patent Document 1). In addition, for example, a method has been proposed in which, when hunting occurs due to a decrease in the grid short-circuit capacity, the gain of the control system is lowered to suppress the hunting (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7183486 [Patent Document 2] Japanese Patent Application Publication No. 4-236131 Summary of the Invention [Problem to be solved by the invention]

[0005] However, for example, when a grid-connected inverter under GFM control and a grid-connected inverter under GFL control coexist in a power system, it may be difficult to secure sufficient grid short-circuit capacity with only the grid-connected inverter under GFM control. If the grid short-circuit capacity is not sufficiently secured, it may cause grid instability. Also, even if only the gain of the control system is reduced, the limit may be reached and grid instability may be caused.

[0006] In view of the above, a problem to be solved by each embodiment is to suppress grid instability with respect to control of a grid-connected inverter according to the state of the grid short-circuit capacity. [Means for solving the problem]

[0007] A system operation plan control device according to an embodiment includes a comparison unit, a determination unit, and a generation unit. The comparison unit compares a system short circuit capacity at the time of an operation plan for a power system to which a plurality of power electronics devices are connected with a system short circuit capacity at the time of actual operation. The determination unit determines that system instability of the power system is predicted when the system short circuit capacity at the time of the operation plan differs from the system short circuit capacity at the time of actual operation, and determines to change an operation mode of a power electronics device to be controlled, which is any one of the plurality of power electronics devices. When system instability of the power system is predicted, the generation unit generates a signal instructing a change of the operation mode of the power electronics device to be controlled, and transmits the signal to the power electronics device to be controlled. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of an overall configuration of a power system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a functional configuration of the operational plan control device according to the first embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a configuration of a power system according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of the inverter power supply according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing an example of a process during operation executed by the power system operation system according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a functional configuration of an operational plan control device according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing an example of the configuration of an inverter power supply according to the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of a functional configuration of an operational plan control device according to the third embodiment. [Figure 9] FIG. 9 is a diagram for explaining an impedance map according to the third embodiment. [Figure 10] FIG. 10 is a flowchart showing an example of a process at the time of planning, which is executed by the power system operation system according to the third embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of a functional configuration of an operational plan control device according to the fourth embodiment. As illustrated in FIG. [Figure 12] FIG. 12 is a diagram illustrating an example of a functional configuration of an operational plan control device according to the fifth embodiment. As illustrated in FIG. [Figure 13] FIG. 13 is a flowchart showing an example of a process at the time of planning, which is executed by the power system operation system according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of a system operation plan control device and a system operation plan control method according to the present invention will be described with reference to the drawings.

[0010] (First embodiment) <Overall configuration of the power system according to the first embodiment> Fig. 1 is a diagram showing an example of an overall configuration of a power system operation system 1 according to a first embodiment. As shown in Fig. 1, the power system operation system 1 includes a power system 3 and an operation plan control device 5. The power system 3 and the operation plan control device 5 are communicatively connected via a communication network N1. Here, the operation plan control device 5 according to the embodiment is an example of the power system operation plan control device.

[0011] As shown in Fig. 1, the power system 3 has a plurality of inverter power sources 31, at least one synchronous generator 32, and at least one synchronous phase modifier 33. The plurality of inverter power sources 31, the at least one synchronous generator 32, and the at least one synchronous phase modifier 33 are electrically connected directly or via a system network N2. Here, the inverter power source 31 according to the embodiment is an example of a power conversion device. Also, the synchronous generator 32 and the synchronous phase modifier 33 according to the embodiment are each an example of a system stabilization device. The power system 3 and each part thereof will be described in detail later.

[0012] <Configuration of each device in the power system according to the first embodiment> Next, the configuration of each device of the power system 1 according to the first embodiment will be described.

[0013] The operational plan control device 5 has a hardware configuration using a normal computer. As an example, the operational plan control device 5 has a processor, a memory, and an interface, which are interconnected by a bus or the like.

[0014] As the processor of the operational plan control device 5, various processors such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc. can be appropriately used. For example, the processor performs overall control of the operational plan control device 5 by executing a program loaded into a memory.

[0015] As the memory of the operation plan control device 5, various storage media and storage devices such as ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), Flash memory, etc. can be appropriately used. For example, the ROM stores various programs and various data executed by the processor. The RAM is, for example, the main storage device of the operation plan control device 5, and temporarily stores various data and various programs required for various processes by the processor.

[0016] For example, the interface of the operational plan control device 5 is an interface circuit for transmitting and receiving data between the outside of the operational plan control device 5 and the outside.

[0017] FIG. 2 is a diagram showing an example of a functional configuration of the operation plan control device 5 according to the first embodiment. As an example, the operation plan control device 5 loads at least one program read from the ROM by the processor into the RAM and executes it, thereby realizing each function of the operation plan control device 5, such as a short circuit capacity comparison unit 52, a planned short circuit capacity storage unit 53, a control content determination unit 54, a control signal storage unit 55, and a control signal generation unit 56. Here, the short circuit capacity comparison unit 52 according to the embodiment is an example of a comparison unit. Also, the control content determination unit 54 according to the embodiment is an example of a determination unit. Also, the control signal generation unit 56 according to the embodiment is an example of a generation unit.

[0018] The short circuit capacity comparison unit 52 acquires the system short circuit capacity at the time of operation planning and the system short circuit capacity at the time of actual operation for the power system 3 to which multiple inverter power sources 31 are connected. Note that in this embodiment, the system short circuit capacity at the time of operation planning may be referred to as the "planned short circuit capacity." Similarly, the system short circuit capacity at the time of actual operation may be referred to as the "detected short circuit capacity."

[0019] As an example, the short circuit capacity comparison unit 52 reads out and acquires the system short circuit capacity at the time of the operation plan from the planned short circuit capacity storage unit 53. As an example, the short circuit capacity comparison unit 52 acquires the system short circuit capacity at the time of operation from the inverter power supply 31. Note that, when the system short circuit capacity at the time of operation is detected, for example, outside the inverter power supply 31, the short circuit capacity comparison unit 52 may acquire the system short circuit capacity at the time of operation from a device that performed the detection or a device that communicates with the device. Also, the system short circuit capacity at the time of operation is detected based on, for example, hunting of the system voltage or detection of harmonics, but may be detected by any detection method.

[0020] The short circuit capacity comparison unit 52 compares the system short circuit capacity at the time of the acquired operation plan with the system short circuit capacity at the time of actual operation. The short circuit capacity comparison unit 52 supplies the comparison result of the system short circuit capacity to the control content determination unit 54.

[0021] The planned short circuit capacity storage unit 53 stores the system short circuit capacity at the time of the operation plan. As an example, the system short circuit capacity at the time of the operation plan is determined in advance and stored in the planned short circuit capacity storage unit 53. Note that the system short circuit capacity at the time of the operation plan is calculated according to, for example, the state of the power system 3, but may be set as a desired value by, for example, a planner of the operation plan of the power system 3.

[0022] The control content determination unit 54 obtains a comparison result between the system short circuit capacity at the time of operation planning and the system short circuit capacity at the time of actual operation from the short circuit capacity comparison unit 52. Furthermore, when the system short circuit capacity differs between the time of operation planning and the time of actual operation, the control content determination unit 54 determines that system instability of the power system 3 is predicted. Note that the system short circuit capacity differing may be a difference of a predetermined value or a predetermined ratio or more.

[0023] As an example, when the system short circuit capacity differs between the time of operation planning and the time of actual operation, the control content determination unit 54 determines whether the system short circuit capacity during actual operation is equal to or less than a threshold value related to system instability of the power system 3. Here, the threshold value related to system instability may be determined in advance and stored in the planned short circuit capacity storage unit 53, for example. For example, the ratio between the system short circuit capacity during actual operation and the system short circuit capacity at the time of planning may be set as the threshold. As an example, when the system short circuit capacity during actual operation is equal to or less than the threshold value related to system instability of the power system 3, the control content determination unit 54 determines that system instability of the power system 3 is predicted.

[0024] Furthermore, when system instability of the power system 3 is predicted, the control content determination unit 54 determines to change the operation mode of the inverter power supply 31 to be controlled. Here, the inverter power supply 31 to be controlled is at least one inverter power supply 31 whose system short-circuit capacity during actual operation differs from the system short-circuit capacity at the time of the operation plan in the comparison by the short-circuit capacity comparison unit 52. It is assumed that grid following control, i.e., GFL (Grid Following) control is being performed in this inverter power supply 31.

[0025] As an example, when the power grid 3 is predicted to become unstable, the control content determination unit 54 determines to change the operation mode of the inverter power supply 31 to be controlled from an operation mode in which GFL control is performed to an operation mode in which grid forming control, i.e., GFM (Grid Forming) control is performed. In other words, when the power grid 3 is predicted to become unstable, the control content determination unit 54 determines to switch the control of the inverter power supply 31 to be controlled from GFL control to GFM control. As an example, when the control content determination unit 54 determines to switch the control of the inverter power supply 31 to be controlled from GFL control to GFM control, it supplies, to the control signal generation unit 56, information indicating the inverter power supply 31 to be controlled and information indicating that it has been determined to switch from GFL control to GFM control.

[0026] The control signal storage unit 55 stores therein a predetermined control signal for instructing a change in the operation mode of the inverter power supply 31.

[0027] When the control signal generating unit 56 receives information indicating the inverter power supply 31 to be controlled and information indicating that it has been determined to switch from GFL control to GFM control from the control content determining unit 54, that is, when instability of the power system 3 is predicted, it generates a control signal to be supplied to the inverter power supply 31 to be controlled. Furthermore, the control signal generating unit 56 transmits the generated control signal to the inverter power supply 31 to be controlled.

[0028] As an example, the control signal generating unit 56 refers to the control signal storage unit 55, reads out and generates a control signal for changing the control of the inverter power supply 31 that is the control target.

[0029] FIG. 3 is a diagram showing an example of the configuration of the power system 3 according to the first embodiment. The power system 3 is a system for supplying power. The power system 3 includes a power supply unit that supplies power and a load unit that consumes power. The power supply unit includes a plurality of inverter power sources 31, at least one synchronous generator 32, and at least one synchronous phase modifier 33. FIG. 3 illustrates inverter power sources 31a, 31b, 31c, and 31d as the plurality of inverter power sources 31 connected to the power system 3. FIG. 3 also illustrates an arbitrary load, synchronous generator 32, and synchronous phase modifier 33 connected to the power system 3.

[0030] 3, inverter power supply 31a, inverter power supply 31b, and inverter power supply 31d are inverter power supplies 31 that are under GFL control, while inverter power supply 31c is an inverter power supply 31 that is under GFM control.

[0031] In the example of FIG. 3, the inverter power supply 31a and the inverter power supply 31b under GFL control are connected to the power system 3 at the same node among a plurality of nodes (points) in the power system 3.

[0032] 3, inverter power supply 31c under GFM control is connected to power system 3 at the same node as an arbitrary load among a plurality of nodes (points) in power system 3. In addition, inverter power supply 31c is connected to inverter power supply 31a, inverter power supply 31b, inverter power supply 31d, and the like via system network N2.

[0033] 3, inverter power supply 31d under GFL control is connected to power system 3 at the same node as an arbitrary load among a plurality of nodes (points) in power system 3. In addition, inverter power supply 31d is connected to inverter power supply 31a, inverter power supply 31b, inverter power supply 31c, etc. via system network N2.

[0034] 3, the synchronous generator 32 and the synchronous phase modifier 33 are each connected to the power system 3 at the same node among a plurality of nodes (points) in the power system 3. The synchronous generator 32 and the synchronous phase modifier 33 are also each connected to each inverter power source 31 and the like via a system network N2.

[0035] The synchronous generator 32 supplies power to a load via the power system 3. The synchronous generator 32 is a rotating machine that suppresses or increases fluctuations in the system short-circuit capacity of the power system 3 through its operation. In other words, the synchronous generator 32 corrects the system short-circuit capacity of the power system 3 to which it is connected.

[0036] The synchronous phase modifier 33 adjusts reactive power via the power system 3. The synchronous phase modifier 33 is a rotating machine that suppresses or increases fluctuations in the system short-circuit capacity of the power system 3 by supplying a constant reactive power even when the system voltage drops. In other words, the synchronous phase modifier 33 corrects the system short-circuit capacity of the power system 3 to which it is connected.

[0037] 4 is a diagram showing an example of the configuration of an inverter power supply 31 according to the first embodiment. The inverter power supply 31 is a grid-connected inverter that is input to the power grid 3, i.e., is grid-connected. The inverter power supply 31 is a power supply derived from renewable energy such as solar power or wind power, but may also be configured using a storage battery. The inverter power supply 31 supplies power to a load via the power grid 3.

[0038] As an example, the inverter power supply 31 is a power conversion device having a grid tracking type control function (GFL function). As an example, the inverter power supply 31 is a power conversion device further having a grid forming type control function (GFM function) that operates as a voltage source.

[0039] As shown in FIG. 4 , the inverter power supply 31 has a DC power supply unit 311, an AC / DC conversion unit 312, an interconnection reactor 313, a current sensor 314, a voltage sensor 315, a GFL control unit 316a, a GFM control unit 316b, a signal transmission / reception unit 317, a control switching unit 318, a PWM (Pulse Width Modulation) control unit 319, and a detected short-circuit capacity calculation unit 51.

[0040] The inverter power supply 31 has a hardware configuration that utilizes a normal computer. As an example, the inverter power supply 31 has a processor, a memory, and an interface, which are interconnected by a bus or the like.

[0041] As the processor of the inverter power supply 31, various processors such as a CPU, a GPU, an ASIC, and an FPGA can be appropriately used. For example, the processor executes at least one program loaded into a memory to comprehensively control the inverter power supply 31. As an example, the inverter power supply 31 realizes each function of the inverter power supply 31, such as the signal transmission / reception unit 317 and the detected short-circuit capacity calculation unit 51, by the processor loading a program read from a ROM into a RAM and executing the program. Note that other elements of the inverter power supply 31, such as the GFL control unit 316a and the GFM control unit 316b, may be similarly realized.

[0042] As the memory of the inverter power supply 31, various storage media and storage devices such as ROM, RAM, HDD, SSD, Flash memory, etc. can be appropriately used. For example, the ROM stores various programs and various data executed by the processor. The RAM is, for example, the main storage device of the inverter power supply 31, and temporarily stores various programs and data required for various processes by the processor.

[0043] For example, the interface of the inverter power supply 31 is an interface circuit for transmitting and receiving data between the inverter power supply 31 and the outside.

[0044] The DC power supply unit 311 supplies DC power. For example, the DC power supply unit 311 is a power supply derived from renewable energy such as a solar power generation facility or a wind power generation facility, or a storage battery.

[0045] An input node of the AC / DC conversion unit 312 is electrically connected to an output node of the DC power supply unit 311. The AC / DC conversion unit 312 converts the DC power from the DC power supply unit 311 into AC power. As an example, the AC / DC conversion unit 312 converts the DC power output from the DC power supply unit 311 into AC power based on a PWM signal from the PWM control unit 319.

[0046] The interconnection reactor 313 is provided between an output node of the AC / DC converter 312 and a connection node with the entire power system 3 , that is, an output node of the inverter power supply 31 .

[0047] The current sensor 314 measures the AC current at the output node of the inverter power supply 31. The voltage sensor 315 measures the AC voltage at the output node of the inverter power supply 31. The current sensor 314 and the voltage sensor 315 are provided between the output node of the interconnection reactor 313 and the output node of the inverter power supply 31, respectively.

[0048] An input node of GFL control unit 316a is electrically connected to output nodes of the detection signals of current sensor 314 and voltage sensor 315. GFL control unit 316a executes GFL control in inverter power supply 31.

[0049] An input node of the GFM control unit 316b is electrically connected to output nodes of the detection signals of the current sensor 314 and the voltage sensor 315. The GFM control unit 316b executes GFM control in the inverter power supply 31.

[0050] The signal transmitter / receiver 317 communicates with the operational plan control device 5 via the interface of the inverter power supply 31. As an example, the signal transmitter / receiver 317 transmits the calculation result of the system short-circuit capacity (own-end short-circuit capacity) by the detected short-circuit capacity calculation unit 51 to the operational plan control device 5. As an example, the signal transmitter / receiver 317 receives a signal from the operational plan control device 5, such as a control switch command according to the own-end short-circuit capacity. This control switch command is an example of a control signal generated and transmitted by the control signal generation unit 56 of the operational plan control device 5.

[0051] A pair of input nodes of the control switching unit 318 are electrically connected to an output node of the GFL control unit 316a and an output node of the GFM control unit 316b, respectively. An output node of the control switching unit 318 is electrically connected to an input node of the PWM control unit 319. A control node of the control switching unit 318 is electrically connected to an internal output node of the signal transmitting / receiving unit 317. The control switching unit 318 electrically connects one of the pair of input nodes to the output node in response to a control switching command received by the signal transmitting / receiving unit 317. In other words, the control switching unit 318 is a switch that switches the operation mode of the inverter power supply 31 between GFL control and GFM control in response to a control switching command.

[0052] An output node of the PWM control unit 319 is electrically connected to a control node of the AC / DC conversion unit 312. The PWM control unit 319 generates a PWM signal using a signal from the GFL control unit 316a or the GFM control unit 316b, and supplies the PWM signal to the AC / DC conversion unit 312.

[0053] An input node of the detected short circuit capacity calculation unit 51 is electrically connected to the output nodes of the detection signals of the current sensor 314 and the voltage sensor 315. An output node of the detected short circuit capacity calculation unit 51 is electrically connected to an internal input node of the signal transmission / reception unit 317. The detected short circuit capacity calculation unit 51 detects a system short circuit capacity (detected short circuit capacity) during actual operation at the output node of the inverter power supply 31, using the AC current and AC voltage measured by the current sensor 314 and the voltage sensor 315. As an example, the detected short circuit capacity calculation unit 51 calculates active power and / or reactive power using the measured AC current and AC voltage, and detects hunting to calculate the detected short circuit capacity. The detected short circuit capacity calculation unit 51 supplies the calculated detected short circuit capacity to the signal transmission / reception unit 317.

[0054] <Processing of the power system according to the first embodiment> Next, a description will be given of processing of the power system operation 1 according to the first embodiment. Fig. 5 is a flowchart showing an example of processing during operation executed by the power system operation 1 according to the first embodiment.

[0055] 5 is repeatedly performed at a predetermined fixed cycle, such as every 30 minutes. The length of the cycle can be set arbitrarily, and the cycle may be repeated at indefinite intervals, i.e., at an indefinite cycle.

[0056] Moreover, the flow of FIG. 5 is carried out in a state where the power system 3 is operated in accordance with a predetermined system operation plan.

[0057] The inverter power supply 31 detects the current system short-circuit capacity (S101). Specifically, the detected short-circuit capacity calculation unit 51 detects the system short-circuit capacity during actual operation. It is assumed that the operation mode of the inverter power supply 31 is GFL control.

[0058] The operation plan control device 5 judges whether the current system short circuit capacity differs from the operation plan (S102). Specifically, the short circuit capacity comparison unit 52 compares the detected system short circuit capacity during actual operation with the system short circuit capacity planned in the operation plan. Furthermore, the control content judgment unit 54 judges whether the system short circuit capacity at the time of the operation plan has been obtained from the comparison result. Here, this judgment is an example of a judgment of whether system instability of the power system 3 is predicted.

[0059] If the current system short-circuit capacity is the system short-circuit capacity according to the operation plan (S102: No), the flow of FIG. 5 ends.

[0060] On the other hand, if the current system short circuit capacity differs from the operation plan (S102: Yes), the operation plan control device 5 judges whether the GFL control will cause system instability (S103). Specifically, if the system short circuit capacity differs between the operation plan and the actual operation, the control content determination unit 54 judges whether the system short circuit capacity during the actual operation is equal to or less than a threshold value related to system instability of the power system 3. Here, this judgment is an example of a judgment of whether system instability of the power system 3 is predicted.

[0061] If the GFL control does not cause grid instability (S103: No), the operation plan control device 5 determines to continue the GFL control (S104). Specifically, the control content determination unit 54 determines not to change the operation mode for the inverter power supply 31 under GFL control as the control target, since grid instability of the power grid 3 is not predicted.

[0062] On the other hand, if the GFL control causes grid instability (S103: Yes), the operation plan control device 5 determines to change to GFM control (S105). Specifically, the control content determination unit 54 determines to change the operation mode of the inverter power supply 31 under GFL control, which is the control target, because grid instability of the power system 3 is predicted. In addition, the control signal generation unit 56 generates a control signal for changing the inverter power supply 31 under GFL control, which is the control target, to GFM control, and transmits it to the inverter power supply 31. Then, in response to the control signal from the operation plan control device 5, the inverter power supply 31 switches the control unit used for power conversion from the GFL control unit 316a to the GFM control unit 316b. After that, the flow of FIG. 5 returns to the process of S101.

[0063] 3, suppose that at a node (point) where inverter power supply 31a and inverter power supply 31b under GFL control are connected to the power system 3, specifically, that instability of the power system 3 is predicted based on the system short-circuit capacity during actual operation detected in inverter power supply 31b. In this case, the control switching unit 318 in inverter power supply 31b is operated, and the operation mode of inverter power supply 31b is changed to GFM control.

[0064] In the above-described first embodiment, the system operation system 1 is exemplified as a device to be controlled, the inverter power supply 31 under GFL control, and is controlled in accordance with the state of the system short-circuit capacity to enhance the system short-circuit capacity of the power system 3, but is not limited thereto. The system operation system 1 may further control at least one of the synchronous generator 32 and the synchronous phase modifier 33 connected to the same power system 3 in addition to the inverter power supply 31 under GFL control, in accordance with the state of the system short-circuit capacity. Specifically, the system operation system 1 may further start rotating machines such as the synchronous generator 32 and the synchronous phase modifier 33 as an enhancement of the system short-circuit capacity during actual operation, when only the control change of the inverter power supply 31 is insufficient or when it is economically rational to do so.

[0065] That is, the grid operation system 1 according to the first embodiment may also use a grid stabilization device that is at least one of a synchronous generator and a synchronous phase modifier as a control target according to the state of the grid short-circuit capacity.

[0066] For example, in the power system operation system 1 according to the first embodiment, when instability of the power system 3 is predicted, the control content judgment unit 54 may determine to start up at least one of the synchronous generator 32 and the synchronous phase modifier 33, which correct the system short circuit capacity of the connected power system 3.

[0067] For example, in the system operation system 1 according to the first embodiment, when instability of the power system 3 is predicted and when it is economically rational to do so, the control content determination unit 54 may determine to start up at least one of the synchronous generator 32 and the synchronous phase modifier 33 that correct the system short circuit capacity of the connected power system 3. Here, the economic rationality may be an index of cost-effectiveness, such as the amount of correction of the system short circuit capacity relative to the operating cost, or an index of whether the operating cost itself is acceptable.

[0068] For example, in the system operation system 1 according to the first embodiment, the control content determination unit 54 may secure a part of the system short-circuit capacity to be reinforced (first system short-circuit capacity), such as a difference from a planned value, by changing the operation mode of the inverter power supply 31 to be controlled. Similarly, the control content determination unit 54 may secure another part of the system short-circuit capacity to be reinforced, for example, the remaining system short-circuit capacity to be reinforced (second system short-circuit capacity), by starting up at least one of the synchronous generator 32 and the synchronous phase modifier 33 to be controlled. Furthermore, the control content determination unit 54 may determine the allocation based on economic rationality.

[0069] <Effects of the power system operation according to the first embodiment> In this way, the power system operation system 1 of the first embodiment is configured to switch the control of the corresponding inverter power supply 31 from GFL control to GFM control when a difference occurs between the predicted amount of power system short circuit capacity and the amount detected during operation.

[0070] According to this configuration, even when a system short circuit capacity is required at a certain node of the power system 3, and it is difficult to secure the system short circuit capacity by the synchronous generator 32, or when it is difficult to secure the system short circuit capacity only by adjusting the inverter constant, the system short circuit capacity can be secured. In other words, according to the configuration of this embodiment, a flexible response can be realized in terms of control of the system-connected inverter according to the state of the system short circuit capacity, and the system short circuit capacity of the actual system can be increased. This makes it possible to suppress system instability caused by a shortage of the system short circuit capacity.

[0071] The above-described first embodiment can be modified as appropriate by changing a part of the configuration or function of each device of the system operation 1. Therefore, the following describes a modified example of the first embodiment as another embodiment. The following mainly describes the differences from the contents already described, and omits detailed description of the points in common with the contents already described. The modified examples described below may be implemented individually or in appropriate combination.

[0072] Second embodiment A system operation system 1 according to a second embodiment will be described. In the second embodiment, a system operation system 1 in which detection of a system short circuit capacity during actual operation is performed in an operation plan control device 5 will be described. In the description of the second embodiment, the same reference numerals are given to parts showing the same configurations or operations as those in the first embodiment in the drawings, etc., and detailed description thereof will be omitted.

[0073] <Configuration of a power system according to the second embodiment> Fig. 6 is a diagram showing an example of a functional configuration of an operation plan control device 5 according to a second embodiment. Fig. 7 is a diagram showing an example of a configuration of an inverter power supply 31 according to a second embodiment. As shown in Figs. 6 and 7, the power system operation system 1 according to the second embodiment has the same configuration as the power system operation system 1 according to the first embodiment, except that a detected short-circuit capacity calculation unit 51 is provided in the operation plan control device 5 instead of the inverter power supply 31.

[0074] For example, in the power system operation system 1 according to the second embodiment, the detected short-circuit capacity calculation unit 51 of the operation plan control device 5 acquires measurement information indicating the AC current and the AC voltage measured by the current sensor 314 and the voltage sensor 315 from the inverter power supply 31. Then, the detected short-circuit capacity calculation unit 51 supplies the detected system short-circuit capacity during actual operation to the short-circuit capacity comparison unit 52.

[0075] For example, in the power system 1 according to the second embodiment, an input node of a signal transmitting / receiving unit 317 of the inverter power supply 31 is electrically connected to output nodes of detection signals of the current sensor 314 and the voltage sensor 315. The signal transmitting / receiving unit 317 transmits the AC current and AC voltage of its own end measured by the current sensor 314 and the voltage sensor 315 to the operation plan control device 5.

[0076] <Effects of the grid operation system according to the second embodiment> In this way, even in the power system operation system 1 according to the second embodiment in which the operation plan control device 5 is provided with the detected short-circuit capacity calculation unit 51, the same effects as those of the power system operation system 1 according to the first embodiment can be obtained.

[0077] (Third embodiment) A system operation system 1 according to a third embodiment will be described. In the first and second embodiments, the system operation system 1 has been described in which the control of the inverter power source 31 is changed using the planned short-circuit capacity of the system operation plan, which is an operation plan of the power system 3 created in advance, during operation according to the system operation plan, but this planned short-circuit capacity may be calculated in the operation plan control device 5. In the description of the third embodiment, parts showing the same configurations or operations as those of the above-mentioned first embodiment are given the same reference numerals in the drawings, etc., and detailed description thereof will be omitted.

[0078] <Configuration of a power system according to a third embodiment> Fig. 8 is a diagram illustrating an example of a functional configuration of an operation plan control device 5 according to the third embodiment. Fig. 8 illustrates a case where the grid operation system 1 is operated by a business entity that can be involved in formulating a synchronous generator operation plan, which is a plan for starting / stopping the synchronous generators 32.

[0079] The operation plan control device 5 according to the third embodiment further realizes a function as an operation planner 6 as shown in Fig. 8 by loading at least one program read from the ROM by the processor into the RAM and executing it. As shown in Fig. 8, the operation planner 6 includes functions as a synchronous generator operation planner 61, an impedance map creator 62, a planned short-circuit capacity calculator 63, and a planned short-circuit and control content planner 67. Here, the operation planner 6 according to the embodiment is an example of a planner.

[0080] The synchronous generator operation planning unit 61 creates an operation plan for the synchronous generator 32 and the storage battery, such as starting / stopping the synchronous generator 32 and the storage battery. For example, the synchronous generator operation planning unit 61 acquires renewable energy power generation forecast information and planning information on the control content. Here, the renewable energy power generation forecast information is, for example, information indicating a predicted value of the amount of power generation by renewable energy power generation. Furthermore, the planning information on the control content is information indicating the operating state or its change, such as starting / stopping the synchronous generator 32 and the storage battery, generated by the control content planning unit 67. Then, the synchronous generator operation planning unit 61 creates an operation plan for the synchronous generator 32 and the storage battery based on the renewable energy power generation forecast information and the planning information on the control content. The synchronous generator operation planning unit 61 supplies information indicating the created operation plan to the impedance map creation unit 62.

[0081] The synchronous generator operation planning unit 61 may predict renewable energy power generation and generate renewable energy power generation prediction information. In this case, the synchronous generator operation planning unit 61 may predict renewable energy power generation based on inverter control information indicating the current control mode of the inverter power source 31 connected to the power system 3, system data indicating information related to the system such as the open / close state of the circuit breaker of the power system 3, information indicating the performance of the inverter power source 31 and the history of the amount of power generation in the past, weather forecast information, predicted current, and other system operation plan information.

[0082] The impedance map creation unit 62 acquires a system operation plan. The impedance map creation unit 62 creates an impedance map in accordance with the system operation plan. As described above, the system operation plan includes information such as operation state information indicating the operation state of the synchronous generator 32 and the storage battery, plan information on the control content of the synchronous generator 32 and the storage battery, renewable energy power generation forecast information, inverter control information, and system data. The impedance map creation unit 62 may acquire the inverter control information by receiving a state signal indicating the control mode from the inverter power source 31, or may acquire the inverter control information from the history of control by the control signal from the control signal generation unit 56. The impedance map creation unit 62 may also acquire a signal indicating the open / close state from a circuit breaker of the power system 3.

[0083] 9 is a diagram for explaining an impedance map according to the third embodiment. The impedance map creating unit 62 creates an impedance map showing the impedance of each part, such as each transmission line, the inverter power source 31, the synchronous generator 32, the synchronous phase modifier 33, and the load, for the power system 3 having a load part and a power source part. Note that the impedance map is not limited to information that can be visually recognized as a map, as long as it is information showing the impedance at each node of the power system 3, as exemplified in FIG. 9. The impedance map creating unit 62 supplies the created impedance map to the planned short-circuit capacity calculating unit 63.

[0084] The planned short circuit capacity calculation unit 63 acquires the impedance map from the impedance map creation unit 62. In addition, the planned short circuit capacity calculation unit 63 calculates the system short circuit capacity (planned short circuit capacity) at the time of operation planning of each node using the acquired impedance map. The planned short circuit capacity calculation unit 63 supplies the calculated planned short circuit capacity to the planned short circuit capacity determination unit 64.

[0085] As an example, the planned short circuit capacity calculation unit 63 calculates the system short circuit capacity of each of a plurality of nodes (points) in the power system 3 when planning the system operation plan.

[0086] As an example, when planning a system operation plan, the planned short circuit capacity calculation unit 63 sets the planned short circuit capacity, which is the system short circuit capacity of each of multiple nodes (points) in the power system 3, as a threshold value for the detected short circuit capacity during actual operation.

[0087] The planned short circuit capacity determination unit 64 determines whether the system short circuit capacity is insufficient for each node of the power system 3. In other words, the planned short circuit capacity determination unit 64 determines whether a node with insufficient system short circuit capacity exists in the power system 3 within the management range. For example, when the planned short circuit capacity from the planned short circuit capacity determination unit 64 is equal to or less than a threshold value related to the planned short circuit capacity that is determined in advance and stored in the internal memory of the operation plan control device 5, the planned short circuit capacity determination unit 64 determines that the system short circuit capacity is insufficient at that node. The fact that the planned short circuit capacity is equal to or less than the threshold value is determined based on, for example, a short circuit ratio, a short circuit capacity ratio, or a ratio between the system short circuit capacity and the apparent power output of the inverter power source 31, but other determination methods may be used. When a node with insufficient system short circuit capacity exists in the power system 3 within the management range, the planned short circuit capacity determination unit 64 supplies the planned short circuit capacity to the planned short circuit capacity correction amount calculation unit 65. In addition, if there is no node with insufficient system short-circuit capacity in the power system 3 within its management range, the planned short-circuit capacity judgment unit 64 supplies the planned short-circuit capacity to the planned short-circuit capacity storage unit 53, and also supplies control signals for controlled objects such as the inverter power supply 31, synchronous generator 32, and synchronous modifier 33 to the control signal storage unit 55 in accordance with the system operation plan.

[0088] When a node with insufficient system short circuit capacity exists in the power system 3 within the management range, the planned short circuit capacity correction amount calculation unit 65 calculates the system short circuit capacity to be corrected at the corresponding node, i.e., the system short circuit capacity to be reinforced. For example, the planned short circuit capacity correction amount calculation unit 65 calculates the difference between the system short circuit capacity to be secured from the viewpoint of suppressing system instability of the power system 3 and the planned short circuit capacity as the system short circuit capacity to be reinforced. In other words, the planned short circuit capacity correction amount calculation unit 65 calculates the correction amount of the system short circuit capacity that stabilizes the system for a node where the calculated planned short circuit capacity is equal to or less than a threshold value.

[0089] When a node with insufficient system short-circuit capacity exists in the power system 3 within the management range, the connected inverter search unit 66 judges whether the inverter power supply 31 is connected to the corresponding node. The connected inverter search unit 66 also searches for the inverter power supply 31 that maximizes the correction value of the system short-circuit capacity when changing from GFL control to GFM control. The connected inverter search unit 66 supplies information indicating the found inverter power supply 31 to the control content planning unit 67.

[0090] The control content planning unit 67 judges whether to change the control of the found inverter power source 31, for example, in the same manner as the control content determination unit 54. For example, the control content planning unit 67 calculates the amount of correction of the system short circuit capacity when the control of the inverter power source 31 connected to the node with insufficient system short circuit capacity or its surrounding nodes is changed from GFL control to GFM control, and changes the control of the inverter with the highest effect from GFL control to GFM control. Note that the control content planning unit 67 may switch the control of two or more inverter power sources 31, and the number of inverter power sources 31 to be switched in control can be appropriately set based on, for example, the relationship between the system short circuit capacity to be increased and the amount of correction by the control change. Here, the amount of correction of the system short circuit capacity when the control of the inverter power source 31 is changed is an example of an improvement effect.

[0091] As an example, the control content planning unit 67 determines, at the time of operational planning, the effect of improving the system short circuit capacity of the power system 3 by changing the operation mode in which the control of any one of the multiple inverter power sources 31 is changed from a system tracking type to a system forming type.

[0092] As an example, the control content planning unit 67 calculates the system short-circuit capacity of each of the multiple nodes (points) in the power system 3 at the time of operational planning, and changes the operating mode of one of the multiple inverter power sources 31 connected to the power system 3 at a node (target point) among the multiple nodes (points) whose system short-circuit capacity at the time of operational planning is below a threshold value for system instability of the power system 3 at the time of operational planning.

[0093] As in the above-described embodiments, the system operation system 1 according to this embodiment may further control at least one of the synchronous generator 32 and the synchronous phase modifier 33 connected to the same power system 3 in addition to the inverter power source 31 under GFL control, depending on the state of the system short-circuit capacity. Specifically, the system operation system 1 according to this embodiment may further start rotating machines such as the synchronous generator 32 and the synchronous phase modifier 33 as a reinforcement of the system short-circuit capacity at the time of operation planning, when only changing the control of the inverter power source 31 is insufficient or when it is economically rational to do so.

[0094] As an example, the control content planning unit 67 further determines the amount of correction (improvement effect) of the system short-circuit capacity when using in combination at least one of the synchronous generators 32 and the synchronous phase modifier 33 that correct the system short-circuit capacity of the connected power system 3 at the time of operation planning.

[0095] As an example, the control content planning unit 67 further determines the economic rationality of simultaneously starting at least one of the synchronous generator 32 and the synchronous phase modifier 33 at the time of planning the operation.

[0096] <Processing of the power system according to the third embodiment> Next, a description will be given of processing of the power system operation system 1 according to the third embodiment. Fig. 10 is a flowchart showing an example of processing at the time of planning, which is executed by the power system operation system 1 according to the third embodiment.

[0097] The flow of FIG. 10 is carried out, for example, at the stage of formulating a system operation plan, that is, at the time of operation planning.

[0098] The operation plan unit 6 of the operation plan control device 5 creates a system operation plan (S201). In addition, the impedance map creation unit 62 of the operation plan unit 6 creates an impedance map in accordance with the system operation plan (S202).

[0099] The planned short circuit capacity calculation unit 63 uses the impedance map to calculate the system short circuit capacity at one target node among the multiple nodes in the power system 3 within the management range (S203). Then, the planned short circuit capacity determination unit 64 determines whether the system short circuit capacity at the target node is insufficient (S204).

[0100] If the system short circuit capacity is not insufficient at the target node (S204: No), the planned short circuit capacity calculation unit 63 determines whether the system short circuit capacity is predicted to be insufficient at any of the multiple nodes in the power system 3 within the management range (S205).

[0101] If it is predicted that the system short circuit capacity will be insufficient at any of the multiple nodes in the power system 3 within the management range (S205: Yes), the flow in Fig. 10 returns to the process of S203. On the other hand, if it is not predicted that the system short circuit capacity will be insufficient at any of the multiple nodes in the power system 3 within the management range (S205: No), the flow in Fig. 10 ends.

[0102] If the system short-circuit capacity is insufficient in the target node (S204: Yes), the planned short-circuit capacity correction amount calculation unit 65 calculates the system short-circuit capacity to be corrected in the corresponding node (S206). Then, the connected inverter search unit 66 determines whether the inverter power supply 31 is connected to the corresponding node (S207).

[0103] If the inverter power supply 31 is connected to the corresponding node (S207: Yes), the control content planning unit 67 judges whether the corresponding inverter power supply 31 is GFL controlled (S208). If the corresponding inverter power supply 31 is GFL controlled (S208: Yes), the control content planning unit 67 changes the corresponding inverter power supply 31 to GFM control (S209). On the other hand, if the corresponding inverter power supply 31 is not GFL controlled, i.e., if it is GFM controlled (S208: No), the flow in FIG. 10 returns to the process of S203.

[0104] Also, if the inverter power supply 31 is not connected to the corresponding node (S207: No), the connected inverter search unit 66 searches for at least one inverter power supply 31 that maximizes the correction amount of the system short-circuit capacity when changing from GFL control to GFM control (S210a). Then, the control content planning unit 67 determines whether the corresponding inverter power supply 31 is GFL controlled (S211) in the same manner as the processes of S208 to S209, and if the corresponding inverter power supply 31 is GFL controlled (S211: Yes), changes the corresponding inverter power supply 31 to GFM control (S212). On the other hand, if the corresponding inverter power supply 31 is not GFL controlled, that is, if it is GFM controlled (S211: No), the flow of FIG. 10 returns to the process of S203 in the same manner as the process of S209.

[0105] <Effects of the grid operation system according to the third embodiment> In this way, the system operation system 1 according to the third embodiment is configured to search for an inverter power supply 31 connected to the node, or an inverter power supply 31 that can achieve the maximum effect for the required system short circuit capacity correction amount, when the system short circuit capacity calculated using the impedance map is insufficient, and to change the control of that inverter power supply 31 from GFL control to GFM control.

[0106] According to this configuration, for a node where the grid short circuit capacity is insufficient, the grid short circuit capacity can be efficiently improved at the timing of formulating an operation plan prior to actual operation. Furthermore, according to the above configuration using the impedance map, even if the grid short circuit capacity during actual operation deviates from the operation plan, the execution of new calculation of the grid short circuit capacity can be minimized. Similarly, according to the above configuration, it is possible to minimize the inverter power supplies 31 that are targets for control switching. Furthermore, according to the above configuration, the control can be switched in consideration of economic rationality.

[0107] The technology according to the third embodiment is applicable to both of the power system operation systems 1 according to the first and second embodiments described above.

[0108] (Fourth embodiment) A system operation system 1 according to a fourth embodiment will be described. In the third embodiment, the system operation system 1 in which the synchronous generator operation plan, which is a plan for starting / stopping the synchronous generator 32, is created in the operation plan control device 5 has been described, but the synchronous generator operation plan may be created outside the operation plan control device 5. In the description of the fourth embodiment, the same reference numerals are given to parts showing the same configurations or operations as those in the above-mentioned third embodiment in the drawings, etc., and detailed description thereof will be omitted.

[0109] <Configuration of a power system according to the fourth embodiment> Fig. 11 is a diagram showing an example of a functional configuration of a system operation 1 according to a fourth embodiment. As shown in Fig. 11, the system operation 1 according to the fourth embodiment is similar to the system operation 1 according to the third embodiment except that a synchronous generator operation planning device 7 is further provided, while the operation plan control device 5 is not provided with a synchronous generator operation planning unit 61.

[0110] The synchronous generator operation planning device 7 has a hardware configuration using a normal computer. As an example, the synchronous generator operation planning device 7 has a processor, a memory, and an interface, which are interconnected by a bus or the like.

[0111] As the processor of the synchronous generator operation planning device 7, various processors such as a CPU, a GPU, an ASIC, an FPGA, etc. can be appropriately used. For example, the processor executes at least one program loaded into a memory to comprehensively control the synchronous generator operation planning device 7. As an example, the synchronous generator operation planning device 7 realizes each function of the synchronous generator operation planning device 7, including the same function as the synchronous generator operation planner 61, by loading a program read from a ROM by the processor into a RAM and executing the program.

[0112] As the memory of the synchronous generator operation planning device 7, various storage media and storage devices such as ROM, RAM, HDD, SSD, Flash memory, etc. can be appropriately used. For example, the ROM stores various programs and various data executed by the processor. The RAM is, for example, a main storage device of the synchronous generator operation planning device 7, and temporarily stores various programs and data required for various processes by the processor.

[0113] The interface of the synchronous generator operation planning device 7 is an interface circuit for transmitting and receiving data between the synchronous generator operation planning device 7 and the outside.

[0114] The synchronous generator operation planning device 7 creates an operation plan for the synchronous generator 32 and the storage battery, such as starting / stopping the synchronous generator 32 and the storage battery. For example, the synchronous generator operation planning device 7 acquires renewable energy power generation prediction information and planning information on control contents from the control content planning unit 67 of the operation plan control device 5. Then, the synchronous generator operation planning device 7 creates an operation plan for the synchronous generator 32 and the storage battery based on the renewable energy power generation prediction information and the planning information on control contents. The synchronous generator operation planning device 7 supplies information indicating the created operation plan to the impedance map creation unit 62 of the operation plan control device 5.

[0115] <Effects of the power system operation according to the fourth embodiment> In this way, the grid operation system 1 according to the fourth embodiment is configured to create an impedance map using an operation plan of the synchronous generator 32 and the storage battery created outside the operation plan control device 5. Even with this configuration, the same effects as those of the grid operation system 1 according to the third embodiment can be obtained.

[0116] The technology according to the fourth embodiment is applicable to any of the power system operation systems 1 according to the first to third embodiments described above.

[0117] Fifth embodiment A grid operation system 1 according to a fifth embodiment will be described. In the third and fourth embodiments, the grid operation system 1 is operated by an operator who can be involved in formulating a synchronous generator operation plan, which is a plan for starting / stopping the synchronous generator 32. However, the grid operation system 1 may be operated by an operator who cannot be involved in starting and stopping the generator. In the description of the fifth embodiment, the same reference numerals are given to parts showing the same configurations or operations as those of the above-mentioned third embodiment in the drawings, etc., and detailed description thereof will be omitted.

[0118] <Configuration of a power system according to the fifth embodiment> Fig. 12 is a diagram showing an example of a functional configuration of the operation plan control device 5 according to the fifth embodiment. As shown in Fig. 12, the power system operation system 1 according to the fifth embodiment has the same configuration as that of the power system operation system 1 according to the third embodiment, except that the operation plan control device 5 does not include a synchronous generator operation plan unit 61.

[0119] The impedance map creation unit 62 of the operation plan control device 5 according to the fifth embodiment acquires, from outside the grid operation system 1, synchronous generator operation plan information, which is plan information on the control details of the synchronous generators 32 and the storage batteries.

[0120] As in the above-described embodiments, the control content planning unit 67 of the operation plan control device 5 according to the fifth embodiment may further control the synchronous modifier 33 connected to the same power system 3 in addition to the inverter power source 31 under GFL control according to the state of the system short-circuit capacity. On the other hand, the control content planning unit 67 does not control the synchronous generator 32 and the storage battery.

[0121] <Effects of the power system operation according to the fifth embodiment> In this way, the grid operation system 1 according to the fifth embodiment is configured to create an impedance map using an operation plan for the synchronous generator 32 and the storage battery created outside the grid operation system 1. Even with this configuration, the same effects as those of the grid operation system 1 according to the third embodiment can be obtained, except that the synchronous modifier 33 and the storage battery cannot be used in combination to increase the grid short-circuit capacity when planning the operation.

[0122] The technology according to the fifth embodiment is applicable to any of the power system operation systems 1 according to the first to fourth embodiments described above.

[0123] Sixth embodiment A system operation system 1 according to a sixth embodiment will be described. In the third to fifth embodiments, the system operation system 1 is described for searching for at least one inverter power source 31 that maximizes the correction amount of the system short-circuit capacity when changing from GFL control to GFM control, but the system operation system 1 may search for an inverter power source 31 for changing from GFL control to GFM control under other conditions. In the description of the sixth embodiment, the same reference numerals are used in the drawings etc. to indicate configurations or operations similar to those of the above-mentioned third embodiment, and detailed descriptions thereof will be omitted.

[0124] <Configuration of power system according to the sixth embodiment> When a node with insufficient system short-circuit capacity exists in the power system 3 within the management range, the connected inverter searching unit 66 according to the sixth embodiment judges whether an inverter power supply 31 is connected to the node. The connected inverter searching unit 66 also searches for at least one inverter power supply 31 with the shortest electrical distance from the node. The connected inverter searching unit 66 supplies information indicating the found inverter power supply 31 to the control content planning unit 67.

[0125] <Processing of the power system according to the sixth embodiment> FIG. 13 is a flowchart showing an example of a process at the time of planning, which is executed by the power system operation system 1 according to the sixth embodiment.

[0126] When the inverter power supply 31 connected to the power grid 3 is not connected to a target node (target point) having a shortage of grid short-circuit capacity (S207: No), the connected inverter search unit 66 according to the sixth embodiment calculates the grid short-circuit capacity to be increased at the target node, i.e., the grid short-circuit capacity required for grid stability. Then, the connected inverter search unit 66 searches for the inverter power supply 31 with the shortest electrical distance so as to obtain the calculated grid short-circuit capacity (S210b). Here, the electrical distance corresponds to, for example, the distance on the impedance map (see FIG. 9). In other words, the inverter power supply 31 with the shortest electrical distance from the target node is the inverter power supply 31 with the smallest impedance as seen from the target node.

[0127] Then, the control content planning unit 67 determines whether the corresponding inverter power supply 31 is under GFL control (S211), and if the corresponding inverter power supply 31 is under GFL control (S211: Yes), changes the corresponding inverter power supply 31 to GFM control (S212). On the other hand, if the corresponding inverter power supply 31 is not under GFL control, i.e., under GFM control (S211: No), the flow in FIG. 13 returns to the process of S203.

[0128] <Effects of the grid operation system according to the sixth embodiment> In this way, the system operation system 1 according to the sixth embodiment is configured to change the operation mode of the inverter power supply 31 that is the shortest electrical distance from the target node and that can compensate for the system short-circuit capacity to be increased at the time of operation planning.

[0129] With this configuration, it is possible to correct the system short circuit capacity for a node that is predicted to have a small system short circuit capacity in advance. This makes it possible to suppress a decrease in the system short circuit capacity before executing a system operation plan. In addition, by incorporating an element of electrical distance, it is possible to reduce the amount of calculation required for changing the control of the inverter power source 31 that is effective when the control is changed. Therefore, with the above configuration, when there is no inverter power source 31 around a node, it is possible to obtain the system short circuit capacity required for system stability at that node and calculate the correction amount in a shorter time.

[0130] The technology according to the sixth embodiment is applicable to any of the power system operation systems 1 according to the first to fifth embodiments described above.

[0131] The programs executed by each device in the above embodiments are provided by being pre-installed in a storage medium (ROM or storage unit) included in each device, but the present invention is not limited to this and may be configured to be provided by being recorded in an installable or executable format on a computer-readable storage medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disc). Furthermore, the storage medium is not limited to a medium independent of the computer or embedded system, but also includes a storage medium in which a program transmitted via a LAN, the Internet, or the like is downloaded and stored or temporarily stored.

[0132] In addition, the programs executed by each device in the above embodiments may be stored on a computer connected to a network such as the Internet and provided by downloading them via the network, or may be provided or distributed via a network such as the Internet.

[0133] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0134] (Additional Note) (1) A comparison unit that compares a system short circuit capacity at the time of an operation plan for a power system to which a plurality of power conversion devices are connected with a system short circuit capacity at the time of actual operation; a determination unit that determines that instability of the power system is predicted when a system short-circuit capacity at the time of the operation plan differs from a system short-circuit capacity at the time of the actual operation, and determines to change an operation mode of a power conversion device to be controlled, which is any one of the plurality of power conversion devices; A generation unit that generates a signal instructing a change in an operation mode of the power conversion device to be controlled when instability of the power system is predicted, and transmits the signal to the power conversion device to be controlled. System operation planning control device. (2) The determination unit determines whether a system short circuit capacity during the actual operation is equal to or less than a threshold value related to system instability of the power system, and determines that system instability of the power system is predicted when a system short circuit capacity at the time of the operation plan differs from a system short circuit capacity during the actual operation and when the system short circuit capacity during the actual operation is equal to or less than the threshold value. The system operation planning control device according to (1) above. (3) the determination unit determines to start up a grid stabilization device to be controlled, which is any one of at least one grid stabilization devices that corrects a grid short circuit capacity of the connected grid, when grid instability of the grid is predicted; The system operation planning control device according to (1) or (2) above. (4) The power system stabilization device to be controlled is at least one of a synchronous generator and a synchronous phase modifier. The system operation planning control device according to (3) above. (5) The power conversion device to be controlled is a power conversion device having a grid tracking type control function. A system operation planning control device according to any one of (1) to (4) above. (6) The power electronics device to be controlled is a power electronics device having a system-forming control function, The change in the operation mode of the power conversion device to be controlled is a change in control from the grid tracking type to the grid forming type. The system operation planning control device according to (5) above. (7) A planning unit is further provided which, when system instability of the power system is predicted, secures a first system short-circuit capacity, which is a part of the system short-circuit capacity to be reinforced, at the time of the operation plan by changing the operation mode of any one of the power conversion devices among the plurality of power conversion devices, and secures a second system short-circuit capacity, which is the remaining system short-circuit capacity to be reinforced, at the time of the operation plan by activating any one of at least one system stabilization devices that corrects the system short-circuit capacity of the connected power system. The system operation planning control device according to any one of claims 1 to 6. (8) The planning unit determines the allocation of the first system short-circuit capacity and the second system short-circuit capacity based on economic rationality. The system operation planning control device according to (7) above. (9) A planning unit that calculates a system short circuit capacity of each of a plurality of points in the power system at the time of the operation planning, A system operation planning control device according to any one of (1) to (8) above. (10) A planning unit that sets a system short circuit capacity at the time of the operation plan for each of a plurality of points in the power system at the time of the operation plan, A system operation planning control device according to any one of (1) to (9) above. (11) A planning unit that determines, at the time of the operation plan, an improvement effect of a system short circuit capacity of the power system in the change of the operation mode in which control of any one of the plurality of power conversion devices is changed from a system tracking type to a system forming type. A system operation planning control device according to any one of (1) to (10) above. (12) The planning unit further determines, at the time of the operation planning, an improvement effect of the system short circuit capacity in a case where activation of any one of at least one system stabilization device that corrects a system short circuit capacity of the connected power system is used in combination. The system operation planning control device according to (11) above. (13) The planning unit further determines economic rationality of using any one of the at least one power system stabilization devices in combination at the time of the operation planning. The system operation planning control device according to (12) above. (14) A planning unit that calculates a system short circuit capacity of each of a plurality of points in the power system at the time of the operation plan, and changes the operation mode of a power conversion device that is connected to the power system at a target point among the plurality of points where the system short circuit capacity at the time of the operation plan is equal to or less than a threshold value related to system instability of the power system, at the time of the operation plan, among the plurality of points. A system operation planning control device according to any one of (1) to (13) above. (15) The planning unit calculates a system short-circuit capacity to be reinforced at the target point when there is no power conversion device connected to the power grid at the target point, A planning unit that changes the operation mode of a power conversion device that is one of the plurality of power conversion devices and has a shortest electrical distance from the target point and can compensate for the grid short-circuit capacity to be reinforced, during the operation plan. The system operation planning control device according to (14) above. (16) A system short circuit capacity at the time of operation planning for a power system to which a plurality of power conversion devices are connected is compared with a system short circuit capacity at the time of actual operation; When a system short circuit capacity at the time of the operation plan differs from a system short circuit capacity during the actual operation, it is determined whether the system short circuit capacity during the actual operation is equal to or less than a threshold value related to system instability of the power system, and when the system short circuit capacity during the actual operation is equal to or less than the threshold value, it is determined to change an operation mode of a power conversion device to be controlled, which is any one of the plurality of power conversion devices; When the system short-circuit capacity during the actual operation is equal to or less than the threshold value, a signal is generated to instruct a change in an operation mode of a power conversion device to be controlled, which is one of the plurality of power conversion devices, and the signal is transmitted to the power conversion device to be controlled. System operation planning and control method. [Explanation of symbols]

[0135] 1. Power grid operation system 3 Power system 31 Inverter power supply 311 DC power supply section 312 AC / DC converter 313 Interconnection reactor 314 Current Sensor 315 Voltage Sensor 316a GFL Control Section 316b GFM control section 317 Signal Transmitter / Receiver 318 Control Switching Unit 319 PWM control unit 32 Synchronous generator 33 Synchronous phase modifier 5 Operational planning control device 51 Detected short circuit capacity calculation section 52 Short circuit capacity comparison section 53 Planned short circuit capacity storage section 54 Control content judgment unit 55 Control signal storage section 56 Control signal generator 6. Operational Planning Department 61 Synchronous Generator Operation Planning Department 62 Impedance map creation section 63 Planned Short Circuit Capacity Calculation Section 64 Planned short circuit capacity determination section 65 Planned short circuit capacity correction amount calculation section 66 Connection inverter search unit 67 Control Content Planning Department 7. Synchronous generator operation planning device N1 Communications Network N2 grid network

Claims

1. A comparison unit that compares a system short circuit capacity at the time of an operation plan for a power system to which a plurality of power conversion devices are connected with a system short circuit capacity at the time of actual operation; a determination unit that determines that instability of the power system is predicted when a system short-circuit capacity at the time of the operation plan differs from a system short-circuit capacity at the time of the actual operation, and determines to change an operation mode of a power conversion device to be controlled, which is any one of the plurality of power conversion devices; A generation unit that generates a signal instructing a change in an operation mode of the power conversion device to be controlled when instability of the power system is predicted, and transmits the signal to the power conversion device to be controlled. System operation planning control device.

2. The determination unit determines whether a system short circuit capacity during the actual operation is equal to or less than a threshold value related to system instability of the power system, and determines that system instability of the power system is predicted when a system short circuit capacity at the time of the operation plan differs from a system short circuit capacity during the actual operation and when the system short circuit capacity during the actual operation is equal to or less than the threshold value. The system operation planning control device according to claim 1 .

3. the determination unit determines to start up a system stabilization device to be controlled, which is any one of at least one system stabilization devices that corrects a system short circuit capacity of the connected power system, when system instability of the power system is predicted; The system operation planning control device according to claim 1 .

4. The power system stabilization device to be controlled is at least one of a synchronous generator and a synchronous phase modifier. The system operation planning control device according to claim 3.

5. The power conversion device to be controlled is a power conversion device having a grid tracking type control function. The system operation planning control device according to claim 1 .

6. The power electronics device to be controlled is a power electronics device having a system-forming control function, The change in the operation mode of the power conversion device to be controlled is a change in control from the grid tracking type to the grid forming type. The system operation planning control device according to claim 5.

7. a planning unit that, when system instability of the power system is predicted, secures a first system short-circuit capacity that is a part of the system short-circuit capacity to be reinforced at the time of the operation plan by changing the operation mode of any one of the plurality of power conversion devices, and secures a second system short-circuit capacity that is the remaining system short-circuit capacity to be reinforced at the time of the operation plan by activating any one of at least one system stabilization devices that corrects the system short-circuit capacity of the connected power system; The system operation planning control device according to any one of claims 1 to 6.

8. The planning unit determines the allocation of the first system short-circuit capacity and the second system short-circuit capacity based on economic rationality. The system operation planning control device according to claim 7.

9. A planning unit that calculates a system short circuit capacity of each of a plurality of points in the power system at the time of the operation planning, The system operation planning control device according to any one of claims 1 to 6.

10. A planning unit that sets a system short circuit capacity at the time of the operation plan for each of a plurality of points in the power system at the time of the operation plan, The system operation planning control device according to any one of claims 1 to 6.

11. A planning unit that determines, at the time of the operation plan, an improvement effect of a system short circuit capacity of the power system in the change of the operation mode in which control of any one of the plurality of power conversion devices is changed from a system tracking type to a system forming type. The system operation planning control device according to any one of claims 1 to 6.

12. The planning unit further determines, at the time of the operation planning, an improvement effect of the system short circuit capacity in a case where activation of any one of at least one system stabilization device that corrects a system short circuit capacity of the connected power system is used in combination. The system operation planning control device according to claim 11.

13. The planning unit further determines economic rationality of using any one of the at least one power system stabilization devices in combination at the time of the operation planning. The system operation planning control device according to claim 12.

14. A planning unit that calculates a system short circuit capacity of each of a plurality of points in the power system at the time of the operation plan, and changes the operation mode of a power conversion device that is connected to the power system at a target point among the plurality of points where the system short circuit capacity at the time of the operation plan is equal to or less than a threshold value related to system instability of the power system, at the time of the operation plan, among the plurality of points. The system operation planning control device according to any one of claims 1 to 6.

15. The planning unit calculates a system short-circuit capacity to be reinforced at the target point when there is no power conversion device connected to the power grid at the target point, A planning unit that changes the operation mode of a power conversion device that is one of the plurality of power conversion devices and has a shortest electrical distance from the target point and can compensate for the grid short-circuit capacity to be reinforced, during the operation plan. The system operation planning control device according to claim 14.

16. A system short circuit capacity at the time of operation planning for a power system to which a plurality of power conversion devices are connected is compared with a system short circuit capacity at the time of actual operation; When a system short circuit capacity at the time of the operation plan differs from a system short circuit capacity during the actual operation, it is determined whether the system short circuit capacity during the actual operation is equal to or less than a threshold value related to system instability of the power system, and when the system short circuit capacity during the actual operation is equal to or less than the threshold value, it is determined to change an operation mode of a power conversion device to be controlled, which is any one of the plurality of power conversion devices; When the system short-circuit capacity during the actual operation is equal to or less than the threshold value, a signal is generated to instruct a change in an operation mode of a power conversion device to be controlled, which is one of the plurality of power conversion devices, and the signal is transmitted to the power conversion device to be controlled. System operation planning and control method.

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