Power grid stabilization system, computer program for power grid stabilization system, and power grid stabilization method

Abstract

To provide a power system stabilization system, a computer program for a power system stabilization system, and a power system stabilization method, for avoiding excessive power control during an N-4 accident.SOLUTION: In a central processing unit 1 configured to acquire system information at a constant cycle and to determine a power control target for each assumed accident, an N-2 accident countermeasure determination unit 110 includes: an N-2 stability calculation unit 112 configured to calculate stability of a power system P in each of a plurality of N-2 assumed accidents and to determine a power control target for each N-2 assumed accident; and an N-2 control table creation unit 113 configured to create an N-2 control table by associating the power control target for each N-2 assumed accident with the N-2 assumed accident. An N-4 accident countermeasure determination unit 120 includes an N-4 stability calculation unit 122 configured to calculate stability of the power system P in an N-4 assumed accident and to determines a power control target for each N-4 assumed accident. The N-4 stability calculation unit 122 inherits contents of the N-2 control table created by the N-2 control table creation unit 113 and to perform stability calculation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present embodiment relates to a power system stabilization system, a computer program for the power system stabilization system, and a power system stabilization method for maintaining the stability of the power system and stably supplying power even when an accident occurs in the power system.

Background Art

[0002] In a power system, many generators operate in synchronization with each other to supply power. When a severe accident occurs in the power system, these generators may no longer be able to maintain synchronous operation and may fall out of step. If the out-of-step condition of some generators is left unaddressed, other generators will also fall out of step in a chain reaction, making it impossible to maintain the stability of the power system. As a result, a large-scale power outage, i.e., a blackout, may be caused. A power system stabilization system that performs control to stably supply power even when an accident occurs in the power system is known. The power system stabilization system performs power supply restriction (hereinafter referred to as power restriction) that disconnects some generators in the power system from the grid, thereby preventing the remaining other generators from falling out of step and maintaining the stable operation of the power system.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0004] Conventional power system stabilization systems are often designed to withstand accident scenarios up to N-2 accidents, which are accidents involving the simultaneous loss of two facilities in the power system caused by, for example, failure of two transmission lines.

[0005] However, in recent years, there has been a need to strengthen the resilience of power systems in order to maintain their operation even when various natural disasters occur, and measures to deal with more severe accidents are necessary. For example, in a power system, it is possible that three or more pieces of equipment within the power system may be lost simultaneously, resulting in the failure of three or more transmission lines. Power system stabilization systems are now required to respond to accidents such as N-4 accidents, which involve the simultaneous loss of four pieces of equipment within the power system, for example, caused by the failure of four transmission lines. However, with conventional power system stabilization systems, depending on the calculated power control content for N-4 accident countermeasures, there was a risk of over-controlling and being unable to stabilize the system.

[0006] This embodiment aims to solve the above-mentioned problems and to provide a power grid stabilization system, a computer program for the power grid stabilization system, and a power grid stabilization method that enable the avoidance of excessive power control during an N-4 accident. [Means for solving the problem]

[0007] The power grid stabilization system of the embodiment is a power grid stabilization system that includes a central processing unit that acquires grid information from the power grid at regular intervals and determines the target of power control for each assumed fault, and comprises the following configuration. (1) The central processing unit includes an N-2 accident response determination unit and an N-4 accident response determination unit. (2) The N-2 accident countermeasure determination unit includes an N-2 stability calculation unit that calculates the stability of the power system in each of the multiple assumed N-2 accidents and determines the power control target for each assumed N-2 accident, and an N-2 control table creation unit that creates an N-2 control table by associating the power control target for each assumed N-2 accident determined by the N-2 stability calculation unit with the assumed N-2 accident. (3) The N-4 accident countermeasure determination unit includes an N-4 stability calculation unit that calculates the stability of the power system in the N-4 assumed accident and determines the power control target for each N-4 assumed accident. (4) The N-4 stability calculation unit takes over the contents of the N-2 control table created by the N-2 control table creation unit and performs the stability calculation. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall diagram illustrating the configuration of the power grid stabilization system according to the first embodiment. [Figure 2] A flowchart showing the operation of the power grid stabilization system according to the first embodiment. [Figure 3] This is an overall diagram illustrating the configuration of the power grid stabilization system according to the second embodiment. [Figure 4] This is a conceptual diagram illustrating the interval between two hypothetical N-2 accidents. [Figure 5] This is a conceptual diagram illustrating the sequence of events for two hypothetical N-2 accidents. [Figure 6] A flowchart showing the operation of the power grid stabilization system according to the second embodiment. [Figure 7] This is an overall diagram illustrating the configuration of the power grid stabilization system according to the third embodiment. [Figure 8] This is a conceptual diagram illustrating the calculation cycles for N-2 and N-4 accident countermeasures. [Figure 9] A flowchart showing the operation of the power grid stabilization system according to the third embodiment. [Figure 10] This is an overall diagram illustrating the configuration of the power grid stabilization system according to the fourth embodiment. [Figure 11] A flowchart showing the operation of the power grid stabilization system according to the fourth embodiment. [Modes for carrying out the invention]

[0009] [1. First Embodiment] [1-1. Overall Structure] Hereinafter, the first embodiment will be specifically described with reference to the drawings. In the following description, when there are a plurality of apparatuses or members having the same configuration, they are described with the same reference numerals. In addition, a plurality of identical constituent elements are distinguished by adding suffixes such as "1" and "2" to the end of a common reference numeral via a "-" (hyphen). When a plurality of identical constituent elements are not distinguished from each other, only the common reference numeral is shown, and the suffix is omitted.

[0010] Figure 1 is a schematic diagram showing an example of the configuration of a power system stabilization system S according to the first embodiment. The power system stabilization system S is configured to include, for example, a central processing unit 1, a central control device 2, a fault detection terminal device 3, and a control terminal device 4. The power system stabilization system S is connected to a power system P and a power supply information network N.

[0011] As described above, "power control" means power supply restriction for disconnecting some generators from the power system P. In addition, the term "power control amount" refers to the output power of the generator to be power-controlled. Note that the "power control amount" may be referred to as a "control amount".

[0012] The central processing unit 1, the central control device 2, the fault detection terminal device 3, and the control terminal device 4 are realized, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software).

[0013] Some or all of these components may be realized by hardware (including a circuit unit: circuitry) such as an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by cooperation of software and hardware.

[0014] (Power System) The power system P is a power supply network including a series of power facilities that generate electric power and supply the generated electric power to load facilities of consumers. The power system P is composed of a plurality of power devices that perform power generation and transmission. The power devices are constituted by, for example, power facilities (also referred to as system facilities) such as generators, buses, transformers, power transmission lines, phase adjusting equipment, circuit breakers, and disconnectors. The detailed configuration of the power system P is not illustrated.

[0015] The generator is a facility that generates electric power using hydraulic power, thermal power, nuclear power or the like. The generator may be a renewable energy power source that generates electric power using renewable energy such as wind power or solar power. A plurality of generators are arranged in the power system P. The generator is the subject of power control in order to stabilize unstable phenomena that occur when an assumed accident occurs in the power system P.

[0016] The circuit breaker is a device that interrupts the flow of electric power generated by the generator that is transmitted through the power transmission line, the transformer, and the bus. When power control is performed in the power system stabilization system S, the generator is disconnected from the power system P by controlling the circuit breaker. The circuit breaker is controlled by the central control device 2 via the control terminal device 4.

[0017] (Power Supply Information Network) The power supply information network N is a communication network configured to enable communication between the power system P and the central processing unit 1. The power supply information network N performs communication by wire or wireless. The power supply information network N includes communication circuits and communication devices, and may be configured by, for example, a dedicated communication line using microwave radio, optical fiber, or the like.

[0018] Communication is performed between a measuring device (not shown) arranged in the power system P and the central processing unit 1 via the power supply information network N. The measuring device is configured to be able to measure the states of power facilities including generators, circuit breakers, disconnectors, buses, power transmission lines, and transformers. The measuring device is installed in a substation or a power plant. System information measured by the measuring device of each power facility included in the power system P is transmitted to the central processing unit 1 via the power supply information network N.

[0019] (Fault Detection Terminal Device) The fault detection terminal device 3 is a terminal device composed of digital relays, including a contact information input circuit, a voltage / current input circuit, an active power measurement circuit, and a transmission / reception circuit. The fault detection terminal device 3 is configured to acquire system information and fault information in the power system P and transmit it to the central control unit 2. Multiple fault detection terminal devices 3 are installed in substations and other locations where anticipated faults can be detected.

[0020] System information is information regarding the connection status and power supply and demand status of power system P detected by the fault detection terminal device 3. System information includes, for example, on / off information of power equipment in power system P and measurement information regarding power supply and demand status. On / off information refers to information regarding the open / closed status of circuit breakers, disconnectors, etc. Measurement information includes information regarding generator output, load, active and reactive power of transmission lines, and busbar voltage of each substation.

[0021] The fault detection terminal device 3 acquires on / off information from circuit breakers, disconnectors, etc., via a contact information input circuit. Furthermore, using the voltage and current information acquired via the voltage and current input circuit, the active power measurement circuit measures the power supply output, load, and active power of the transmission lines to create system information.

[0022] Accident information refers to information about accidents that have occurred in power equipment within the power system P. For example, it is information indicating the power equipment involved in an accident and the nature of the accident, such as when an accident occurs in a transmission line. The accident detection terminal device 3 creates accident information by receiving, for example, the operation signal of the accident removal relay and the on / off information of the circuit breaker through a contact information input circuit.

[0023] (Control terminal device) The control terminal device 4 is a terminal device composed of digital relays, including a contact information input circuit, a contact information output circuit, a voltage and current input circuit, an active power measurement circuit, and a transmitting and receiving circuit. Based on control commands received from the central control device 2, the control terminal device 4 controls the circuit breaker using the contact information output circuit, and is configured to disconnect the generator designated as the target of electric control from the power system P. Multiple control terminal devices 4 are installed in power plants and other facilities that have power sources to be controlled.

[0024] (Central control system) The central control unit 2 periodically acquires system information from the fault detection terminal device 3 and uses the latest state of the power system P to select a generator to be controlled and output a control command. The central control unit 2 is composed of digital relays equipped with transmitting and receiving circuits, etc. The central control unit 2 is connected to the central processing unit 1, the fault detection terminal device 3, and the control terminal device 4. When a simulated fault actually occurs, the central control unit 2 transmits a control command to the control terminal device 4 to shut off the generator to be controlled in the control table determined in advance by the central processing unit 1. The central control unit 2 is installed in substations of general power transmission and distribution companies.

[0025] (central processing unit) The central computing unit 1 is a computing device that periodically receives system information of the power system P via the power supply information network N and uses the latest state of the power system P to calculate and determine the power control target. The central computing unit 1 is installed in the central power dispatch center of a general power transmission and distribution company. The central computing unit 1 comprises an information transmission unit 101, a system model creation unit 102, a state estimation unit 103, an N-2 fault countermeasure determination unit 110, an N-4 fault countermeasure determination unit 120, and a control table downlink transmission unit 130.

[0026] The central computing unit 1 may include a memory unit (not shown) for storing various types of information. The memory unit stores various types of information necessary for the operation of the power system stabilization system S. The memory unit is composed of a storage medium such as semiconductor memory or a hard disk. The memory unit stores assumed fault conditions in the power system P, system information acquired via the power supply information network N, and data and calculation results created by each component of the central computing unit 1. The stored information is configured to be usable for calculations by each component of the central computing unit 1 and for output to the central control unit 2.

[0027] The information transmission unit 101 is a processing unit connected to the power supply information network N and which acquires system information at regular intervals. In the example in Figure 1, the information transmission unit 101 is shown as acquiring system information via the power supply information network N, but it can also be configured to acquire it from the power system P via a different communication network than the power supply information network N. The information transmission unit 101 transmits the received system information to the system model creation unit 102.

[0028] The system model creation unit 102 is a processing unit that creates a system model based on system information acquired by the information transmission unit 101 and various setting information stored in advance. Before an accident occurs, the system model creation unit 102 creates a system model representing the system state at that time based on the acquired system information and system equipment data stored in advance. The system model creation unit 102 transmits the created system model to the state estimation unit 103.

[0029] A system model is data that models a power system P. A system model may consist of nodes and branches. Nodes are data representations of busbars, generators, and loads, with a node number (identification information) associated with information such as electrical output, active and reactive power of loads, and busbar voltage. Branches are data representations of transmission lines and transformers, with a branch number (identification information) associated with the node number of the connected node (starting and ending node), the number of operational lines, impedance, etc.

[0030] The state estimation unit 103 is a calculation unit that estimates the system state. The state estimation unit 103 uses the system information acquired by the information transmission unit 101 to calculate the latest system state in the system model created by the system model creation unit 102. The state estimation unit 103 estimates the most likely system state, for example, using the weighted least squares method. The state estimation unit 103 transmits the calculated state estimation result to the N-2 accident countermeasure decision unit 110 and the N-4 accident countermeasure decision unit 120.

[0031] The N-2 accident countermeasure decision unit 110 is a processing unit that determines the target of electric control in an N-2 accident. The N-2 accident countermeasure decision unit 110 includes an N-2 assumed accident selection unit 111, an N-2 stability calculation unit 112, and an N-2 control table creation unit 113.

[0032] The N-2 assumed accident selection unit 111 is a processing unit that takes the state estimation calculation results calculated by the state estimation unit 103 as input data and determines the N-2 assumed accidents to be subject to stability calculation. The N-2 assumed accident selection unit 111 is configured to select two or more N-2 assumed accidents from a plurality of pre-set N-2 assumed accidents. The N-2 assumed accident selection unit 111 transmits the determined N-2 assumed accidents to the N-2 stability calculation unit 112.

[0033] Here, the N-2 assumed fault selection unit 111 is configured to select assumed faults for multiple routes of the power transmission network in the power system P. For example, the N-2 assumed fault selection unit 111 can select an N-2 assumed fault on route A and an N-2 assumed fault on route B, respectively.

[0034] The N-2 stability calculation unit 112 is a calculation unit that calculates the stability of the power system P in the event of an N-2 assumed fault. The N-2 stability calculation unit 112 is configured to calculate the stability for each of the multiple N-2 assumed faults determined by the N-2 assumed fault selection unit 111. For example, the N-2 stability calculation unit 112 calculates the stability for the N-2 assumed fault on route A and the N-2 assumed fault on route B.

[0035] Specifically, the N-2 stability calculation unit 112 uses the state estimation calculation results from the state estimation unit 103 as input data for the N-2 assumed fault received from the N-2 assumed fault selection unit 111, and performs stability calculations. The N-2 stability calculation unit 112 calculates one or more of the following stability values: transient stability, steady state stability, frequency stability, and voltage stability. Based on the calculated stability values, the N-2 stability calculation unit 112 evaluates whether the power system P can be operated stably.

[0036] The N-2 stability calculation unit 112 terminates the stability calculation if the stability evaluation result is stable. The N-2 stability calculation unit 112 determines the electrically controlled object selected in the stable calculation as the electrically controlled object for N-2 fault countermeasures and transmits it to the N-2 control table creation unit 113. On the other hand, if the stability evaluation result is unstable, the N-2 stability calculation unit 112 is configured to select an additional electrically controlled object and perform the N-2 stability calculation again. The N-2 stability calculation unit 112 performs the N-2 stability calculation while changing the electrically controlled object until the stability evaluation result becomes stable.

[0037] The N-2 control table creation unit 113 sets the targets for electric control of N-2 fault countermeasures, calculated by the N-2 stability calculation unit 112, into the N-2 control table. The N-2 control table creation unit 113 creates the N-2 control table by associating the identification information of the determined electric control targets with the assumed N-2 fault conditions.

[0038] Table 1 shows an example of a control table created by the N-2 control table creation unit 113. [Table 1]

[0039] In the example in Table 1, generators G1 and G2 are associated with electric control for a two-circuit fault on route A. Similarly, generators G1 and G3 are associated with electric control for a two-circuit fault on route B. The N-2 control table creation unit 113 transmits the created N-2 control table to the N-4 fault countermeasure decision unit 120 and the control table downlink transmission unit 130.

[0040] The N-4 accident countermeasure decision unit 120 is a processing unit that determines the target of electric control in an N-4 accident. The N-4 accident countermeasure decision unit 120 includes an N-4 assumed accident selection unit 121, an N-4 stability calculation unit 122, and an N-4 control table creation unit 123.

[0041] The N-4 assumed accident selection unit 121 is a processing unit that determines the N-4 assumed accident to be included in the stability calculation. The N-4 assumed accident selection unit 121 takes the state estimation calculation results calculated by the state estimation unit 103 as input data and determines the N-4 assumed accident based on the N-2 assumed accident selected by the N-2 assumed accident selection unit 111.

[0042] An N-4 accident occurs as a combination of N-2 accidents. Therefore, a hypothetical N-4 accident could be, for example, one of two N-2 accidents occurring, such as an accident on route A and an accident on route B. Thus, the N-4 hypothetical accident selection unit 121 is configured to select one N-4 hypothetical accident from a combination of N-2 hypothetical accidents selected by the N-2 hypothetical accident selection unit 111, from a plurality of pre-set N-4 hypothetical accidents. The N-4 hypothetical accident selection unit 121 transmits the determined N-4 hypothetical accident to the N-4 stability calculation unit 122.

[0043] The N-4 stability calculation unit 122 is a calculation unit that calculates the stability of the power system P in the case of an N-4 assumed fault. The N-4 stability calculation unit 122 performs stability calculations for the N-4 assumed fault received from the N-4 assumed fault selection unit 121. At this time, in addition to the state estimation calculation results of the state estimation unit 103, the N-4 stability calculation unit 122 uses the contents of the N-2 control table created by the N-2 control table creation unit 113 as the N-2 fault countermeasure result in its calculations.

[0044] In other words, the N-2 control table creation unit 113 refers to the N-2 control table it has created and pre-sets the targets for electric control of N-2 fault countermeasures in routes A and B of the N-2 control table as targets for electric control of N-4 fault countermeasures. Then, it performs a stability calculation for the assumed N-4 fault. As a result, the N-4 stability calculation unit 122 does not start the stability calculation from a state where electric control is not being performed, but rather starts the stability calculation from a state where the targets for electric control of N-2 fault countermeasures are being controlled. For example, if the contents of the N-2 control table in Table 1 above are inherited, the N-4 stability calculation unit 122 will start the stability calculation from a state where generators G1, G2, and G3 are controlled.

[0045] The N-4 stability calculation unit 122 calculates one or more of the following stability parameters: transient stability, steady-state stability, frequency stability, and voltage stability. Based on the calculated stability parameters, the N-4 stability calculation unit 122 evaluates whether the power system P can be operated stably.

[0046] The N-4 stability calculation unit 122 terminates the stability calculation if the stability evaluation result is stable. The N-4 stability calculation unit 122 determines the electrically controlled object selected in the stable calculation as the electrically controlled object for N-4 fault countermeasures and transmits it to the N-4 control table creation unit 123. On the other hand, if the stability evaluation result is unstable, the N-4 stability calculation unit 122 is configured to select an additional electrically controlled object and perform the N4 stability calculation again. The N-4 stability calculation unit 122 performs the N-4 stability calculation while changing the electrically controlled object until the stability evaluation result becomes stable.

[0047] The N-4 control table creation unit 123 sets the electronically controlled targets for N-4 fault countermeasures, calculated by the N-4 stability calculation unit 122, into the N-4 control table. The N-4 control table creation unit 123 creates the N-4 control table by associating the identification information of the determined electronically controlled targets with the N-4 assumed fault conditions.

[0048] Table 2 shows an example of an N-4 control table created by the N-4 control table creation unit 123. The control table in Table 2 is the N-4 control table obtained by performing stability calculations, taking over from the N-2 control table in Table 1 above. [Table 2]

[0049] Table 2's example assumes a case where an N-4 fault occurs due to a combination of a double-circuit fault in Route A and a double-circuit fault in Route B. In this example, as described in Table 1, it is assumed that generators G1 and G2 are electrically controlled when a double-circuit fault occurs in Route A, and generators G1 and G3 are electrically controlled when a double-circuit fault occurs in Route B. In the case of an N-4 fault (Route A fault + Route B fault), the stability calculation is performed with the generators in Route A and Route B under electric control.

[0050] Referring to Table 2, it can be seen that, after performing a stability calculation based on the contents of Table 1, the power system P became unstable, and after additional power control was applied to G4 and the stability calculation was performed again, it became stable. In other words, Table 2 shows an example where stability is achieved by implementing N-2 fault countermeasures for both routes A and B, and then applying additional power control. Therefore, in Table 2, generators G1, G2, G3, and G4 are associated with being the targets of power control for the assumed N-4 fault. The N-4 control table creation unit 123 transmits the created N-4 control table to the control table downlink transmission unit 130.

[0051] The control table downlink transmission unit 130 is a transmission unit that transmits the control table to the central control device 2. The control table downlink transmission unit 130 transmits to the central control device 2 the N-2 control table created by the N-2 control table creation unit 113 and the N-4 control table created by the N-4 control table creation unit 123, respectively.

[0052] [1-2. Operation of the First Embodiment] The procedure for determining the target of power control in this embodiment will be described with reference to Figure 2. Figure 2 is a flowchart showing the process for determining the target of power control by the power system stabilization system S of this embodiment. Figure 2 is a diagram showing the program flow when the central processing unit 1 is configured with software modules. The program is built into the central processing unit 1. In the following description, the flow related to determining the target of power control will be described in detail, and the actual details of the fault and the tripping of the target of power control will be omitted.

[0053] The information transmission unit 101 of the central processing unit 1 receives system information from the power supply information network N at regular intervals (step S01) and transmits it to the system model creation unit 102. The system model creation unit 102 creates a system model based on the system information acquired by the information transmission unit 101 and various pre-stored setting information (step S02). The state estimation unit 103 uses the system information acquired by the information transmission unit 101 to calculate the latest system state in the system model created by the system model creation unit 102 (step S03).

[0054] The N-2 assumed accident selection unit 111 takes the state estimation calculation results calculated by the state estimation unit 103 as input data and determines the N-2 assumed accidents to be subject to stability calculation (step S04). For example, the N-2 assumed accident selection unit 111 selects the N-2 assumed accidents for route A and the N-2 assumed accidents for route B, respectively.

[0055] The N-2 stability calculation unit 112 calculates the stability of the N-2 assumed accident on Route A determined by the N-2 assumed accident selection unit 111 (step S05a). If the stability evaluation result is stable, the N-2 stability calculation unit 112 terminates the stability calculation (step S06a, YES).

[0056] On the other hand, if the N-2 stability calculation unit 112 determines that the stability evaluation result is unstable (step S06a, NO), it selects an additional electronically controlled object (step S07a). After selecting the additional electronically controlled object, the N-2 stability calculation unit 112 returns to step S05a and performs the N-2 stability calculation again. In step S06a, the N-2 stability calculation unit 112 repeats steps S05a to S07a until the stability calculation result becomes stable.

[0057] Similarly, the N-2 stability calculation unit 112 calculates the stability for the N-2 assumed accident on Route B determined by the N-2 assumed accident selection unit 111 (step S05b). If the stability evaluation result is stable, the N-2 stability calculation unit 112 terminates the stability calculation (step S06b, YES).

[0058] On the other hand, if the N-2 stability calculation unit 112 determines that the stability evaluation result is unstable (step S06b, NO), it selects an additional electronically controlled object (step S07b). After selecting the additional electronically controlled object, the N-2 stability calculation unit 112 returns to step S05b and performs the N-2 stability calculation again. In step S06b, the N-2 stability calculation unit 112 repeats steps S05b to S07b until the stability calculation result becomes stable.

[0059] The N-2 control table creation unit 113 sets the targets for electric control of N-2 fault countermeasures, calculated by the N-2 stability calculation unit 112, into the N-2 control table (step S08). The N-2 control table is then passed on to the N-4 stability calculation unit 122 and the control table downlink transmission unit 130.

[0060] The N-4 assumed accident selection unit 121 determines the N-4 assumed accident to be included in the stability calculation based on the N-2 assumed accident selected by the N-2 assumed accident selection unit 111 (step S09). For example, the N-4 assumed accident selection unit 121 selects the simultaneous occurrence of accidents on route A and route B as the N-4 assumed accident.

[0061] The N-4 stability calculation unit 122 sets the N-2 control table created by the N-2 control table creation unit 113 as the N-2 fault countermeasure (step S10). For example, if the N-2 control table in Table 1 above is input, the N-4 stability calculation unit 122 sets the already determined generators G1, G2, and G3 that are subject to electric control as the N-2 fault countermeasure.

[0062] Then, the N-4 assumed accident selection unit 121 calculates the stability of the N-4 assumed accident it has determined (step S11). The N-4 stability calculation unit 122 terminates the stability calculation if the stability evaluation result is stable (step S12, YES).

[0063] On the other hand, if the N-4 stability calculation unit 122 finds that the stability evaluation result is unstable (step S12, NO), it selects an additional electrically controlled object (step S13). For example, if the stability calculation is performed after electrically controlling generators G1, G2, and G3, which are electrically controlled objects for N-2 fault countermeasures, and the result is unstable, it selects to additionally electrically control generator G4. After selecting an additional electrically controlled object, the N-4 stability calculation unit 122 returns to step S11 and performs the N-4 stability calculation again. In step S12, the N-4 stability calculation unit 122 repeats steps S11 to S13 until the stability calculation result becomes stable.

[0064] The N-4 control table creation unit 123 sets the targets for electric control of N-4 fault countermeasures calculated by the N-4 stability calculation unit 122 into the N-4 control table (step S14). The N-4 control table is then passed on to the control table downlink transmission unit 130.

[0065] [1-3. Effects of the First Embodiment] (1) The power system stabilization system S of this embodiment is a power system stabilization system S that includes a central processing unit 1 that acquires system information from the power system P at a fixed period and determines the target of power control for each assumed fault, the central processing unit 1 includes an N-2 fault countermeasure determination unit 110 and an N-4 fault countermeasure determination unit 120, the N-2 fault countermeasure determination unit 110 includes an N-2 stability calculation unit 112 that calculates the stability of the power system P in a plurality of assumed N-2 faults and determines the target of power control for each assumed N-2 fault, and the N-2 stability The N-4 accident countermeasure determination unit 120 includes an N-2 control table creation unit 113 that creates an N-2 control table by associating the electric control targets for each N-2 assumed accident determined by the degree calculation unit 112 with the N-2 assumed accident, and an N-4 stability calculation unit 122 that calculates the stability of the power system P in an N-4 assumed accident and determines the electric control targets for each N-4 assumed accident, and the N-4 stability calculation unit 122 takes over the contents of the N-2 control table created by the N-2 control table creation unit 113 and performs the stability calculation.

[0066] Conventional power grid stabilization systems lacked the functionality to determine which systems would be subject to electric control in the event of an N-4 fault. Furthermore, when using existing power grid stabilization systems to determine which systems would be subject to electric control in the event of an N-4 fault, the electric control measures for N-2 and N-4 faults would be calculated independently.

[0067] For example, if the electric control targets for N-2 fault countermeasures and N-4 fault countermeasures are calculated using a conventional power grid stabilization system, the control contents shown in Tables 3 and 4 below will be determined. [Table 3] [Table 4]

[0068] The contents of Table 3, which shows the targets of electric control for the N-2 assumed fault, are the same as those in Table 1 above. That is, in the example in Table 3, generators G1 and G2 are associated with electric control for a two-circuit fault on Route A. Also, generators G1 and G3 are associated with electric control for a two-circuit fault on Route B.

[0069] In the example in Table 4 showing the targets of electrical control for the N-4 assumed fault, similar to the example in Table 2 above, the case is assumed where the N-4 fault occurs due to a combination of a two-circuit fault on route A and a two-circuit fault on route B. However, in conventional power grid stabilization systems, the targets of electrical control for the N-4 assumed fault are calculated independently. Therefore, in Table 4, generators G4, G5, and G6 are associated with the targets of electrical control for the N-4 assumed fault.

[0070] In conventional power grid stabilization systems as described above, if an N-4 fault occurs due to a combination of two faults in route A and two faults in route B, G1 and G2 are controlled by the two faults in route A, and G1 and G3 are controlled by the two faults in route B. Furthermore, as targets for electric control in the N-4 fault, G4, G5, and G6, which are not included in the targets for electric control in the N-2 fault, are also controlled. In other words, conventional power grid stabilization systems cause excessive electric control, resulting in generators G1, G2, G3, G4, G5, and G6 being electrically controlled.

[0071] On the other hand, in the power system stabilization system S of this embodiment, the N-4 fault countermeasure decision unit 120 includes an N-4 stability calculation unit 122 that calculates the stability of the power system P in the event of an N-4 assumed fault and determines the electric control targets for each N-4 assumed fault. The N-4 stability calculation unit 122 takes over the contents of the N-2 control table created by the N-2 control table creation unit 113 and performs the stability calculation. In other words, the N-4 fault countermeasure decision unit 120 is configured to perform the stability calculation taking into account the electric control contents in the event of an N-2 assumed fault.

[0072] As explained above, the N-4 stability calculation unit 122 sets the N-2 control table created by the N-2 control table creation unit 113 as the result of the N-2 fault countermeasure before starting the stability calculation. Therefore, the electric control content for the N-2 fault countermeasure and the N-4 fault countermeasure are not calculated independently. In such a power system stabilization system S, as shown in Table 2 above, generators G1, G2, G3, and G4 are determined as targets for electric control in the case of the assumed N-4 fault. In other words, by inheriting the electric control results for the N-2 fault countermeasure and determining the targets for electric control in the N-4 fault, it is possible to avoid excessive electric control during the N-4 fault.

[0073] (2) The N-4 accident countermeasure decision unit 120 further includes an N-4 assumed accident selection unit 121 that determines an N-4 assumed accident from a combination of two N-2 assumed accidents.

[0074] In the power grid stabilization system S of this embodiment, the N-4 assumed fault is treated as a combination of two N-2 assumed faults. Therefore, it is possible to inherit the electric control results of the N-2 fault countermeasures and determine the target of electric control for the N-4 fault, thereby making it possible to avoid excessive electric control during the N-4 fault.

[0075] (3) The N-4 stability calculation unit 122 calculates the stability of the N-4 assumed fault based on the state in which the electrically controlled objects for the two N-2 assumed faults in the N-2 control table are controlled. If the power system is found to be unstable as a result of this calculation, the unit adds an electrically controlled object to the two N-2 assumed faults and performs the stability calculation again.

[0076] The N-4 stability calculation unit 122 determines the targets for electric control in the N-4 assumed fault by applying additional electric control to the targets for electric control in the N-2 assumed fault. This prevents excessive electric control during the N-4 fault. Furthermore, since the calculation starts from a state where the electric control targets for the N-2 assumed fault are controlled, the amount of computation can be reduced compared to the case where the electric control targets for the N-4 assumed fault are determined independently. In such a power system stabilization system S, it is possible to avoid prolonged calculations and system complexity.

[0077] [2. Second Embodiment] [2-1. Overall Structure] The power system stabilization system S according to the second embodiment will be described with reference to Figures 3 and 4. The power system stabilization system S of this embodiment is basically the same as the power system stabilization system S of the first embodiment. However, in the power system stabilization system S of this embodiment, the N-4 assumed fault selection unit 121 further includes a fault interval setting unit 121a and a fault sequence setting unit 121b. In addition, the N-4 stability calculation unit 122 further includes a control amount determination unit 122a.

[0078] The accident interval setting unit 121a is a processing unit that sets the interval between two N-2 assumed accidents in an N-4 assumed accident determined by the N-4 assumed accident selection unit 121. The interval between two N-2 assumed accidents will be explained with reference to Figure 4. As shown in Figure 4, in the case of an N-4 assumed accident, for example, the interval between an A-route accident and a B-route accident can range from the typical order of nmsec to, in some cases, tens to hundreds of msec.

[0079] To account for cases where the intervals between two assumed N-2 accidents are different, the accident interval setting unit 121a sets the intervals between the two assumed N-2 accidents. The accident interval setting unit 121a may also be configured to set the intervals between the two assumed N-2 accidents using a preset time interval. Alternatively, the intervals between the two assumed N-2 accidents can be set using values ​​entered by an operator via an input unit (not shown), etc.

[0080] The accident sequence setting unit 121b is a processing unit that sets the occurrence order of two N-2 assumed accidents in the N-4 assumed accident determined by the N-4 assumed accident selection unit 121. To account for cases where the occurrence order of the two N-2 assumed accidents is different, the accident sequence setting unit 121b sets the occurrence order of the two N-2 assumed accidents. For example, as shown in Figure 5, it may be a case where the A route accident occurs first, or a case where the B route accident occurs first.

[0081] As described above, the power system stabilization system S of this embodiment is configured such that the fault interval setting unit 121a and the fault sequence setting unit 121b change the fault conditions in a single N-4 assumed fault, and the N-4 stability calculation unit 122 performs stability calculations for N-4 assumed faults under multiple fault conditions. The embodiments of changing the fault conditions include changing the fault interval, changing the fault sequence, and changing both the fault interval and the fault sequence.

[0082] The control amount determination unit 122a is a processing unit that compares and determines the control amount for the results of stability calculations for multiple N-4 assumed faults. The control amount refers to the amount of generators that are subject to electric control. For example, the control amount determination unit 122a compares the results of stability calculations for two fault conditions, determines the electric control target for the fault condition with the larger control amount as the electric control target for N-4 fault countermeasures, and transmits this to the N-4 control table creation unit 123.

[0083] [2-2. Operation of the Second Embodiment] The procedure for determining the target of electric control in this embodiment will be described with reference to Figure 6. Figure 6 is a flowchart showing the process for evaluating the effectiveness ranking of stabilization control candidates. In the following description, the flow for determining the target of electric control in the N-4 accident countermeasure determination unit 120 will be described in detail. Steps up to S08 are the same as in the above embodiment, so the explanation will be omitted.

[0084] The N-4 assumed accident selection unit 121 determines the N-4 assumed accidents to be included in the stability calculation based on the N-2 assumed accidents selected by the N-2 assumed accident selection unit 111 (step S09). In the example in Figure 6, when determining the N-4 assumed accidents, the accident sequence setting unit 121b sets two accident conditions for each N-4 assumed accident: one in which the A route accident occurs first, and another in which the B route accident occurs first.

[0085] Therefore, in steps S10a to S13a, the N-4 stability calculation unit 122 performs stability calculations under accident conditions where the A-route accident occurs first. Also, in steps S10b to S13b, the N-4 stability calculation unit 122 performs stability calculations under accident conditions where the B-route accident occurs first. The specific calculation flow is the same as steps S10 to S13 of the above embodiment.

[0086] Once the stability calculation using the accident conditions in which the A-route accident occurs first and the accident conditions in which the B-route accident occurs first is completed, the control amount determination unit 122a compares the control amounts, which are the results of the stability calculation under the two accident conditions (step S15). The control amount determination unit 122a determines that the electric control target for the accident condition with the larger control amount is the electric control target for the N-4 accident countermeasure and transmits this to the N-4 control table creation unit 123.

[0087] The N-4 control table creation unit 123 sets the N-4 fault countermeasure targets for which the control amount is determined to be large by the control amount determination unit 122a into the N-4 control table (step S16). The N-4 control table is then passed on to the control table downlink transmission unit 130.

[0088] [2-3. Effects of the Second Embodiment] (1) The N-4 assumed accident selection unit 121 includes an accident interval setting unit 121a that sets the interval between two N-2 assumed accidents, and the N-4 stability calculation unit 122 includes a control amount determination unit 122a that compares and determines the control amounts of multiple stability calculation results, and the control amount determination unit 122a determines the electric control target for the accident condition with a large control amount from multiple stability calculation results calculated using multiple accident conditions in which the interval between two N-2 assumed accidents is changed, as the electric control target for N-4 accident countermeasures.

[0089] In an N-4 accident, two N-2 accidents do not necessarily occur simultaneously. The accident interval setting unit 121a makes it possible to perform stability calculations that take into account changes in the interval between the occurrence of two N-2 accidents. If the severity of stability differs due to changes in the accident interval, the control amount of the electrically controlled object required for stabilization may change. Therefore, by performing stability calculations under multiple accident conditions, it is possible to identify accident conditions that require more control. Furthermore, by determining the electrically controlled object for accident conditions with a large control amount using the control amount determination unit 122a, it is possible to prevent excessive electric control while suppressing insufficient electric control that occurs when assuming the simultaneous occurrence of A-route and B-route accidents. Therefore, it is possible to determine the electric controlled object for N-4 accident countermeasures that is more appropriate.

[0090] (2) The N-4 assumed accident selection unit 121 includes an accident sequence setting unit 121b that sets the occurrence order of two N-2 assumed accidents, and the N-4 stability calculation unit 122 includes a control amount determination unit 122a that compares and determines the control amounts of multiple stability calculation results, and the control amount determination unit 122a determines the electric control target for the accident condition with a large control amount from multiple stability calculation results calculated using multiple accident conditions in which the occurrence order of the two N-2 assumed accidents is changed, and identifies the electric control target for the N-4 accident countermeasure as the electric control target for the accident condition with a large control amount.

[0091] Similar to the fault interval, the fault sequence setting unit 121b enables stability calculations that take into account changes in the occurrence order of the two N-2 faults. If the severity of stability differs due to changes in the occurrence order, the control amount of the electrically controlled object required for stabilization may change. Therefore, by performing stability calculations under multiple fault conditions, it is possible to identify fault conditions that require more control. Furthermore, by determining the electrically controlled object for fault conditions with a large control amount using the control amount determination unit 122a, it is possible to prevent excessive electric control while suppressing insufficient electric control that occurs when assuming the simultaneous occurrence of A-route and B-route faults. Therefore, it is possible to determine the electric controlled object for N-4 fault countermeasures that is more appropriate.

[0092] [3. Variant] In the modified power system stabilization system S of the first embodiment, as in the first embodiment, the N-4 assumed fault selection unit 121 selects a case with a severe fault profile from the N-2 assumed fault selection unit 111 and determines the N-4 assumed fault. A severe fault profile means a fault profile with a large control amount, as determined by the N-2 fault countermeasure determination unit 110.

[0093] For example, in an N-2 fault, a high-speed reclosing failure may lead to a more severe fault. In this embodiment, when selecting an N-4 assumed fault, for example, a case in which the fault pattern is severe due to high-speed reclosing failures in the A and B routes of the N-2 assumed fault is selected and designated as an N-4 assumed fault. Then, when the N-4 stability calculation unit 122 performs the stability calculation for the N-4 assumed fault, it selects the fault case with the largest control amount (such as an H-Rec failure) from the respective N-2 control tables for the A and B routes, and performs the calculation from the state in which the electrically controlled object is under control.

[0094] In this way, by taking the accident pattern with the largest control amount for each assumed N-2 accident from the N-2 control table and performing calculations for N-4 accident countermeasures, it is possible to target severe accident cases and prevent under-control.

[0095] [4. Third Embodiment] Referring to Figures 7 and 8, the power system stabilization system S according to the third embodiment will be described. The power system stabilization system S of this embodiment is basically the same as the power system stabilization system S of the first embodiment. However, in the power system stabilization system S of this embodiment, the N-2 fault countermeasure determination unit 110 and the N-4 fault countermeasure determination unit 120 are configured to calculate fault countermeasures in parallel. That is, as shown in Figure 7, the storage unit of the central processing unit 1 has an N-2 power control content database D1. The N-2 power control content database D1 stores the N-2 control table.

[0096] As shown in Figure 8, the N-2 fault countermeasure decision unit 110 uses the system information for the current cycle to determine the target of electric control for the N-2 fault. The N-4 fault countermeasure decision unit 120 inherits the contents of the N-2 fault countermeasure for the entire cycle and determines the target of electric control for the N-4 fault, and is configured to perform calculations simultaneously with the N-2 fault countermeasure decision unit 110.

[0097] As shown in the flowchart of Figure 9, similar to the embodiment described above, the N-2 fault countermeasure determination unit 110 is configured to calculate the target of the N-2 fault countermeasure electric control using the system information of the current cycle acquired by the information transmission unit 101 (steps S04 to S08). Then, in step S20, the N-2 control table created by the N-2 control table creation unit 113 is configured to be stored in the N-2 electric control content database D1 held by the storage unit.

[0098] Furthermore, in step S021, the N-4 accident countermeasure determination unit 120 retrieves the N-2 control table from the N-2 electric control content database D1 for the previous cycle. Then, similar to the embodiment described above, the N-4 stability calculation unit 122, in addition to the state estimation calculation results of the state estimation unit 103, pre-sets the electric control targets for N-2 accident countermeasures from the retrieved N-2 control table for the previous cycle as the electric control targets for N-4 accident countermeasures. After that, it performs a stability calculation for the assumed N-4 accident and creates an N-4 control table (steps S09 to S14).

[0099] As described above, the power system stabilization system of this embodiment further includes an N-2 control table creation unit 113 and an N-2 control content database D1 for storing the N-2 control table created by the N-2 control table creation unit 113, and the N-4 fault countermeasure determination unit 120 is configured to take the N-2 control table from the previous cycle from the N-2 control content database D1 and perform stability calculations.

[0100] In the N-4 fault countermeasure, by inheriting the electronic control settings from the previous cycle's N-2 fault countermeasure, it becomes possible to calculate the N-2 and N-4 fault countermeasures in parallel. This allows for a shorter calculation period compared to calculating the N-4 fault countermeasure by inheriting the electronic control settings from the current cycle's N-2 fault countermeasure. Furthermore, although the results from the previous cycle are inherited, stabilization measures are implemented using the current cycle's system information, thus preventing insufficient control.

[0101] [5. Fourth Embodiment] Referring to Figure 10, the power system stabilization system S according to the fourth embodiment will be described. The power system stabilization system S of this embodiment is basically the same as the configuration of the power system stabilization system S according to the third embodiment. However, the power system stabilization system S of this embodiment further includes a flow for selecting the N-2 control table to be used in the event of an N-4 fault. As shown in Figure 10, the power system stabilization system S of this embodiment further includes an electric control content determination unit 140.

[0102] The electric control content determination unit 140 is a processing unit that compares the control amount of the N-2 control table for the current cycle with the N-2 control table for the previous cycle and determines the N-2 control table with the larger control amount as the electric control content. Although the electric control content determination unit 140 is shown as an independent component in Figure 10, it can also be considered as part of the N-2 accident countermeasure determination unit 110 or as part of the N-4 accident countermeasure determination unit.

[0103] As shown in the flowchart in Figure 11, the control content determination unit 140 retrieves the N-2 control table for the current period and the N-2 control table for the previous period, which are stored in the N-2 control content database D1 (step S30). Then, in step S31, it compares the control amounts of the N-2 control table for the current period and the N-2 control table for the previous period. If the control content determination unit 140 determines that the control amount of the N-2 control table for the current period is larger (step S31 YES), then, as in the third embodiment, the process proceeds to step S20, where the N-4 fault countermeasure determination unit 120 retrieves the N-2 control table for the previous period from the N-2 control content database D1 and is configured to perform a stability calculation.

[0104] On the other hand, if the control content determination unit 140 determines that the control amount is greater in the previous cycle's N-2 control table (step S31 NO), it proceeds to step S32, takes in the current cycle's N-2 control table, and performs the stability calculation again from step S09 onwards. In other words, in the fourth embodiment, as in the third embodiment, while performing the stability calculation based on the previous cycle's N-2 control table, once the current cycle's N-2 control table is created, it compares the control amount with the previous cycle's N-2 control table. If the control amount is greater in the previous cycle's N-2 control table, it is configured to perform the stability calculation again based on the current cycle's N-2 control table.

[0105] As described above, the power system stabilization system of this embodiment further includes an electric control content determination unit 140 that determines the electric control content based on the control amounts of the previous cycle's N-2 control table and the current cycle's N-2 control table. If the electric control content determination unit 140 determines that the control amount of the previous cycle's N-2 control table is greater, the N-4 fault countermeasure determination unit 120 is configured to take in the current cycle's N-2 control table and perform the stability calculation again.

[0106] When calculating the stability of an N-4 fault using the N-2 control table from the previous cycle, if the control amount in the N-2 control table from the previous cycle is greater than that in the N-2 control table from the current cycle, there is a risk that the amount of electronically controlled N-4 faults calculated will be excessive. In this embodiment, the system is configured to recalculate the amount of electronically controlled N-4 faults using the control contents of the N-2 control table from the current cycle only when the control amount in the previous cycle is greater than that of the current cycle for N-2 fault countermeasures. Therefore, it is possible to shorten the calculation cycle while preventing excessive electronic control for N-4 fault countermeasures.

[0107] [6. Other Embodiments] While several embodiments of the present invention have been described herein, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments described above can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and their variations are included within the scope and essence of the invention, as well as within the scope of the claims and its equivalents. [Explanation of Symbols]

[0108] S: Power grid stabilization system N: Power supply information network P: Power system 1: Central processing unit 2: Central Control Unit 3: Accident detection terminal device 4: Control terminal device 101: Information Transmission Department 102: System Model Creation Department 103: State Estimation Unit 110: N-2 Accident Countermeasures Decision-Making Department 111: N-2 Accident Scenario Selection Department 112:N-2 stability calculation section 113: N-2 Control Table Creation Section 120: N-4 Accident Countermeasure Decision-Making Department 121: N-4 Scenario Accident Selection Department 121a: Accident interval setting unit 121b: Accident sequence setting section 122:N-4 stability calculation section 122a: Control variable determination unit 123: N-4 Control Table Creation Section 130: Control Table Downward Transmitter 140:Electronic content determination department D1:N-2 Electric Control Content Database

Claims

1. In a power grid stabilization system equipped with a central processing unit that acquires grid information from the power grid at regular intervals and determines the target of power control for each assumed fault, The central processing unit includes an N-2 accident response determination unit and an N-4 accident response determination unit, The aforementioned N-2 accident countermeasure decision unit is: An N-2 stability calculation unit calculates the stability of the power system in multiple N-2 hypothetical faults and determines the power control target for each N-2 hypothetical fault, The system includes an N-2 control table creation unit that creates an N-2 control table by associating the electrically controlled object for each of the N-2 assumed accidents determined by the N-2 stability calculation unit with the N-2 assumed accident, The aforementioned N-4 accident response decision unit is: It includes an N-4 stability calculation unit that calculates the stability of the power system in the N-4 assumed fault and determines the power control target for each N-4 assumed fault, The N-4 stability calculation unit takes over the contents of the N-2 control table created by the N-2 control table creation unit and performs the stability calculation. Power grid stabilization system.

2. The power system stabilization system according to claim 1, wherein the N-4 accident countermeasure determination unit further includes an N-4 assumed accident selection unit that determines the N-4 assumed accident from a combination of two of the N-2 assumed accidents.

3. The power system stabilization system according to claim 1 or 2, wherein the N-4 stability calculation unit performs a stability calculation for the N-4 assumed fault from the state in which the electrically controlled objects for the two assumed N-2 faults in the N-2 control table are controlled, and if the power system is found to be unstable as a result, the electrically controlled object is added to the electrically controlled objects for the two assumed N-2 faults and the stability calculation is performed again.

4. The aforementioned N-4 assumed accident selection unit includes an accident interval setting unit that sets the interval between the two aforementioned N-2 assumed accidents, The N-4 stability calculation unit includes a control variable determination unit that compares and determines the control variables of multiple stability calculation results, The control amount determination unit determines, from the multiple stability calculation results calculated using multiple accident conditions in which the interval between the two assumed N-2 accidents is varied, that the electrically controlled target for the accident condition with a large control amount is the electrically controlled target for the N-4 accident countermeasure. The power grid stabilization system according to claim 2.

5. The aforementioned N-4 assumed accident selection unit includes an accident sequence setting unit that sets the occurrence sequence of the two aforementioned N-2 assumed accidents, The N-4 stability calculation unit includes a control variable determination unit that compares and determines the control variables of multiple stability calculation results, The control amount determination unit determines, from the multiple stability calculation results calculated using multiple accident conditions in which the occurrence order of the two assumed N-2 accidents is changed, that the electrically controlled target for the accident condition with a large control amount is the electrically controlled target for the N-4 accident countermeasure. The power grid stabilization system according to claim 2.

6. The power system stabilization system according to claim 2, wherein the N-4 stability calculation unit is configured to take the fault pattern with the largest control amount in each of the two assumed N-2 faults from the N-2 control table and perform a stability calculation.

7. The system further includes an N-2 control content database for storing the N-2 control table created by the N-2 control table creation unit, The power system stabilization system according to claim 1, wherein the N-4 fault response determination unit is configured to take the N-2 control table for the previous cycle from the N-2 power control content database and perform the stability calculation.

8. The system further comprises an electric control content determination unit that determines the electric control content based on the control amounts of the N-2 control table for the previous cycle and the N-2 control table for the current cycle. The power system stabilization system according to claim 7, wherein if the electric control content determination unit determines that the control amount is greater in the N-2 control table of the previous cycle, the N-4 fault countermeasure determination unit is configured to take in the N-2 control table of the current cycle and perform the stability calculation again.

9. A computer program for a power grid stabilization system having a central processing unit that acquires grid information from the power grid at regular intervals and determines the target of power control for each assumed fault, The central computing unit of the aforementioned power grid stabilization system, The N-2 accident countermeasure decision step and the N-4 accident countermeasure decision step will be carried out. The aforementioned N-2 accident countermeasures decision step is: An N-2 stability calculation step is performed to calculate the stability of the power system in multiple assumed N-2 faults and to determine the power control target for each assumed N-2 fault, The N-2 control table creation step includes creating an N-2 control table by associating the electrically controlled object for each of the N-2 assumed accidents determined by the N-2 stability calculation step with the N-2 assumed accident, The aforementioned N-4 accident countermeasure decision step is: The process includes an N-4 stability calculation step which calculates the stability of the power system in the N-4 assumed fault and determines the power control target for each N-4 assumed fault, The N-4 stability calculation step takes over the contents of the N-2 control table created by the N-2 control table creation unit and performs the stability calculation. Computer program for power grid stabilization systems.

10. A power system stabilization method using a power system stabilization system having a central processing unit that acquires system information from the power system at regular intervals and determines the target of power control for each assumed fault, The central computing unit of the aforementioned power grid stabilization system, The N-2 accident countermeasure decision step and the N-4 accident countermeasure decision step were carried out. The aforementioned N-2 accident countermeasures decision step is: An N-2 stability calculation step is performed to calculate the stability of the power system in multiple assumed N-2 faults and to determine the power control target for each assumed N-2 fault, The N-2 control table creation step includes creating an N-2 control table by associating the electrically controlled object for each of the N-2 assumed accidents determined by the N-2 stability calculation step with the N-2 assumed accident, The aforementioned N-4 accident countermeasure decision step is: The process includes an N-4 stability calculation step which calculates the stability of the power system in the N-4 assumed fault and determines the power control target for each N-4 assumed fault, The N-4 stability calculation step takes over the contents of the N-2 control table created by the N-2 control table creation unit and performs the stability calculation. Power system stabilization method.

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