Power source estimation device, computer program for power source estimation device, and power source estimation method

Abstract

To provide a power source estimation device, method, and program for accurately estimating a power source whose parallel-off from a power system improves transient stability of the power system.SOLUTION: A pre-calculation type system stabilization system comprises a power source estimation device 1 including: an initial system data generation unit 13 that on the basis of system information on power systems 9a to 9c to which a renewable energy power source 3 and a power generator 2 for generating power are connected, creates initial system data which is system data in an initial state in the case of no accidents; an after-accident removal system data generation unit 15 that on the basis of the initial system data created by the initial system data generation unit 13, creates after-accident removal system data which is system data after removal of an accident imagined to be generated in the power system; and a renewable energy position determination unit 22 that on the basis of a difference between the initial system data and the after-accident removal system data, estimates a renewable energy power source to be paralleled off from the power system to improve transient stability of the power system.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present embodiment relates to a power supply estimation device, a computer program for the power supply estimation device, and a power supply estimation method that estimate a power supply that improves the transient stability of a power system by being disconnected from the power system. [Background technology]

[0002] 2. Description of the Related Art In order to ensure the transient stability of a power system in the event of a system fault, a power system stabilization device is known that controls a plurality of generators that supply power to the power system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-096472 [Patent Document 2] Japanese Patent Application Publication No. 08-182199 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the introduction of renewable energy power sources (hereinafter sometimes referred to as "renewable energy power sources") into power systems has been expanding. The main power source in conventional power systems has been synchronous generators. Renewable energy power sources have different dynamic characteristics from synchronous generators, so a different model from conventional power sources may be required.

[0005] For example, when a renewable energy power source is operated in an isolated mode in a power grid, it is preferable that the renewable energy power source be quickly disconnected from the power grid. Also, when the voltage or frequency in the power grid fluctuates beyond a specified threshold, it is preferable that the output of the renewable energy power source be restricted or that the renewable energy power source be disconnected in order to protect the equipment.

[0006] Pre-calculation type grid stabilization systems are installed for the purpose of stabilizing the power grid. Conventional pre-calculation type grid stabilization systems generally create control tables to deal with the occurrence of a fault in the grid. Pre-calculation type grid stabilization systems perform transient stability calculations in the event of a hypothetical fault based on the state of the power grid before the fault occurs, and create a control table by selecting in advance the generators to be paralleled off. The control table is created by performing transient stability calculations at regular intervals, such as 30 seconds.

[0007] The control of disconnecting generators from the power grid for stabilization is called power source limitation (hereinafter sometimes referred to as "shearing control"). When an accident actually occurs in the power grid, control content corresponding to the accident is selected from a control table and shearing control is quickly implemented.

[0008] In power systems where the introduction of renewable energy sources has expanded, the stability of the power system will be affected by the disconnection of renewable energy sources. For this reason, it is preferable to perform a more accurate simulation of the power system stabilization system. In order to perform a more accurate simulation, it is preferable to also simulate the dynamic characteristics related to the disconnection and output suppression of renewable energy sources when performing transient stability calculations.

[0009] The present embodiment aims to provide a power source estimation device, a computer program for the power source estimation device, and a power source estimation method that more accurately estimate a power source that improves the transient stability of a power system by being disconnected from the power system, in order to more reliably stabilize the power system that includes both synchronous generators and renewable energy power sources. [Means for solving the problem]

[0010] The power supply estimation device of this embodiment has the following features. (1) The system has an initial system data generation unit that generates initial system data, which is system data in the initial state when there is no accident, by power flow calculation based on system information of a power system to which a synchronous generator that generates electricity and a renewable energy power source are connected. (2) A post-fault removal system data generation unit is provided that generates post-fault removal system data, which is system data after removing a fault that is expected to occur in the power system, by power flow calculation based on the initial system data generated by the initial system data generation unit. (3) A renewable energy location determination unit is provided that estimates the renewable energy power source that will improve the transient stability of the power system by being disconnected from the power system based on the difference between the initial system data created by the initial system data generation unit and the post-fault system data created by the post-fault system data generation unit. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an overall diagram showing the configuration of a system using a power supply estimation device according to a first embodiment; [Figure 2] FIG. 1 is a diagram showing a program flow of a power supply estimation device according to a first embodiment; [Figure 3] FIG. 10 is a diagram showing an example of the phase of a renewable energy power source for calculation by the power source estimation device of the first embodiment; [Figure 4] FIG. 1 is a diagram showing an example of an assumed location of an accident and a state of the accident according to calculations of the power supply estimating device of the first embodiment; [Figure 5] FIG. 10 is a diagram showing an example of the phase of a power transmission line used in calculations by the power source estimating device of the first embodiment; [Figure 6] FIG. 10 is a diagram illustrating an example of a process for determining a supply-side subsystem in the calculation of the power supply estimation device of the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a system configuration related to calculations of a power supply estimating device according to a second embodiment; [Figure 8] FIG. 10 is a diagram showing an example of the phase of a power transmission line used in calculations by a power source estimating device according to a second embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0012] [1. First embodiment] [1-1. Overall structure] FIG. 1 is an overall diagram showing the configuration of a system using a power source estimation device 1 according to a first embodiment. As an example, a case will be described in which the power source estimation device 1 is applied to an extra-high voltage system. The power source estimation device 1 may be applied not only to extra-high voltage systems but also to systems of other voltage classes. In this embodiment, when there are multiple devices or components with the same configuration, they will be described using the same number, and when describing individual devices or components with the same configuration, they will be distinguished by adding a hyphen to the common number.

[0013] As an example, the grid of this system is composed of power grids 9a, 9b, and 9c and a main grid 90. The power grids 9a, 9b, and 9c are interconnected. Furthermore, the power grids 9a, 9b, and 9c are connected to the main grid 90. As an example, this system has the power grids 9a, 9b, and 9c, but the power grids 9 that make up the grid are not limited to this. The power grid 9 may have any power generation equipment, any power transmission equipment, and any connection configuration.

[0014] As an example, the power system 9a includes a synchronous generator 2 and a renewable energy power source 3. The renewable energy power source 3 is a power generation facility generally called a renewable energy power source. The power systems 9a, 9b, and 9c may be configured by any main grid. The power systems 9a, 9b, and 9c may have any number of synchronous generators 2 and renewable energy power sources 3.

[0015] The synchronous generator 2 is connected to the utility grid 90 via a transformer 6-1, a circuit breaker 5-1, and transmission lines 4-2 and 4-1. The synchronous generator 2 is composed of a power generating device such as a nuclear, hydroelectric, or thermal power plant. The transformer 6-1 converts the voltage of the power output from the synchronous generator 2 into a predetermined voltage.

[0016] The renewable energy power source 3 is connected to the main grid 90 via a transformer 6-2, a circuit breaker 5-2, a transmission line 4-3, and a transmission line 4-1. The renewable energy power source 3 is composed of a power generation device such as a solar or wind power generator. The transformer 6-2 converts the voltage of the power output from the renewable energy power source 3 into a predetermined voltage.

[0017] The circuit breakers 5-1 and 5-2 are configured by switches that cut off electric power, and cut off the electric power output from the synchronous generator 2 and the electric power output from the renewable energy power source 3, respectively. The circuit breakers 5-1 and 5-2 are connected to the power system stabilization device 200 by communication lines (not shown), and their opening and closing is controlled by the power system stabilization device 200.

[0018] The information collection devices 7-1, 7-2, 7-3, 7-4, and 7-5 are configured by detection devices that detect state quantities such as frequency, voltage, current, voltage phase (hereinafter sometimes simply referred to as "phase"), active power, and reactive power. The information collection device 7-1 is installed on the synchronous generator 2. The information collection device 7-1 detects state quantities of the synchronous generator 2, such as frequency, voltage, current, phase, active power, and reactive power, and transmits the detected state quantities to the power source estimation device 1 via the communication line 80.

[0019] The information collection device 7-2 is installed in the renewable energy power source 3. The information collection device 7-2 detects state quantities of the renewable energy power source 3, such as frequency, voltage, current, phase, active power, and reactive power, and transmits the detected state quantities to the power source estimation device 1 via a communication line 80.

[0020] Information collection devices 7-3, 7-4, and 7-5 are installed on power transmission lines 4-1, 4-2, and 4-3. The information collection devices 7-3, 7-4, and 7-5 detect state quantities, such as frequency, voltage, current, phase, active power, and reactive power, of the power transmission lines 4-1, 4-2, and 4-3, respectively, and transmit the state quantities to the power source estimation device 1 via a communication line 80.

[0021] The fault detection device 8 is configured by a detection device that detects faults due to abnormal voltage, ground fault current, etc. The fault detection device 8 detects a fault in the power system configured by the main system 90, the synchronous generator 2, and the renewable energy power source 3, and transmits the detected fault to the power system stabilization device 200.

[0022] The communication line 80 is configured by a communication line such as the Internet, a dedicated line, a telephone line, etc. Communication is carried out between the power source estimation device 1 and the information collection device 7 arranged in the power system 9 via the communication line 80.

[0023] The power system stabilization device 200 is configured by a computer. The power system stabilization device 200 is connected to the power source estimation device 1 and a circuit breaker 5 arranged in the power system 9. The power system stabilization device 200 uses supply-side renewable energy power source data D22, which will be described later and which is created by the power source estimation device 1, as reference information for selecting targets for power control in the event of an accident, and selects targets for power control in the event of an accident. The power system stabilization device 200 transmits a command to open or close an electric circuit to the connected circuit breaker 5 via a communication line (not shown). The supply-side renewable energy power source data D22 is data that predicts and estimates whether a renewable energy power source 3 is a power source that will improve the transient stability of the power system 9 when it is disconnected from the power system 9 in the event of an accident.

[0024] [1-2. Configuration of power source estimation device 1] The power source estimation device 1 is a device that estimates a renewable energy power source 3 that is disconnected from the power grid 9, thereby improving the transient stability of the power grid 9. Improving the transient stability of the power grid 9 improves the stability of the entire system, including the power grid 9 and the main grid 90. The power source estimation device 1 is a device configured by a computer or the like. The power source estimation device 1 is connected to an information collection device 7 arranged in the power grid 9 via a communication line 80. The power source estimation device 1 is also connected to a power system stabilization device 200.

[0025] When an accident occurs in the power grid 9, the power source estimation device 1 determines whether each renewable energy power source 3 in the power grid 9 is located on the supply side or the demand side. In the system topology, a power source that is located in a position where the transient stability of the power grid 9 is improved by being disconnected from the power grid 9 is called a power source located on the supply side.

[0026] The supply side refers to a subsystem located on the side that sends out power in the system topology. A supply side subsystem is a subsystem that has a generator that becomes unstable when a fault occurs or has a large voltage phase expansion. The demand side refers to a subsystem located on the side that receives power in the system topology. A demand side subsystem is a subsystem that has a small voltage phase expansion when a fault occurs.

[0027] When the renewable energy power source 3 located on the supply side is disconnected or its output is suppressed, the transient stability of the power grid 9 improves. On the other hand, when the renewable energy power source 3 located on the demand side is disconnected or its output is suppressed, the transient stability of the power grid 9 deteriorates.

[0028] The power source estimation device 1 determines whether each renewable energy power source 3 in the power system 9 will be located on the supply side or the demand side in the event of an accident, and creates supply-side renewable energy power source data D22, which will be described later. The power source estimation device 1 transmits the created supply-side renewable energy power source data D22 to the power system stabilization device 200.

[0029] The power source estimation device 1 is composed of a system information collection unit 11, a power flow calculation execution unit 12, an initial system data generation unit 13, a renewable energy initial phase acquisition unit 14, a system data generation unit after fault removal 15, a renewable energy phase acquisition unit after fault removal 16, a transmission line initial phase acquisition unit 17, a transmission line phase acquisition unit after fault removal 18, a supply side judgment threshold determination unit 19, a supply side partial system extraction unit 21, and a renewable energy position judgment unit 22.

[0030] The above-mentioned components constituting the power source estimation apparatus 1 may be configured by a calculation unit in a computer or a software module. Furthermore, the above-mentioned components constituting the power source estimation apparatus 1 may be configured by separate devices, or may be configured as an integrated unit.

[0031] The power system information collection unit 11 includes a transmission / reception circuit. The power system information collection unit 11 is a receiving module or a receiving device that receives information about the power system 9. The power system information collection unit 11 is connected to the information collection device 7 arranged in the power system 9 via a communication line 80. The power system information collection unit 11 is also connected to the initial power system data generation unit 13.

[0032] The system information collection unit 11 receives data indicating the state quantities of each synchronous generator 2, each renewable energy power source 3, and each bus in the power system 9 (for example, TM data relating to voltage, current, phase, active power, and reactive power, and SV data relating to generator start / stop and the operational state of the transmission line) from the information collection devices 7-1, 7-2, 7-3, 7-4, and 7-5. The system information collection unit 11 transmits the received data to the initial system data generation unit 13 as system information D11.

[0033] The initial system data generation unit 13 is a calculation module or calculation device that generates initial system data D13. The initial system data generation unit 13 is connected to the power flow calculation execution unit 12, the renewable energy initial phase acquisition unit 14, the post-fault removal system data generation unit 15, and the transmission line initial phase acquisition unit 17. The initial system data generation unit 13 generates the initial system data D13 based on the state quantities of the power system 9 related to the system information D11 received from the system information collection unit 11. The initial system data D13 is system data in an initial state when the power system 9 is fault-free.

[0034] The initial system data generation unit 13 transmits the state quantities of the power system 9 according to the system information D11 to the power flow calculation execution unit 12, which will be described later. The power flow calculation execution unit 12 executes a power flow calculation using the AC method based on the state quantities of the power system 9 according to the system information D11, and transmits the calculation results to the initial system data generation unit 13. The initial system data generation unit 13 receives the calculation results of the power flow calculation from the power flow calculation execution unit 12, creates system data in the initial state, and stores it as initial system data D13.

[0035] The initial system data generation unit 13 transmits the initial system data D13 to the renewable energy initial phase acquisition unit 14, the post-fault-clearance system data generation unit 15, and the power transmission line initial phase acquisition unit 17.

[0036] The power flow calculation execution unit 12 is a calculation module or calculation device that executes power flow calculations. The power flow calculation execution unit 12 is connected to the initial system data generation unit 13 and the post-fault-clearance system data generation unit 15. The power flow calculation execution unit 12 executes power flow calculations using the AC method based on the data received from the initial system data generation unit 13 and the post-fault-clearance system data generation unit 15, and transmits the calculation results to the initial system data generation unit 13 and the post-fault-clearance system data generation unit 15, respectively.

[0037] The renewable energy initial phase acquisition unit 14 is a calculation module or calculation device that creates renewable energy initial phase data D14. The renewable energy initial phase acquisition unit 14 is connected to the power flow calculation execution unit 12 and the renewable energy position determination unit 22. The renewable energy initial phase acquisition unit 14 extracts the initial phase of each renewable energy power source 3 in the power system 9 based on the initial system data D13 received from the initial system data generation unit 13, and creates renewable energy initial phase data D14. The renewable energy initial phase acquisition unit 14 transmits the renewable energy initial phase data D14 to the renewable energy position determination unit 22.

[0038] The post-fault clearance system data generation unit 15 is a calculation module or calculation device that generates post-fault clearance system data D15. The post-fault clearance system data generation unit 15 is connected to the power flow calculation execution unit 12, the initial system data generation unit 13, the post-renewable energy fault clearance phase acquisition unit 16, and the post-transmission line fault clearance phase acquisition unit 18.

[0039] The post-fault removal system data generation unit 15 generates post-fault removal system data D15, which is system data after the anticipated fault has been removed, based on the initial system data D13 received from the initial system data generation unit 13. The post-fault removal system data generation unit 15 generates system data in the case where the transmission line 4, which is the location of the anticipated fault when the fault occurs, is opened. The post-fault removal system data generation unit 15 generates system data after the fault has been removed for each anticipated fault, and sets the data as post-fault removal system data D15.

[0040] The anticipated fault and the anticipated location of the fault are received from an external database (not shown) or the like. The post-fault removal system data generation unit 15 transmits the system data after the anticipated fault has been removed to the power flow calculation execution unit 12. The power flow calculation execution unit 12 executes a power flow calculation using the AC method based on the state quantities of the power system 9 related to the system data after the anticipated fault has been removed, and transmits the calculation result to the post-fault removal system data generation unit 15.

[0041] The post-fault removal system data generation unit 15 receives the calculation results of the power flow calculation from the power flow calculation execution unit 12, creates system data after the expected fault has been removed, and stores the data as post-fault removal system data D15. The post-fault removal system data generation unit 15 transmits the post-fault removal system data D15 to the post-renewable energy fault removal phase acquisition unit 16 and the post-transmission line fault removal phase acquisition unit 18.

[0042] The post-renewable energy accident removal phase acquisition unit 16 is a calculation module or calculation device that creates post-renewable energy accident removal phase data D16. The post-renewable energy accident removal phase acquisition unit 16 is connected to the post-fault removal system data generation unit 15 and the renewable energy position determination unit 22. The post-renewable energy accident removal phase acquisition unit 16 extracts the phase of each renewable energy power source 3 in the power system 9 after the expected accident has been removed, based on the post-fault removal system data D15 received from the post-fault removal system data generation unit 15, and creates post-renewable energy accident removal phase data D16. The post-renewable energy accident removal phase acquisition unit 16 transmits the post-renewable energy accident removal phase data D16 to the renewable energy position determination unit 22.

[0043] The transmission line initial phase acquisition unit 17 is a calculation module or calculation device that creates transmission line initial phase data D17. The transmission line initial phase acquisition unit 17 is connected to the initial system data generation unit 13 and the supply-side judgment threshold determination unit 19. The transmission line initial phase acquisition unit 17 extracts the initial phases of the nodes at both ends of the transmission line 4 at the postulated fault occurrence location in the power system 9 based on the initial system data D13 received from the initial system data generation unit 13, and creates the transmission line initial phase data D17. The transmission line initial phase acquisition unit 17 transmits the transmission line initial phase data D17 to the supply-side judgment threshold determination unit 19.

[0044] The transmission line fault removal phase acquisition unit 18 is an arithmetic module or arithmetic device that creates the transmission line fault removal phase data D18. The transmission line fault removal phase acquisition unit 18 is connected to the fault removal system data generation unit 15 and the supply side judgment threshold determination unit 19. The transmission line fault removal phase acquisition unit 18 extracts the phases of the nodes at both ends of the transmission line 4 at the location of the assumed fault in the power system 9 after the assumed fault has been removed, based on the fault removal system data D15 received from the fault removal system data generation unit 15, and creates the transmission line fault removal phase data D18. The transmission line fault removal phase acquisition unit 18 transmits the transmission line fault removal phase data D18 to the supply side judgment threshold determination unit 19.

[0045] The supply-side judgment threshold determiner 19 is a calculation module or calculation device that calculates supply-side judgment threshold data D19. The supply-side judgment threshold determiner 19 is connected to the power transmission line initial phase acquirer 17 and the power transmission line fault cleared phase acquirer 18. Based on the power transmission line initial phase data D17 received from the power transmission line initial phase acquirer 17 and the power transmission line fault cleared phase data D18 received from the power transmission line fault cleared phase acquirer 18, the supply-side judgment threshold determiner 19 calculates a supply-side judgment threshold from the difference between both phases.

[0046] The calculated supply-side determination threshold is stored as supply-side determination threshold data D19 in the supply-side determination threshold determiner 19. The supply-side determination threshold determiner 19 transmits the supply-side determination threshold data D19 to the renewable energy location determiner 22.

[0047] The supply-side subsystem extraction unit 21 is a calculation module or calculation device that creates supply-side subsystem data D21. The supply-side subsystem extraction unit 21 is connected to the renewable energy location determination unit 22. The supply-side subsystem extraction unit 21 extracts isolated systems that would occur if all transmission lines 4 of a specific voltage class, such as 500 kV, were cut off, and determines whether the extracted isolated systems are supply-side subsystems.

[0048] If the extracted separated system is a supply-side subsystem, the extracted separated system is stored as supply-side subsystem data D21 in the supply-side subsystem extraction unit 21. The supply-side subsystem extraction unit 21 transmits the supply-side subsystem data D21 to the renewable energy location determination unit 22.

[0049] The renewable energy location determination unit 22 is a calculation module or calculation device that determines a renewable energy power source 3 located on the supply side and creates supply-side renewable energy power source data D22. The renewable energy location determination unit 22 is connected to the renewable energy initial phase acquisition unit 14, the post-renewable energy fault removal phase acquisition unit 16, the supply-side determination threshold determination unit 19, and the supply-side partial-system extraction unit 21. The renewable energy location determination unit 22 determines whether a renewable energy power source 3 is located on the supply side based on the renewable energy initial phase data D14 received from the renewable energy initial phase acquisition unit 14, the post-renewable energy fault removal phase data D16 received from the post-renewable energy fault removal phase acquisition unit 16, the supply-side determination threshold data D19 received from the supply-side determination threshold determination unit 19, and the supply-side partial-system data D21 received from the supply-side partial-system extraction unit 21.

[0050] The renewable energy location determination unit 22 determines whether each renewable energy power source 3 included in the supply-side subsystem according to the supply-side subsystem data D21 is located on the supply side. If the difference between the initial phase according to the renewable energy initial phase data D14 and the phase after fault removal according to the renewable energy post-fault removal phase data D16 is equal to or greater than the supply-side determination threshold according to the supply-side determination threshold data D19, the renewable energy power source 3 is determined to be located on the supply side. A renewable energy power source 3 not determined to be located on the supply side is determined to be located on the demand side.

[0051] The renewable energy power source 3 that is determined to be located on the supply side is stored as supply-side renewable energy power source data D22 in the renewable energy location determination unit 22. The renewable energy location determination unit 22 transmits the supply-side renewable energy power source data D22 to the power system stabilization device 200.

[0052] The power system stabilization device 200 utilizes the supply-side renewable energy power source data D22 created by the power source estimation device 1 as reference information for selecting targets for power control, and selects targets for power control when an accident occurs.

[0053] The above is the configuration of the power source estimation device 1 according to this embodiment.

[0054] [1-2. Effect] Next, an outline of the operation of the power source estimation device 1 of this embodiment will be described with reference to FIGS.

[0055] The power source estimation device 1 estimates renewable energy power sources 3 that will improve the transient stability of the power grid 9 when disconnected from the power grid 9. When an accident occurs in the power grid 9, the power source estimation device 1 determines whether each renewable energy power source 3 in the power grid 9 is located on the supply side or the demand side. In the system topology, a power source that is located in a position where the transient stability of the power grid 9 will improve when disconnected from the power grid 9 is called a power source located on the supply side.

[0056] The supply side refers to a subsystem located on the side that sends out electricity. A supply side subsystem is a subsystem that has a generator that becomes unstable when a fault occurs or has a large voltage phase expansion. The demand side refers to a subsystem that receives electricity. A demand side subsystem is a subsystem that has a small voltage phase expansion when a fault occurs.

[0057] When the renewable energy power source 3 located on the supply side is disconnected or its output is suppressed, the transient stability of the power grid 9 improves. On the other hand, when the renewable energy power source 3 located on the demand side is disconnected or its output is suppressed, the transient stability of the power grid 9 deteriorates.

[0058] The initial system data generation unit 13 of the power source estimation device 1 generates initial system data D13 by power flow calculation, which is system data in an initial state when there is no fault, based on system information of the power system 9 to which the synchronous generator 2 that generates power and the renewable energy power source 3 are connected. The post-fault removal system data generation unit 15 generates post-fault removal system data D15 by power flow calculation, which is system data after a fault that is expected to occur in the power system 9 has been removed, based on the initial system data D13 generated by the initial system data generation unit 13.

[0059] The renewable energy location determination unit 22 estimates the renewable energy power source 3 whose transient stability of the power system 9 will be improved by being disconnected from the power system 9, based on the difference between the initial system data D13 created by the initial system data generation unit 13 and the post-fault clearance system data D15 created by the post-fault clearance system data generation unit 15. The renewable energy location determination unit 22 estimates the renewable energy power source 3 whose transient stability of the power system 9 will be improved by being disconnected from the power system 9, based on the difference between the phase and the active power flow in the initial system data D13 and the post-fault clearance system data D15.

[0060] The renewable energy location determination unit 22 estimates that the transient stability of the power system 9 will be improved by disconnecting the renewable energy power source 3 from the power system 9 when the difference between the phase of the renewable energy power source 3 in the case of no accident, which is based on the initial system data D13 created by the initial system data generation unit 13, and the phase after the expected accident has been removed, which is based on the post-fault removal system data D15 created by the post-fault removal system data generation unit 15, exceeds a set threshold.

[0061] The supply-side judgment threshold determiner 19 calculates, as a threshold, the smaller of the differences between the phase in a fault-free state according to the initial system data D13 created by the initial system data generator 13 and the phase after the fault has been removed according to the post-fault-clearance system data generator 15, for each of a plurality of nodes located on either side of a location where a potential fault will occur or a location that will be shut off due to a potential fault in the transmission line 4 arranged in the power system 9. The plurality of nodes may be located at both ends of the transmission line 4.

[0062] The supply-side subsystem extraction unit 21 extracts isolated subsystems that are formed when a transmission line 4 of a predetermined voltage class is cut off in the power system 9, and determines that an isolated subsystem that includes a synchronous generator 2 that will lose synchronism among the extracted isolated subsystems is a subsystem in which the transient stability of the power system 9 will be improved by disconnecting a renewable energy power source 3 from the power system 9. The renewable energy location determination unit 22 estimates a renewable energy power source 3 in the subsystem determined by the supply-side subsystem extraction unit 21, the transient stability of the power system 9 will be improved by disconnecting it from the power system 9. The subsystem determined by the supply-side subsystem extraction unit 21 is determined to be a supply-side subsystem.

[0063] The supply-side subsystem extraction unit 21 extracts an isolated system that is formed when a transmission line 4 of a predetermined voltage class is cut off in the power system 9, and determines that an isolated system that includes a synchronous generator 2 or a renewable energy power source 3 in which at least one of the internal phase difference angle, the internal phase difference angle deviation, the angular velocity, and the angular velocity deviation exceeds a predetermined specified value or becomes a larger value in the power system 9, is a subsystem in which the transient stability of the power system 9 will be improved by disconnecting the renewable energy power source 3 from the power system 9. The renewable energy location determination unit 22 estimates the renewable energy power source 3 in the subsystem determined by the supply-side subsystem extraction unit 21, in which the transient stability of the power system 9 will be improved by disconnecting it from the power system 9. The subsystem determined by the supply-side subsystem extraction unit 21 is determined to be a supply-side subsystem.

[0064] Nowadays, a plurality of renewable energy power sources 3 are connected to a power grid 9. For this reason, the stability of the power grid 9 differs depending on whether the renewable energy power sources 3 are disconnected or not. In particular, in the event of an accident, it is necessary to appropriately determine which renewable energy power sources 3 will be disconnected or not disconnected from the power grid 9. It is preferable to determine and predict in advance, through simulation, which renewable energy power sources 3 will be disconnected or not disconnected in the event of a potential accident. It is preferable to perform a highly accurate simulation using transient stability calculations to determine the dynamic characteristics of the disconnection and output suppression of the renewable energy power sources 3.

[0065] The impact that the disconnection or output curtailment of the renewable energy power source 3 has on the stability of the power grid 9 varies depending on the position of the renewable energy power source 3 in the system topology. For example, if the renewable energy power source 3 is located in a supply-side subsystem, disconnecting the renewable energy power source 3 reduces the power flow sent out from the supply-side subsystem. As a result, the phase of the supply-side subsystem decreases, and the stability of the power grid 9 improves.

[0066] On the other hand, if the renewable energy power source 3 is located in the demand-side subsystem, disconnecting the renewable energy power source 3 increases the power flow sent from the supply-side subsystem. As a result, the voltage phase of the supply-side subsystem expands, and the stability of the power grid 9 deteriorates.

[0067] In order to reliably control the stabilization of the power grid 9, it is preferable to perform a simulation that includes the impact of disconnection or output suppression of the renewable energy power source 3. It is also preferable to perform a simulation that includes the risk of deterioration in stability when a discrepancy occurs between the magnitude of the output power of the renewable energy power source 3 when it is actually disconnected from the power grid 9 and the magnitude of the output power of the renewable energy power source 3 in the transient stability calculation. In order to achieve the above, it is preferable to determine whether each of the multiple renewable energy power sources 3 is on the demand side or the supply side in the system topology.

[0068] The power source estimation device 1 determines whether each renewable energy power source 3 in the power system 9 will be located on the supply side or the demand side in the event of an accident, and creates supply-side renewable energy power source data D22. The power source estimation device 1 transmits the created supply-side renewable energy power source data D22 to the power system stabilization device 200.

[0069] The details of the operation of the power source estimation device 1 are as follows.

[0070] The system information collector 11 of the power source estimation device 1 receives information about the power system 9 from the information collector 7. The system information collector 11 receives data indicating the state quantities of each synchronous generator 2, each renewable energy power source 3, and each bus in the power system 9 (for example, TM data related to voltage, current, phase, active power, and reactive power, and SV data related to generator start / stop and the operational state of the transmission line) from the information collectors 7-1, 7-2, 7-3, 7-4, and 7-5. The system information collector 11 transmits the received data to the initial system data generator 13 as system information D11.

[0071] The initial system data generator 13 of the power supply estimation device 1 creates initial system data D13. The initial system data generator 13 creates the initial system data D13 based on the state quantities of the power system 9 related to the system information D11 received from the system information collector 11. The initial system data D13 is system data in an initial state when the power system 9 is accident-free. The initial system data generator 13 transmits the state quantities of the power system 9 related to the system information D11 to the power flow calculation execution unit 12.

[0072] The power flow calculation execution unit 12 of the power source estimation device 1 executes a power flow calculation. The power flow calculation execution unit 12 executes a power flow calculation by the AC method based on the state quantities of the power system 9 related to the system information D11, and transmits the calculation result to the initial system data generation unit 13.

[0073] The initial system data generation unit 13 receives the calculation results of the power flow calculation from the power flow calculation execution unit 12, creates system data in the initial state, and stores it as initial system data D13. The initial system data generation unit 13 transmits the initial system data D13 to the renewable energy initial phase acquisition unit 14, the post-fault clearance system data generation unit 15, and the transmission line initial phase acquisition unit 17.

[0074] The renewable energy initial phase acquisition unit 14 of the power source estimation device 1 creates renewable energy initial phase data D14. The renewable energy initial phase acquisition unit 14 extracts the initial phase of each renewable energy power source 3 in the power system 9 based on the initial system data D13 received from the initial system data generation unit 13, and creates the renewable energy initial phase data D14. The renewable energy initial phase acquisition unit 14 transmits the renewable energy initial phase data D14 to the renewable energy position determination unit 22.

[0075] The post-fault removal system data generating unit 15 of the power supply estimation device 1 generates post-fault removal system data D15. Based on the initial system data D13 received from the initial system data generating unit 13, the post-fault removal system data generating unit 15 generates post-fault removal system data D15, which is system data after an assumed fault has been removed. The post-fault removal system data generating unit 15 generates system data for the case where the transmission line 4, which is the location of the fault when the assumed fault occurs, is opened. The post-fault removal system data generating unit 15 generates system data after fault removal for each assumed fault, and sets the data as post-fault removal system data D15.

[0076] The anticipated faults and the anticipated locations of the faults are received from an external database (not shown), etc. The post-fault removal system data generator 15 transmits the system data after the anticipated faults have been removed to the power flow calculation execution unit 12.

[0077] The power flow calculation execution unit 12 executes a power flow calculation using the AC method based on the state quantities of the power system 9 related to the system data after the anticipated fault has been removed, and transmits the calculation results to the post-fault removal system data generation unit 15.

[0078] The post-fault removal system data generation unit 15 receives the calculation results of the power flow calculation from the power flow calculation execution unit 12, creates system data after the expected fault has been removed, and stores the data as post-fault removal system data D15. The post-fault removal system data generation unit 15 transmits the post-fault removal system data D15 to the post-renewable energy fault removal phase acquisition unit 16 and the post-transmission line fault removal phase acquisition unit 18.

[0079] The post-renewable energy accident removal phase acquisition unit 16 of the power source estimation device 1 creates post-renewable energy accident removal phase data D16. The post-renewable energy accident removal phase acquisition unit 16 extracts the phase of each renewable energy power source 3 in the power system 9 after the expected accident has been removed, based on the post-fault removal system data D15 received from the post-fault removal system data generation unit 15, and creates the post-renewable energy accident removal phase data D16. The post-renewable energy accident removal phase acquisition unit 16 transmits the post-renewable energy accident removal phase data D16 to the renewable energy position determination unit 22.

[0080] The power transmission line initial phase acquisition unit 17 of the power source estimation device 1 creates power transmission line initial phase data D17. Based on the initial system data D13 received from the initial system data generation unit 13, the power transmission line initial phase acquisition unit 17 extracts the initial phases of the nodes at both ends of each power transmission line 4 in the power system 9, and creates the power transmission line initial phase data D17. The power transmission line initial phase acquisition unit 17 transmits the power transmission line initial phase data D17 to the supply-side determination threshold determination unit 19.

[0081] The post-transmission line fault removal phase acquisition unit 18 of the power source estimation device 1 creates post-transmission line fault removal phase data D18. Based on the post-fault removal system data D15 received from the post-fault removal system data generation unit 15, the post-transmission line fault removal phase acquisition unit 18 extracts the phases of the nodes at both ends of each transmission line 4 in the power system 9 after the assumed fault has been removed, and creates the post-transmission line fault removal phase data D18. The post-transmission line fault removal phase acquisition unit 18 transmits the post-transmission line fault removal phase data D18 to the supply-side determination threshold determination unit 19.

[0082] The supply-side determination threshold determiner 19 of the power source estimation device 1 calculates supply-side determination threshold data D19. Based on the transmission line initial phase data D17 received from the transmission line initial phase acquirer 17 and the transmission line fault cleared phase data D18 received from the transmission line fault cleared phase acquirer 18, the supply-side determination threshold determiner 19 calculates the supply-side determination threshold from the difference between both phases.

[0083] The supply-side judgment threshold determiner 19 calculates the smaller of the difference between the initial phase and the phase after the fault has been cleared at the node at one end of the power transmission line 4, and the difference between the initial phase and the phase after the fault has been cleared at the node at the other end, as the supply-side judgment threshold. The phase change of the node with the smaller phase change across the fault occurrence point is calculated as the supply-side judgment threshold.

[0084] The calculated supply-side determination threshold is stored as supply-side determination threshold data D19 in the supply-side determination threshold determiner 19. The supply-side determination threshold determiner 19 transmits the supply-side determination threshold data D19 to the renewable energy location determiner 22.

[0085] The supply-side subsystem extraction unit 21 of the power source estimation device 1 creates supply-side subsystem data D21. The supply-side subsystem extraction unit 21 extracts isolated systems that would occur if all transmission lines 4 of a specific voltage class, such as 500 kV, were cut off, and determines whether the extracted isolated systems are supply-side subsystems.

[0086] If the extracted separated system is a supply-side subsystem, the extracted separated system is stored as supply-side subsystem data D21 in the supply-side subsystem extraction unit 21. The supply-side subsystem extraction unit 21 transmits the supply-side subsystem data D21 to the renewable energy location determination unit 22.

[0087] The renewable energy location determination unit 22 of the power source estimation device 1 determines a renewable energy power source 3 located on the supply side and creates supply-side renewable energy power source data D22. The renewable energy location determination unit 22 determines whether the renewable energy power source 3 is located on the supply side based on the renewable energy initial phase data D14 received from the renewable energy initial phase acquisition unit 14, the post-renewable energy accident removal phase data D16 received from the post-renewable energy accident removal phase acquisition unit 16, the supply-side determination threshold data D19 received from the supply-side determination threshold decision unit 19, and the supply-side partial system data D21 received from the supply-side partial system extraction unit 21.

[0088] The renewable energy location determination unit 22 determines whether each renewable energy power source 3 included in the supply-side subsystem according to the supply-side subsystem data D21 is located on the supply side. If the difference between the initial phase according to the renewable energy initial phase data D14 and the phase after fault removal according to the renewable energy post-fault removal phase data D16 is equal to or greater than the supply-side determination threshold according to the supply-side determination threshold data D19, the renewable energy power source 3 is determined to be located on the supply side. A renewable energy power source 3 not determined to be located on the supply side is determined to be located on the demand side.

[0089] The renewable energy power source 3 that is determined to be located on the supply side is stored as supply-side renewable energy power source data D22 in the renewable energy location determination unit 22. The renewable energy location determination unit 22 transmits the supply-side renewable energy power source data D22 to the power system stabilization device 200.

[0090] The power system stabilization device 200 utilizes the supply-side renewable energy power source data D22 created by the power source estimation device 1 as reference information for selecting targets for power control, and selects targets for power control when an accident occurs.

[0091] The above operation is realized by a computer program shown in Fig. 2. The computer program shown in Fig. 2 is built into the power source estimation device 1.

[0092] (Step S01: Creating initial system data) The operation in step S01 is performed by the system information collecting unit 11 and the initial system data generating unit 13. The system information collecting unit 11 creates system information D11. The initial system data generating unit 13 transmits the state quantities of the power system 9 related to the system information D11 created by the system information collecting unit 11 to the power flow calculation executing unit 12 as system data of the initial state.

[0093] The system information D11 is data received from the information collection device 7 that indicates the state quantities of each synchronous generator 2, each renewable energy source 3, and each bus in the power system 9 (for example, TM data related to voltage, current, phase, active power, and reactive power, and SV data related to generator start / stop and the operational status of the transmission line).

[0094] (Step S02: Execute power flow calculation using initial system data) The operation in step S02 is performed by the power flow calculation execution unit 12 and the initial system data generation unit 13. The power flow calculation execution unit 12 receives initial state system data related to system information D11 from the initial system data generation unit 13. The power flow calculation execution unit 12 executes a power flow calculation using the AC method based on the state quantities of the power system 9 included in the initial state system data. The power flow calculation execution unit 12 transmits the calculation results of the power flow calculation to the initial system data generation unit 13. The initial system data generation unit 13 receives the calculation results of the power flow calculation from the power flow calculation execution unit 12 and creates initial system data D13. The initial system data D13 is system data in an initial state when the power system 9 is fault-free. The processing by the initial system data generation unit 13 in step S02 may be referred to as an initial system data generation step or an initial system data generation procedure.

[0095] (Step S03: Extraction of the initial phase of each renewable energy source 3) The operation in step S03 is executed by the renewable energy initial phase acquisition unit 14. The renewable energy initial phase acquisition unit 14 extracts the initial phase of each renewable energy power source 3 in the power system 9 based on the initial system data D13 received from the initial system data generation unit 13, and creates renewable energy initial phase data D14. FIG. 3 shows an example of the initial phase of the renewable energy power source 3. The "initial phase" column in FIG. 3 shows the initial phase of each renewable energy power source 3. In FIG. 3, renewable energy sources A to C may be multiple renewable energy power sources 3 provided in one power system 9, or may be renewable energy power sources 3 provided in multiple different power systems 9.

[0096] (Step S04: Selection of the location where the accident is expected to occur) The operation in step S04 is executed by the post-fault clearance system data generator 15. The post-fault clearance system data generator 15 selects the location of a predicted accident or a predicted accident case to be used for determining the demand side and the supply side. The predicted accident location or the predicted accident case is received from an external database (not shown) or the like. FIG. 4 shows an example of a predicted accident location and accident state. In FIG. 4, the transmission lines A and B may be multiple transmission lines 4 provided within one power system 9, or may be transmission lines 4 provided within multiple different power systems 9.

[0097] The "Accident Mode" column in Figure 4 shows the nature of the accident at the location where it occurred. For example, in the description "3φ4LG," "3φ" indicates that the accident occurred in three phases of a three-phase, two-circuit transmission line. Also, in the description "3φ4LG," "4LG" indicates that a ground fault occurred in wire four of a three-phase, two-circuit transmission line. Similarly, the description "3φ6LG" indicates that a fault occurred in three phases of a three-phase, two-circuit transmission line, and a ground fault occurred in wire six.

[0098] (Step S05: Creating system data after accident removal for assumed accident cases) The operation in step S05 is executed by the post-fault clearance system data generating unit 15. The post-fault clearance system data generating unit 15 generates system data after the anticipated fault has been removed, based on the initial system data D13 generated in step S02 and the location of the anticipated fault selected in step S04. The post-fault clearance system data generating unit 15 generates system data for when the transmission line 4 at the location of the fault is opened when the anticipated fault occurs, and uses this as the system data after the fault has been removed.

[0099] The transmission line 4 that is opened varies depending on the assumed location and nature of the accident. For example, if "Case 1" in Figure 4 (location of accident: transmission line A, nature of accident: 3φ4LG) is selected as the assumed location and nature of the accident, only one circuit of transmission line A will be opened. "3φ4LG" indicates that, as mentioned above, an accident has occurred in three phases of the three-phase, two-circuit transmission line, and a ground fault has occurred in the fourth circuit. One of the two circuits of transmission line A has a three-phase ground fault, and the other has a single-phase ground fault, but if the single-phase ground fault is cleared by fast reclosing and the interrupted circuit is quickly re-closed, it can be determined that one circuit has returned to a healthy state.

[0100] If "Case 2" in Figure 4 (fault location: transmission line A, fault type: 3φ6LG) is selected as the assumed location and type of fault, both circuits of transmission line A will be open. "3φ6LG" indicates that, as mentioned above, a fault has occurred in three phases of the three-phase, two-circuit transmission line, and a ground fault has occurred in wire 6. Both circuits of transmission line A are three-phase ground faults.

[0101] If "Case 3" in Figure 4 (location of fault: transmission line B, fault type: 3φ3LG) is selected as the assumed location and type of fault, only one circuit of transmission line B will be opened. "3φ3LG" indicates that, as mentioned above, a fault has occurred in three phases of the three-phase, two-circuit transmission line, and a ground fault has occurred in the third circuit. One of the two circuits of transmission line A has a three-phase ground fault, and the other has not.

[0102] (Step S06: Execute power flow calculation using system data after fault removal) The operation in step S06 is performed by the power flow calculation execution unit 12 and the post-fault-clearance system data generation unit 15. The power flow calculation execution unit 12 receives the system data after the fault has been cleared from the post-fault-clearance system data generation unit 15. The power flow calculation execution unit 12 executes a power flow calculation using the AC method based on the state quantities of the power system 9 included in the system data after the fault has been cleared. The power flow calculation execution unit 12 transmits the calculation results of the power flow calculation to the post-fault-clearance system data generation unit 15.

[0103] The post-fault removal system data generating unit 15 receives the calculation results of the power flow calculation from the power flow calculation executing unit 12 and creates post-fault removal system data D15. The post-fault removal system data D15 is system data after removing an assumed fault in the power system 9. The processing by the post-fault removal system data generating unit 15 in step S06 may be referred to as a post-fault removal system data generating step or a post-fault removal system data generating procedure.

[0104] (Step S07: Extraction of phases after fault removal for each renewable energy source 3) The operation in step S07 is executed by the post-renewable energy accident removal phase acquisition unit 16. The post-renewable energy accident removal phase acquisition unit 16 extracts the phase of each renewable energy power source 3 in the power system 9 after the expected accident has been removed, based on the post-fault removal system data D15 received from the post-fault removal system data generation unit 15, and creates post-renewable energy accident removal phase data D16.

[0105] Fig. 3 shows an example of the phase after fault clearance of a renewable energy power source 3. The column "Phase after fault clearance" in Fig. 3 shows the phase after fault clearance of each renewable energy power source 3. In Fig. 3, renewable energy sources A to C may be multiple renewable energy power sources 3 provided in one power system 9, or may be renewable energy power sources 3 provided in multiple different power systems 9.

[0106] (Step S08: Extraction of initial phases of nodes at both ends of transmission line 4) The operation of step S08 is executed by the transmission line initial phase acquisition unit 17. Based on the initial system data D13 received from the initial system data generation unit 13, the transmission line initial phase acquisition unit 17 extracts the initial phases of the nodes at both ends of the transmission line 4 at the location where the postulated fault occurs in the power system 9, and creates transmission line initial phase data D17. FIG. 5 shows an example of the initial phase of the transmission line 4. The "initial phase" column in FIG. 5 shows the initial phase of the transmission line 4. In FIG. 5, the transmission line A is one of the multiple transmission lines 4 provided in the power system 9 and is the transmission line at which the postulated fault occurs. Node a is one end of the transmission line A, and node b is the other end of the transmission line A.

[0107] (Step S09: Extraction of phases after fault removal at nodes on both ends of transmission line 4) The operation in step S09 is executed by the post-fault-clearance phase acquisition unit 18. The post-fault-clearance phase acquisition unit 18 extracts the phases of the nodes at both ends of the transmission line 4 at the location where the assumed fault occurred in the power system 9 after the assumed fault has been cleared, based on the post-fault-clearance system data D15 received from the post-fault-clearance system data generation unit 15, and creates post-fault-clearance phase data D18. Figure 5 shows an example of the phases of the transmission line 4 after the fault has been cleared. The "post-fault-clearance phase" column in Figure 5 shows the phases of the transmission line 4 after the fault has been cleared.

[0108] (Step S10: Calculation of supply-side determination threshold) The operation of step S10 is executed by the supply-side judgment threshold determiner 19. The supply-side judgment threshold determiner 19 calculates a supply-side judgment threshold. Based on the transmission line initial phase data D17 received from the transmission line initial phase acquirer 17 and the transmission line post-fault clearance phase data D18 received from the transmission line post-fault clearance phase acquirer 18, the supply-side judgment threshold determiner 19 calculates a supply-side judgment threshold from the difference between both phases. The calculated supply-side judgment threshold is stored in the supply-side judgment threshold determiner 19 as supply-side judgment threshold data D19.

[0109] The supply-side judgment threshold determination unit 19 calculates the supply-side judgment threshold using the following (Equation 1) using the initial phases of the nodes at both ends of the transmission line 4, where the assumed fault will occur, according to the transmission line initial phase data D17 created in step S08, and the phases of the nodes at both ends of the transmission line 4 after the fault has been removed according to the transmission line post-fault removal phase data D18 extracted in step S09. Δθa=θa'-θa Δθb=θb'-θb θth=min(Δθa,Δθb) ...(Formula 1) In (Equation 1), the parameters are as follows: θa: initial phase of node a at one end of transmission line 4 θb: initial phase of node b at the other end of transmission line 4 θa': Phase after fault clearance at node a at one end of transmission line 4 θb': Phase after fault clearance at node b at the other end of transmission line 4 θth: supply-side judgment threshold

[0110] The supply-side judgment threshold determiner 19 calculates the smaller of the difference between the initial phase θa and the phase θa' after the fault has been cleared at node a at one end of the transmission line 4, and the difference between the initial phase θb ​​and the phase θb' after the fault has been cleared at node b at the other end, as the supply-side judgment threshold θth using Equation 1. The phase change of the node with the smaller phase change across the fault location is calculated as the supply-side judgment threshold θth.

[0111] Figure 5 shows an example of the difference between the initial phase and the phase after the fault is cleared at nodes a and b, which are the nodes at both ends of a transmission line 4 where a hypothetical fault occurs. In Figure 5, transmission line A is one of multiple transmission lines 4 installed in a power system 9. Node a is one end of transmission line A, and node b is the other end of transmission line A.

[0112] In Figure 5, the phase θa' at node a after the fault has been cleared is 35.4 deg, and the initial phase θa is 26.4 deg, with a difference of 9.0 deg. The phase θb' at node b after the fault has been cleared is 10.2 deg, and the initial phase θb ​​is 9.5 deg, with a difference of 0.7 deg. Of the differences between the phases after the fault has been cleared at nodes a and b and the initial phases, the smaller phase change of 0.7 deg is calculated as the supply-side determination threshold θth.

[0113] (Step S11: Extraction of supply-side subsystem) The operation in step S11 is executed by the supply-side subsystem extraction unit 21. The supply-side subsystem extraction unit 21 creates supply-side subsystem data D21. If the extracted separated system becomes a supply-side subsystem, the extracted separated system is stored in the supply-side subsystem extraction unit 21 as the supply-side subsystem data D21.

[0114] The supply-side subsystem extraction unit 21 extracts isolated systems that would result if all transmission lines 4 of a specific voltage class were cut off, and determines whether these isolated systems would become supply-side subsystems. Figure 6 shows an example of the process for determining supply-side subsystems. In Figure 6, power systems 9a, 9b, and 9c correspond to the power systems 9a, 9b, and 9c in Figure 1. Power systems 9a, 9b, and 9c are equipped with synchronous generators 2a, 2b, and 2c, respectively. Power system 9b and power system 9c are interconnected via a 275 kV bus b. Other components of power systems 9a, 9b, and 9c are not shown in Figure 6. Power systems 9a, 9b, and 9c each include multiple or a single renewable energy power source.

[0115] As an example, the supply-side subsystem extraction unit 21 cuts off all 500 kV transmission lines and extracts separated systems of a voltage class of 275 kV or less, as shown in Figure 6. Bus bar b and bus bar c are connected by a 275 kV transmission line and are included in the same separated system. On the other hand, bus bar a is not connected to bus bar b or bus bar c by a transmission line of 275 kV or less, and is therefore included in a different separated system. The supply-side subsystem extraction unit 21 determines whether each separated system extracted as described above is a supply-side subsystem.

[0116] As an example of a method for determining a supply-side subsystem, the supply-side subsystem extraction unit 21 may determine whether the separated system includes a synchronous generator 2 that will lose synchronism based on the transient stability calculation results, and may determine the separated system that includes the synchronous generator 2 that will lose synchronism as the supply-side subsystem, and the separated system that does not include the synchronous generator 2 that will lose synchronism as the demand-side subsystem. Note that loss of synchronism is a phenomenon in which the rotational speed of a generator accelerates out of synchronization, and unstable transient stability generally indicates the presence of a synchronous generator 2 that will lose synchronism.

[0117] The determination of whether the separated system is a supply-side subsystem may be made by a determination different from that described above. The determination of whether the renewable energy power source 3 is located on the supply side or the demand side is not necessarily required only when the transient stability is unstable, but may be required even when the transient stability is stable. When the transient stability is stable, there is no synchronous generator 2 that will step out, so the method described above cannot determine whether the separated system is a supply-side subsystem or a demand-side subsystem.

[0118] If the transient stability is stable, a separated system including a synchronous generator 2 or a renewable energy power source 3 in which at least one of the indexes of the internal phase difference angle, the internal phase difference angle deviation, the angular velocity, and the angular velocity deviation exceeds an arbitrary specified value (for example, a value set as a set value) may be determined to be a supply-side subsystem. If a synchronous generator 2 with large fluctuations exists, even though it has not lost step, the separated system can be said to have a high risk of becoming unstable.

[0119] In addition, the supply-side partial system extraction unit 21 may determine that the separated system including the synchronous generator 2 for which at least one of the indicators of the internal phase difference angle, the internal phase difference angle deviation, the angular velocity, and the angular velocity deviation is the largest in the power system 9 is the supply-side partial system.

[0120] Furthermore, the supply-side subsystem extraction unit 21 may combine a plurality of the above-mentioned determinations to determine that a separated system is a supply-side subsystem.

[0121] (Step S12: Determine whether the renewable energy source 3 is located on the supply side) The operation in step S12 is executed by the renewable energy location determination unit 22. The renewable energy location determination unit 22 determines the renewable energy power source 3 located on the supply side and creates supply-side renewable energy power source data D22. The renewable energy location determination unit 22 determines whether the renewable energy power source 3 is located on the supply side based on the renewable energy initial phase data D14 created in step S03 and the renewable energy post-fault removal phase data D16 created in step S07.

[0122] The renewable energy location determination unit 22 determines whether each renewable energy power source 3 included in the supply-side subsystem related to the supply-side subsystem data D21 created in step S11 is located on the supply side. The renewable energy location determination unit 22 determines whether the renewable energy power source 3 is located on the supply side using the following (Equation 2). Judgment formula: θi'-θi>θth ...(Formula 2) In (Equation 2), the parameters are as follows: i: The number of the renewable energy source 3 included in the set of renewable energy sources 3 located in the supply-side partial system θi: Initial phase of renewable energy source 3 θi': Phase after fault removal of renewable energy source 3 θth: supply-side judgment threshold A renewable energy power source 3 for which θi'-θi>θth according to (Equation 2) is determined to be located on the supply side. A renewable energy power source 3 for which θi'-θi>θth is not determined to be located on the demand side according to (Equation 2).

[0123] If the difference between the initial phase according to the renewable energy initial phase data D14 and the phase after fault removal according to the renewable energy post-fault removal phase data D16 is equal to or greater than the supply-side determination threshold according to the supply-side determination threshold data D19, the renewable energy power source 3 is determined to be located on the supply side. A renewable energy power source 3 that is not determined to be located on the supply side is determined to be located on the demand side.

[0124] Between the initial state and the state after the fault is cleared, the active power output (reactive power output) of the synchronous generator 2 and the renewable energy source 3 and the active power consumption (reactive power consumption) of the load do not change. Therefore, the difference between the initial phase and the phase after the fault is cleared occurs due to the following two factors: (1) Power flow detouring due to fault clearance (opening of the transmission line) and phase shift due to impedance change of transmission line 4 (2) Phase change due to increase or decrease in transmission loss caused by fault removal

[0125] When the transmission loss changes, the power flow to the slack node in the power flow calculation changes, and the change in the amount of active power flow in the power flow path to the slack node appears as a phase change at each node. Renewable energy source 3 located on the demand side is only affected by the phase change due to the increase or decrease in transmission loss described above in (2).

[0126] On the other hand, the phase change due to the bypass of the power flow in (1) above has a greater impact than the change in transmission loss, and only the supply-side subsystem is affected. Therefore, the phase change of a renewable energy power source 3 located on the supply side is larger than that of a renewable energy power source located on the demand side. The supply determination threshold θth is based on the value at which the phase change is greatest among the nodes in the demand-side subsystem that are only affected by the change in transmission loss. Therefore, a renewable energy power source 3 with a phase change that exceeds the supply determination threshold θth can be determined to be located on the supply side.

[0127] The renewable energy power source 3 determined to be located on the supply side is stored as supply-side renewable energy power source data D22 in the renewable energy location determination unit 22. The process by the renewable energy location determination unit 22 in step S12 may be referred to as a renewable energy location determination step or a renewable energy location determination procedure.

[0128] (Step S13: Determine whether all hypothetical accident cases have been evaluated) If it is not determined that all the assumed accident cases have been evaluated, the program proceeds to step S04, and repeats the processing of steps S04 to S12 until it is determined that all the assumed accident cases have been evaluated. If it is determined that all the assumed accident cases have been evaluated, the renewable energy location determination unit 22 transmits the supply-side renewable energy power source data D22 to the power system stabilization device 200, and the program ends.

[0129] The above is the operation of the power source estimation device 1 according to this embodiment.

[0130] [1-3.Effects] (1) According to this embodiment, the power source estimation device 1 includes an initial system data generation unit 13 that generates initial system data D13, which is system data in an initial state when there is no accident, by power flow calculation based on system information of the power system 9 to which the synchronous generator 2 that generates electric power and the renewable energy power source 3 are connected; a post-fault removal system data generation unit 15 that generates post-fault removal system data D15, which is system data after removing a fault that is expected to occur in the power system 9, by power flow calculation based on the initial system data D13 created by the initial system data generation unit 13; and a renewable energy location determination unit 22 that estimates a renewable energy power source 3 whose transient stability will be improved by being disconnected from the power system 9, based on the difference between the initial system data D13 created by the initial system data generation unit 13 and the post-fault removal system data D15 created by the post-fault removal system data generation unit 15. Therefore, it is possible to provide a power source estimation device 1 that more accurately estimates a power source whose transient stability will be improved by being disconnected from the power system 9.

[0131] By controlling the power system 9 with reference to the renewable energy power source 3 estimated by the renewable energy position determination unit 22 of the power source estimation device 1, which improves the transient stability of the power system 9 when disconnected from the power system 9, the power system including both the synchronous generator 2 and the renewable energy power source 3 can be more reliably stabilized.

[0132] (2) According to this embodiment, when the difference between the phase of the renewable energy power source 3 in the initial system data D13 created by the initial system data generation unit 13 when there is no accident and the phase after the expected accident is removed in the post-fault system data D15 created by the post-fault system data generation unit 15 exceeds a set threshold, the renewable energy location determination unit 22 estimates that the transient stability of the power system 9 will improve when the renewable energy power source 3 is disconnected from the power system 9. Therefore, it is possible to more accurately estimate the renewable energy power source 3 whose transient stability of the power system 9 will improve when it is disconnected from the power system 9.

[0133] Based on the difference between the phase of the renewable energy power source 3 when there is no accident and the phase after removing the expected accident, the renewable energy power source 3 with a phase change is determined to be located on the supply side in the topology of the power system 9.Therefore, it is possible to more accurately estimate the renewable energy power source 3 located on the supply side in the topology of the power system 9 without relying on data from past cases, for example.

[0134] (3) According to this embodiment, the power source estimation device 1 includes a supply-side determination threshold determiner 19 that calculates, as a threshold, the smaller of the differences between the phase in an accident-free state according to the initial system data D13 created by the initial system data generator 13 and the phase after the assumed accident has been removed according to the post-fault-clearance system data generator 15, for each of a plurality of nodes located on either side of a location where an assumed accident will occur or a location that will be shut off due to an assumed accident in a transmission line 4 arranged in the power system 9. This makes it possible to more accurately estimate the renewable energy power source 3 located on the supply side in the topology of the power system 9. The plurality of nodes may be located at both ends of the transmission line 4.

[0135] The supply side judgment threshold determination unit 19 calculates an appropriate threshold corresponding to the current power grid 9, and estimates that the transient stability of the power grid 9 will improve if a renewable energy source 3 that exceeds the threshold is disconnected from the power grid 9, so that it is possible to more accurately estimate the renewable energy source 3 located on the supply side in the topology of the power grid 9.

[0136] (4) According to this embodiment, the power source estimation device 1 includes a supply-side subsystem extraction unit 21 that extracts a separated system that is configured when a transmission line 4 in a predetermined voltage class is interrupted in the power system 9, and determines that a separated system that includes a synchronous generator 2 that loses synchronization or a renewable energy power source 3 among the extracted separated systems is a subsystem that improves the transient stability of the power system 9 when disconnected from the power system 9. The renewable energy location determination unit 22 estimates a renewable energy power source 3 in the subsystem determined by the supply-side subsystem extraction unit 21 that improves the transient stability of the power system 9 when disconnected from the power system 9. Therefore, the renewable energy power source 3 is estimated for the subsystem determined by the supply-side subsystem extraction unit 21. This allows renewable energy power sources 3 included in unnecessary subsystems to be excluded from candidates, and makes it possible to more accurately estimate the renewable energy power source 3 located on the supply side in the topology of the power system 9. The subsystem determined by the supply-side subsystem extraction unit 21 is determined to be the supply-side subsystem.

[0137] (5) According to this embodiment, the power source estimation device 1 extracts an isolated system in the power system 9 that is formed when a transmission line 4 of a predetermined voltage class is interrupted, and includes a supply-side subsystem extraction unit 21 that determines that an isolated system including a synchronous generator 2 or a renewable energy power source 3 in which at least one of the internal phase difference angle, the internal phase difference angle deviation, the angular velocity, and the angular velocity deviation exceeds a predetermined value or has a larger value in the power system 9 is a subsystem in which the transient stability of the power system 9 improves when the renewable energy power source 3 is disconnected from the power system 9. The renewable energy location determination unit 22 estimates the renewable energy power source 3 in the subsystem determined by the supply-side subsystem extraction unit 21, in which the transient stability of the power system 9 improves when the renewable energy power source 3 is disconnected from the power system 9. This makes it possible to more accurately estimate the renewable energy power source 3 located on the supply side in the topology of the power system 9. The subsystem determined by the supply-side subsystem extraction unit 21 is determined to be the supply-side subsystem.

[0138] [2. Second Embodiment] [2-1. Composition and Function] The power supply estimation device 1 according to the second embodiment will be described. The configuration of the power supply estimation device 1 according to the second embodiment is the same as the configuration of the power supply estimation device 1 according to the first embodiment. The power supply estimation device 1 according to the second embodiment differs from the power supply estimation device 1 according to the first embodiment in the supply side determination threshold determination unit 19 and the processing of step S10 in the computer program.

[0139] In addition to the power source estimation device 1 according to the first embodiment, the power source estimation device 1 according to the second embodiment estimates a renewable energy power source 3 that will improve the transient stability of the power system 9 when it is disconnected from the power system 9 in the event of a bus fault. When an fault occurs on a bus in the power system 9, the power source estimation device 1 determines whether each renewable energy power source 3 in the power system 9 is located on the supply side or the demand side. In the system topology, a power source that is located in a position where it will improve the transient stability of the power system 9 when it is disconnected from the power system 9 is called a power source located on the supply side.

[0140] The configuration of the power supply estimation device 1 according to the second embodiment is the same as the configuration of the power supply estimation device 1 according to the first embodiment shown in Fig. 1. Explanations overlapping with those of the power supply estimation device 1 according to the first embodiment will be omitted.

[0141] The power source estimation device 1 according to the first embodiment estimates a renewable energy power source 3 that will improve the transient stability of the power grid 9 when it is disconnected from the power grid 9, when the facility where the postulated fault occurs is a power transmission line 4. The power source estimation device 1 according to the second embodiment estimates a renewable energy power source 3 that will improve the transient stability of the power grid 9 when it is disconnected from the power grid 9, when the power transmission line 4 where the postulated fault occurs is a bus.

[0142] The supply-side judgment threshold determiner 19 calculates, as a threshold, the smaller of the differences between the phase in a fault-free state according to the initial system data D13 created by the initial system data generator 13 and the phase after the fault has been removed according to the post-fault-clearance system data generator 15, for each of a plurality of nodes located on either side of a location where an anticipated fault will occur or a location that will be shut off due to an anticipated fault in the transmission line 4, which is a bus bar arranged in the power system 9. The plurality of nodes may be end portions of the transmission line 4 to be shut off. Alternatively, the plurality of nodes may be bus bars to which the transmission line 4 is connected.

[0143] The renewable energy location determination unit 22 estimates that the transient stability of the power system 9 will improve when the renewable energy power source 3 is disconnected from the power system 9 if the difference between the phase of the renewable energy power source 3 in the case of no accident, which is based on the initial system data D13 created by the initial system data generation unit 13, and the phase after the expected accident has been removed, which is based on the post-fault removal system data D15 created by the post-fault removal system data generation unit 15, exceeds the threshold calculated by the supply side determination threshold determination unit 19.

[0144] The operation of the power source estimation device 1 according to the second embodiment will be described with reference to FIG.

[0145] Let us consider the case where a fault occurs at bus bar z1 shown in Figure 7. Bus bar z1 and bus bar z2 form two circuits. Transmission lines A, B, C, and D are connected to bus bar z1 and bus bar z2, respectively. Transmission lines A, B, C, and D are connected to synchronous generators 2a, 2b, 2c, and 2d via bus bars a, b, c, and d, respectively.

[0146] In step S05 of the computer program, the post-fault removal system data generation unit 15 creates post-fault removal system data D15, which is system data after the expected accident has been removed, based on the initial system data D13 created in step S02 and the location of the expected accident selected in step S04.

[0147] As an example, the post-fault clearance system data generator 15 of the power source estimation device 1 according to this embodiment creates system data for a case where an assumed fault occurs on bus z1 and as a result, transmission lines A, B, C, and D are opened, and sets the system data as post-fault clearance system data D15. The post-fault clearance system data D15 is created when one line of each of transmission lines A, B, C, and D is opened.

[0148] In step S10 of the computer program, the supply-side judgment threshold determiner 19 calculates a supply-side judgment threshold from the phase difference based on the power transmission line initial phase data D17 received from the power transmission line initial phase acquirer 17 and the power transmission line post-fault clearance phase data D18 received from the power transmission line post-fault clearance phase acquirer 18, and generates supply-side judgment threshold data D19.

[0149] The supply-side judgment threshold determination unit 19 calculates the supply-side judgment threshold based on the post-fault-clearance system data D15 created in step S05, using the initial phases and the phases after the fault is cleared of the nodes at both ends of each of the transmission lines A, B, C, and D.

[0150] The supply-side judgment threshold determination unit 19 calculates the supply-side judgment threshold by the following (Equation 3) using the initial phases of the nodes at both ends of the transmission lines A, B, C, and D according to the transmission line initial phase data D17 created in step S08, and the phases of the nodes at both ends of the transmission lines A, B, C, and D after the fault has been removed according to the transmission line post-fault removal phase data D18 extracted in step S09. Δθa=θa'-θa Δθb=θb'-θb Δθc=θc'-θc Δθd=θd'-θd Δθz2=θz2'-θz2 θth=min(Δθa, Δθb, Δθc, Δθd, Δθz2) ...(Formula 3) In (Equation 3), the parameters are as follows: θa, θb, θc, θd, θz2: Initial phases of end nodes of transmission line A, transmission line B, transmission line C, transmission line D, and nodes of bus z2 θa', θb', θc', θd', θz2': Phases after fault clearance of end nodes of transmission line A, transmission line B, transmission line C, and transmission line D, and nodes of bus z2 θth: supply-side judgment threshold

[0151] Figure 8 shows an example of the initial phase, phase after fault clearance, and phase difference of bus z2, bus a, bus b, bus c, and bus d, which constitute the nodes at both ends of transmission line A, transmission line B, transmission line C, and transmission line D when a fault occurs at bus z1. Bus z2 and bus a are the nodes at both ends of transmission line A. Bus z2 and bus b are the nodes at both ends of transmission line B. Bus z2 and bus c are the nodes at both ends of transmission line C. Bus z2 and bus d are the nodes at both ends of transmission line D. The phase difference indicates the phase change between the initial phase and the phase after the fault is cleared.

[0152] Of the differences between the initial phase and the phase after fault clearance for bus z2, bus a, bus b, bus c, and bus d, the smaller of the phase changes, 0.1 deg, is calculated as the supply-side judgment threshold θth. The supply-side judgment threshold determiner 19 sets the calculated supply-side judgment threshold θth as supply-side judgment threshold data D19.

[0153] In step S12 of the computer program, the renewable energy location determination unit 22 determines the renewable energy power source 3 located on the supply side and creates supply-side renewable energy power source data D22. The renewable energy location determination unit 22 determines whether the renewable energy power source 3 is located on the supply side based on the renewable energy initial phase data D14 created in step S03 and the renewable energy post-fault removal phase data D16 created in step S07.

[0154] The renewable energy location determination unit 22 determines whether each renewable energy power source 3 included in the supply-side subsystem related to the supply-side subsystem data D21 created in step S11 is located on the supply side. The renewable energy location determination unit 22 determines whether the renewable energy power source 3 is located on the supply side using the above-mentioned (Equation 2). The renewable energy power source 3 determined to be located on the supply side is stored in the renewable energy location determination unit 22 as supply-side renewable energy power source data D22. The renewable energy location determination unit 22 transmits the supply-side renewable energy power source data D22 to the power system stabilization device 200.

[0155] The other processes are the same as those in the first embodiment. The above is the operation of the power source estimation device 1 according to this embodiment.

[0156] [2-2. Effects] (1) According to this embodiment, the power source estimation device 1 has a supply side judgment threshold determination unit 19 that calculates the smaller of the differences between the phase in an accident-free state according to the initial system data D13 created by the initial system data generation unit 13 and the phase after the expected accident has been removed according to the post-fault removal system data generation unit 15 for each of multiple nodes located on either side of a location where an expected accident will occur or a location that will be cut off due to an expected accident on a transmission line 4 arranged in the power system 9. This makes it possible to more accurately estimate the renewable energy power source 3 located on the supply side in the topology of the power system 9.

[0157] The plurality of nodes may be end portions of the power transmission line 4. The plurality of nodes may also be bus bars to which the power transmission line 4 is connected. According to this embodiment, in the event of a fault on the bus bar, it is possible to estimate the renewable energy power source 3 that will be disconnected from the power grid 9, thereby improving the transient stability of the power grid 9.

[0158] The supply-side judgment threshold determiner 19 calculates an appropriate threshold corresponding to the current state of the power grid 9. When the difference between the phase of the renewable energy power source 3 in the initial system data D13 created by the initial system data generator 13 when there is no fault and the phase of the renewable energy power source 3 after the expected fault has been removed in the post-fault removal system data D15 created by the post-fault removal system data generator 15 exceeds the threshold calculated by the supply-side judgment threshold determiner 19, the renewable energy location determiner 22 estimates that the transient stability of the power grid 9 will improve when the renewable energy power source 3 is disconnected from the power grid 9, and therefore it is possible to more accurately estimate the renewable energy power source 3 whose transient stability of the power grid 9 will improve when disconnected from the power grid 9.

[0159] Based on the difference between the phase of the renewable energy power source 3 when there is no accident and the phase after removing the expected accident, the renewable energy power source 3 with a phase change is determined to be located on the supply side in the topology of the power system 9.Therefore, it is possible to more accurately estimate the renewable energy power source 3 located on the supply side in the topology of the power system 9 without relying on data from past cases, for example.

[0160] 3. Other Embodiments Although embodiments including modifications have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These 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 within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. The following is an example.

[0161] (1) In the above embodiment, the power flow calculation execution unit 12 executes power flow calculation based on the AC method, but it may also execute power flow calculation based on the DC method. Power flow calculation based on the DC method is executed based on assumptions such as a constant voltage (for example, 1.0 pu) and line resistance R=0. Power flow calculation based on the DC method has lower calculation accuracy than power flow calculation based on the AC method, but can reduce the calculation load of the power flow calculation.

[0162] Power flow calculation using the DC method results in a different active power flow compared to power flow calculation using the AC method. However, the renewable energy location determination unit 22 of the power source estimation device 1 according to the above embodiment determines whether the renewable energy power source 3 is located on the supply side or the demand side based on the difference between the initial phase and the phase after the fault is cleared. Therefore, even when power flow calculation using the DC method is used, it is possible to determine whether the renewable energy power source 3 is located on the supply side, which is a position where the transient stability of the power grid 9 is improved by disconnecting it from the power grid 9.

[0163] In addition, in the DC method, since R = 0, power flow calculations can be performed assuming transmission loss to be 0. Therefore, the influence of phase changes due to changes in transmission loss does not appear, so the supply determination threshold value can be set to 0.0.

[0164] The initial system data D13 and the system data after fault removal D15 are created by power flow calculation based on the AC method or power flow calculation based on the DC method. Therefore, power flow calculation based on the AC method or power flow calculation based on the DC method can be used depending on the complexity of the power flow calculation and the accuracy of the calculation.

[0165] (2) The power source estimation device 1 may determine whether the renewable energy power source 3 is located on the supply side or the demand side using a calculation different from that in the above embodiment. The power source estimation device 1 may determine whether the renewable energy power source 3 is located on the supply side or the demand side based on a branch that becomes a step-out locus. A step-out locus is a branch in which the phase difference between the nodes at both ends increases significantly when a step-out synchronous generator 2 or a renewable energy power source 3 is present.

[0166] The power source estimation device 1 extracts a branch that is an out-of-step locus, changes the output of any renewable energy power source 3 to 0, and performs a power flow calculation. If the power flow of the out-of-step locus has decreased compared to before the output change, it is determined that the renewable energy power source 3 is located on the supply side, and if it has not decreased, it is determined that the renewable energy power source 3 is located on the demand side.

[0167] However, it is preferable to determine whether a renewable energy power source 3 is located on the supply side or the demand side based on the branch that is the out-of-step locus only when the transient stability is unstable. When the transient stability is stable, it is not possible to determine whether a renewable energy power source 3 is located on the supply side or the demand side based on the branch that is the out-of-step locus. In addition, it is necessary to perform power flow calculations as many times as the number of renewable energy power sources 3 in the system. Therefore, the calculations of the power source estimation device 1 according to the first and second embodiments are more versatile and efficient.

[0168] (3) In the above embodiment, the phase in the case of no fault according to the initial system data D13 and the phase after the anticipated fault has been removed according to the post-fault-clearance system data D15 are the phases at each of the multiple nodes of the transmission line 4, and the multiple nodes of the transmission line 4 are assumed to be the ends of the transmission line 4. However, the multiple nodes of the transmission line 4 are not limited to the ends of the transmission line 4. The multiple nodes may be nodes spaced apart from each other and sandwiching a location on the transmission line 4 where an anticipated fault will occur or a location that will be shut off due to an anticipated fault. The transmission line 4 may be a bus bar. [Explanation of symbols]

[0169] 1...Power estimation device 11. System Information Collection Department 12. Power flow calculation execution unit 13. Initial system data generation section 14. Renewable energy initial phase acquisition unit 15. Post-fault removal system data generation unit 16. Phase acquisition section after removal of renewable energy fault 17...Transmission line initial phase acquisition section 18...Phase acquisition unit after transmission line fault removal 19. Supply-side judgment threshold determination unit 21... Supply side partial system extraction part 22 Renewable energy location determination unit 2. Synchronous generator 3. Renewable energy sources 4, 4-1, 4-2, 4-3... Transmission lines 5, 5-1, 5-2... Circuit breaker 6, 6-1, 6-2... Transformer 7, 7-1, 7-2, 7-3, 7-4, 7-5... Information gathering device 8. Accident detection device 9, 9a, 9b, 9c...Power system 80...Communication line 90...Main grid 200...Power system stabilization device

Claims

1. an initial system data generation unit that generates initial system data by power flow calculation, the initial system data being system data in an initial state when there is no accident, based on system information of a power system to which a synchronous generator that generates power and a renewable energy power source are connected; a post-fault-cleared system data generating unit that generates post-fault-cleared system data, which is system data after removing a fault that is expected to occur in the power system, by power flow calculation based on the initial system data generated by the initial system data generating unit; a renewable energy location determination unit that estimates the renewable energy power source that will improve the transient stability of the power system by being disconnected from the power system, based on a difference between the initial system data created by the initial system data generation unit and the post-fault clearance system data created by the post-fault clearance system data generation unit; and A power supply estimation device comprising:

2. The renewable energy location determination unit determines the location of the renewable energy power source. When a difference between a phase in a case where there is no fault in the initial system data created by the initial system data generation unit and a phase after an assumed fault has been removed in the post-fault removal system data created by the post-fault removal system data generation unit exceeds a set threshold, it is estimated that the transient stability of the power system will be improved by disconnecting the renewable energy power source from the power system. The power supply estimation device according to claim 1 .

3. Each of a plurality of nodes located on either side of a location where the fault is expected to occur or a location where the fault will be shut off due to the expected fault, in a transmission line arranged in the power system, a supply-side determination threshold value determining unit that calculates, as the threshold value, a smaller value of a difference between a phase in a case where there is no fault in the initial system data created by the initial system data creating unit and a phase after an expected fault has been removed in the post-fault-cleared system data created by the post-fault-cleared system data creating unit; The power supply estimation device according to claim 2 .

4. a supply-side partial system extraction unit that extracts isolated systems that are configured when a transmission line of a predetermined voltage class is cut off in the power system, and determines that the isolated system that includes the synchronous generator that steps out of the extracted isolated systems is a partial system in which transient stability of the power system is improved by paralleling off the renewable energy power source from the power system; The renewable energy location determination unit estimates a renewable energy power source in the subsystem determined by the supply-side subsystem extraction unit, which will improve transient stability of the power system when disconnected from the power system. The power supply estimation device according to claim 2 .

5. a supply-side partial system extraction unit that extracts a separated system that is configured when a transmission line of a predetermined voltage class is cut off in the power system, and determines that the separated system including the synchronous generator or the renewable energy power source in which at least one of an internal phase difference angle, an internal phase difference angle deviation, an angular velocity, and an angular velocity deviation exceeds a predetermined specified value or has a larger value in the power system, is a partial system in which transient stability of the power system is improved by paralleling off the renewable energy power source from the power system; The renewable energy location determination unit estimates a renewable energy power source in the subsystem determined by the supply-side subsystem extraction unit, which will improve transient stability of the power system when disconnected from the power system. The power supply estimation device according to claim 2 .

6. The initial system data and the post-fault clearance system data are created by power flow calculation based on an AC method or power flow calculation based on a DC method. The power supply estimation device according to claim 2 .

7. On the computer, an initial system data generation step of generating initial system data by power flow calculation, the initial system data being system data in an initial state when there is no accident, based on system information of a power system to which a synchronous generator that generates electric power and a renewable energy power source are connected; a post-fault-cleared system data generating step of generating post-fault-cleared system data, which is system data after removing a fault that is expected to occur in the power system, by power flow calculation based on the initial system data generated in the initial system data generating step; a renewable energy location determination step of estimating the renewable energy power source that will improve the transient stability of the power system when disconnected from the power system, based on the initial system data created in the initial system data generation step and the post-fault clearance system data created in the post-fault clearance system data generation step; A computer program for a power supply estimation device.

8. an initial system data generation procedure for generating initial system data, which is system data in an initial state when there is no accident, by power flow calculation based on system information of a power system to which a synchronous generator that generates power and a renewable energy power source are connected; a post-fault-cleared system data generation procedure for generating post-fault-cleared system data, which is system data after removing a fault that is expected to occur in the power system, by power flow calculation based on the initial system data generated by the initial system data generation procedure; a renewable energy location determination procedure for estimating the renewable energy power source that will improve the transient stability of the power system when disconnected from the power system, based on the initial system data created by the initial system data generation procedure and the post-fault clearance system data created by the post-fault clearance system data generation procedure; A power supply estimation method comprising:

Images