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

Abstract

To control for maintaining both transient stability and voltage stability of a power system.SOLUTION: In a system related to a power system, a power system stabilization device 1 has: a voltage stability evaluation unit 104 for calculating a load increase amount and a reactive power loss by which voltage stability is maintained using a transient stability calculation that simulates a case where power supply is limited; a reactive power loss target calculation unit 105 for selecting at least one of a synchronous generator and a renewable energy power supply as a first power control machine, being a target of power supply limitation, by which voltage stability is maintained, and calculating a reactive power loss target value based on a difference between a reactive power loss when power is controlled by the first power control machine and the reactive power loss calculated by the voltage stability evaluation unit; and a power control amount adjustment unit 106 for adding the reactive power loss target value in which the reactive power loss is calculated, selecting at least one of the synchronous generator and the renewable energy power supply as a second power control machine being a target of the power supply limitation so as to further reduce the power control amount related to the power supply limitation, and creating power control amount adjustment information D213.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present embodiment relates to a power system stabilization device, a power system stabilization system, a computer program for the power system stabilization device, and a power system stabilization method that create control information for stabilizing a power system. [Background technology]

[0002] BACKGROUND ART A power system stabilizer that calculates operation amounts of a plurality of generators, including renewable energy power sources, arranged in a power system is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-011933 [Patent Document 2] JP 2021-141790 A [Patent Document 3] Japanese Patent Application Publication No. 2023-023185 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, renewable energy sources (hereafter referred to as "renewable energy sources") have been introduced in large quantities into power grids. These power grids are operated with a configuration that has a lower ratio of synchronous generators than conventional systems. If an accident occurs in a power grid with such a configuration and power supply restrictions (hereafter referred to as "power restrictions") are imposed, the number of operating synchronous generators, which are voltage maintenance sources, may decrease further, potentially reducing voltage stability.

[0005] Conventional technologies are known for maintaining voltage stability in power systems through additional control, such as additional shedding control, load shedding control (sometimes called "negative control"), and the introduction of phase modifying equipment. Implementing additional control increases the voltage, thereby improving voltage stability.

[0006] However, adding control targets to maintain voltage stability increases the amount of control, which can affect transient stability and reduce frequency regulation. Furthermore, it can reduce the margin for voltage and reactive power control (VQC) and other human-controlled control targets. It is preferable for power systems to be controlled to simultaneously maintain both transient stability and voltage stability, leaving as much margin for frequency regulation and voltage and reactive power control as possible.

[0007] Furthermore, in the control for maintaining voltage stability in the prior art, control for adding a shedding machine is performed without considering transient stability, and a process for checking transient stability is performed after the control. Therefore, although the selected control may be able to maintain transient stability, it may not be able to maintain voltage stability.

[0008] If voltage stability cannot be maintained, the process of selecting a generator to be shedding is executed again. This increases the amount of calculation required for control and causes delays in control. It is preferable that the power system be controlled so as to maintain both transient stability and voltage stability in a single process.

[0009] In view of the above problems, the present embodiment aims to provide a power system stabilization device, a power system stabilization system, a computer program for the power system stabilization device, and a power system stabilization method that perform control to maintain both the transient stability and voltage stability of the power system. [Means for solving the problem]

[0010] The power system stabilization device of this embodiment has the following features. (1) The system has a voltage stability evaluation unit that calculates the load increase at which voltage stability is maintained and the reactive power loss at that load increase through transient stability calculations that simulate the case where power supply limitation, a control method for maintaining transient stability, is performed on a power system composed of synchronous generators and renewable energy power sources. (2) At least one of the synchronous generator and the renewable energy power source is selected as a first control unit that is subject to power supply restrictions to maintain voltage stability, and a reactive power loss target calculation unit is provided that calculates a reactive power loss target value based on the difference between the reactive power loss when controlled by the first control unit and the reactive power loss in the load increase amount calculated by the voltage stability evaluation unit. (3) A power control amount adjustment unit is provided that selects at least one of the synchronous generator and the renewable energy power source as a second power control machine that is subject to power supply restriction so that the reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation unit and the power control amount subject to the power supply restriction is reduced, and creates power control amount adjustment information. (4) Outputting the electrical control amount adjustment information created by the electrical control amount adjustment unit. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of an entire system using a power system stabilization device 1 according to a first embodiment. [Figure 2] FIG. 1 is a diagram showing a configuration of a power system stabilization device 1 according to a first embodiment. [Figure 3] FIG. 1 is a diagram showing an overall flow of a program of a power system stabilizing device 1 according to a first embodiment. [Figure 4] FIG. 1 is a diagram showing a detailed flow of step S1 of the program of the power system stabilizing device 1 according to the first embodiment. [Figure 5] FIG. 10 is a diagram showing a detailed flow of step S4 of the program of the power system stabilizing device 1 according to the first embodiment. [Figure 6] FIG. 10 is a diagram showing a detailed flow of step S42 of the program of the power system stabilizing device 1 according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing a detailed flow of step S45 of the program of the power system stabilizing device 1 according to the first embodiment. [Figure 8] FIG. 10 is a diagram showing a detailed flow of step S5 of the program of the power system stabilizing device 1 according to the first embodiment. [Figure 9]FIG. 1 is a diagram showing an example of system information D201 of the power system stabilization device 1 according to the first embodiment. [Figure 10] FIG. 1 is a diagram showing an example of system data D202 of the power system stabilizing device 1 according to the first embodiment. [Figure 11] FIG. 10 is a diagram showing an example of assumed accident case information D203 of the power system stabilizing device 1 according to the first embodiment. [Figure 12] FIG. 10 is a diagram showing an example of voltage stability target information D204 of the power system stabilizing device 1 according to the first embodiment. [Figure 13] FIG. 1 is a diagram showing an example of transient stability maintenance shear control machine information D205 of the power system stabilization device 1 according to the first embodiment. [Figure 14] FIG. 10 is a diagram showing an example of out-of-step order information D206 of the power system stabilizing device 1 according to the first embodiment. [Figure 15] FIG. 1 is a diagram showing an example of transient stability calculation representative value information D207 of the power system stabilization device 1 according to the first embodiment. [Figure 16] FIG. 10 is a diagram showing an example of unstable system information D208 of the power system stabilization device 1 according to the first embodiment. [Figure 17] FIG. 1 is a diagram showing an example of system cross-sectional data before a load increase of the power system stabilization device 1 according to the first embodiment. [Figure 18] FIG. 10 is a diagram showing an example of system cross-sectional data after a load increase of the power system stabilization device 1 according to the first embodiment. [Figure 19] FIG. 10 is a diagram showing an example of voltage stability evaluation information D209 of the power system stabilization device 1 according to the first embodiment. [Figure 20] FIG. 10 is a diagram showing an example of reactive power loss target information D210 of the power system stabilizing device 1 according to the first embodiment. [Figure 21] FIG. 10 is a diagram showing an example of target cross-section information D211 of the power system stabilizing device 1 according to the first embodiment. [Figure 22] FIG. 10 is a diagram showing an example of change cross-section information D212 of the power system stabilizing device 1 according to the first embodiment. [Figure 23] FIG. 10 is a diagram showing an example of a result of power flow calculation by the reactive power loss target calculation unit 105 of the power system stabilization device 1 according to the first embodiment. [Figure 24]FIG. 10 is a diagram showing an example of power control amount adjustment information D213 of the power system stabilizing device 1 according to the first embodiment. [Figure 25] FIG. 1 is a diagram illustrating an image of a load margin of a power system stabilization device 1 according to a first embodiment. [Figure 26] FIG. 1 is a diagram illustrating an image of an incremental margin of reactive power loss in the power system stabilization device 1 according to the first embodiment. [Figure 27] FIG. 1 is a diagram showing a configuration of a power system stabilization device 1 according to a second embodiment. [Figure 28] FIG. 10 is a diagram showing a configuration of a power system stabilization device 1 according to a third embodiment. [Figure 29] FIG. 10 is a diagram showing an overall flow of a program of the power system stabilizing device 1 according to the third embodiment. [Figure 30] FIG. 10 is a diagram showing a configuration of a power system stabilization device 1 according to a fourth embodiment. [Figure 31] FIG. 10 is a diagram showing an overall flow of a program of the power system stabilizing device 1 according to the fourth embodiment. [Figure 32] FIG. 10 is a diagram showing an example of power control amount adjustment division information D215 of the power system stabilizing device 1 according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment] [1-1.Configuration] [1-1-1. Overall structure] Fig. 1 is a diagram showing the configuration of the entire system using a power system stabilization device 1 according to the first embodiment. Fig. 1 shows the configuration of a system related to a power system 70 to which a power system stabilization system 100 is applied. The power system stabilization system 100 is made up of the power system stabilization device 1 and a control terminal device 40.

[0013] 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.

[0014] Power supply limitation (hereinafter, sometimes referred to as "power control") is a control that cuts off the synchronous generator 71 or the renewable energy power source 72, which will be described later. The synchronous generator 71 and the renewable energy power source 72 may be collectively referred to as generators. The synchronous generator 71 may also be operated as an electric motor.

[0015] As an example, the power system 70 has a plurality of synchronous generators 71 (71a, 71b, 71c, 71d, 71e) and a plurality of renewable energy power sources 72 (72a, 72b, 72c, 72d, 72e). The power system 70 may have any number of synchronous generators 71 and renewable energy power sources 72. Renewable energy power sources may be referred to as renewable energy power sources.

[0016] A plurality of synchronous generators 71 and a plurality of renewable energy power sources 72 are interconnected via a power transmission line. Electric power generated by the synchronous generator 71 and the plurality of renewable energy power sources 72 is supplied to loads 77 (77a, 77b) via the power transmission line. The loads 77 are loads such as devices used in a plurality of consumers such as buildings, factories, and ordinary homes.

[0017] The synchronous generators 71 (71a, 71b, 71c, 71d, 71e) are connected to the transmission line via transformers 73 (73a, 73b, 73c, 73d, 73e) and circuit breakers 75 (75a, 75b, 75c, 75d, 75e), respectively. The synchronous generators 71 are composed of power generation equipment such as nuclear, hydroelectric, or thermal power. The transformers 73 convert the voltage of the power output from the synchronous generators 71 into a predetermined voltage.

[0018] The circuit breaker 75 is composed of a switch that cuts off power, and cuts off the power output from the synchronous generator 71. The circuit breaker 75 is connected to a control terminal device 40, which will be described later, by a control cable (not shown). Although the control terminal device 40 is represented by one block in FIG. 1 , multiple control terminal devices 40 are arranged in the power system 70. A control terminal device 40 is installed in each power plant where a synchronous generator 71, which is to be controlled by the power system stabilization device 1, is arranged. The opening and closing of the circuit breaker 75 is controlled by the control terminal device 40. When the circuit breaker 75 is opened and closed, the synchronous generator 71 is disconnected from the power system 70.

[0019] The renewable energy power sources 72 (72a, 72b, 72c, 72d, 72e) are connected to power transmission lines via transformers 74 (74a, 74b, 74c, 74d, 74e), respectively. The renewable energy power sources 72 are composed of power generation devices such as solar and wind power. The transformers 74 convert the voltage of the power output from the renewable energy power sources 72 into a predetermined voltage.

[0020] The renewable energy power source 72 is connected to a control terminal device 40 (described later) via a communication line. The output of the renewable energy power source 72 is controlled by the control terminal device 40. When the output of the renewable energy power source 72 is cut off, the renewable energy power source 72 is disconnected from the power grid 70.

[0021] The information collection devices 76 (76a, 76b, 76c, 76d, 76e, 76f) are composed of detection devices that detect state quantities of the power system 70. The information collection devices 76 are placed at predetermined measurement points in the power system 70. The information collection devices 76 measure and output the open / close states of the circuit breakers 75 and disconnecting switches (not shown), the active power and reactive power of the load, and the active power and voltage of the synchronous generator 71 and the renewable energy power source 72. The information collection devices 76 also receive and output information about system faults detected by protective devices (not shown) in the synchronous generator 71 and the renewable energy power source 72. The information output from the information collection devices 76 is transmitted to the power system stabilization device 1 via a communication line 80 (described later).

[0022] The communication line 80 is configured by a dedicated line such as a microwave radio line, a public line such as the Internet, a telephone line, etc. Communication is performed between the power system stabilizing device 1 and the information collecting device 76 and the control terminal device 40 via the communication line 80.

[0023] The control terminal device 40 is configured by a control device having a communication function. The control terminal device 40 is connected to a circuit breaker 75 of the power system 70 and a renewable energy power source 72. The control terminal device 40 is also connected to an information collection device 76 of the power system 70 via a communication line 80. The control terminal device 40 is connected to a control signal transmission unit 107 of the power system stabilization device 1, which will be described later, by a communication line. The control terminal device 40 is placed in the power system 70. The communication line connecting the control terminal device 40 and the control signal transmission unit 107 of the power system stabilization device 1 may be a dedicated line.

[0024] When the control terminal device 40 receives information from the information collection device 76 indicating that an accident has occurred in the power system 70, it selects one of the optimization results related to the power control amount adjustment information D213 (described later) transmitted from the power system stabilization device 1, and controls the target circuit breaker 75 and renewable energy power source 72. The control terminal device 40 transmits a control signal to open the circuit breaker 75 and a control signal to stop the output of the renewable energy power source 72.

[0025] [1-1-2. Configuration of Power System Stabilizer 1] The configuration of the power system stabilization device 1 will be described as an example of this embodiment with reference to Fig. 2. The power system stabilization device 1 is configured by a computer. The power system stabilization device 1 includes one or more processors. The power system stabilization device 1 may be configured by a single computer device or a digital relay device. Furthermore, the power system stabilization device 1 may be configured by two or more distributed computer devices or digital relay devices.

[0026] The power system stabilization device 1 calculates control to maintain both the transient stability and voltage stability of the power system 70. The power system stabilization device 1 is connected to the control terminal device 40 and the information collection device 76 via a communication line 80. The power system stabilization device 1 may be connected to the control terminal device 40 via a dedicated communication line.

[0027] The power system stabilizing device 1 has a calculation unit 10, a storage unit 20, and an input unit 30. The calculation unit 10 is connected to the storage unit 20 and the input unit 30. The calculation unit 10 is also connected to a control terminal device 40 and an information collection device 76 via a communication line 80 or a communication wire.

[0028] The calculation unit 10 is configured by a CPU (Central Processing Unit) of a microcomputer, etc. The calculation unit 10 has a data management unit 101, a system data creation unit 102, a transient stability maintenance shearing control machine selection unit 103, a voltage stability evaluation unit 104, a reactive power loss target calculation unit 105, a shearing control amount adjustment unit 106, and a control signal transmission unit 107.

[0029] Some or all of these units may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The operations of these units may be realized by the programs shown in FIGS. 3 to 8.

[0030] The storage unit 20 is configured with a storage medium such as a hard disk or semiconductor memory. The storage unit 20 may be configured with, for example, a random access memory (RAM), a read only memory (ROM), a flash memory such as a solid state drive (SSD), or a hard disk drive (HDD). The storage unit 20 is connected to the calculation unit 10. The calculation unit 10 controls the writing and reading of data to and from the storage unit 20.

[0031] The input unit 30 is configured with an operating device such as a keyboard, mouse, or touch panel, or a receiving circuit or an external memory connection circuit. The input unit 30 is connected to the calculation unit 10. Information is input via the input unit 30 by communication or from an external device. Information may be input from the input unit 30 by operation by an operator.

[0032] A power system model when power system 70 is in one state may be referred to as a "system cross section" or a "cross section."

[0033] The data management unit 101 of the calculation unit 10 stores the system information D201 in the storage unit 20. The system information D201 is information relating to the open or closed state of the circuit breaker 75, the active power output of the synchronous generator 71 and the renewable energy power source 72, the impedance and capacitance of the transmission line, etc. The data management unit 101 regards information indicating the state quantities of the power system 70 input to the input unit 40 as the system information D201.

[0034] The data management unit 101 of the calculation unit 10 stores the postulated accident case information D203 in the storage unit 20. The postulated accident case information D203 includes information on the location and nature of an accident that is expected to occur in the power system 70. The postulated accident case information D203 is operated by an operator and input to the input unit 30.

[0035] The data management unit 101 of the calculation unit 10 stores the voltage stability target information D204 in the storage unit 20. The voltage stability target information D204 includes information that is one or more target values ​​for voltage stability. The voltage stability target information D204 is operated by an operator and input to the input unit 30.

[0036] The system data creation unit 102 of the calculation unit 10 creates system data D202 based on the system information D201 stored in the storage unit 20. The system data D202 includes information about each node in the power system 70, such as PQ designation, PV designation in power flow calculation, node type (e.g., slack node), active power, reactive power, and voltage, as well as information about each branch (e.g., start node ID, end node ID, impedance, capacitance, etc.). The system data creation unit 102 stores the created system data D202 in the storage unit 20.

[0037] The transient stability maintenance shearing control machine selection unit 103 of the calculation unit 10 creates transient stability maintenance shearing control machine information D205 based on the system data D202 and assumed accident case information D203. The transient stability maintenance shearing control machine selection unit 103 selects a shearing control machine to be controlled to maintain transient stability from among the synchronous generators 71 and renewable energy power sources 72 of the power system 70, and creates transient stability maintenance shearing control machine information D205. The transient stability maintenance shearing control machine selection unit 103 stores the created transient stability maintenance shearing control machine information D205 in the storage unit 20.

[0038] The transient stability maintenance shearing control machine selection unit 103 creates out-of-step order information D206. The out-of-step order information D206 is information related to the out-of-step order of the shearing control machines selected as the control targets. The transient stability maintenance shearing control machine selection unit 103 creates the out-of-step order information D206 in the process of selecting the shearing control machines to be controlled to maintain transient stability. The transient stability maintenance shearing control machine selection unit 103 stores the created out-of-step order information D206 in the memory unit 20.

[0039] The transient stability maintenance shearing control machine selection unit 103 creates transient stability calculation representative value information D207. The transient stability calculation representative value information D207 is information on the representative value of transient stability calculation in the combination of shearing control machines for maintaining transient stability. The transient stability calculation representative value information D207 includes information on the active power, reactive power, voltage, phase, etc. of each node in the representative value of transient stability calculation.

[0040] The transient stability maintaining shearing control machine selection unit 103 creates transient stability calculation representative value information D207 in the process of selecting shearing control machines to be controlled to maintain transient stability. The transient stability maintaining shearing control machine selection unit 103 stores the created transient stability calculation representative value information D207 in the storage unit 20.

[0041] The transient stability maintenance shearing control unit selection unit 103 generates unstable system information D208. The unstable system information D208 is information on unstable nodes and unstable branches associated with shearing control units that become unstable, selected based on transient stability calculations. The unstable system information D208 includes binary information, unstable or stable, for each node and branch.

[0042] The transient stability maintenance shearing control machine selection unit 103 generates unstable system information D208 in the process of selecting shearing control machines to be controlled in order to maintain transient stability. The transient stability maintenance shearing control machine selection unit 103 stores the generated unstable system information D208 in the storage unit 20.

[0043] The voltage stability evaluation unit 104 of the calculation unit 10 generates voltage stability evaluation information D209 based on the transient stability calculation representative value information D207. The voltage stability evaluation information D209 is information about the power flow calculation result when the power flow calculation converges.

[0044] The voltage stability evaluation unit 104 creates cross-sectional data before the load increase based on the transient stability calculation representative value information D207. The cross-sectional data before the load increase is used for power flow calculation. The voltage stability evaluation unit 104 performs power flow calculation based on the cross-sectional data before the load increase and creates system cross-sectional data after the load increase.

[0045] When the power flow calculation converges, the voltage stability evaluation unit 104 sets the power flow calculation result as voltage stability evaluation information D209. The voltage stability evaluation unit 104 stores the created voltage stability evaluation information D209 in the storage unit 20.

[0046] Based on the results of the power flow calculation, the voltage stability evaluation unit 104 sums up the reactive power losses of the unstable branches to generate reactive power loss target information D210. The reactive power loss target information D210 is information related to the reactive power loss target value when the power flow calculation converges. The voltage stability evaluation unit 104 stores the generated reactive power loss target information D210 in the storage unit 20.

[0047] The voltage stability evaluation unit 104 generates target cross-sectional information D211 based on the transient stability calculation representative value information D207. The target cross-sectional information D211 is information related to a cross-section where the load has increased to the target value of voltage stability. The voltage stability evaluation unit 104 stores the generated target cross-sectional information D211 in the storage unit 20.

[0048] The reactive power loss target calculation unit 105 of the calculation unit 10 generates changed cross section information D212 based on the target cross section information D211. The changed cross section information D212 is information on a cross section in which the combination of shearing machines in the target cross section according to the target cross section information D211 has been changed. The reactive power loss target calculation unit 105 stores the generated changed cross section information D212 in the storage unit 20.

[0049] The reactive power loss target calculation unit 105 updates the reactive power loss target information D210 based on the changed cross-section information D212. The reactive power loss target information D210 is information related to a reactive power loss target value. The reactive power loss target calculation unit 105 adds up the reactive power losses of the unstable branches based on the result of the power flow calculation, and creates new reactive power loss target information D210. The reactive power loss target calculation unit 105 updates the reactive power loss target information D210 to the newly created reactive power loss target information D210. The reactive power loss target calculation unit 105 stores the updated reactive power loss target information D210 in the storage unit 20.

[0050] The power control amount adjustment unit 106 of the calculation unit 10 creates power control amount adjustment information D213 based on the optimization result. The power control amount adjustment information D213 is information related to the result of the optimization calculation. The power control amount adjustment unit 106 executes the optimization calculation based on the system data D202, transient stability maintenance power control machine information D205, reactive power loss target information D210, and changed cross section information D212. The power control amount adjustment unit 106 stores the created power control amount adjustment information D213 in the storage unit 20.

[0051] The control signal transmission unit 107 of the calculation unit 10 is configured by a transmission circuit, an external memory connection circuit, etc. The control signal transmission unit 107 transmits the electrical control amount adjustment information D213 to the control terminal device 40.

[0052] The memory unit 20 stores system information D201, system data D202, assumed accident case information D203, voltage stability target information D204, transient stability maintenance shear control machine information D205, step-out order information D206, transient stability calculation representative value information D207, unstable system information D208, voltage stability evaluation information D209, reactive power loss target information D210, target cross section information D211, changed cross section information D212, and shear control amount adjustment information D213.

[0053] The system information D201 is information that indicates the state quantities of the power system 70. The system information D201 includes information on the open or closed state of the circuit breaker 75, the active power output of the synchronous generator 71 and the renewable energy power source 72, the impedance and capacitance of the transmission line, etc. The system information D201 is created by the data management unit 101 of the calculation unit 10 and stored in the storage unit 20. Fig. 9 shows an example of the system information D201.

[0054] The system data D202 is information indicating state quantities at each node of the power system 70. The system data D202 includes information regarding each node of the power system 70, such as PQ designation in power flow calculation, PV designation, node type such as slack node, active power, reactive power, and voltage, as well as information regarding each branch, such as start node ID, end node ID, impedance, and capacitance.

[0055] The system data D202 may include information used in transient stability calculations, such as parameter values ​​of a generator model. The parameters of the system data D202 may be changed via the input unit 109. The system data D202 is created by the system data creation unit 102 of the calculation unit 10 and stored in the storage unit 20. Fig. 10 shows an example of the system data D202.

[0056] The assumed accident case information D203 is information relating to the assumed location and nature of an accident in the power system 70. The assumed accident case information D203 is operated by an operator and input to the input unit 30. The assumed accident case information D203 is stored in the memory unit 20 by the system data creation unit 102 of the calculation unit 10. Fig. 11 shows an example of the assumed accident case information D203.

[0057] The type of accident at the location where the accident occurred is shown in the "Accident Aspects" column in Figure 11. For example, in the entry "3φ6LG," "3φ" indicates that the accident occurred in three phases of a three-phase, two-circuit transmission line, and "6LG" indicates that a ground fault occurred in wire six of the three-phase, two-circuit transmission line.

[0058] The voltage stability target information D204 is information relating to one or more voltage stability target values. The voltage stability target value is selected based on a numerical value indicating the capacity to maintain the voltage. As the numerical value indicating the capacity to maintain the voltage, a "load margin" is used, which indicates the maximum load increase amount at which the voltage can be maintained. The voltage stability target information D204 is operated by an operator and input to the input unit 30. The voltage stability target information D204 is stored in the memory unit 20 by the system data creation unit 102 of the calculation unit 10. Figure 12 shows an example of the voltage stability target information D204. The "voltage stability target value" in Figure 12 indicates the "load margin."

[0059] The transient stability maintenance shearing control machine information D205 is information on shearing control machines to be controlled in order to maintain transient stability. The transient stability maintenance shearing control machine information D205 is created by selecting shearing control machines to be controlled in order to maintain transient stability from among the synchronous generators 71 and renewable energy sources 72 in the power system 70. The transient stability maintenance shearing control machine information D205 is created by the transient stability maintenance shearing control machine selection unit 103 of the calculation unit 10 and stored in the storage unit 20. Figure 13 shows an example of the transient stability maintenance shearing control machine information D205. As shown in Figure 13, the shearing control machines to be controlled are stored together with their control priority.

[0060] The out-of-step order information D206 is information relating to the out-of-step order of the shearing control machines selected as the control targets. The out-of-step order information D206 indicates the out-of-step order of the synchronous generator 71 and the renewable energy power source 72, which are the control targets for maintaining transient stability. The out-of-step order information D206 is created by the transient stability maintenance shearing control machine selection unit 103 in the process of selecting the shearing control machines to be the control targets for maintaining transient stability. Fig. 14 shows an example of the out-of-step order information D206.

[0061] The transient stability calculation representative value information D207 is information regarding a representative value of the transient stability calculation in the combination of shear-control machines for maintaining transient stability. The transient stability calculation representative value information D207 is a representative value of the transient stability calculation, and is, for example, a value at a point when the fluctuation has sufficiently subsided, such as 30 seconds after the occurrence of a simulated fault in the transient stability calculation. The representative value of the transient stability calculation may be a value obtained by averaging values ​​calculated at multiple steps in the transient stability calculation.

[0062] The transient stability calculation representative value information D207 includes information such as the active power, reactive power, voltage, and phase of each node in the representative value of the transient stability calculation. The transient stability calculation representative value information D207 is created by the transient stability maintenance shearing machine selection unit 103 in the process of selecting shearing machines to be controlled to maintain transient stability. Fig. 15 shows an example of the transient stability calculation representative value information D207.

[0063] The unstable system information D208 is information about unstable nodes and unstable branches related to the shearing control units selected based on transient stability calculations. The unstable system information D208 includes binary information indicating unstable or stable for each node and branch. The information indicating instability or stability is called a "node flag" and a "branch flag," respectively. The unstable system information D208 is created by the transient stability maintenance shearing control unit selection unit 103 in the process of selecting shearing control units to be controlled to maintain transient stability. Figure 16 shows an example of the unstable system information D208.

[0064] The voltage stability evaluation information D209 is information related to the power flow calculation result when the power flow calculation converges. The voltage stability evaluation information D209 is information related to the power flow calculation result when the power flow calculation converges in a power flow calculation using the system cross-sectional data before the load increase (FIG. 17) created based on the transient stability calculation representative value information D207 and the system cross-sectional data after the load increase in which the supply and demand balance is maintained (FIG. 18). The voltage stability evaluation information D209 is created by the voltage stability evaluation unit 104. FIG. 19 shows an example of the voltage stability evaluation information D209.

[0065] The reactive power loss target information D210 is information regarding the target value of reactive power loss when the power flow calculation converges. The reactive power loss target information D210 is created by adding up the reactive power losses of unstable branches based on the results of the power flow calculation. The reactive power loss target information D210 is created by the voltage stability evaluation unit 104 and updated by the reactive power loss target calculation unit 105. Fig. 20 shows an example of the reactive power loss target information D210.

[0066] The reactive power loss target information D210 is updated by the reactive power loss target calculation unit 105. The reactive power loss target calculation unit 105 executes a power flow calculation for the system related to the changed cross section information D212. Based on the result of the power flow calculation, the reactive power loss target calculation unit 105 sums up the reactive power losses of the unstable branches to generate the reactive power loss target information D210. The generated reactive power loss target information D210 is updated as new reactive power loss target information D210. FIG. 23 shows an example of the result of the power flow calculation by the reactive power loss target calculation unit 105.

[0067] The target cross section information D211 is information relating to a cross section where the load has increased to the target value of voltage stability. The cross section where the load has increased from the cross section corresponding to the transient stability calculation representative value information D207 to the target value of voltage stability is set as the target cross section information D211. The target cross section information D211 is created by the voltage stability evaluation unit 104. Fig. 21 shows an example of the target cross section information D211.

[0068] The changed cross section information D212 is created by changing the combination of shearing units in the target cross section according to the target cross section information D211. As an example, the changed cross section information D212 is created by changing some of the generators in the target cross section information D211 to PQ designated nodes and setting the designated values ​​of active power and reactive power to 0. The changed cross section information D212 is created by the reactive power loss target calculation unit 105. Fig. 22 shows an example of the changed cross section information D212.

[0069] The power control amount adjustment information D213 is information that indicates the results of optimization calculations for a cross section related to the changed cross section information D212. The optimization results of optimization calculations based on the system data D202, transient stability maintenance shear control machine information D205, reactive power loss target information D210, and changed cross section information D212 are used as the power control amount adjustment information D213. The power control amount adjustment information D213 is created by the power control amount adjustment unit 106. Fig. 24 shows an example of the power control amount adjustment information D213.

[0070] The above is the configuration of the power system stabilization device 1 according to this embodiment.

[0071] [1-2. Effect] Next, the operation of the power system stabilizing device 1 of this embodiment will be described with reference to FIGS.

[0072] The power system stabilization device 1 performs calculations for control to maintain both the transient stability and voltage stability of the power system 70.

[0073] The operation of the power system stabilization device 1 is outlined below.

[0074] The voltage stability evaluation unit 104 calculates the load increase at which voltage stability is maintained and the reactive power loss at the load increase by performing a transient stability calculation that simulates the case where power supply limitation, which is a control for maintaining transient stability, is performed on the power system 70 composed of the synchronous generator 71 and the renewable energy power source 72.

[0075] The voltage stability evaluation unit 104 calculates the load increase amount by increasing the load stepwise through power flow calculation, so that voltage stability is maintained.

[0076] The reactive power loss target calculation unit 105 selects at least one of the synchronous generator 71 and the renewable energy power source 72 as a first control unit that is subject to power supply restrictions to maintain voltage stability, and calculates a reactive power loss target value based on the difference between the reactive power loss when controlled by the first control unit and the reactive power loss at the load increase amount calculated by the voltage stability evaluation unit 104.

[0077] The power control amount adjustment unit 106 selects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power control machine that is subject to power supply restriction so that the reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation unit 105 and the power control amount subject to power supply restriction is reduced, and creates power control amount adjustment information D213.

[0078] The power control amount adjustment unit 106 may select a combination of two or more of the synchronous generator 71 and the renewable energy power source 72 as second power control machines that are subject to power supply restriction, and create multiple pieces of power control amount adjustment information D213.

[0079] The power control amount adjustment unit 106 switches at least one of the synchronous generator 71 and the renewable energy power source 72 that are connected to the first power control unit and selects it as the second power control unit.

[0080] The control signal transmission unit 107 outputs the electrical control amount adjustment information D213 created by the electrical control amount adjustment unit 106.

[0081] The control terminal device 40 selects one of the multiple pieces of power control amount adjustment information D213 output from the power system stabilization device 1 based on the state quantity of the power system 70, and controls the synchronous generator 71 and the renewable energy power source 72.

[0082] The details of the operation of the power system stabilization device 1 are as follows.

[0083] The data management unit 101 of the calculation unit 10 stores the system information D201 in the storage unit 20. The data management unit 101 sets the input information indicating the state quantities of the power system 70 as the system information D201. The information indicating the state quantities of the power system 70 is input to the data management unit 101 of the power system stabilization device 1 from an information collection device 76 arranged in the power system 70 via a communication line 80.

[0084] As shown in FIG. 9, the system information D201 includes information on the open or closed state of the circuit breaker 75, the active power output of the synchronous generator 71 and the renewable energy power source 72, the impedance and capacitance of the transmission line, and the like.

[0085] The data management unit 101 of the calculation unit 10 stores the assumed accident case information D203 in the storage unit 20. The assumed accident case information D203 is operated by an operator and input to the input unit 30. As shown in FIG. 11 , the assumed accident case information D203 includes information on the assumed location and nature of the accident in the power system 70.

[0086] The data management unit 101 of the calculation unit 10 stores the voltage stability target information D204 in the storage unit 20. The voltage stability target information D204 is operated by an operator and input to the input unit 30. As shown in Fig. 12 , the voltage stability target information D204 includes information that becomes one or more target values ​​for voltage stability.

[0087] Generally, when the load increases, the voltage of the power grid 70 decreases. Voltage stability is the ability to maintain the voltage of the power grid 70 in response to an increase in load. As an example, a "load margin" is used as a numerical value indicating the ability to maintain voltage, which represents the maximum load increase at which voltage can be maintained. The load margin is set as the target value for voltage stability. For example, a value such as 1,000 MW, which is the load margin, is set as the target value for voltage stability.

[0088] Here, the load increase refers to an increase in power consumption that fluctuates over a period of time ranging from several tens of seconds to several minutes, and does not include an increase in power consumption that fluctuates transiently at a certain time. Also, the load increase does not simply include an increase in the power consumption of the load 77, but also includes an apparent increase in power consumption that results from a decrease in the output of renewable energy sources 72 such as solar power generation and wind power generation depending on the weather.

[0089] The system data creation unit 102 of the calculation unit 10 creates system data D202 based on the system information D201 stored in the storage unit 20. The system data creation unit 102 collects information on the voltage of the synchronous generator 71 and the active power and reactive power of the load 77 from the information collection device 76. The system data creation unit 102 performs a state estimation calculation using the collected information and the information in the system information D201 to create the system data D202.

[0090] As shown in FIG. 10, the system data D202 includes information regarding each node of the power system 70, such as PQ designation in power flow calculation, PV designation, node type such as slack node, active power, reactive power, voltage, etc., as well as information regarding each branch, such as start node ID, end node ID, impedance, capacitance, etc.

[0091] The system data D202 may include information used in transient stability calculations, such as parameter values ​​of a generator model. The parameters of the system data D202 may be changed via the input unit 109. The system data creation unit 102 stores the created system data D202 in the storage unit 20.

[0092] The transient stability maintenance shearing control machine selection unit 103 of the calculation unit 10 creates transient stability maintenance shearing control machine information D205 based on the system data D202 and assumed accident case information D203. The transient stability maintenance shearing control machine selection unit 103 selects a shearing control machine to be controlled to maintain transient stability from among the synchronous generators 71 and renewable energy power sources 72 of the power system 70, and creates transient stability maintenance shearing control machine information D205 shown in Fig. 13. The transient stability maintenance shearing control machine selection unit 103 stores the created transient stability maintenance shearing control machine information D205 in the storage unit 20.

[0093] The transient stability maintenance shearing control machine selection unit 103 generates out-of-step order information D206. As shown in Fig. 14, the out-of-step order information D206 is information regarding the out-of-step order of the shearing control machines selected as the control targets. The transient stability maintenance shearing control machine selection unit 103 generates the out-of-step order information D206 in the process of selecting the shearing control machines to be controlled in order to maintain transient stability.

[0094] The transient stability maintenance shear control machine selection unit 103 calculates the out-of-step order of the synchronous generator 71 to be controlled or the renewable energy power source 72. The transient stability maintenance shear control machine selection unit 103 stores the created out-of-step order information D206 in the storage unit 20.

[0095] The transient stability maintenance shearing control machine selection unit 103 creates transient stability calculation representative value information D207. The transient stability calculation representative value information D207 is information on a representative value of transient stability calculation in a combination of shearing control machines for maintaining transient stability. The transient stability maintenance shearing control machine selection unit 103 creates the transient stability calculation representative value information D207 in the process of selecting shearing control machines to be controlled for maintaining transient stability.

[0096] For example, the representative value of the transient stability calculation is the value obtained when the fluctuations have sufficiently subsided, for example, 30 seconds after the fault occurrence simulation in the transient stability calculation. The representative value of the transient stability calculation may be a value obtained by averaging the values ​​calculated at multiple steps in the transient stability calculation.

[0097] 15 , the transient stability calculation representative value information D207 includes information such as the active power, reactive power, voltage, and phase of each node in the representative value of the transient stability calculation. The transient stability maintaining shear control machine selection unit 103 stores the created transient stability calculation representative value information D207 in the storage unit 20.

[0098] The transient stability maintaining shearing control unit selection unit 103 generates unstable system information D208. The unstable system information D208 is information indicating whether a node or branch related to a shearing control unit selected based on transient stability calculation is stable or unstable. As shown in Fig. 16, the unstable system information D208 includes binary information of stable or unstable for each node or branch.

[0099] The information indicating stability or instability is called a "node flag" or a "branch flag." The transient stability maintenance shearing control unit selection unit 103 creates unstable system information D208 in the process of selecting shearing control units to be controlled to maintain transient stability. The transient stability maintenance shearing control unit selection unit 103 stores the created unstable system information D208 in the storage unit 20.

[0100] The voltage stability evaluation unit 104 of the calculation unit 10 generates voltage stability evaluation information D209 based on the transient stability calculation representative value information D207. The voltage stability evaluation information D209 is information about the power flow calculation result when the power flow calculation converges.

[0101] Based on the transient stability calculation representative value information D207, the voltage stability evaluation unit 104 creates system cross-sectional data before the load increase shown in Fig. 17. The system cross-sectional data before the load increase is used for power flow calculation.

[0102] The voltage stability evaluation unit 104 creates a system cross-sectional data cross section in which the load increases from the state shown in the system cross-sectional data before the load increase and the supply and demand balance is maintained, and performs power flow calculations. The voltage stability evaluation unit 104 creates the system cross-sectional data after the load increase shown in Figure 18.

[0103] The voltage stability evaluation unit 104 generates the power flow calculation result when the power flow calculation converges as voltage stability evaluation information D209 shown in Fig. 19. The voltage stability evaluation unit 104 stores the generated voltage stability evaluation information D209 in the storage unit 20.

[0104] The voltage stability evaluation unit 104 totals the reactive power losses of branches whose branch flags indicate "unstable" based on the power flow calculation results, and generates reactive power loss target information D210. As shown in FIG. 20 , the reactive power loss target information D210 is information related to the target value of reactive power loss when the power flow calculation converges. The voltage stability evaluation unit 104 stores the generated reactive power loss target information D210 in the storage unit 20.

[0105] The voltage stability evaluation unit 104 generates target cross section information D211 based on the transient stability calculation representative value information D207. As shown in FIG. 21 , the target cross section information D211 is information related to a system cross section where the load has increased to the target value of voltage stability. The voltage stability evaluation unit 104 generates a system cross section where the load has increased to the target value of voltage stability from the system cross section related to the transient stability calculation representative value information D207, and sets this as the target cross section information D211. The voltage stability evaluation unit 104 stores the generated target cross section information D211 in the storage unit 20.

[0106] The reactive power loss target calculation unit 105 of the calculation unit 10 creates changed cross section information D212 based on the target cross section information D211. The reactive power loss target calculation unit 105 creates a cross section by changing the combination of shearing machines in the target cross section according to the target cross section information D211, and sets the created cross section information as the changed cross section information D212. As an example, the changed cross section information D212 shown in FIG. 22 is created by changing some of the generators in the target cross section information D211 to PQ designated nodes, and setting the designated values ​​of active power and reactive power to 0. The reactive power loss target calculation unit 105 stores the created changed cross section information D212 in the storage unit 20.

[0107] The reactive power loss target calculation unit 105 updates the reactive power loss target information D210 based on the changed cross section information D212. The reactive power loss target calculation unit 105 performs a power flow calculation for the system related to the changed cross section information D212. The reactive power loss target calculation unit 105 sums up the reactive power losses of branches whose branch flags are "unstable" from the power flow calculation results, and creates the reactive power loss target information D210. The reactive power loss target calculation unit 105 updates the reactive power loss target information D210. Figure 23 shows an example of the results of the power flow calculation performed by the reactive power loss target calculation unit 105.

[0108] The power control amount adjustment unit 106 of the calculation unit 10 creates power control amount adjustment information D213 based on the optimization results. The power control amount adjustment unit 106 performs optimization calculations based on the system data D202, transient stability maintenance power control machine information D205, reactive power loss target information D210, and changed cross section information D212. The power control amount adjustment unit 106 selects a power control target based on the optimization calculation results, and creates the power control amount adjustment information D213 shown in FIG. 24. The power control amount adjustment unit 106 stores the created power control amount adjustment information D213 in the storage unit 20.

[0109] The control signal transmitter 107 transmits the power control amount adjustment information D213 to the control terminal device 40.

[0110] The control terminal device 40 receives information indicating that an accident has occurred in the power grid 70 from the information collection device 76, selects one of the optimization results related to the power control amount adjustment information D213, and controls the power control target. The control terminal device 40 transmits a control signal to open the circuit breaker 75 and a control signal to stop the output of the renewable energy power source 72.

[0111] The processing of the transient stability maintaining shear control machine selection unit 103, the voltage stability evaluation unit 104, the reactive power loss target calculation unit 105, and the shear control amount adjustment unit 106 is realized by the program shown in Fig. 3. The program shown in Fig. 3 is built into the calculation unit 10 of the power system stabilization device 1. The power system stabilization device 1 repeats the processing of the flowchart shown in Fig. 3 a number of times corresponding to the number of cases in the assumed accident case information D203.

[0112] (Step S1: Select a generator to be controlled to maintain transient stability) The transient stability maintenance shearing control machine selection unit 103 selects a shearing control machine for maintaining transient stability. The processing in step S1 is executed by the transient stability maintenance shearing control machine selection unit 103 of the calculation unit 10. As an example, the transient stability maintenance shearing control machine selection unit 103 determines whether the synchronous generator 71 and the renewable energy power source 72 have lost synchronism through a transient stability calculation that simulates the power system 70, and selects the targets for shearing control in the order in which they lost synchronism.

[0113] An example of a detailed flow of step S1 is shown in Figure 4. In step S11, the transient stability maintenance shearing control machine selection unit 103 executes a transient stability calculation. The transient stability maintenance shearing control machine selection unit 103 executes a power flow calculation based on the system information D201 and the system data D202. The transient stability maintenance shearing control machine selection unit 103 executes a transient stability calculation for an assumed fault case using the power flow calculation result as an initial value.

[0114] In step S12, the transient stability maintenance shedding control machine selection unit 103 determines whether the result of the transient stability calculation is stable. As an example, the transient stability maintenance shedding control machine selection unit 103 determines that a synchronous generator 71 whose internal phase difference angle exceeds 180 degrees is unstable, and that the rest are stable. If it is determined to be stable (YES in step S12), the program proceeds to step S13. If it is determined to be unstable (NO in step S12), the program proceeds to step S14.

[0115] If it is determined in step S12 that the result of the transient stability calculation is stable, the transient stability maintenance shear control unit selection unit 103 stores the representative value of the transient stability calculation in the memory unit 20 as transient stability calculation representative value information D207 in step S13.

[0116] If it is determined in step S12 that the result of the transient stability calculation is unstable, the transient stability maintenance shear control unit selection unit 103 stores information about the system that is unstable in the transient stability calculation in the memory unit 20 as unstable system information D208 in step S14.

[0117] The transient stability maintaining shearing control unit selection unit 103 determines the system with a larger phase angle than the node with the larger phase angle, either the start node or the end node of the branch with the widest phase angle in the power system 70, as an unstable system. The transient stability maintaining shearing control unit selection unit 103 sets the node flags of the nodes and the branch flags of the branches included in the unstable system to "unstable". It sets the node flags of the other nodes and the branch flags of the branches to "stable".

[0118] In step S15, the transient stability maintenance shearing control machine selection unit 103 adds shearing control machines for maintaining transient stability in the order of step-out and stores the shearing control selection order. The transient stability maintenance shearing control machine selection unit 103 rearranges the internal phase difference angles of the synchronous generators 71 in descending order at the time when the transient stability calculation result determined that the generators were unstable, and stores the order of the internal phase difference angles of the synchronous generators 71 in the storage unit 20 as step-out order information D206.

[0119] The transient stability maintenance shearing control machine selection unit 103 adds the synchronous generator 71, which has the highest out-of-step ranking information in the out-of-step ranking information D206 in the power system 70, to the shearing control machines and updates the transient stability maintenance shearing control machine information D205.

[0120] The processing in step S1 is not limited to the above. For example, the transient stability maintenance shedding control machine selection unit 103 may create the out-of-step ranking information D206 by ranking the synchronous generators 71 based on the "index representing the stabilization effect." The "index representing the stabilization effect" can be calculated, for example, by dividing the amount by which the rate of change of the angular velocity deviation of the synchronous generator in a one-machine infinite bus model decreases when shedding is performed by the shedding amount. The out-of-step ranking information D206 includes both the synchronous generator 71 and the renewable energy power source 72 as machines to be shedding controlled for maintaining transient stability.

[0121] (Step S2: Set variable i=1) The transient stability maintaining shedding control unit selection unit 103 sets a variable i for repeated calculations to 1.

[0122] (Step S3: Read the i-th target value in the voltage stability target information D204) The transient stability maintaining shear control unit selection unit 103 reads the i-th target value in the voltage stability target information D204. As the program is repeatedly executed, i is incremented.

[0123] (Step S4: Evaluate voltage stability) The voltage stability evaluation unit 104 evaluates the voltage stability of the i-th target value in the voltage stability target information D204. The process of step S4 is executed by the voltage stability evaluation unit 104 of the calculation unit 10.

[0124] An example of a detailed flow of step S4 is shown in Figure 5. In step S41, the voltage stability evaluation unit 104 creates an evaluation system cross section based on the transient stability calculation representative value information D207. Figure 17 shows an example of system cross section data before load increase as the evaluation system cross section. The evaluation system cross section is used for power flow calculation.

[0125] In step S42, the voltage stability evaluation unit 104 checks the voltage stability with respect to the i-th target value in the voltage stability target information D204.

[0126] An example of the detailed flow of step S42 is shown in Fig. 6. In step S421, the voltage stability evaluation unit 104 creates a cross section in which the active power load (sometimes simply referred to as "load") in the load 77 is increased by an amount applied to the target value. The voltage stability evaluation unit 104 stores the created cross section in the storage unit 20 as target cross section information D211.

[0127] In step S422, the voltage stability evaluation unit 104 executes the power flow calculation. In step S423, the voltage stability evaluation unit 104 outputs whether or not the power flow calculation has converged.

[0128] In step S43, the voltage stability evaluation unit 104 determines whether the voltage stability of the cross section created based on the target cross section information D211 is maintained. As an example, the voltage stability evaluation unit 104 determines that the voltage stability is maintained when the power flow calculation converges.

[0129] If it is determined that voltage stability is maintained (YES in step S43), the program proceeds to step S44, skips the processing from step S5 onwards, ends the processing for the i-th accident case, and proceeds to the processing for the (i+1)-th accident case.If it is not determined that voltage stability is maintained (NO in step S43), the program proceeds to step S45.

[0130] In step S45, the voltage stability evaluation unit 104 checks the load margin. An example of a detailed flow of step S45 is shown in FIG. 7. In step S451, the voltage stability evaluation unit 104 creates a cross section in which the load has increased by α from the evaluation system cross section related to the system cross section data before the load increase shown in FIG. 17 created in step S41. FIG. 18 shows an example of system cross section data after the load increase in which the load has increased by α. α is a value sufficiently smaller than the target value, and is set to a value such as 10 MW. The value of α may be variable within the loop.

[0131] In step S452, the voltage stability evaluation unit 104 executes the power flow calculation. In step S453, the voltage stability evaluation unit 104 determines whether the power flow calculation converges. If it is determined that the power flow calculation converges (YES in step S453), the program proceeds to step S451. If it is not determined that the power flow calculation converges (NO in step S453), the program proceeds to step S454.

[0132] If it is determined in step S453 that the power flow calculation has not converged, in step S454 the voltage stability evaluation unit 104 stores the load increase amount at the last cross section where the power flow calculation in step S452 has converged as a load margin in the storage unit 20. In addition, the voltage stability evaluation unit 104 stores the power flow calculation result in the storage unit 20 as voltage stability evaluation information D209.

[0133] Furthermore, the voltage stability evaluation unit 104 calculates the total reactive power loss for branches whose branch flags in the unstable system information D208 are "unstable" among the power flow calculation results, and generates reactive power loss target information D210. The voltage stability evaluation unit 104 stores the generated reactive power loss target information D210 in the storage unit 20.

[0134] The reactive power loss target information D210 stores a number of results corresponding to the number of voltage stability target values, and the value calculated for "No. 1" in the voltage stability target information D204 is stored in "Target cross section 1."

[0135] The load margin will be explained based on Fig. 25. Fig. 25 shows the relationship between the load increase amount of the entire system and the voltage at an arbitrary bus. The horizontal axis represents the load increase amount of the entire system, and the vertical axis represents the voltage at an arbitrary bus.

[0136] In Figure 25, (A) shows one case based on the results of the power flow calculation for the evaluation system cross section created in step S41. (F) shows one case based on the results of the power flow calculation performed in step S422. (F) shows a case where the power flow calculation has not converged to the target load margin, and it is determined that voltage stability is not being maintained.

[0137] (B) shows one case based on the results of power flow calculation for a cross section where the load has increased by α from the cross section of (A). (B) is calculated by creating a cross section in step S451 for the first iteration of the loop, and then executing the power flow calculation in step S452. If it is determined in step S453 that the power flow calculation has converged (YES in step S453), the cross section of (C) is created in step S451 for the second iteration of the loop.

[0138] The loop processing is repeated, and a cross section (E) is created where the power flow calculation has not yet converged. The cross section (E) is the limit point of voltage stability. The load increase at the cross section (D) before the cross section (E) is set as the load margin at the current stage. The 700 MW applied to (D) is set as the "load increase at which voltage stability is maintained." The voltage stability evaluation unit 104 calculates the reactive power loss at the load increase at (D).

[0139] (Step S5: Calculate the reactive power loss target value) The reactive power loss target calculation unit 105 calculates the reactive power loss target value. The process in step S5 is executed by the reactive power loss target calculation unit 105 of the calculation unit 10.

[0140] An example of a detailed flow of step S5 is shown in Fig. 8. In step S51, the reactive power loss target calculation unit 105 adds machines to be sheared off in a predetermined order. As an example, the reactive power loss target calculation unit 105 adds the synchronous generator 71 that is last in the out-of-step order order information D206 in the power system 70 to the machines to be sheared off. Furthermore, the reactive power loss target calculation unit 105 may add a machine to be sheared off when the estimated increment value of reactive power loss described below is a negative value and is smaller.

[0141] In step S52, the reactive power loss target calculation unit 105 simulates the addition of a shearing controlled machine based on the target cross-section information D211. The addition of a shearing controlled machine is simulated by changing some generators to PQ designated nodes and setting the designated values ​​of active power and reactive power to 0.

[0142] In step S53, the reactive power loss target calculation unit 105 simulates supply and demand adjustment for the power cut and updates the changed cross-section information D212. As an example, the reactive power loss target calculation unit 105 increases the active power of the generators in governor-free operation by proportionally dividing the decrease in active power due to the power cut based on the capacity ratio of the generators, thereby simulating supply and demand adjustment. The increased active power is set to a value that satisfies the upper limit of each generator.

[0143] In step S54, the reactive power loss target calculation unit 105 executes a power flow calculation.

[0144] In step S55, the reactive power loss target calculation unit 105 determines whether the power flow calculation executed in step S54 converges. If it is determined that it converges (YES in step S55), the program proceeds to step S56. If it is not determined that it converges (NO in step S55), the program proceeds to step S51.

[0145] In step S56, the reactive power loss target calculation unit 105 calculates the total reactive power loss for branches whose branch flags in the unstable system information D208 are "unstable" based on the results of the power flow calculation performed in step S54, and stores the total reactive power loss in the "changed section" of the reactive power loss target information D210.

[0146] In step S57, the reactive power loss target calculation unit 105 calculates the "reactive power loss incremental margin." The "reactive power loss incremental margin" is calculated as the difference between the reactive power loss value corresponding to the "target cross section" in the reactive power loss target information D210 and the reactive power loss value corresponding to the "changed cross section." In the example of the reactive power loss target information D210 in Fig. 20, the "reactive power loss incremental margin" is 1.563-1.346=0.217 [pu].

[0147] The incremental margin of reactive power loss will be explained with reference to Fig. 26. Fig. 26 shows the relationship between the load increase amount and the total reactive power loss value in an unstable system.

[0148] In Fig. 26, (A) shows one case of reactive power loss in the system of the transient stability calculation representative value information D207 created in step S41. The cross section of (A) in Fig. 26 is the same as the cross section of (A) in Fig. 25.

[0149] (A) represents the change in reactive power loss relative to the power flow calculation results when the load increases in the processing of steps S451, S452, and S453.

[0150] (C) shows the cross section created in step S454, i.e., the reactive power loss at the limit of voltage stability. The cross section (C) in FIG. 26 is the same cross section as the cross section (D) in FIG. 25. The 700 MW applied to (D) is the "load increase amount at which voltage stability is maintained." The reactive power loss target calculation unit 105 calculates the reactive power loss (C) at the "load increase amount at which voltage stability is maintained" of (D).

[0151] (D) shows one case of reactive power loss in the cross section created in step S42. In Fig. 26, the power flow calculation in step S42 for (D) does not converge.

[0152] (E) shows one case of reactive power loss in the cross section created in step S53 for the first time in the loop processing. In Fig. 26, the power flow calculation in step S54 for (E) does not converge.

[0153] (F) is an image of reactive power loss of the cross section created in step S53 for the second time of the loop processing. In Fig. 26, the power flow calculation in step S54 for (F) converges. (F) shows reactive power loss when shearing is performed by the first shearing machine.

[0154] In Figure 26, (G) represents the "reactive power loss incremental margin." (C) shows the reactive power loss at the limit point of voltage stability under the conditions before the shearing control machine combination is changed. Assuming that the reactive power loss in (C) is the same as the reactive power loss at the limit point of voltage stability after the shearing control machine combination is changed, the reactive power loss that can be increased from (F) is defined as the "reactive power loss incremental margin."

[0155] The reactive power loss at the limit of voltage stability in a power system is largely determined by the load power factor and the voltage ratio at the sending and receiving ends, and is only slightly affected by factors such as the load power and the magnitude of generator output. For this reason, it can be said that the reactive power loss at the limit of voltage stability does not fluctuate significantly even if the combination of shedding machines is changed. The reactive power loss target calculation unit 105 sets the "reactive power loss incremental margin" as the reactive power loss target value related to the reactive power loss target information D210 and ends step S5.

[0156] (Step S6: Execute optimization calculation) The electrical control amount adjustment unit 106 executes an optimization calculation. The process in step S6 is executed by the electrical control amount adjustment unit 106 of the calculation unit 10. The optimization calculation is executed in the following procedure.

[0157] Variable: Whether or not a generator subject to shedding in an unstable system is shedding (binary variable) Objective function (minimization of power control amount): Minimize Σn (active power of control unit n (power generation) - active power of control unit n (load)) ...(Formula 1) Constraints: -Constraints on maintaining transient stability Power control amount ≧ Power control amount to maintain transient stability ...(Formula 2) Voltage stability constraints Incremental margin of reactive power loss - Margin ≥ Estimated incremental value of reactive power loss when changing the generator from the combination of generators in the change section information D212 ...(Formula 3)

[0158] The shear control amount adjustment unit 106 refers to the unstable system information D208 and sets the generator to be sheared whose node flag is "unstable" as a variable. The system data D202 is referenced for the active power (power generation) of the shear control machine n and the active power (load) of the shear control machine n in the objective function.

[0159] The right side of (Equation 3) is calculated as follows:

[0160] The reactive power loss on the right side of (Equation 3) is calculated by (Equation 4).

number

[0161] In equation (4), Vi and Vj are the magnitudes of the voltages at node i and node j, respectively, and θi and θj are the phases of the voltages at node i and node j, respectively. Bij is the i and j components of the susceptance matrix, and bij is the susceptance of the earth capacitance of the transmission line connecting nodes i and j, and is calculated based on the system data D202.

[0162] If dVi / dPn and dVi / dQn are the sensitivity of the voltage change at node i to the active power and reactive power of node n, respectively, and dθi / dPn and dθi / dQn are the sensitivity of the phase change at node i to the active power and reactive power of node n, respectively, then the voltage Vin and phase θin will be as shown in (Equation 5) and (Equation 6), respectively, based on the amount of electrical control.

number

[0163] In (Equation 5) and (Equation 6), V * in, θ * in are the estimated values ​​of voltage and phase when the generator at node n is sheared. Vi,org and θi,org are the voltage and phase before the shearing control unit is changed in the power flow calculation results for the changed cross-sectional information D212. Pn is the active power (generation) - active power (load) of the shearing control unit at node n in the system data D202. Qn is the reactive power (generation) - reactive power (load) of the shearing control unit at node n in the system data D202.

[0164] The voltage change sensitivities dVi / dPn, dVi / dQn and phase change sensitivities dθi / dPn, dθi / dQn are calculated based on the power flow calculation results for the changed cross-sectional information D212. By substituting (Equation 5) and (Equation 6) into (Equation 4), the reactive power loss when the generator at node n is shedding is calculated. The "increment in reactive power loss" is calculated by subtracting the reactive power loss before the shedding machine change from the calculated reactive power loss.

[0165] If reactive power loss decreases due to shearing, the "increment in reactive power loss" will be a negative value. If a sheared machine is added to the combination of sheared machines related to the changed cross-section information D212, the "increment in reactive power loss" is added, and if a sheared machine is removed, the "increment in reactive power loss" is subtracted. The right-hand side of (Equation 3) is calculated by performing the above process for all branches whose branch flag is "unstable" in the unstable system information D208 and calculating the total value.

[0166] Here, when the active power P and reactive power Q of an arbitrary node change, the voltage change sensitivity ΔV and phase change sensitivity Δθ ​​of another arbitrary node are calculated as follows.

[0167] First, the current Ii flowing into node i is expressed by (Equation 7) using the voltage Vi of node j, the i and j components Yij of the admittance matrix, and the number of nodes N. Furthermore, the power of node i is expressed by (Equation 8).

number

[0168] Using Viejθ, where V i is the magnitude of the voltage and θ is the phase, (Equation 8) is transformed into (Equation 9). G ij is the conductance matrix, and Bij is the susceptance matrix.

number

[0169] By partially differentiating Pi and Qi with respect to θi and Vi, respectively, (Equation 10), (Equation 11), (Equation 12), and (Equation 13) are calculated.

number

[0170] Equation 10, Equation 11, Equation 12, and Equation 13 are applied to each node in the power system 70, and Equation 14 is calculated for the Jacobian matrix J. In power flow calculations, dPi / dθj is generally composed of a submatrix having the number of rows and columns of (number of PV-designated nodes + number of PQ-designated nodes). dPi / dVj is composed of a submatrix having the number of rows and columns of (number of PV-designated nodes + number of PQ-designated nodes).

[0171] dQi / dθj is composed of a submatrix with the number of rows equal to (number of PQ-specified nodes) and the number of columns equal to (number of PV-specified nodes + number of PQ-specified nodes). dQi / dVj is composed of a submatrix with the number of rows equal to (number of PQ-specified nodes) and the number of columns equal to (number of PQ-specified nodes).

number

[0172] Using the J matrix, the relationship between the small changes ΔP and ΔQ in P and Q and the small changes Δθ and ΔV in θ and V is as shown in (Equation 15).

number

[0173] Equation 15 is solved for Δθ and ΔV to calculate equation 16. Equation 16 shows that the sensitivity of Δθ and ΔV to ΔP and ΔQ is determined by the inverse matrix J-1. The power flow calculation repeats the process of substituting the mismatch amount for ΔP and ΔQ and performing matrix calculations to calculate Δθ and ΔV. J-1 is calculated for the converged value of the power flow calculation, and the components between ΔP and ΔQ of the generator node and Δθ and ΔV of any load bus node are extracted to calculate the voltage change sensitivity ΔV and the phase change sensitivity Δθ.

number

[0174] The value calculated in step S5 is used for the "reactive power loss incremental margin" on the left side of (Equation 3). The margin on the left side of (Equation 3) is a value input from the input unit 30. Generally, reactive power loss at the limit point of voltage stability does not fluctuate significantly even if the combination of shearing control machines changes. However, in an actual system, reactive power loss may fluctuate due to a change in the combination of shearing control machines. A margin is set to prepare for such a case. The margin is an arbitrary real number. The margin may be 0. If the margin is set to 0, the margin is not taken into account.

[0175] The right side of (Equation 2) is the shearing control amount of the shearing-controlled machine stored in the transient stability maintenance shearing control machine information D205. The constraints on maintaining transient stability are not limited to those shown in (Equation 2). For example, the "index representing the stabilization effect" calculated for the candidate shearing-controlled machine may be used as the constraint on maintaining transient stability. The optimization calculation may be performed based on the constraint conditions shown in (Equation 17).

[0176] The total value of the "indicator of stabilization effect" for the current combination of power generators ≧ Total value of "indicators showing stabilization effect" for transient stability maintenance power control units ...(Formula 17)

[0177] The power control amount adjustment unit 106 stores the calculated optimization result in the storage unit 20 as power control amount adjustment information D213.

[0178] (Step S7: Determine whether the variable i has reached the target value) The power control amount adjustment unit 106 determines whether the variable i has reached the target value stored in the voltage stability target information D204. If it is determined that the variable i has reached the target value (YES in step S7), the program ends. If it is not determined that the variable i has reached the target value (NO in step S7), the program proceeds to step S8. In step S8, the variable i is incremented by "1" and the program proceeds to step S3.

[0179] The power control amount adjustment information D213 stores the optimization result of the number of target values ​​stored in the voltage stability target information D204.

[0180] The control signal transmission unit 107 transmits the power control amount adjustment information D213 to the control terminal device 40. When the control terminal device 40 receives information indicating that a grid accident has occurred from the information collection device 76, it selects an object to be controlled based on the power control amount adjustment information D213 and controls the circuit breaker 75 and the renewable energy power source 72.

[0181] When there are multiple optimization results related to the power control amount adjustment information D213, the control terminal device 40 selects one optimization result and controls the power control target. The control terminal device 40 selects the optimization result based on the measurement values ​​received from the power grid 70 via the communication line 80. When there is one optimization result related to the power control amount adjustment information D213, the control terminal device 40 controls the power control target according to the one optimization result.

[0182] As an example, if the active power flow of the target transmission line or transformer in the assumed accident case has increased by a predetermined value or more compared to the value at the time the information was collected by the data management unit 101, the control content "No. 2" in the power control amount adjustment information D213 shown in Figure 24 is selected, and in all other cases, the control content "No. 1" is selected.

[0183] As an example, the predetermined value is set to a value such as 200 MW. The value at the time when the information is collected by the data management unit 101 may be transmitted from the control signal transmission unit 107 to the control terminal device 40 together with the power control amount adjustment information D213.

[0184] The above computer program is repeatedly executed at intervals of, for example, 30 seconds.

[0185] In determining whether the power flow calculation has converged in steps S453 and S55, an upper limit may be set for the reactive power output of the generator, and if the reactive power output in the power flow calculation result exceeds the upper limit, it may be determined that the power flow calculation has not converged.For a generator node for which it is determined that the power flow calculation has not converged, the power flow calculation may be performed again as a PQ designated node with the upper limit of the reactive power output set to a designated value.

[0186] Furthermore, if the voltage value in the power flow calculation result exceeds a predetermined value or falls below the predetermined value, the calculation unit 10 may perform processing to simulate the operation of voltage adjustment devices such as phase modifying equipment and transformer taps arranged in the power system 70. In step S51, processing may be performed to change the combination of shedding control machines so that the amount of shedding control is reduced.

[0187] The above is the operation of the power system stabilizing device 1 according to this embodiment.

[0188] [1-3.Effects] (1) According to this embodiment, the power system stabilization device 1 includes a voltage stability evaluation unit 104 that calculates a load increase amount at which voltage stability is maintained and a reactive power loss at the load increase amount by a transient stability calculation simulating a case where power supply limitation, which is a control for maintaining transient stability, is performed on the power system 70 configured by the synchronous generator 71 and the renewable energy power source 72, and a voltage stability evaluation unit 104 that selects at least one of the synchronous generator 71 and the renewable energy power source 72 as a first shearing control machine that is subject to power supply limitation for maintaining voltage stability, and calculates the reactive power loss when sheared by the first shearing control machine and the reactive power loss at the load increase amount calculated by the voltage stability evaluation unit 104. and a power control quantity adjustment unit 106 that selects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power control machine that is subject to power supply restriction so that the reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation unit 105 and the power control quantity subject to power supply restriction is reduced, and that outputs the power control quantity adjustment information D213, thereby providing a power system stabilization device 1 that performs control to maintain both the transient stability and voltage stability of the power system 70.

[0189] The power control amount adjustment unit 106 of the power system stabilization device 1 selects the synchronous generator 71 and the renewable energy power source 72 so that the power control amount imposed on the power supply limit is reduced through optimization calculations, thereby enabling control to be performed that more appropriately maintains the transient stability and voltage stability of the power system 70.

[0190] (2) According to this embodiment, the power control amount adjustment unit 106 of the power system stabilization device 1 selects a combination of two or more of the synchronous generators 71 and the renewable energy power sources 72 as second power control units that are subject to power supply limitation, and creates multiple pieces of power control amount adjustment information D213. This makes it possible to select a more appropriate combination of power control units. By combining appropriate power control units, it is possible to increase or decrease the power control amount more finely. This makes it possible to perform control that more appropriately maintains the transient stability and voltage stability of the power system 70.

[0191] (3) According to this embodiment, the power control amount adjustment unit 106 of the power system stabilization device 1 switches at least one of the synchronous generator 71 and the renewable energy power source 72 related to the first power control machine and selects it as the second power control machine. This allows the power control amount to be increased or decreased more precisely, and enables control to be performed in which the transient stability and voltage stability of the power system 70 are more appropriately maintained.

[0192] The power system stabilization device 1 according to this embodiment adds a shearing control unit and changes the combination of shearing control units to select a shearing control unit, thereby reducing the amount of control. In the prior art, the power system 70 was controlled by adding a shearing control unit to be controlled to maintain voltage stability in addition to the shearing control units to be controlled to maintain transient stability.

[0193] Therefore, the control amount is the sum of the control amount by the shearing control unit for maintaining transient stability and the control amount by the shearing control unit for maintaining voltage stability. The power system stabilization device 1 according to this embodiment can reduce the control amount compared to the processing according to the conventional technology. This makes it possible to secure a larger control margin.

[0194] As an example, a case will be described in which three controlled units with outputs of 100 MW, 200 MW, and 300 MW are candidates for shedding. In the processing according to the conventional technology, for example, a 100 MW controlled unit is selected as a controlled unit for maintaining transient stability, and a 300 MW controlled unit is further selected as a controlled unit for maintaining voltage stability, resulting in a total of 400 MW being controlled.

[0195] According to the power system stabilization device 1 of this embodiment, 200 MW is calculated as the shedding control amount that simultaneously satisfies transient stability and voltage stability, and a 200 MW shedding control machine is selected. This makes it possible to reduce the control amount by 200 MW. In addition, the number of shedding control machines can be reduced by one, ensuring control margin. In the processing of the prior art, a shedding control machine for maintaining transient stability and a shedding control machine for maintaining voltage stability are selected separately, so it was not possible to appropriately select one 200 MW shedding control machine.

[0196] (4) According to this embodiment, the voltage stability evaluation unit 104 of the power system stabilizing device 1 calculates the load increase amount at which voltage stability is maintained by increasing the load stepwise through power flow calculation, so that the load increase amount at which voltage stability is maintained can be calculated more accurately. As a result, the reactive power loss corresponding to the calculated load increase amount is calculated, and the reactive power loss target value can be calculated more accurately.

[0197] (5) According to this embodiment, the power system stabilization system includes the power system stabilization device 1 and the control terminal device 40 that selects one of the multiple pieces of power control amount adjustment information D213 output from the power system stabilization device 1 based on the state quantity of the power system 70 and controls the synchronous generator 71 and the renewable energy power source 72. Therefore, it is possible to provide a power system stabilization system that performs control to maintain both the transient stability and voltage stability of the power system 70.

[0198] The renewable energy power source 72 selected as the control target may be difficult to control depending on the operating conditions, etc. For example, if there is no control margin or if communication with the control device is not working properly, the renewable energy power source 72 may be difficult to control. Even in such cases, the control terminal device 40 of the power grid stabilization system controls the synchronous generator 71 and the renewable energy power source 72 based on the state quantities of the power grid 70, so that control that is more suited to the state of the power grid 70 can be performed.

[0199] [2. Second Embodiment] [2-1. Composition and Function] The power system stabilizing device 1 according to the second embodiment will be described with reference to Fig. 27. The power system stabilizing device 1 according to the second embodiment differs from the power system stabilizing device 1 according to the first embodiment in that the storage unit 20 stores frequency stability information 214 and in the calculation processing by the power control amount adjusting unit 106 of the calculation unit 10.

[0200] Other configurations of the power system stabilization device 1 according to the second embodiment are the same as those of the power system stabilization device 1 according to the first embodiment shown in Fig. 2. The same components as those of the power system stabilization device 1 according to the first embodiment are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0201] The frequency stability information 214 is information regarding a combination of the synchronous generator 71 and the renewable energy power source 72 selected as a shedding control machine for maintaining the frequency. The frequency stability information 214 is input from the input unit 30 and stored in the storage unit 20 by the data management unit 101.

[0202] As an example, the combination of shear-control machines for maintaining the frequency according to the frequency stability information 214 is selected based on the fluctuation in the frequency of the power system after a predetermined time has elapsed since the power supply control, using a frequency model that simulates the response of the frequency to disturbances such as power supply loss.

[0203] Based on information regarding the combination of power control units for maintaining frequency according to the frequency stability information 214, the power control amount adjustment unit 106 selects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power control unit that is subject to power supply restrictions, and creates power control amount adjustment information D213.

[0204] 3, the power control amount adjustment unit 106 executes an optimization calculation. The process in step S6 is executed by the power control amount adjustment unit 106 of the calculation unit 10. The power control amount adjustment unit 106 of the power system stabilization device 1 according to the second embodiment executes an optimization calculation including constraints related to frequency stability.

[0205] As an example, the constraints on frequency stability are given by (Equation 18) and (Equation 19). SIR (Synchronous Inertial Response) total of generators that are not sheared ≥ SIR total of synchronous generators left in the system to maintain frequency ...(Formula 18) Governor-free capacity of generators that are not controlled ≧Total governor-free capacity of synchronous generators left in the system to maintain frequency ...(Formula 19)

[0206] The synchronous generators to be left in the grid to maintain the frequency are the synchronous generators that would be left in the grid if the sheared generators recorded in the frequency stability information 214 were sheared. The SIR is calculated by (Equation 20). SIR [MW s] = Σ(Hi [s] Si [MW]) i=1~N ...(Formula 20) H: Unit inertia constant [s] S: Rated capacity [MW] N: Number of synchronous generators

[0207] The power control amount adjusting unit 106 executes optimization calculations including constraints related to frequency stability according to (Equation 18), (Equation 19), and (Equation 20).

[0208] The power control amount adjustment unit 106 selects at least one of the synchronous generator 71 and the renewable energy power source 72, whose reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation unit 105, satisfies the constraints on frequency stability, and reduces the power control amount imposed by the power source restriction, as a second power control machine subject to power source restriction, and creates power control amount adjustment information D213.

[0209] The power control amount adjustment unit 106 selects a combination of two or more of the synchronous generator 71 and the renewable energy power source 72 as second power control generators that are subject to power source restriction, and creates multiple pieces of power control amount adjustment information D213.

[0210] The power control amount adjustment unit 106 switches at least one of the synchronous generator 71 and the renewable energy power source 72 that are connected to the first power control unit and selects it as the second power control unit.

[0211] The control signal transmission unit 107 outputs the electrical control amount adjustment information D213 created by the electrical control amount adjustment unit 106.

[0212] The control terminal device 40 selects one of the multiple pieces of power control amount adjustment information D213 output from the power system stabilization device 1 based on the state quantity of the power system 70, and controls the synchronous generator 71 and the renewable energy power source 72.

[0213] The above is the operation of the power system stabilizing device 1 according to this embodiment.

[0214] [2-2. Effects] (1) According to this embodiment, the power control amount adjustment unit 106 of the power system stabilization device 1 selects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power control unit that is subject to power supply limitation based on information regarding the combination of the synchronous generator 71 and the renewable energy power source 72 selected as a power control unit for maintaining frequency, and creates power control amount adjustment information D213. Therefore, it is possible to provide a power system stabilization device 1 that performs control that maintains frequency stability in addition to transient stability and voltage stability of the power system 70.

[0215] The power system 70 is controlled based on the power control amount adjustment information D213 created by the power control amount adjustment unit 106, and frequency stability is maintained in addition to transient stability and voltage stability.

[0216] 3. Third Embodiment [3-1. Composition and Function] The power system stabilizing device 1 according to the third embodiment will be described with reference to Fig. 28. The power system stabilizing device 1 according to the third embodiment differs from the power system stabilizing device 1 according to the first embodiment in that the calculation unit 10 has a voltage stability confirmation correction unit 108.

[0217] Other configurations of the power system stabilization device 1 according to the third embodiment are the same as the configuration of the power system stabilization device 1 according to the first embodiment shown in Fig. 2. The same components as those of the power system stabilization device 1 according to the first embodiment are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0218] The voltage stability confirmation correction unit 108 checks whether voltage stability can be maintained for the combination of power control machines related to the power control amount adjustment information D213 created by the processing of the power control amount adjustment unit 106, and if voltage stability cannot be maintained, changes the constraint conditions and executes the processing by the power control amount adjustment unit 106 again.

[0219] The voltage stability confirmation correction unit 108 judges the voltage stability of the combination of the synchronous generator 71 and the renewable energy power source 72 selected by the power control amount adjustment unit 106 as the second power control machine that is subject to power supply restriction, and if it determines that the voltage stability is not being maintained, it changes the constraint conditions.

[0220] Based on the constraint conditions changed by the voltage stability confirmation correction unit 108, the power control amount adjustment unit 106 reselects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power control machine that is subject to power source restriction, and corrects the created power control amount adjustment information D213.

[0221] Fig. 29 shows a program of the power system stabilizing device 1 according to the third embodiment. The operation of the power system stabilizing device 1 will be described with reference to Fig. 29. The program of the power system stabilizing device 1 according to the third embodiment includes steps S9A, S9B, and S9C in addition to the program of the power system stabilizing device 1 according to the first embodiment shown in Fig. 3. The processing of steps S9A, S9B, and S9C is executed by the voltage stability confirmation corrector 108. The processing up to S8 is the same as the processing of the power system stabilizing device 1 according to the first embodiment shown in Fig. 3, and therefore description thereof will be omitted.

[0222] (Step S9A: Evaluate voltage stability) Step S9A is executed after step S6. The voltage stability confirmation and correction unit 108 evaluates the voltage stability of the combination of the synchronous generator 71 and the renewable energy power source 72 selected by the shedding control amount adjustment unit 106 as the second shedding control machine.

[0223] In step S6, the power control amount adjustment unit 106 selects the synchronous generator 71 and the renewable energy power source 72 as the second power control machines through optimization calculations.

[0224] As an example of a method for evaluating voltage stability, the voltage stability confirmation and correction unit 108 performs a transient stability calculation on the combination of shearing control machines obtained by performing an optimization calculation using the shearing control amount adjustment unit 106, and then evaluates the voltage stability using processing equivalent to step S4.

[0225] If the combination of shearing control machines selected in step S6 by the optimization calculation of the shearing control amount adjustment unit 106 includes a combination of shearing control machines related to the transient stability maintenance shearing control machine information D205, the voltage stability confirmation correction unit 108 may evaluate voltage stability by simulating the addition of shearing control machines based on the target cross-sectional information D211, as in step S52.

[0226] (Step S9B: Determine whether voltage stability is maintained) The voltage stability confirmation and correction unit 108 determines whether voltage stability is maintained based on the voltage stability evaluation performed in step S9A. If it is determined that voltage stability is maintained (YES in step S9B), the program proceeds to step S7. If it is not determined that voltage stability is maintained (NO in step S9B), the program proceeds to step S9C.

[0227] (Step S9C: Add a constraint to the optimization problem that prohibits the current optimal solution) If it is determined in step S9B that voltage stability is not maintained, the voltage stability confirmation corrector 108 adds a constraint that prohibits the current optimal solution to the optimization problem. As an example, the voltage stability confirmation corrector 108 creates an inequality (Equation 21) as the constraint that prohibits the current optimal solution. The power control amount selected in the previous step S6 < power control amount ≦ power control amount of the first power control machine ...(Formula 21)

[0228] Since it is difficult for a general optimization solver to solve a formulation using the inequality sign "<", a constraint that prohibits the current optimal solution may be formulated using an inequality sign with an equality sign "≦", for example, as in (Equation 22). The amount of electrical control selected in the previous step S6 + 0.0001 ≦Power control amount≦Power control amount of the first power control machine ...(Formula 22)

[0229] Thereafter, in step S6, the power control amount adjustment unit 106 executes an optimization calculation. The power control amount adjustment unit 106 changes the constraint conditions, reselects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power control unit that is subject to power source limitation, and corrects the created power control amount adjustment information D213.

[0230] The above is the operation of the power system stabilizing device 1 according to this embodiment.

[0231] [3-2. Effects] According to this embodiment, the power system stabilization device 1 includes a voltage stability confirmation correction unit 108 that determines voltage stability for a combination of a synchronous generator 71 and a renewable energy power source 72 selected by the power control amount adjustment unit 106 as a second power source to be limited by power supply restrictions, and modifies the constraint conditions if it determines that voltage stability is not maintained. The power control amount adjustment unit 106 reselects at least one of the synchronous generator 71 and the renewable energy power source 72 as a second power source to be limited by power supply restrictions based on the constraint conditions modified by the voltage stability confirmation correction unit 108, and modifies the created power control amount adjustment information D213. Therefore, if voltage stability is not maintained by the combination of power sources to be limited by the power control amount adjustment unit 106, the constraint conditions are modified and the power control amount adjustment unit 106 reselects the second power source to be limited by power supply restrictions. As a result, even if the power control amount adjustment unit 106 selects a synchronous generator 71 and a renewable energy power source 72 that cannot maintain voltage stability, the synchronous generator 71 and the renewable energy power source 72 can be modified to a combination that can maintain voltage stability.

[0232] [4. Fourth Embodiment] [4-1. Composition and Function] The power system stabilizing device 1 according to the fourth embodiment will be described with reference to Fig. 30. The power system stabilizing device 1 according to the fourth embodiment differs from the power system stabilizing device 1 according to the first embodiment in that the calculation unit 10 has a power control amount adjustment information division processing unit 109.

[0233] Other configurations of the power system stabilization device 1 according to the fourth embodiment are the same as the configuration of the power system stabilization device 1 according to the first embodiment shown in Fig. 2. The same components as those of the power system stabilization device 1 according to the first embodiment are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0234] The power control amount adjustment information division processing unit 109 divides the combination of power control machines related to the power control amount adjustment information D213 created by processing by the power control amount adjustment unit 106 into power control machines for maintaining transient stability and power control machines for maintaining voltage stability based on predetermined rules.

[0235] The power control amount adjustment information division processing unit 109 classifies the synchronous generator 71 and the renewable energy power source 72 selected by the power control amount adjustment unit 106 as second power control units that are subject to power supply restrictions into power control units for maintaining transient stability and power control units for maintaining voltage stability based on predetermined indicators.

[0236] Fig. 31 shows a program for the power system stabilizing device 1 according to the fourth embodiment. The operation of the power system stabilizing device 1 will be described with reference to Fig. 31. The program for the power system stabilizing device 1 according to the fourth embodiment includes step S9D in addition to the program for the power system stabilizing device 1 according to the first embodiment shown in Fig. 3. The processing of step S9D is executed by the power control amount adjustment information division processing unit 109. The processing up to S8 is the same as the processing of the power system stabilizing device 1 according to the first embodiment shown in Fig. 3, and therefore description thereof will be omitted.

[0237] (Step S9D: Classify the shearing control machine selected as the second shearing control machine) Step S9D is executed after step S6. The shearing control amount adjustment information division processing unit 109 classifies the synchronous generators 71 and renewable energy power sources 72 selected by the shearing control amount adjustment unit 106 as second shearing control units that are subject to power supply limitation into shearing control units for maintaining transient stability and shearing control units for maintaining voltage stability based on a predetermined index.

[0238] In step S6, the power control amount adjustment unit 106 selects the synchronous generator 71 and the renewable energy power source 72 as the second power control machines through optimization calculations.

[0239] The shear control amount adjustment information division processing unit 109 classifies the synchronous generator 71 and the renewable energy power source 72 selected as the second shear control machines into shear control machines for maintaining transient stability and shear control machines for maintaining voltage stability based on the step-out order as a predetermined index. The step-out order is the order indicated by the step-out order information D206.

[0240] As an example, the power control amount adjustment information division processing unit 109 selects a control candidate from the highest out-of-step priority based on the out-of-step priority information D206. The power control amount adjustment information division processing unit 109 selects a control candidate so that the power control amount exceeds the power control amount of the transient stability maintenance shear control machine information D205, and sets the selected control candidate as the shear control machine for maintaining transient stability. The control candidate is at least one of the synchronous generator 71 and the renewable energy power source 72 selected as the second shear control machine.

[0241] The shear control amount adjustment information division processing unit 109 sets the remaining control candidates as shear control machines for maintaining voltage stability. The remaining control candidates are the synchronous generators 71 and renewable energy power sources 72 selected as the second shear control machines, but are not set as shear control machines for maintaining transient stability.

[0242] Alternatively, the power control amount adjustment information division processing unit 109 may classify the synchronous generator 71 and the renewable energy power source 72 selected as the second power control machine into a power control machine for maintaining transient stability and a power control machine for maintaining voltage stability based on an "index representing the stabilization effect" as a predetermined index.

[0243] The "index representing the stabilization effect" is calculated by the shear control amount adjustment information division processing unit 109. The shear control amount adjustment information division processing unit 109 calculates the "index representing the stabilization effect" based on the combination of shear control machines according to the transient stability maintenance shear control machine information D205. Furthermore, the shear control amount adjustment information division processing unit 109 similarly calculates the "index representing the stabilization effect" for each shear control machine of the optimal solution according to the transient stability maintenance shear control machine information D205. The "index representing the stabilization effect" indicates the degree of contribution to the stabilization of the power system.

[0244] As an example, the shear control amount adjustment information division processing unit 109 selects control candidates in descending order of stabilization effect based on the calculated "index representing the stabilization effect" of each shear control machine. The shear control amount adjustment information division processing unit 109 selects control candidates so that the "index representing the stabilization effect" exceeds the "index representing the stabilization effect" of the combination of shear control machines related to the transient stability maintenance shear control machine information D205, and sets the selected control candidate as the shear control machine for maintaining transient stability. The control candidate is at least one of the synchronous generator 71 and the renewable energy power source 72 selected as the second shear control machine.

[0245] The shear control amount adjustment information division processing unit 109 sets the remaining control candidates as shear control machines for maintaining voltage stability. The remaining control candidates are the synchronous generators 71 and renewable energy power sources 72 selected as the second shear control machines, but are not set as shear control machines for maintaining transient stability.

[0246] The power control amount adjustment information division processing unit 109 divides the synchronous generator 71 and the renewable energy power source 72 selected as the second power control units into power control units for maintaining transient stability and power control units for maintaining voltage stability, and creates power control amount adjustment division information D215 shown in Fig. 32. The power control amount adjustment division information D215 is stored in the storage unit 20.

[0247] The control terminal device 40 according to this embodiment first controls the transient stability maintaining shearing machine as a first-stage shearing control. Based on the measurement values ​​received from the power grid 70 via the communication line 80, the control terminal device 40 determines whether or not control of the voltage stability maintaining shearing machine is necessary, and if it determines that control is necessary, it controls the voltage stability maintaining shearing machine as a second-stage shearing control. As an example, the control terminal device 40 determines that control of the voltage stability maintaining shearing machine is necessary when any voltage value falls below 0.8 pu.

[0248] The above is the operation of the power system stabilizing device 1 according to this embodiment.

[0249] [4-2. Effects] According to this embodiment, the power system stabilization device 1 has a power control amount adjustment information division processing unit 109 that divides the synchronous generator 71 and the renewable energy power source 72 selected by the power control amount adjustment unit 106 as second power control machines that are subject to power supply restriction into power control machines for maintaining transient stability and power control machines for maintaining voltage stability based on a predetermined index, so that the power control machines for maintaining transient stability and the power control machines for maintaining voltage stability can be controlled at different control timings.

[0250] Generally, transient stability indicates the degree to which a synchronous generator can continue synchronous operation in the face of transient system disturbances, and control to maintain transient stability is required to be implemented as quickly as possible. On the other hand, voltage stability indicates the degree to which voltage can be maintained in the face of load increases, transformer tap control, and other factors that fluctuate over a period of tens of seconds to several minutes. For this reason, control to maintain voltage stability may be executed at a later timing than control to maintain transient stability. By dividing the synchronous generators 71 and renewable energy sources 72 selected as shedding control units into shedding control units for maintaining transient stability and shedding control units for maintaining voltage stability, control can be executed at a more appropriate timing. This allows for more appropriate stabilization of the power system 70.

[0251] 5. 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.

[0252] (1) Each unit in the above embodiment may be realized by steps according to a computer program for a power system stabilization device or procedures according to a power system stabilization method. The steps executed by the voltage stability evaluation unit 104 may be voltage stability evaluation steps, and the procedures executed may be realized by a voltage stability evaluation procedure. The steps executed by the reactive power loss target calculation unit 105 may be reactive power loss target calculation steps, and the procedures executed may be realized by a reactive power loss target calculation procedure. The steps executed by the power control amount adjustment unit 106 may be power control amount adjustment steps, and the procedures executed may be realized by a power control amount adjustment procedure.

[0253] (2) The data stored in the storage unit 20 is not limited to the above embodiment. In addition to the above embodiment, any data may be stored in the storage unit 20. [Explanation of symbols]

[0254] 1...Power system stabilization device 10... Arithmetic section 101 Data Management Department 102 System Data Creation Unit 103 Transient stability maintenance shear control unit selection section 104...Voltage stability evaluation section 105... Reactive power loss target calculation unit 106...Electrical control amount adjustment section 107 Control signal transmitter 108 Voltage stability check and correction unit 109 Power control amount adjustment information division processing unit 20...Storage section 30 Input section 40 Control terminal device 70...Power system 71, 71a, 71b, 71c, 71d, 71e...Synchronous generator 72, 72a, 72b, 72c, 72d, 72e... Renewable energy sources 73, 73a, 73b, 73c, 73d, 73e... Transformers 74, 74a, 74b, 74c, 74d, 74e... Transformers 75, 75a, 75b, 75c, 75d, 75e circuit breakers 76, 76a, 76b, 76c, 76d, 76e, 76f... Information gathering device 77, 77a, 77b...Load 80...Communication line

Claims

1. a voltage stability evaluation unit that calculates a load increase amount at which voltage stability is maintained and a reactive power loss at the load increase amount by performing a transient stability calculation simulating a case where power supply limitation, which is a control for maintaining transient stability, is performed on a power system configured with a synchronous generator and a renewable energy power source; and a reactive power loss target calculation unit that selects at least one of the synchronous generator and the renewable energy power source as a first control unit that is subject to power source limitation for maintaining voltage stability, and calculates a reactive power loss target value based on the difference between the reactive power loss when the first control unit is controlled and the reactive power loss in the load increase amount calculated by the voltage stability evaluation unit; a power control amount adjustment unit that selects at least one of the synchronous generator and the renewable energy power source as a second power control machine that is subject to power source restriction so that reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation unit and the power control amount subject to the power source restriction is reduced, and creates power control amount adjustment information; outputting the electrical control amount adjustment information created by the electrical control amount adjustment unit; Power system stabilizer.

2. The power control amount adjustment unit selects a combination of two or more of the synchronous generator and the renewable energy power source as the second power control machine that is subject to power supply limitation, and creates a plurality of pieces of power control amount adjustment information. The power system stabilization device according to claim 1 .

3. The power control amount adjustment unit replaces at least one of the synchronous generator and the renewable energy power source associated with the first power control machine and selects it as the second power control machine. The power system stabilization device according to claim 1 .

4. The voltage stability evaluation unit calculates, by power flow calculation, the load increase amount at which voltage stability is maintained by gradually increasing the load. The power system stabilization device according to claim 1 .

5. The power control amount adjustment unit selects at least one of the synchronous generator and the renewable energy power source as the second power control unit that is subject to power supply restriction based on information regarding a combination of the synchronous generator and the renewable energy power source selected as a power control unit for maintaining frequency, and creates power control amount adjustment information. The power system stabilization device according to claim 1 .

6. a voltage stability confirmation correction unit that determines voltage stability by a combination of the synchronous generator and the renewable energy power source selected as the second shearing control machine that is subject to power source limitation by the shearing control amount adjustment unit, and changes constraint conditions when it determines that voltage stability is not being maintained; The power control amount adjustment unit reselects at least one of the synchronous generator and the renewable energy power source as a second power control machine that is subject to power source limitation based on the constraint conditions changed by the voltage stability confirmation correction unit, and corrects the created power control amount adjustment information. The power system stabilization device according to claim 1 .

7. The power control amount adjustment information division processing unit divides the synchronous generator and the renewable energy power source selected as the second power control machine that is the target of power supply limitation by the power control amount adjustment unit into a power control machine for maintaining transient stability and a power control machine for maintaining voltage stability based on a predetermined index. The power system stabilization device according to claim 1 .

8. a voltage stability evaluation unit that calculates a load increase amount at which voltage stability is maintained and a reactive power loss at the load increase amount by performing a transient stability calculation simulating a case where power supply limitation, which is a control for maintaining transient stability, is performed on a power system configured with a synchronous generator and a renewable energy power source; and a reactive power loss target calculation unit that selects at least one of the synchronous generator and the renewable energy power source as a first control unit that is subject to power source limitation for maintaining voltage stability, and calculates a reactive power loss target value based on the difference between the reactive power loss when the first control unit is controlled and the reactive power loss in the load increase amount calculated by the voltage stability evaluation unit; a power control amount adjustment unit that selects a combination of two or more of the synchronous generator and the renewable energy power source as the second power control machine that is subject to power source restriction so that reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation unit and the power control amount subject to the power source restriction is reduced, and creates a plurality of the power control amount adjustment information; a power system stabilization device that outputs the power control amount adjustment information created by the power control amount adjustment unit; A control terminal device that selects one of the plurality of pieces of power control amount adjustment information output from the power system stabilization device based on the state quantity of the power system and controls the synchronous generator and the renewable energy power source. Power system stabilization system.

9. On the computer, a voltage stability evaluation step of calculating a load increase amount at which voltage stability is maintained and a reactive power loss at the load increase amount by a transient stability calculation simulating a case where power supply limitation, which is a control for maintaining transient stability, is performed on a power system configured with a synchronous generator and a renewable energy power source; a reactive power loss target calculation step of selecting at least one of the synchronous generator and the renewable energy power source as a first control machine that is subject to power supply limitation for maintaining voltage stability, and calculating a reactive power loss target value based on the difference between the reactive power loss when the first control machine is controlled and the reactive power loss in the load increase amount calculated in the voltage stability evaluation step; a power control amount adjustment step of selecting at least one of the synchronous generator and the renewable energy power source as a second power control machine that is subject to power source restriction so that reactive power loss satisfies the reactive power loss target value calculated in the reactive power loss target calculation step and the power control amount subject to the power source restriction is reduced, and creating power control amount adjustment information; outputting the electrical control amount adjustment information created in the electrical control amount adjustment step; Computer program for power system stabilizers.

10. a voltage stability evaluation procedure that calculates the load increase amount at which voltage stability is maintained and the reactive power loss at the load increase amount by a transient stability calculation that simulates a case where power supply limitation, which is a control for maintaining transient stability, is performed on a power system composed of a synchronous generator and a renewable energy power source; a reactive power loss target calculation step of selecting at least one of the synchronous generator and the renewable energy power source as a first control machine that is subject to power source limitation for maintaining voltage stability, and calculating a reactive power loss target value based on the difference between the reactive power loss when the first control machine is controlled and the reactive power loss in the load increase amount calculated by the voltage stability evaluation step; a power control amount adjustment procedure for selecting at least one of the synchronous generator and the renewable energy power source as a second power control machine that is subject to power source restriction so that reactive power loss satisfies the reactive power loss target value calculated by the reactive power loss target calculation procedure and the power control amount subject to the power source restriction is reduced, and for creating power control amount adjustment information. outputting the electrical control amount adjustment information created by the electrical control amount adjustment procedure; Power system stabilization method.

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