Power grid stabilizing system and power grid stabilizing method

Abstract

To provide a power grid stabilizing system capable of suppressing computational resources while keeping computational accuracy for evaluating a state of a power grid.SOLUTION: A power grid stabilizing system comprises: a power grid computational unit for receiving a power grid state, a power grid model, and an event case as inputs to execute one or more of a simple event computation and an event computation; and a margin setting unit for receiving a margin setting parameter as an input to compute a screening margin from a simple event computation result and an event computation result with respect to the event case targeted by the power grid computational unit. The margin setting unit computes the screening margin from results of both the simple event computation and the event computation, which suppresses possibility of erroneous screening to keep computational accuracy, and reduces grid states to be evaluated using power flow computation to suppress computational resources.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a power system stabilization system and a power system stabilization method. [Background technology]

[0002] In recent years, with the increase in renewable energy sources connected to the power grid and the electrification of consumer equipment, there are concerns that overloading of power transmission lines may occur, which was not previously anticipated. Attention is being drawn to special protection schemes (SPS), which can eliminate overloads in the electric power system by using the output of renewable energy sources as alternative energy even when an overload occurs in the electric power system.

[0003] In recent years, typical power system stabilization systems plan countermeasures in the event of an overload by calculating the impact of changes in the power system state in advance through simulation. However, it is known that the scale of calculations required for power system simulations becomes enormous as the scale of the power system increases. This is thought to be due to two reasons: the increase in the amount of calculation processing required for power flow state calculations as the scale of the power system expands, and the increase in the number of expected state changes, which requires a large amount of calculation resources. For this reason, efforts have been made to reduce calculation resources.

[0004] Patent Document 1 describes a calculation method for generating a Thevenin equivalent circuit. Patent Document 2 describes a technique that utilizes two-stage screening. Patent Document 3 describes a screening method using eigenvalue analysis. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. US2017 / 0025853 [Patent Document 2] US Patent Application Publication No. US2020 / 0258168 [Patent Document 3] US Patent Application Publication No. US6,496,757 Summary of the Invention [Problem to be solved by the invention]

[0006] The method described in Patent Document 1 reduces the scale of calculations by simplifying the target model when analyzing a power system. Although this method is suitable for analyzing wide-area phenomena, it simplifies the connection configuration of the power system itself. For this reason, it is difficult to evaluate overloads occurring in the power system using the method described in Patent Document 1. In addition, although Patent Document 2 introduces a method for reducing constraints in optimal power flow calculations by two-stage screening, it is difficult to apply the method described in Patent Document 2 to the evaluation of state changes required by a power system stabilization system. Furthermore, although the method described in Patent Document 3 can be used for voltage stability analysis of power systems, it cannot be used for power system overload.

[0007] In this way, in order to reduce the computational resources of a power grid stabilization system, it is necessary to simultaneously reduce computational resources and increase the computational accuracy required for the use case. Furthermore, in systems that have a large social impact, such as a power grid stabilization system, it is even more important to increase the computational accuracy.

[0008] In view of these points, an object of the present invention is to provide a power system stabilization system and a power system stabilization method that can reduce calculation resources while maintaining the calculation accuracy for evaluating the state of the power system. [Means for solving the problem]

[0009] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes a plurality of means for solving the above-mentioned problems. As one example, a power system stabilization system of the present invention includes a power system calculation unit that receives a power system state, a power system model, and an event case as input, and executes one or more of a simplified event calculation and an event calculation, and a margin setting unit that receives a margin setting parameter as input, and calculates a result of the simplified event calculation and a screening margin from the result of the event calculation for the event case targeted by the power system calculation unit. Effect of the Invention

[0010] According to the present invention, it is possible to maintain calculation accuracy by suppressing the possibility of erroneous screening, and it is also possible to reduce the system states to be evaluated by power flow calculation, thereby saving calculation resources. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing an example of a power system to which a power system stabilization system according to a first embodiment of the present invention is applied. [Diagram 2] FIG. 1 is a diagram showing an example of an event in a power system to which a power system stabilization system according to a first embodiment of the invention is applied. [Diagram 3] 1 is a diagram illustrating an example of a hardware configuration of a power system stabilization system according to a first embodiment of the present invention. [Figure 4] 1 is a functional block diagram of a power system stabilization system according to a first embodiment of the present invention. [Diagram 5] 1 is a flowchart showing an overall process performed by a power system stabilization system according to a first embodiment of the present invention. [Figure 6] 4 is a flowchart showing the process of a margin setting unit of the power system stabilization system according to the first embodiment of the present invention. [Figure 7]FIG. 2 is a diagram showing an example of a difference between a simplified power flow calculation and a power flow calculation performed by the power system stabilization system according to the first embodiment of the present invention. [Figure 8] FIG. 2 is a diagram showing an example in which a margin is set for each event by the power system stabilization system according to the first embodiment of the present invention. [Figure 9] FIG. 2 is a diagram showing an example in which a margin is set for each voltage class in the power system stabilization system according to the first embodiment of the present invention. [Figure 10] 5 is a flowchart showing the processing of an anticipated event screening unit of the power system stabilization system according to the first embodiment of the present invention. [Figure 11] FIG. 2 is a diagram showing an example of an event evaluation result of the power system stabilization system according to the first embodiment of the present invention. [Figure 12] FIG. 2 is a diagram showing an example of display of an event evaluation result of the power system stabilization system according to the first embodiment of the present invention. [Figure 13] FIG. 11 is a block diagram showing an example of a power system stabilization system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <First embodiment> A power system stabilization system and a power system stabilization method according to a first embodiment of the present invention will be described below with reference to Figs. 1 to 12.

[0013] [Example of a power system] FIG. 1 is a diagram showing in a simplified manner the connection configuration of a power system to which a power system stabilization system according to a first embodiment of the present invention is applied. 1 is composed of generators G1 to G3, Load1 to Load3, buses B1 to B8, and transmission lines L1 to L9. The purpose of the power system GR1 is to supply power to Load1 to Load3, and when an event occurs in the power system, for example, the power system GR1 supplies power to Load1 to Load3 by changing the output of the generators G1 to G3.

[0014] [Event example] FIG. 2 shows examples of types of events that can occur in power system GR1. In a power system, various events occur due to a wide range of factors. For example, as shown in power system GR1a in Fig. 2, when generator G1 is a renewable energy power source, the output of generator G1 fluctuates. Also, as shown in power system GR1b in Fig. 2, a lightning strike can open a transmission line at a specific location (indicated by an x), causing a change in the system configuration. Furthermore, as shown in power system GR1c in Fig. 2, a cold wave can cause a specific load to increase suddenly. In either event, the current flowing through each transmission line and the voltage at each busbar change.

[0015] Power system equipment is designed on the assumption that voltage and power flow will be operated within a specified range. Therefore, if the voltage and power flow exceed the design value for a certain period of time, protective devices to prevent damage to the equipment will be activated, which may lead to a chain reaction of events. Therefore, the power system stabilization system must take appropriate measures against such anticipated events when they occur.

[0016] [Hardware configuration of power system stabilization system] Next, the hardware configuration of the power system stabilization system 1 will be described. 3 shows an example of a hardware configuration of the power system stabilization system 1. The power system stabilization system 1 is configured, for example, by a computer (calculator), and includes a program database DB1, a database DB2, an input unit 91, a calculation unit 92, a display unit 93, a memory 94, and a communication unit 95. These components of the power system stabilization system 1 are capable of exchanging data with each other via a bus BD1. In addition, a measuring instrument 97 and a control terminal 98 are connected to the computer constituting the power system stabilization system 1 via a communication network 96. The measuring instrument 97 and the control terminal 98 are also components constituting the power system stabilization system 1.

[0017] The program database DB1 stores a set of programs for calculation processing related to the power system stabilization system 1. The database DB2 stores the results of calculation processing, etc. The input unit 91 includes input devices such as a keyboard, a mouse, a stylus, and a microphone. The calculation unit 92 is composed of, for example, a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), an FPGA (Field Programmable Gate Array), a TPU (Tensor Processing Unit), etc., and is used to execute calculation processing. The display unit 93 displays input data and the results of system calculations, for example, on a monitor or speaker. The memory 94 stores various programs when they are executed, and also stores intermediate results from the calculation unit 92 . The communication unit 95 communicates data with a measuring instrument 97 and a control terminal 98 via a communication network 96 .

[0018] The program database DB1, database DB2, input unit 91, calculation unit 92, display unit 93, memory 94, and communication unit 95 transmit and receive data to and from each other via bus BD1. For example, the results of the calculation unit 92 are transmitted to memory 94, and data in memory 94 is transmitted to display unit 93, etc. In this case, bus BD1 does not necessarily have to be a physical bus of one computer, and may play a similar role when multiple computers are combined.

[0019] The measuring instruments 97 are installed in the power system and measure, for example, one or more of effective values, phasor forms, and three-phase instantaneous values ​​of voltage, current, voltage phase, frequency, and current phase. Examples include SV / TM and PMU, and transmit the measurement data to the communication unit 95 of the power system stabilization system 1 via the communication network 96. The control terminal 98 is composed of relays and the like that can change the configuration of the power system, and can change the state of the power system itself.

[0020] [Configuration of power system stabilization systems from the viewpoint of their functions] FIG. 4 is a functional block diagram of the power system stabilization system 1. As shown in FIG. The power system stabilization system 1 is a system that is operated by a computer. As input data to the power system stabilization system 1, various data from a power system model DB3, a power system state DB4, an event case DB5, a margin setting parameter DB6, etc. are used. In addition, as output data to the power system stabilization system 1, there are a screening margin DB10, a screening result DB11, an event evaluation result DB12, and an event countermeasure DB13. The power system stabilization system 1 also includes, as processing units, a power system calculation unit 2, a margin setting unit 3, an event case screening unit 4, an event evaluation unit 5, an event countermeasure planning unit 6, an event comparison unit 7, and a countermeasure execution unit 8.

[0021] Here, the input data of the power system stabilization system 1 will be described. The power system model DB3 stores models of the configuration and components of the power system, such as the impedance of the transmission line, the position of the load, and the upper and lower limits of the generator. The power system state DB4 represents the state of the power system, and stores at least one of, for example, the voltage and voltage phase of each bus, the active power and reactive power flowing in the transmission lines and transformers, and the on / off state of the power transmission equipment.

[0022] The event case DB5 stores a list of events in the target power system. As described above, the list of events includes equipment failure, an increase in power demand or power generation, etc. In this embodiment, a power transmission line failure is treated as an event. Parameters for specifying a group for setting a margin are stored in the margin setting parameter DB 6. For example, the margin setting parameters can specify one or more of the following: for each power line voltage class, for each event, for each power line, for each power line owner, for each time, etc. Depending on the method of setting the margin setting parameters, for example, it is possible to expect an improvement in the screening rate according to the situation.

[0023] Next, the output data of the power system stabilization system 1 will be described. The screening margin DB10 is a margin for correcting the result of the simple event calculation when the simple event calculation is executed, and can be set for each power transmission route characteristic and each event characteristic. The screening result DB11 includes events screened out based on the correction result of the simplified event calculation and the screening margin, and the simplified event evaluation results used for screening. The event evaluation result DB12 is the result of evaluating the screened events by the simple event calculation. The event countermeasure DB 13 is a countermeasure plan for an event based on the event evaluation result.

[0024] The power system calculation unit 2 has a function of calculating an assumed state of the power system. That is, the power system calculation unit 2 has a simple event calculation function 2a and an event calculation function 2b as internal functions, and performs power system calculation processing. The internally held data of the power system calculation unit 2 also includes an internal power system model DB7, an internal power system state DB8, and an internal event case DB9. The power system calculation unit 2 reads the power system model DB 3, the power system state DB 4, and the event case DB 5. Then, the power system calculation unit 2 stores them as an internal power system model DB 7, an internal power system state DB 8, and an internal event case DB 9, respectively, so that the subsequent processing can be smoothly executed.

[0025] In this embodiment, the power system calculation unit 2 executes power flow calculation using the DC method as the simplified event calculation function 2a, and executes power flow calculation using the AC method as the event calculation function 2b. However, it is only an example that the power system calculation unit 2 executes power flow calculation using the DC method as the simplified event calculation function 2a, and executes power flow calculation using the AC method as the event calculation function 2b, and two other types of power flow calculations having different calculation scales other than the DC method and the AC method may be executed as the simplified event calculation function 2a and the event calculation function 2b. For example, the event calculation function 2b may perform the event calculation using one or more of a power system power flow calculation function, a circuit calculation function, a transient stability calculation function, a voltage stability calculation function, and a short circuit calculation function. In addition, the simple event calculation function 2a reduces the calculation processing of the event calculation function 2b, and event calculation can be performed by using one or more of the following: model degeneration, reduction in calculation steps, relaxation of calculation conditions, reduction in calculation accuracy, change in numerical accuracy, and creation of a substitute model.

[0026] The margin setting unit 3 receives the margin setting parameter DB6 as an input and calculates the screening margin DB10 by calling the simple event calculation function 2a and the event calculation function 2b of the power system calculation unit 2. The margin setting unit 3 calculates the screening margin DB10 for each group set by the margin setting parameter DB6, for example.

[0027] The event case screening unit 4 receives the screening margin DB10 as an input and calculates a screening result DB11 by calling the simple event calculation function 2a of the power system calculation unit 2. Here, the event case screening unit 4 calculates the screening result by adding a margin to the result of the simple event calculation function of the power system calculation unit 2. The event evaluation unit 5 receives the screening result DB 11 as an input, and uses the event calculation function of the power system calculation unit 2 to generate an event evaluation result DB 12.

[0028] The event countermeasure planning unit 6 uses the event evaluation result DB 12 as an input to calculate the event countermeasure DB 13 . The event collation unit 7 collates events from the power system state DB 4 and transmits the target countermeasure to the countermeasure execution unit 8 . The countermeasure execution unit 8 executes the countermeasure collated by the event collation unit 7. When executing the countermeasure, the countermeasure execution unit 8 controls the control terminal 98.

[0029] [Processing performed by the power system stabilization system] FIG. 5 is a flowchart showing an example of the overall processing of the power system stabilization system 1. In FIG. 5, the operation of the power system stabilization system 1 is explained as separate flowcharts for normal operation and for an event occurrence, but it may be explained as a continuous series of flowcharts on the assumption that normal operation and an event occurrence occur consecutively.

[0030] First, the operation during normal times shown in the flowchart on the left side of Fig. 5 will be described. The power system calculation unit 2 reads the power system model DB3 and the event case DB5 (step S1). Next, the power system calculation unit 2 and the margin setting unit 3 read the power system state DB4 and the margin setting parameter DB6 (step S2). Then, the margin setting unit 3 sets the margin (step S3).

[0031] Next, the event case screening unit 4 screens the events (step S4). Also, the event evaluation unit 5 evaluates the events (step S5). Furthermore, the event countermeasure planning unit 6 plans an event countermeasure (step S6). Furthermore, the countermeasure execution unit 8 updates the event countermeasures to be executed with the event countermeasures planned by the event countermeasure planning unit 6 (step S7). Then, the display unit 93 displays various results of the event countermeasures and the like (step S8). An example of the display performed here will be described later. The processes from step S2 to step S8 are repeatedly executed in a periodic manner.

[0032] Next, the flow of processing when an event occurs, shown in the flowchart on the right side of FIG. 5, will be described. First, the power system calculation unit 2 acquires the state of the power system (step S9). Next, the event collation unit 7 collates events (step S10). Then, the countermeasure execution unit 8 executes an event countermeasure based on the collation by the event collation unit 7 (step S11).

[0033] As described above, by executing the series of processes shown in the flowchart of Fig. 5, it is possible to reduce the computational resources and handle more events. Also, it is possible to plan countermeasures against events more quickly.

[0034] [Processing performed by the margin setting unit] FIG. 6 is a flowchart showing the details of the process performed by the margin setting unit 3. First, the margin setting unit 3 reads the power system state from the power system calculation unit 2 and acquires the margin setting parameter DB6 (step S31). Then, the margin setting unit 3 checks the system configuration of the acquired power system state and determines whether or not there is a change in the system configuration (step S32).

[0035] If there is a change in the system configuration in step S32 (YES in step S32), the margin setting unit 3 executes an event evaluation calculation using the event calculation function 2b (step S33). Furthermore, the margin setting unit 3 executes a simple event evaluation calculation using the simple event calculation function 2a (step S34). Thereafter, the margin setting unit 3 calculates the difference between the event evaluation calculation result and the simple event evaluation calculation result (step S35). Furthermore, the margin setting unit 3 calculates a margin from the difference between the result of the simple event evaluation calculation and the result of the event evaluation calculation based on the margin setting parameters (step S36).

[0036] Furthermore, if there is no change in the system configuration in step S32 (NO in step S32), the margin setting unit 3 rereads the calculated margin (step S37). After calculating the margin in step S36 and after re-reading the margin in step S37, the margin setting unit 3 outputs the obtained margin (step S38).

[0037] In the simplified event evaluation calculation in step S33 and the event evaluation calculation in step S34, the margin setting unit 3 performs a DC power flow calculation and an AC power flow calculation, respectively, for an event due to, for example, an open transmission line in a power system. In DC power flow calculation, the voltage of the power system is assumed to be constant, and the margin setting unit 3 determines the power flow of the power system by linearizing the resistance of the power transmission route and the nonlinear elements of the power flow equation. With appropriate ingenuity, the above-mentioned power system events can be evaluated without iterative calculations, which is advantageous in evaluating multiple events. However, the power flow calculated by DC power flow calculation contains errors.

[0038] Here, an example of obtaining the difference between the event evaluation calculation result and the simplified event evaluation calculation result in step S35 will be described with reference to FIG. In step S35 of FIG. 6, the margin setting unit 3 obtains the difference between the simplified event evaluation calculation and the event evaluation calculation for each event. The example in FIG. 7 shows the difference value (vertical axis in FIG. 7) between the simplified event rating calculation and the event rating calculation for an event (horizontal axis in FIG. 7). Here, Fig. 7 shows an error in the apparent power S of the power transmission route as an example, but it may be the active power P. When utilizing the apparent power S, if the reactive power Q after the event cannot be obtained by the simple event evaluation, it may be corrected with the reactive power Q before the event.

[0039] Figure 7 shows the error for each event and for each voltage class of the transmission route. That is, in Figure 7, the voltage classes are shown as 110 kV (values ​​shown by stars in Figure 7), 275 kV (values ​​shown by triangles in Figure 7), and 500 kV (values ​​shown by circles in Figure 7). As can be seen from Figure 7, there is a tendency for errors to become larger for certain voltage classes and certain events. This is due to the principles of the simple event evaluation and event evaluation described above. Here, the margin is used to grasp the error between the simple event evaluation and event evaluation, and is held in various forms.

[0040] As an example, a case where a margin is set for each event (for each group) will be described. Figure 8 shows an example of setting a margin to an event. In the example of Fig. 8, the highest applicable margin value for event 1 is 0.15 (15%). Also, the highest applicable margin value for event 2 is 0.20 (20%). Thus, the screening margin DB10 shown in Fig. 8 indicates the maximum error between the simplified event evaluation and the event evaluation for each event.

[0041] As described above, by grasping the simplified event rating and the maximum error of the event rating for each event, the result of the simplified event rating can be used as a reliable index for each event. For example, when the event is an open power line, the error differs for each event, and therefore this indicator is an effective measure. By grasping the maximum error for each event in this way, an indicator that can be trusted for the results of simple event evaluation for each event can be obtained. For example, when the event is an open power line, the error differs for each event, and therefore this indicator is an effective measure.

[0042] Figure 9 shows an example of setting a margin for each voltage class of a transmission route. That is, the voltage classes of the transmission route are divided into 110kV (values ​​shown by stars in Figure 7), 275kV (values ​​shown by triangles in Figure 7), and 500kV (values ​​shown by circles in Figure 7), and the highest value among each voltage class is set as the margin for that voltage class. For example, in the 110kV voltage class, the highest margin value for the corresponding voltage class is 0.20 (20%), in the 275kV voltage class, the highest margin value for the corresponding voltage class is 0.10 (10%), and in the 500kV voltage class, the highest margin value for the corresponding voltage class is 0.05 (5%).

[0043] In this way, by setting an appropriate margin for each voltage class, it is possible to avoid erroneous judgments (false negatives and false positives) due to a uniform margin. Furthermore, by setting a margin for each voltage class, the interpretability is improved compared to setting a margin for each event.

[0044] In the above explanation, the processing is divided into processing for each event and processing for each voltage class, but both processing may be combined, and the margin may be set using at least one of geography, transmission line owner, number of transmission line circuits, etc.

[0045] As described above, by setting a margin for each event and for each voltage class, the power system stabilization system 1 of this embodiment can take into account errors in the simplified event evaluation.

[0046] [Processing performed by the Event Case Screening Department] FIG. 10 is a flowchart showing the details of the process in the event case screening unit 4. First, the event case screening unit 4 reads the margin (step S41). Next, the event case screening unit 4 executes the simplified event calculation by the simplified event calculation function 2a (step S42). The event case screening unit 4 also corrects the result of the simplified event calculation (step S43). Then, the event case screening unit 4 judges an event violation using a margin (step S44). Furthermore, the event case screening unit 4 outputs a violation event (step S45).

[0047] As already explained, the evaluation based on the simplified event calculation does not require calculation resources, but there is a risk of erroneous judgment due to an error in the event evaluation. Here, by fixing the margin once for each system configuration as in this embodiment, it is possible to reduce the risk of erroneously screening an event that causes a violation, while rationally reducing the scale of calculation.

[0048] Furthermore, when the area set by the margin is exceeded, only the results screened by the event evaluation unit 5 are executed in the event evaluation function, so that calculation resources can be allocated only to important events.

[0049] [Examples of screening results and event evaluation results] Next, examples of screening results and event evaluation results will be described with reference to FIG. The example in Fig. 11 summarizes the maximum overload of a transmission line for each event for the power system operator. That is, the event cases for which detailed calculation is required in the simplified event evaluation results (center) included in the screening result DB11 and the event cases for which detailed calculation is required in the event evaluation result DB12 (right) are shown to the power system operator. By displaying this information on the display unit 93, it becomes clear why a particular event was screened out from the information about the event case for which detailed calculation was required, so that the power system operator can clearly understand the reason why the event was screened out.

[0050] For example, in the example in Figure 11, the overload rate of event 2 was calculated to be 85%, but since there was a margin of 20%, it was not subject to screening. This allows the power system operator to know that the event evaluation results indicate an overload. On the other hand, although the case of event 1 is an 80% overload, adding a 15% margin does not result in an overload, so it is not subject to screening.

[0051] For cases where countermeasures are required as a result of the event evaluation, the countermeasure execution unit 8 calculates countermeasures to eliminate the violation in step S6 and updates the countermeasures in step S7, as explained in the flowchart of Fig. 5. Then, the display unit 93 displays the countermeasures in step S8. Furthermore, when an event occurs, the event collation unit 7 can collate the event and execute a countermeasure that has been prepared in advance.

[0052] [Examples of screening results and event evaluation results] Next, an example of the display screen 93a of the display unit 93 will be shown with reference to FIG. Display screen 93a shown in FIG. 12 displays target system GR1, display 35 of margins for each voltage class when the margins shown in FIG. 8 are set as events, screening margin DB10 as screening results, and the screening results and event evaluation results shown in FIG. 11. 12 shows an example in which these are displayed simultaneously, but it is also possible to display at least one of these and omit displaying any of them.Alternatively, it is also possible to configure the display on multiple screens, with these display elements being displayed on separate screens. In addition to what is displayed in FIG. 12, details of measures to resolve the violation may also be displayed.

[0053] <Second embodiment> Next, a power system stabilization system and a power system stabilization method according to a second embodiment of the present invention will be described with reference to FIG. In the configuration of this embodiment shown in FIG. 13, the power system stabilization system 1 is the same as the power system stabilization system 1 described in the first embodiment with reference to FIGS. 1 to 12. The second embodiment of the present invention differs from the first embodiment in that a controlled variable calculation system 10 to which the result (margin) obtained by the power system stabilization system 1 is supplied is provided.

[0054] The control amount calculation system 10 shown in FIG. 13 calculates a control amount by using a preventive control function to avoid the influence of an event before the event occurs. As shown in FIG. 13, the controlled variable calculation system 10 includes an optimization model generating unit 11, an optimization model margin providing unit 12, and an optimization calculation unit 13.

[0055] The optimization model generating unit 11 receives as input the screening margin output by the power system stabilization system 1, the power system state, the power system model, and the event case, and generates an optimization model having simplified constraint conditions. The optimization model margin adding unit 12 uses the screening margin of the optimization model generating unit 11 to add a margin to the optimization model. The optimization calculation unit 13 calculates the solution of the optimization model to calculate the control points that will avoid all possible violations.

[0056] Here, when calculating a control point that can avoid all possible violations, the control point can be obtained by minimizing the evaluation index of a function that evaluates the control amount, as shown in the following equation.

[0057] [Number 1] Min f(C) st g(V,θ,C)=b A(V,θ,C) ≦b

[0058] Here, f(C) is the objective function that evaluates the controlled variable, stg(V,θ,C)=b is an equality constraint calculated from the voltage (V), phase (θ), and controlled variable (C), and A(V,θ,C)≦b is an inequality constraint calculated from the voltage (V), phase (θ), and controlled variable (C). Examples of the objective function include the amount of control of the generator, the number of times the device is controlled, the cost of control, etc. Similarly, an example of an equality constraint is that the inflow power and the output power of the power system must match.

[0059] In addition, examples of inequality constraints include, when considering a plurality of time slices, the control amount between the time slices being within a predetermined range, and the control amount being within a specific range. The power flow equation is a type of equality constraint, and is known to mainly include nonlinear elements. In the technical field, it is also called optimal power flow (OPF).

[0060] In solving the above optimization problem, it has been considered in the past to linearize the nonlinear elements that are still nonlinear in order to find a solution, or to change the format to eliminate as many nonlinear elements as possible. When finding a solution while still nonlinear, the optimization problem takes on a non-convex format, which generally reduces the chances of converging to a useful solution. In addition, when the format of an optimization problem is made closer to linearity, it takes longer to calculate than when it is simply linearized. In an environment with limited computing resources, there is a need to perform calculations with the constraints linearized as much as possible. However, as already explained, linearization involves errors, so there is a possibility that it will not be possible to calculate a control point that satisfies the constraints.

[0061] Therefore, in this embodiment, by using the screening margin of the margin setting unit 3 (FIG. 4) of the power system stabilization system 1, a margin can be added to the linearized constraint equation. In the controlled variable calculation system 10, an optimization model generation unit 11 generates an optimization model having simplified constraint conditions by inputting the screening margin, the power system state, the power system model, and the event case output by the power system stabilization system 1. Then, an optimization model margin assignment unit 12 assigns a margin to the optimization model using the screening margin, and an optimization calculation unit 13 calculates a solution of the optimization model.

[0062] Specifically, the control amount is calculated by adding a margin to the above-mentioned optimization model.

[0063] [Number 2] Min f(C) st g′(V,θ,C,M)=b A(V,θ,C)≦b

[0064] Here, st g'(V, θ, C, M) = b is a simplified constraint condition, which is the state in which a margin (M) is added to the optimization model. By generating a model in this way, for example, it is possible to narrow the solution space while preserving the linearized state, thereby shortening the convergence and the time required for convergence.

[0065] <Modification> The embodiment described above has been described in detail to make the present invention easier to understand, and is not necessarily limited to those having all of the configurations described. Also, the configurations and processes described in the above embodiment can be modified or changed in various ways.

[0066] In the above-described embodiment, a CPU is used as the calculation unit (FIG. 3), but other calculation processing units may be used. For example, part or all of the processing functions of the calculation unit 92 may be realized by dedicated hardware such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC).

[0067] In addition, in the configuration diagrams such as Figures 3 and 4, only control lines and information lines that are considered necessary for explanation are shown, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other. In addition, in the flowcharts shown in Figures 5, 6, and 10, the processing order may be changed or multiple processes may be executed simultaneously as long as the processing results are the same.

[0068] Furthermore, the calculation unit (CPU) needs to implement a program that executes the processes described in the flowcharts of Figures 8 and 9, etc., and in addition to being prepared in the memory that stores the program database DB1, the program may also be stored in an external memory, an IC card, an SD card, an optical disk, or other recording medium and transferred to the power system stabilization system 1. [Explanation of symbols]

[0069] 1...power system stabilization system, 2...power system calculation unit, 2a...simple event calculation function, 2b...event calculation function, 3...margin setting unit, 4...event case screening unit, 5...event evaluation unit, 6...event countermeasure planning unit, 7...event matching unit, 8...countermeasure execution unit, 10...control quantity calculation system, 11...optimization model generation unit, 12...optimization model margin assignment unit, 13...optimization calculation unit, 35...display, 91...input unit, 92...calculation unit, 93...display unit, 93a...display screen, 94...memory, 95...communication unit, 96...communication network, 97...total Instrument, 98...Control terminal, B1...Busbar, BD1...Bus, DB1...Program database, DB2...Database, DB3...Power system model, DB4...Power system state, DB5...Event case, DB6...Margin setting parameters, DB7...Internal power system model, DB8...Internal power system state, DB9...Internal event case, DB10...Screening margin, DB11...Screening result, DB12...Event evaluation result, DB13...Event countermeasure, G1...Generator, GR1,GR1a,GR1b,GR1c...Power system, L1...Transmission line

Claims

1. a power system calculation unit that receives a power system state, a power system model, and an event case as input and executes one or more of a simplified event calculation and an event calculation; a margin setting unit that receives a margin setting parameter as an input and calculates a screening margin from the result of the simplified event calculation and the result of the event calculation for an event case targeted by the power system calculation unit. Power system stabilization system.

2. The margin setting unit calculates a screening margin for each group set by the margin setting parameters. The power system stabilization system according to claim 1 .

3. The margin setting unit uses a maximum error between the simplified event calculation and the event calculation as a screening margin. The power system stabilization system according to claim 2 .

4. The margin setting parameter is a parameter for specifying a group for which a margin is set, and specifies a target for which a margin is set by at least one of the following: for each power transmission line voltage class, for each event, for each power transmission line, for each power transmission line owner, and for each time. The power system stabilization system according to claim 3 .

5. The power system calculation unit further includes an event case screening unit that calculates a screening result by inputting the screening margin and adding a margin to the result of the simplified event calculation by the power system calculation unit. The power system stabilization system according to claim 4.

6. The event case screening unit screens event cases using the screening margin calculated by the margin setting unit. The power system stabilization system according to claim 5 .

7. The screening result includes the result of the simplified event calculation and an event case for which a detailed calculation is required. The power system stabilization system according to claim 6.

8. The system further includes an event evaluation unit that receives the screening result as an input and executes the event calculation in the power system calculation unit to calculate an event evaluation result. The power system stabilization system according to claim 7.

9. The event calculation in the power system calculation unit is at least one of a power system power flow calculation, a circuit calculation, a transient stability calculation, a voltage stability calculation, and a short circuit calculation. The power system stabilization system according to claim 8.

10. The simplified event calculation in the power system calculation unit reduces the calculation process of the event calculation, and simplifies the calculation by using at least one of the following: model degeneration, reduction in calculation steps, relaxation of calculation conditions, reduction in calculation accuracy, change in numerical accuracy, and creation of a substitute model. The power system stabilization system according to claim 9.

11. The event evaluation unit further includes an event countermeasure planning unit that calculates a countermeasure for an event using an event evaluation result by the event evaluation unit as an input. The power system stabilization system according to claim 8.

12. an event matching unit that matches an event using a power system state and an event countermeasure as an input and selects an event countermeasure; a countermeasure execution unit that executes the event countermeasure selected by the event collation unit; and a display unit for displaying one or more of the input data and the output data. The power system stabilization system according to claim 11.

13. an optimization model generating unit that generates an optimization model having simplified constraint conditions by using as input the screening margin output by the power system stabilization system, the power system state, the power system model, and the event case; an optimization model margin providing unit that provides a margin to the optimization model by using the screening margin of the optimization model generating unit; an optimization calculation unit for calculating a solution of the optimization model; The power system stabilization system according to claim 10.

14. A power system stabilization method for performing a power system stabilization process by a computer, A power system calculation process that uses the power system state, the power system model, and the event case as input and executes one or more of a simple event calculation and an event calculation; A margin setting process that uses a margin setting parameter as an input and calculates a screening margin from the result of the simplified event calculation and the result of the event calculation for an event case that is a target of the power system calculation process. Power system stabilization method.

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