JP2016167904A - Voltage stability calculation device and voltage stability calculation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage stability calculation device which executes the processing for evaluating the voltage stability of each bus in a power system including a plurality of buses efficiently.SOLUTION: A voltage stability calculation device has an information input unit for acquiring the bus state representing the state of time series for each of a plurality of buses, an evaluation object bus determination unit for determining an evaluation object bus, i.e., a bus of object for re-calculating the stability curve for calculating the voltage stability index of a bus, among the plurality of buses, based on the bus state thereof, a stability curve calculation unit for re-calculating the stability curve of the evaluation object bus, based on the bus state information of the evaluation object bus, and a stability index calculation unit for calculating the stability index of the evaluation object bus based on the stability curve of the evaluation object bus.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for evaluating voltage stability of a power system.

  In power system monitoring, there is an evaluation method for obtaining a PV curve representing a change in the bus voltage V with respect to a change in the total demand (electric power) P of the power system and evaluating the voltage stability of the power system from the PV curve. (See Patent Documents 1 and 2). The bus bar has a limit of power that can be transmitted, and the PV curve has a tip where the power reaches a peak. The tip of the PV curve is also called a nose end due to its shape.

  The effective power margin of the power system is represented by the difference between the total demand at the nose end of the PV curve and the current total demand of the power system. The larger the effective power margin, the more stable the power system. In this way, the voltage stability of the entire power system can be evaluated from the PV curve of the power system.

Japanese Patent No. 3031934 Japanese Patent No. 5423357

  However, the power system includes a plurality of buses, and some of the buses have a high power margin and some have a low power margin. Among them, a bus having a low power margin tends to cause a voltage collapse of the power system. Therefore, in the evaluation of the voltage stability of the power system, it is desirable to be able to evaluate the power margin not only for the entire power system but also for each bus. By obtaining a PV curve for each bus and calculating the difference between the active load power at the nose end and the current bus demand, the power margin of each bus can be evaluated.

  Since the state of the electric power system changes from moment to moment, it is necessary to know a PV curve representing the current state of the electric power system in real time, and it is necessary to repeat the process to obtain the PV curve at a certain short period. However, when the power system becomes larger, the buses included in the power system become enormous. When the number of buses becomes enormous, the amount of calculation for obtaining a PV curve for each bus becomes enormous, making it difficult to execute the process in a short cycle.

  An object of the present invention is to provide a technique that makes it possible to efficiently execute a process for evaluating voltage stability for each bus in an electric power system including a plurality of buses.

  A voltage stability calculation apparatus according to an embodiment of the present invention is a voltage stability calculation apparatus that calculates a stability index representing voltage stability of an electric power system including a plurality of buses, and each of the plurality of buses. A stability curve for calculating a voltage stability index of a bus from the plurality of buses based on an information input unit that acquires a bus state representing a time-series state and the bus state for the plurality of buses An evaluation target bus determining unit that determines an evaluation target bus that is a target bus to be recalculated, and a stability curve calculation that recalculates a stability curve for the evaluation target bus based on the bus state information of the evaluation target bus And a stability index calculation unit that calculates a stability index of the evaluation target bus based on the stability curve of the evaluation target bus.

  According to the present invention, since the bus for recalculating the stability curve is limited based on the time-series bus state information, it can be recalculated with the priority according to the bus state, and the bus stability index is While maintaining high calculation accuracy, it is possible to efficiently execute processing for evaluating the voltage stability for each bus.

3 is a block diagram showing a configuration of a voltage stability monitoring device 2. FIG. It is a flowchart which shows the outline of the process which the evaluation object bus-line determination part 12 in Example 1 performs for every period. It is a figure for demonstrating an example of calculation of the deviation L in step S1 of FIG. It is one of the data tables for demonstrating an example of the priority determination procedure in step S2-S3 of FIG. It is one of the data tables for demonstrating an example of the priority determination procedure in step S2-S3 of FIG. It is one of the data tables for demonstrating an example of the priority determination procedure in step S2-S3 of FIG. It is one of the data tables for demonstrating an example of the priority determination procedure in step S2-S3 of FIG. It is one of the data tables for demonstrating an example of the priority determination procedure in step S2-S3 of FIG. It is a flowchart which shows the outline of the process which the evaluation object bus-line determination part 12 in Example 2 performs for every period. It is a figure for demonstrating a PV curve drawing process. It is a figure for demonstrating calculation of the inclination of the stability curve in step S5 and step S6. It is a flowchart which shows the outline | summary of the process which the evaluation object bus determination part 12 in Example 3 performs for every period. It is one of the data tables for demonstrating an example of the evaluation object bus-line determination procedure in step S13-S14 of FIG. It is one of the data tables for demonstrating an example of the evaluation object bus-line determination procedure in step S13-S14 of FIG. It is one of the data tables for demonstrating an example of the evaluation object bus-line determination procedure in step S13-S14 of FIG. It is one of the data tables for demonstrating an example of the evaluation object bus-line determination procedure in step S13-S14 of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the voltage stability monitoring device 2.

  The voltage stability monitoring device 2 is a voltage stability calculation device that calculates a stability index representing the voltage stability of the power system 1 including a plurality of buses (not shown), and is connected to the power system 1.

  The voltage stability monitoring device 2 includes a power system information input unit 11, an evaluation target bus determination unit 12, a voltage stability curve calculation unit 13, a voltage stability index calculation unit 14, a calculation result display unit 15, a threshold value Data 16 is included.

  The voltage stability monitoring device 2 operates periodically in order to appropriately monitor various states of the power system 1 that change from moment to moment. The power system 1 includes a plurality of bus bars (not shown). The state of the power system 1 includes the bus state of each bus included in the power system 1.

  The power system information input unit 11 includes system connection information of the power system 1, bus voltage, power flow values of transmission lines and transformers, active power output values and reactive power output values of generators, active power values and reactive power of bus loads. Measurement values indicating various states such as values are acquired as time-series input data at a predetermined calculation cycle. The power system information input unit 11 may acquire, as input data, measurement values collected by other systems (not shown) or input measurement values directly collected by a measurement device (not shown) in the power system 1. You may acquire periodically as data.

  The system connection information of the power system 1 is information regarding various connections in the power system 1. The bus voltage is a voltage value of each bus included in the power system 1. The active power output value and reactive power output value of the generator are values of the active power output and reactive power output of the generator included in the power system 1. The active power value and reactive power value of the bus load are values of the active power and reactive power of the bus load included in the power system 1.

  Based on the information indicating the bus state included in the input data of the power system information input unit 11, the evaluation target bus determination unit 12 is stabilized by the voltage stability curve calculation unit 13 from a plurality of buses existing in the power system 1. An evaluation target bus that is a bus for which a degree curve is calculated is repeatedly determined at a predetermined cycle. At this time, the evaluation target bus determining unit 12 determines the evaluation target bus by comparing the input data for each bus or data calculated based on the input data with the threshold data 16. The threshold data 16 is data used in the evaluation target bus determining unit 12 and can be arbitrarily set by the operator.

  The voltage stability curve calculation unit 13 calculates a stability curve for evaluating voltage stability with respect to the evaluation target bus determined by the evaluation target bus determination unit 12 in a predetermined calculation cycle. In the calculation for each calculation cycle, the stability curve calculated last time is held for the bus that is not the evaluation target bus this time. The stability curve includes various types of curves such as a PV curve and a VQ curve. In the present embodiment, the PV curve will be described as an example.

  The voltage stability index calculation unit 14 calculates a stability index such as an active power margin for the current evaluation target bus based on the stability curve calculated by the voltage stability curve calculation unit 13 every predetermined calculation cycle.

  For example, the stability curve is a PV curve representing the relationship between the demand power P and the bus voltage V. The active power margin, which is a stability index, is a difference between the magnitude of active power at the nose end of the PV curve and the magnitude of active power in the latest bus state. The larger the effective power margin, the more stable the bus.

  In the calculation for each calculation cycle, the stability index that is the result of the previous calculation is held for the bus that is not the evaluation target bus this time.

  The calculation result display unit 15 displays one or both of the calculation results of the voltage stability curve calculation unit 13 and the voltage stability index calculation unit 14 to the operator on a screen or the like.

  According to the present embodiment, the bus for recalculating the stability curve is limited based on the information on the time series bus state, so that it can be recalculated with the priority according to the bus state, and the voltage stability for each bus It is possible to efficiently execute the process for evaluating the degree and calculate the stability index of the bus with high accuracy.

  In the present embodiment, the evaluation target bus determining unit 12 calculates the state change of the plurality of buses based on the bus state for the plurality of buses, and the state change for the plurality of buses and the stability for the plurality of buses. Based on the degree index, an evaluation target bus that is a bus for which the stability curve is to be recalculated may be determined from among a plurality of buses.

  According to this, since the bus for recalculating the stability curve is limited based on the two indicators of state change and voltage stability, priority is given to the bus with large change or low voltage stability, and higher accuracy is achieved. The stability index can be calculated.

  Moreover, the evaluation object bus determining unit 12 may calculate a deviation between the latest value of the bus state and the value of the bus state when the previous stability curve is calculated, and may use the obtained value as the state change. .

  According to this, since the difference between the values of the bus state is calculated and used as the state change, the evaluation target bus can be determined by a relatively simple calculation.

  Also, the evaluation target bus determining unit 12 calculates a deviation between the slope of the stability curve at the coordinates representing the latest bus state and the slope of the stability curve at the coordinates representing the bus state when the previous stability curve was calculated. It is good also as a state change by calculating.

  According to this, since the change in the slope of the stability curve is calculated and used as a state change, the stability curve can be recalculated using the bus whose stability curve has changed as the evaluation target bus, and the change in the stability curve can be calculated. It can be appropriately reflected in the stability index.

  Also, the evaluation target bus determining unit 12 classifies the plurality of buses into a plurality of bus groups according to the magnitude of the state change, gives a high priority to the bus group having a large state change, and stabilizes the buses belonging to the same bus group. A high priority may be given to the buses with a small stability index arranged in ascending order of the degree index, and a bus with a predetermined priority or higher may be used as the evaluation target bus.

  According to this, since the order of the buses in the bus group is determined after classifying into the bus group by the state change, prioritization based on the state change and the stability index can be realized by a relatively easy process.

  Moreover, the evaluation target bus determining unit 12 classifies the plurality of buses into a plurality of bus groups by a combination of the magnitude of the state change and the stability index, and gives priority to each of the bus groups. You may decide to select the evaluation object bus based on the priority.

  According to this, a complicated priority can be set for the bus group by a combination of the state change and the voltage stability.

  Hereinafter, some more specific embodiments will be described in detail. The voltage stability monitoring device 2 in each embodiment shown below has the configuration shown in FIG.

  The voltage stability monitoring device 2 of the first embodiment has the configuration shown in FIG.

  FIG. 2 is a flowchart illustrating an outline of processing executed by the evaluation target bus determining unit 12 in each cycle in the first embodiment.

  First, the evaluation target bus determining unit 12 has coordinates (bus voltage V and bus load effective power P) indicating the state of the bus on which the stability curve is drawn at the previous calculation timing in a predetermined calculation cycle for all the buses. Then, the deviation L from the coordinates at the current calculation timing is calculated by the following equation (1) (step S1).

In the equation (1),
Lx: coordinate deviation a, b of bus X: arbitrarily set weight constant V: voltage value of bus X at current calculation timing P: load active power value V ₀ of bus X at current calculation timing: previous curve drawing The voltage value P ₀ of the bus X at the calculation timing at which the calculation is performed: The load active power value of the bus X at the calculation timing at which the previous curve drawing was performed.

  Subsequently, the evaluation target bus determination unit 12 classifies all the buses into one of a plurality of bus groups by comparing the calculated deviation L with the threshold value stored in the threshold data 16 (step S2). The plurality of bus groups are classified according to priority for determining buses for preferentially calculating stability curves. It is determined that the larger the deviation L is, the larger the difference between the bus timing state at which the previous stability curve of the bus belonging to the bus group is drawn and the bus state at the current calculation timing is greater, and the stability curve is calculated. Increase priority.

  Subsequently, the evaluation target bus determining unit 12 sorts the buses belonging to the bus group in the sorted order in ascending order of the voltage stability index at the calculation timing at which the previous stability curve was drawn (step S3). . This is a process for giving priority to buses belonging to the same bus group and having the same divergence between the bus state at the calculation timing at which the stability curve is drawn and the bus state at the current calculation timing. Among buses where the deviation of the bus state at the current calculation timing and the calculation timing at which the previous stability curve was drawn are the same, it is determined that the smaller the voltage stability index, the greater the influence of the deviation of the bus state. The priority will be increased.

  The priority is calculated for each bus by the above processing. The evaluation target bus determining unit 12 determines as many buses as the evaluation target buses according to the calculated priority, as many buses as the number of calculation execution buses set in advance by the operator (step S4). The number of calculation execution buses is the number of buses for calculating the stability curve. For example, the priority curve calculation may be continued according to the priority until the next calculation timing, and the number of buses that can be calculated by the priority curve may be determined as the number of calculation execution buses.

  FIG. 3 is a diagram for explaining an example of calculation of the deviation L in step S1 of FIG. A curve 100 shown in FIG. 3 is a PV curve of the bus X at the calculation timing when the previous stability curve was drawn. The coordinates 101 are the coordinates of the bus X at the calculation timing when the previous stability curve was drawn. Due to the state change of the power system 1, at the current calculation timing, the coordinates of the bus X move from the coordinate 101 at the previous calculation timing to the coordinate 102 at the current calculation timing. The evaluation target bus determining unit 12 calculates the moving distance 103 from the coordinate 101 to the coordinate 102 as the deviation Lx.

  4 to 8 are data tables for explaining an example of the priority determination procedure in steps S2 to S3 in FIG. FIG. 4 to FIG. 8 show information on each bus at each stage of an example process for giving priority to the bus.

  FIG. 4 shows information on a state in which the deviation L of each bus calculated in step S1 of FIG. 2 is recorded. From this state, in step S2, the deviation L of each bus is compared with a threshold value, and each bus is classified into a bus group. FIG. 5 shows a state in which each bus is classified into a bus group.

  Here, the priority is higher in the order of the bus group (1), the bus group (2), and the bus group (3). Here, two threshold values (threshold value 1 = 2.0, threshold value 2 = 1.0) are set.

  For example, the buses B and D with the deviation L exceeding the threshold 1 are classified into the bus group (1), and the buses F and G with the deviation L exceeding the threshold 2 but not more than the threshold 1 are the buses. The buses A, C, and E, which are classified into the group (2) and the deviation L is equal to or less than the threshold 2, are classified into the bus group (3).

  Further, in step S3, the priority of each bus in each bus group is determined according to the voltage stability index at the calculation timing at which the previous stable dynamic curve was drawn. First, when comparing the voltage stability index of the bus B and the bus D belonging to the bus group (1), the voltage stability index of the bus D is smaller. Therefore, the priority of bus D is the highest and bus B is the next point. FIG. 6 shows a state where the priorities of the buses D and B are determined.

  Subsequently, when the voltage stability index of the bus F and the bus G belonging to the bus group (2) is compared, the voltage stability index of the bus F is smaller. Accordingly, the bus F is set to have a higher priority than the bus G. FIG. 7 shows a state in which the priorities of the bus F and the bus G are determined.

  Further, the buses A, C, and E belonging to the bus group (3) are similarly compared to determine the priority of all buses. High priority is given in the order of buses C, A, E. FIG. 8 shows a state in which all priorities of the buses A to G are determined.

  If there is a large system sway in the power system 1 due to an accident, etc., the number of buses with a large discrepancy between the bus state at the calculation timing at which the previous stability curve was drawn and the bus state at the current calculation timing is set in advance. There is a possibility that the calculated number of calculation buses will be exceeded. In this case, a bus is generated in which the stability curve is not recalculated although there is a large discrepancy between the bus state between the calculation timing at which the previous stability curve was drawn and the current calculation timing. As a result, the state where the voltage stability displayed on the screen for the operator deviates from the actual voltage stability of the power system 1 at the relevant time may continue over a plurality of calculation timings. .

  As a countermeasure, when an accident is detected, the calculation results of all buses may be reset once and the stability curve may be drawn again. Alternatively, when an accident is detected, the operator may be notified as shown below.

  For example, the stability curve and the voltage stability index are displayed for the buses that are not the evaluation target buses in step S4 in FIG. 2, and at the same time, information on which bus group determined in step S2 belongs to which bus group. May also be displayed. By displaying which bus group belongs to which bus group, the operator of the voltage stability monitoring device 2 can determine the voltage stability of the power system 1 displayed on the screen and the actual voltage of the current power system 1. It is possible to know whether there is a deviation from the stability. Thereby, it is possible to reduce an operator from misrecognizing the state of the power system 1 when an accident occurs.

  For example, a bus group to be treated as having a large discrepancy between the calculation timing at which the previous stability curve was drawn and the current calculation timing is large is specified in advance, and when the evaluation target bus is determined, it belongs to the specified bus group Nevertheless, it is only necessary to extract the bus that has not become the evaluation target bus and notify the operator of the extracted bus as a bus whose exact state is unknown. For example, the notification may be performed by resetting display information related to the bus or changing the display color of the display unit related to the bus to a different color.

  The second embodiment is different from the first embodiment in the process of determining the evaluation target bus. In the first embodiment, the buses are classified into the bus group based on the deviation of the coordinates of the PV curve at the time when the previous stability curve is drawn and at the current calculation timing, but in the second embodiment, the previous stability curve is displayed. Based on the deviation of the slope of the PV curve at the time of drawing and the current calculation timing, the bus is classified into a bus group. The basic configuration of the voltage stability monitoring apparatus 2 of the second embodiment is the same as that shown in FIG.

  FIG. 9 is a flowchart illustrating an outline of processing executed by the evaluation target bus determining unit 12 in each cycle in the second embodiment.

  The method of drawing the PV curve is a known technique, and the method is to connect the coordinates obtained as a result of the tidal current calculation in the system section with the load value and the generator output changed with the curve to the bus coordinate at the start of calculation. There is.

  FIG. 10 is a diagram for explaining the PV curve drawing process. In FIG. 10, a curve 100 is a PV curve on the bus X, and a coordinate 101 is a coordinate based on a measurement value of the power system 1 of the bus X at the start of calculation. From the coordinate 101, the next coordinate 111 is obtained from the power flow calculation result in the system cross section in which the load value and the generator output are increased. From the coordinates 111, the tidal current calculation is performed in the system section where the load value and the generator output are further increased, and the next coordinates 112 are obtained.

The process of obtaining the next coordinate from a certain coordinate is defined as one step. By repeatedly executing this step, a region (higher solution portion) where the bus voltage in the PV curve is higher than the stability limit is obtained.

  In this embodiment, in FIG. 9, the evaluation target bus determination unit 12 executes the PV curve drawing process step for all buses only once, and calculates the coordinates at the start of calculation and the coordinates next to the stability curve. Two points are obtained (step S5).

  Subsequently, the evaluation target bus determining unit 12 calculates the slope A of the straight line connecting the two points with respect to all the buses according to the following equation (2) (step S6). The slope A is generally a negative value.

In the formula (2),
Ax: slope of the curve at coordinates based on the measured value of bus X V: voltage value based on the measured value of bus X P: active load power value based on the measured value of bus X
⁽¹⁾ V: Voltage value of the next coordinate of the curve of bus X
⁽¹⁾ P: The load active power value of the next coordinate of the curve of the bus line X is used.

Next, the evaluation target bus determining unit 12 calculates a deviation L ′ between the calculated slope A and the slope A ₀ when the previous stability curve is drawn (step S7). This deviation L ′ may be any value as long as the magnitude of the change in inclination can be evaluated. Although the here is the difference between A and A ₀ As an example, it may be a ratio such as A and A ₀ As another example.

  FIG. 11 is a diagram for explaining the calculation of the slope of the stability curve in step S5 and step S6.

In FIG. 11, a curve 102 is a PV curve of the bus X at the calculation timing when the previous stability curve was drawn, and a coordinate 116 is a measurement of the bus X at the calculation timing when the previous stability curve was drawn. The coordinate 122 is a coordinate based on the measured value of the bus X at the current calculation timing. The slope 131 is the slope Ax ₀ when the previous stability curve is drawn, and the slope 132 is the slope Ax obtained at the current calculation timing.

  When drawing the previous stability curve, the evaluation target bus determining unit 12 obtains the coordinates of points on the curve such as the coordinates 117 and 118. Therefore, the slope 131 when the previous stability curve is drawn is calculated by the equation (2) using the coordinates 116 based on the measured values and the coordinates 117 closest to the coordinates 116 among the points on the curve obtained by the calculation. can do.

  At the current calculation timing, the evaluation target bus determining unit 12 executes the PV curve drawing processing step only once based on the system data acquired by the power system information input unit 11 to obtain the next coordinate 123 on the curve. . Therefore, the slope 132 at the current calculation timing can be calculated by the equation (2) using the coordinates 122 and the coordinates 123.

  Returning to FIG. 9, next, the evaluation target bus determination unit 12 classifies all buses into a plurality of bus groups by comparing the calculated deviation L ′ with the threshold values stored in the threshold data 16 (step S <b> 8). It is determined that the larger the deviation L ′ is, the larger the difference between the bus state of the calculation timing at which the previous stability curve of the bus belonging to the bus group is drawn and the bus state of the current calculation timing is greater, and the priority To increase. Steps S9 and S10 in FIG. 9 are the same as steps S3 and S4 in the first embodiment shown in FIG.

  Through the above processing, the priority is determined for all the buses, and the evaluation target bus is determined based on the priority.

  The third embodiment is different from the first and second embodiments in the process of determining the evaluation target bus. In the first and second embodiments, after classifying all the buses into the bus group based on the state change of the bus, the priority of each bus is determined by arranging the buses in the bus group in order of priority. On the other hand, in Example 3, after classifying all the buses into the bus group based on the state change of the bus, the inside of the bus group is further classified into a small group.

  FIG. 12 is a flowchart illustrating an overview of the processing executed by the evaluation target bus determining unit 12 in each cycle in the third embodiment.

  Steps S11 and S12 in FIG. 12 are the same as steps S1 and S2 in the first embodiment shown in FIG.

  In the present embodiment, the evaluation target bus determining unit 12 has not only a threshold value for a state change but also a threshold value for a voltage stability index. Subsequent to step S12, the evaluation target bus determining unit 12 determines, for each bus group classified in step S12, the bus belonging to the bus group based on a comparison between each voltage stability index and a threshold. (Step S13).

  Next, the evaluation target bus determining unit 12 determines whether or not to execute the process of drawing the stability curve of the small group for each classified small group. The evaluation target bus determining unit 12 sets all buses belonging to the small group determined to execute drawing as evaluation target buses (step S14).

  The determination of whether or not to perform drawing of this small group is based on the viewpoint that the difference in coordinates at the time of the previous calculation of the stability curve and the current calculation timing is large, and the voltage stability index is small. The priority for drawing may be obtained, or a small group to be evaluated may be set in advance.

  FIGS. 13 to 16 are diagrams for explaining an example of an evaluation target bus determining procedure in steps S13 to S14 of FIG.

  Here, in step S11 and step S12 in the preceding stage, the 12 buses from bus A to bus L are arranged in order of bus divergence (high priority), bus group (1), bus group (2), bus group ( It shall be classified in 3).

  FIG. 13 shows the voltage stability index at the previous calculation timing of bus A to bus L. The buses A to L can be classified into three, a section X, a section Y, and a section Z, using a voltage stability index and two threshold values at the previous calculation timing.

  Here, two threshold values (threshold value 1 = 10.0, threshold value 2 = 5.0) are set for the voltage stability index.

  After step S12 is completed and the buses are classified into bus groups (1), (2), and (3) as shown in FIG. 14 according to the magnitude of the divergence, the evaluation target bus determining unit 12 determines in step S13 the bus Divide the group into smaller groups.

  The bus group (1) includes three buses, that is, a bus C, a bus G, and a bus L. These are further classified by comparing the voltage stability index and the threshold value at the previous calculation timing. As shown in FIG. 15, the bus G belongs to the section X, and the bus C and the bus L belong to the section Z.

  Here, the bus (in this case, bus G) belonging to the bus group (1) and belonging to the section X is referred to as belonging to the small group (1) X. There is no bus belonging to the small group Y in the bus group (1). The buses belonging to the small group (1) Z are the two buses of the bus C and the bus L.

  In the same manner as the bus group (1) described above, the bus group (2) and the bus group (3) are also classified into small groups. FIG. 16 shows a state in which the buses of the bus group (1), (2), and (3) are classified into small groups.

  Next, in step S14, the evaluation target bus determining unit 12 determines a small group having the bus to which the evaluation belongs as an evaluation target bus. Here, it is assumed that the operator sets a small group of buses to which the buses to be evaluated belong. For example, the setting is made based on the following concept. Since the buses belonging to the bus group (1) have a large difference in coordinates between the time when the previous stability curve was drawn and the current calculation timing, all the buses belonging to the bus group are set as evaluation target buses regardless of the division. That is, the buses belonging to the small group (1) X, the small group (1) Y, and the small group (1) Z are all evaluated buses.

  The buses belonging to the bus group (2) have relatively small discrepancies between the calculation timing of drawing the previous stability curve and the coordinates of the current calculation timing compared to the bus group (1). Therefore, the evaluation target bus determination unit 12 does not recalculate the stability curve of the bus belonging to the section Z having a large voltage stability margin, and sets the bus belonging to the section X and the section Y as the evaluation target bus. Assume that the buses belonging to the small group (2) X and the small group (2) Y are to be evaluated, and the buses belonging to the small group (2) Z are not to be evaluated.

  The buses belonging to the bus group (3) have a small difference between the coordinates of the calculation timing at which the previous stability curve was drawn and the current calculation timing. For this reason, the stability curve of the bus is not recalculated for the sections Y and Z having a certain degree of voltage stability margin, and the stability curve of the bus is recalculated for the section X having a small voltage stability margin. To do. That is, it is assumed that the bus belonging to the small group (3) X is an evaluation target bus, and the bus belonging to the small group (3) Y and the small group (3) Z is not an evaluation target.

  Although the embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments or examples, and these embodiments are within the scope of the technical idea of the present invention. Or you may use combining an Example and may change a one part structure.

DESCRIPTION OF SYMBOLS 1 ... Electric power system, 11 ... Electric power system information input part, 12 ... Evaluation object bus-line determination part, 13 ... Voltage stability curve calculation part, 14 ... Voltage stability parameter | index calculation part, 15 ... Calculation result display part, 2 ... Voltage stability Degree monitoring device

Claims (10)

A voltage stability calculation device for calculating a stability index representing a voltage stability of a power system including a plurality of buses,
An information input unit for acquiring a bus state representing a time-series state for each of the plurality of buses;
Evaluation for determining an evaluation target bus that is a target bus for recalculating a stability curve for calculating a voltage stability index of the bus from the plurality of buses based on the bus state of the plurality of buses A target bus determining unit;
A stability curve calculation unit that recalculates a stability curve for the evaluation target bus based on the bus state information of the evaluation target bus;
A stability index calculation unit that calculates a stability index of the evaluation target bus based on the stability curve of the evaluation target bus;
A voltage stability calculation device.   The evaluation target bus determining unit calculates a state change of the plurality of buses based on the bus state for the plurality of buses, and the state change for the plurality of buses and the stability for the plurality of buses. The voltage stability calculation apparatus according to claim 1, wherein the evaluation target bus is determined from the plurality of buses based on an index.   3. The voltage according to claim 2, wherein the evaluation target bus determination unit calculates a deviation between the latest value of the bus state and a value of the bus state when the stability curve was calculated last time, and determines the state change. Stability calculator.   The evaluation object bus determining unit calculates a deviation between the slope of the stability curve at the coordinates representing the latest bus state and the slope of the stability curve at the coordinates representing the previous bus state to obtain the state change. Item 3. The voltage stability calculation device according to Item 2.   The evaluation target bus determining unit classifies the plurality of buses into a plurality of bus groups according to the magnitude of the state change, and gives high priority to a bus group having a large state change, and for buses belonging to the same bus group, The voltage stability calculation apparatus according to claim 2, wherein a high priority is given to a bus having a small stability index, arranged in ascending order of a stability index, and a bus having a predetermined priority or higher is used as the evaluation target bus.   The evaluation target bus determining unit classifies the bus into a plurality of bus groups according to a combination of the magnitude of the state change and the stability index, and gives priority to each of the bus groups, based on the priority of the bus group The voltage stability calculation device according to claim 2, wherein the evaluation target bus is selected.   The voltage stability calculation apparatus according to any one of claims 1 to 6, wherein the stability curve is a PV curve representing a relationship between the demand power P and the bus voltage V.   The voltage stability calculation apparatus according to claim 7, wherein the stability index is a difference between a magnitude of active power at a nose end of the PV curve and a magnitude of active power in the latest bus state. A voltage stability calculation method for calculating a stability index representing voltage stability of a power system including a plurality of buses,
The information input means obtains a bus state representing a time-series state for each of the plurality of buses,
The evaluation target bus determining means is a target bus for recalculating a stability curve for calculating a voltage stability index of the bus from the plurality of buses based on the bus state of the plurality of buses. Determine the bus to be evaluated,
The stability curve calculation means recalculates a stability curve for the evaluation target bus based on the bus state information of the evaluation target bus,
A stability index calculation means calculates a stability index of the evaluation target bus based on the stability curve of the evaluation target bus;
Voltage stability calculation method. The evaluation target bus determining means calculates a state change of the plurality of buses based on the bus state for the plurality of buses, and the state change for the plurality of buses and the stability for the plurality of buses. The voltage stability calculation method according to claim 9, wherein the evaluation target bus is determined from the plurality of buses based on an index.

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