JP2002300722A - Voltage stability evaluation device, voltage stability evaluation method, voltage stability evaluation program and computer-readable recording medium recording voltage stability evaluation program in power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an online evaluatable and practical voltage stability evaluation device, voltage stability evaluation method, voltage stability evaluation program and computer-readable recording medium recording the voltage stability evaluation program. SOLUTION: The device comprises: a reactive power loss calculation part 20 for calculating a reactive power loss increase amount that is a variation of a reactive power reaching amount to a monitored busbar, which is set by a monitored busbar setting part 31, associated with a current variation before and after a power interruption to a target line designated by a line designation part 30; an excess amount calculation part 21 for calculating the excess amount of reactive power that can be supplied from a generator, which constitutes a power system, with respect to the variation of the reactive power of the monitored busbar in the power system after the power interruption of the target line; and a voltage stability evaluation part 22 for evaluating voltage stability by comparing the reactive power loss increase amount calculated by the reactive power calculation part 20 and the excess amount calculated by the excess amount calculation part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage stability evaluation technique for evaluating the voltage stability of a power system.

[0002]

2. Description of the Related Art The main purpose of supply and demand control in a power system is to stably supply power of good quality with stable voltage and frequency. Among them, a change in voltage is a very important quality factor because it causes failure or malfunction of electric equipment. In order to stably operate the voltage of the power system, it is necessary to quantitatively grasp in advance the voltage instability phenomenon that occurs due to a power transmission stop accident on the lines that make up the power system. Stability evaluation methods have been proposed.

[0003] Voltage stability evaluation methods are broadly classified into those that evaluate on a bus basis and those that evaluate on the entire system. On the other hand, the control operation for maintaining the predetermined voltage is to change the reactive power by operating the phase adjustment equipment or the transformer tap, and the control operation is performed locally (in the case where the voltage is changed or the voltage may be changed). Power stations or substations located near railway tracks). Therefore, among the conventional voltage stability evaluation methods, those that are evaluated for the entire system do not specify the line on which the voltage has changed or may change, so that the control operation is not clear, and There are certain limitations in terms of purpose.

[0004] In the voltage stability evaluation method, even if the evaluation is performed on a bus basis, the critical power in the PV curve (a curve plotting the received voltage V when the load P is changed) is calculated. Such a method requires an enormous amount of calculation time, and is not suitable as a method for evaluating the voltage stability online. In other methods, the criterion for evaluating the stability is unclear, and many methods are not practical.

[0005]

Further, the conventional voltage stability evaluation method is not practical because it does not take into account the limit (rating) of the reactive power output of the generator in the system. That is, the conventional voltage stability evaluation method cannot be evaluated online because of the enormous calculation time, or is not practical for various reasons.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is capable of on-line evaluation and is a practical voltage stability evaluation device, a voltage stability evaluation method, a voltage stability evaluation program, a voltage stability evaluation program, It is an object of the present invention to provide a computer-readable recording medium recording a degree evaluation program.

[0007]

According to a first aspect of the present invention, there is provided a voltage stability evaluation apparatus, wherein at least one of the lines constituting a power system is designated as a target line;
Monitoring target bus setting means for setting at least one bus of the bus constituting the power system as a monitoring target bus which is a monitoring target bus, and A reactive power loss calculating means for calculating an increase in reactive power loss, which is an amount of change in the amount of reactive power reaching the monitored bus, and a power system for detecting a change in reactive power of the monitored bus in the power system after the power transmission is stopped. A margin calculating means for calculating a margin of reactive power that can be supplied from the generator constituting the generator, and a voltage stability evaluating means for evaluating the voltage stability by comparing the reactive power loss increase and the margin. It is characterized by having.

According to a fifth aspect of the present invention, there is provided a voltage stability evaluation method,
At least one of the lines constituting the power system is specified, at least one of the buses constituting the power system is set as a monitored bus which is a bus to be monitored, and the power transmission of the target line is stopped. Calculates an increase in reactive power loss, which is a change in the amount of reactive power reaching the monitored bus due to a change in power flow before and after, and provides power with respect to a change in reactive power of the monitored bus in the power system after the power transmission is stopped. The present invention is characterized in that a surplus amount of reactive power that can be supplied from a generator constituting a system is calculated, and the reactive power loss increase amount is compared with the surplus amount to evaluate voltage stability.

According to a sixth aspect of the present invention, in the voltage stability evaluation program, at least one of the lines constituting the power system is designated, and at least one of the buses constituting the power system is designated.
The two buses are set as monitored buses to be monitored, and the reactive power loss increase, which is the amount of change in the amount of reactive power reaching the monitored buses due to power flow changes before and after the power transmission to the target line is stopped. Calculating the amount of reactive power that can be supplied from the generator constituting the power system with respect to the change in the reactive power of the monitored bus in the power system after the power transmission stop, and calculating the reactive power loss increase amount. And the margin is evaluated to evaluate the voltage stability.

A computer-readable recording medium on which the voltage stability evaluation program according to claim 7 is recorded,
At least one of the lines constituting the power system is specified, at least one of the buses constituting the power system is set as a monitored bus which is a bus to be monitored, and the power transmission of the target line is stopped. Calculates an increase in reactive power loss, which is a change in the amount of reactive power reaching the monitored bus due to a change in power flow before and after, and provides power with respect to a change in reactive power of the monitored bus in the power system after the power transmission is stopped. A voltage stability evaluation program for calculating a margin of reactive power that can be supplied from a generator constituting a system, and evaluating voltage stability by comparing the reactive power loss increase and the margin. Is a computer-readable recording medium having recorded thereon.

According to the invention, at least one of the lines constituting the power system is designated, and at least one of the buses constituting the power system is monitored as a monitored bus which is a bus to be monitored. When set, transmission stop is assumed for the specified target line, and the reactive power loss increase amount, which is a change amount of the reactive power arrival amount to the monitoring target bus due to the power flow change before and after this is calculated,
Further, a surplus amount of reactive power that can be supplied from a generator configuring the power system with respect to a change in the reactive power of the monitored bus in the power system after the power transmission is stopped is calculated. And
The voltage stability is evaluated by comparing the increase amount of the reactive power loss and the margin amount. Therefore, since the process is relatively simple, it is possible to evaluate the voltage stability online,
In addition, a practical evaluation of the voltage stability can be made because the criteria are clear.

According to a second aspect of the present invention, there is provided a voltage stability evaluation apparatus comprising:
Information collecting means for collecting and storing, at a predetermined timing, an actual connection state, which is an actual connection state of the power system, and an actual power state, which is an actual power flow state, and a power flow calculation means for performing power flow calculation of the power system And a rating storage means for storing a rating of the generator constituting the power system, wherein the reactive power loss calculating means calculates the power flow state after the power transmission stop, which is the power flow state after the power transmission stop, by the power flow calculating means. Calculating an increase in reactive power loss from the amount of reactive power reached in the actual power flow state to the monitoring target bus and the power flow state after power transmission is stopped, and the margin calculating means calculates the rated and actual power of the generator. The reactive power possible output amount for each generator was calculated using the power flow state, and a predetermined amount of reactive power was increased to the reactive power in the actual power flow state of the monitored bus in the power system after the power transmission was stopped. The combined power flow state is calculated by the power flow calculation means to determine the amount of reactive power increase for each generator, and the margin is calculated using the reactive power possible output amount and the reactive power increase amount. .

According to the above configuration, the information collection means collects and stores the actual connection state, which is the actual connection state of the power system, and the actual power flow state, which is the actual power flow state, at a predetermined timing. The rating storage means stores the ratings of the generators constituting the power system. Then, by the reactive power loss calculating means, the power flow after power transmission stop state which is the power flow state after the power transmission stop is calculated using the power flow calculating means, and in the actual power flow state to the monitored bus and the power flow after power transmission stop state. An increase in reactive power loss is calculated from the respective amounts of reactive power reached. Further, the surplus amount calculating means calculates the reactive power possible output amount of each generator using the generator rating and the actual power flow state, and disables the monitored bus in the actual power flow state in the power system after the power transmission is stopped. The power flow state when a predetermined amount of reactive power is increased in the power is calculated using the power flow calculating means, the reactive power increase amount for each generator is obtained, and the reactive power available output amount and the reactive power increase amount are calculated. The surplus amount is calculated using this. Therefore, the reactive power loss increase and the margin are efficiently calculated, and the voltage stability evaluation device according to claim 1 is efficiently realized.

According to a third aspect of the present invention, there is provided a voltage stability evaluation device, comprising:
Display means for displaying a margin of voltage stability, wherein the voltage stability evaluation means displays a difference between the margin and the increase in reactive power loss on the display means as a margin of voltage stability. It is characterized by. According to the above configuration,
The voltage stability evaluation means displays the difference between the margin and the increase in reactive power loss on the display as a margin for the voltage stability, so that the stability margin can be quantitatively grasped.

According to a fourth aspect of the present invention, there is provided a voltage stability evaluation device, comprising:
The surplus amount calculating means obtains a value obtained by dividing the reactive power possible output amount by the reactive power increase amount for each generator, and calculates the surplus amount for the generator having the smallest value. According to the above configuration, a value obtained by dividing the reactive power possible output amount by the reactive power increase amount for each generator is obtained by the margin calculating means, and the margin is calculated for the generator having the smallest value. Thus, a voltage stability evaluation device capable of performing the strictest evaluation is realized.

[0016]

FIG. 1 is a block diagram of a voltage stability evaluation apparatus according to the present invention. The voltage stability evaluation device 1 includes a line designation unit 30 that designates at least one of the lines constituting the power system as a target line, and a bus that monitors at least one of the buses constituting the power system. Monitoring target bus setting unit 31 to be set as a certain monitoring target bus
A power flow calculator 40 for calculating the power flow of the power system, and a rating storage unit 4 for storing the ratings of the generators constituting the power system.
1, an information collection unit 10 that collects and stores, at a predetermined timing, an actual connection state, which is an actual connection state of the power system, and an actual power flow state, which is an actual power flow state. Assuming power transmission stop for the target line,
Monitoring target bus setting unit 3 accompanying the tidal change before and after
1 and a reactive power loss calculator 20 that calculates an increase in reactive power loss, which is an amount of change in the amount of reactive power reaching the monitoring target bus, and a target line specified by the line specifying unit 30 after power transmission is stopped. A margin calculation unit 21 that calculates a margin of reactive power that can be supplied from a generator configuring the power system with respect to a change in reactive power of the monitored bus set by the monitored bus setting unit 31 in the power system; A voltage stability evaluation unit 22 that evaluates voltage stability by comparing the increase amount of reactive power loss calculated by the reactive power loss calculation unit 20 and the margin amount calculated by the margin amount calculation unit 21.
And a display unit 50 for displaying a margin of voltage stability.

The line designating section 30 designates at least one of the lines constituting the electric power system as a target line for which transmission stop is assumed. For example, a power system diagram is reproduced on a computer, displayed on a monitor, and an operator specifies a target line by specifying a target line with a pointing device such as a mouse.
Alternatively, the target line may be stored in advance.
The target line may be specified by the operator each time the voltage stability is evaluated, may be specified by the operator as necessary, or may be a plurality of lines in which power transmission is assumed to be stopped in advance. May be stored as target lines, and each line may be designated as a target line, and the evaluation of the voltage stability may be performed the number of times corresponding to the number of stored target lines.

The monitoring target bus setting section 31 sets at least one of the buses constituting the electric power system as a monitoring target bus which is a target bus for which the evaluation of the voltage stability is performed. For example, the power system diagram is reproduced on a computer, displayed on a monitor, and the operator sets the monitoring target bus by setting the monitoring target bus with a pointing device such as a mouse. Alternatively, the monitoring target bus may be stored in advance. The setting of the monitoring target bus may be performed by the operator every time the voltage stability is evaluated, or may be set by the operator as needed, or it is assumed that monitoring is necessary in advance. A plurality of lines may be stored as monitoring target buses, and each line may be designated as a monitoring target bus, and the evaluation of the voltage stability may be performed as many times as the number of stored monitoring target buses.

The power flow calculation unit 40 performs power flow calculation by solving the power equation of the power system by specifying the PV. Specifically, in the power equation, the circle in the chart shown in FIG.
Given the elements of the mark as input items,
Outputs the element of the mark. In other words, the input items are
The active power output and terminal voltage of the generator, the switching of circuit breakers in substations, the opening and closing of disconnectors, the active power of loads, the reactive power of loads, the operating conditions of phase adjustment equipment, and the tap conditions of transformers. The output items are the reactive power output of the generator, the active power flow at the transmitting end, the active power flow at the receiving end, the reactive power flow at the transmitting end, the reactive power flow at the receiving end, and the bus voltage at the substation.

The rating storage unit 41 stores at least a rated capacity and a rated power factor for each generator constituting the power system. The recording medium of the rating storage unit 41 is RAM
May be used, or a ROM such as a CD-ROM may be used.

The information collecting unit 10 includes various sensors, such as a voltmeter and an ammeter, disposed in the power system to determine the actual connection state, which is the actual connection state of the power system, and the actual power state, which is the actual power flow state. At a predetermined timing and stored in a recording medium (not shown). Here, the connection status of the power system is as follows: transmission / non-transmission status of the line, power plant and substation operation stop status, substation breaker switching / disconnector switching / phase adjustment equipment operating condition / transformer Tap conditions. The power flow status of the power system is based on the active power output, reactive power output, and terminal voltage of the generator, the bus voltage of the substation,
The active power of the load, the reactive power of the load, the active power flow of the transmission end of the line, the active power flow of the receiving end, the reactive power flow of the transmission end,
And the receiving end reactive power flow.

The reactive power loss calculating section 20 includes the line specifying section 3
The power flow after the power transmission stop, which is the power flow after the power transmission stop of the target line designated by 0, is calculated by the power flow calculation unit 40, and the actual power flow state to the monitoring target bus set by the monitoring target bus setting unit 31 and the power transmission Reactive power loss increase Δ
And calculates the Q _L. Reactive power loss increase ΔQ
_L is obtained by subtracting the amount of reactive power reaching the monitored bus in the power flow state after the transmission stoppage from the amount of reactive power reaching the monitored bus in the actual power flow state.

The margin calculating unit 21 reads out the generator rating stored in the rating storage unit 41 and the actual power flow state collected and stored by the information collecting unit 10, and calculates the reactive power for each generator. The output amount ΔQ _Mi is calculated, and the track designation unit 30
In the power system after the transmission stop of the target line specified by the above, the power flow state when the predetermined amount of reactive power ΔQ is increased to the reactive power in the actual power flow state of the monitored bus set by the monitored bus setting unit 31 in the power system. calculated by flow calculation unit 40 obtains the reactive power increment Delta] Q _Gi of each generator, relative to the change of the reactive power of the monitored bus by using the reactive power can be output quantity Delta] Q _Mi reactive power increment Delta] Q _Gi Reactive power margin ΔQ _S that can be supplied from a generator constituting the power system
Is calculated. Here, the power system for which the voltage stability is evaluated includes N generators, and each generator is given a serial number, and the reactive power possible output amount ΔQ _Mi and the reactive power increase. The suffix i of the quantity ΔQ _Gi represents the serial number of the generator. That is, i is an integer from 1 to N.

FIG. 3 is a graph showing the possible reactive power output ΔQ of the generator.
FIG. 6 is a diagram for explaining a method of calculating _Mi. The horizontal axis in FIG. 3 is the active power output of the generator, and the vertical axis is the reactive power output. The radius of the semicircle about the origin is the rated capacity of the generator, and the dotted line passing through the origin represents the rated power factor.
The crosses in the figure indicate points (called operating points) where the active power output and the reactive power output of the generator in the actual power flow state are plotted on coordinates. The length on the coordinate of the double arrow in the figure is the reactive power possible output amount ΔQ _{Mi of the} generator.
It is.

FIG. 4 is a diagram for describing a method of calculating the reactive power increase ΔQ _Gi of the generator. The horizontal axis in FIG. 4 is the active power output of the generator, and the vertical axis is the reactive power output.
The radius of the semicircle about the origin is the rated capacity of the generator, and the dotted line passing through the origin represents the rated power factor. The crosses in the figure indicate operating points in the actual power flow state, and the crosses indicate operating points in the power flow state when a predetermined amount of reactive power ΔQ is increased to the reactive power in the actual power flow state of the monitored bus. is there. The length on the coordinates of the double arrow in the figure is the reactive power increase amount ΔQ _Gi of the generator. That is, the reactive power increase between the operating point in the actual power flow state and the reactive point in the power flow state when the reactive power in the actual power flow state of the monitored bus is increased by a predetermined amount of reactive power ΔQ is the reactive power increase. The quantity ΔQ _Gi .

Next, a method of calculating the margin ΔQ _S will be described. Here, it is assumed to perform the most rigorous evaluation, obtains a value obtained by dividing the reactive power increment Delta] Q _Gi reactive power can be output amount Delta] Q _Mi for each generator, it calculates the allowance Delta] Q _S with respect to the smallest generator of the value I do. Specifically, ΔQ _S
= MIN (ΔQ _Mi / ΔQ _Gi ) × ΔQ and the margin ΔQ _S
Is calculated. Here, MIN (ΔQ _Mi / ΔQ _Gi ) is the minimum value of the values obtained by dividing the reactive power possible output amount ΔQ _Mi of all the generators by the reactive power increase amount ΔQ _Gi .

The voltage stability evaluator 22 calculates the reactive power loss increase ΔQ _L calculated by the reactive power loss calculator 20.
And by comparing the calculated surplus amount Delta] Q _S by margin amount calculating section 21, the latter is evaluated as if the former is larger than the power system is stable, and assessed as unstable Otherwise A value obtained by subtracting the former from the latter is calculated as a margin for the voltage stability and output to the display unit 50.

The display unit 50 displays a margin (ΔQ _S) of the voltage stability of the power system calculated by the voltage stability evaluation unit 22.
−ΔQ _L ). The display unit 50 has a CR
It is a monitor composed of a liquid crystal and a liquid crystal.

FIG. 5 is a flowchart of a process performed by the voltage stability evaluation device of the present invention. Here, one of the lines constituting the power system is previously determined by the line designation unit 30.
One of the lines is designated as a target line for which power transmission is to be stopped, and one of the buses constituting the power system is a target bus for which the evaluation of the voltage stability is to be performed by the monitoring target bus setting unit 31. It is set as a target bus, and the rated storage unit 41 stores at least the rated capacity and the rated power factor for each generator constituting the power system.

First, the information collecting unit 10 determines the actual connection state, which is the actual connection state of the power system, and the actual power flow state, which is the actual power flow state, by using a voltage machine, a current machine, or the like disposed in the power system. Collected from various sensors and stored in a recording medium (not shown) (S1). Next, the reactive power loss calculator 20
Performs the following processing. The power flow state after the power transmission stop, which is the power flow state after the power transmission stop of the target line specified by the line specifying unit 30, is calculated using the power flow calculation unit 40 (S3). Then, the reactive power loss increment Delta] Q _L is calculated from the respective reactive power reaches the amount of the real power flow state power and after stop power flow state to the monitored bus set by the monitored bus setting unit 31 (S5).

Next, the following processing is performed by the margin calculating unit 21. The rating of the generator stored in the rating storage unit 41 and the actual power flow state collected and stored by the information collection unit 10 are read, and the reactive power possible output amount ΔQ _{Mi for} each generator is calculated. (S7). Next, a predetermined amount of reactive power ΔQ is increased to the reactive power in the actual power flow state of the monitoring target bus set by the monitoring target bus setting unit 31 in the power system after the transmission stop of the target line specified by the line specifying unit 30. The tidal current state when the
Is used to calculate the reactive power increase amount ΔQ _Gi for each generator (S9). Then, the reactive power possible output amount ΔQ
_{Using the Mi} and the reactive power increase amount ΔQ _Gi , a surplus amount ΔQ _{S of} reactive power that can be supplied from the generator constituting the power system with respect to the change in the reactive power of the monitored bus is calculated (S1)
1).

Next, the voltage stability evaluation section 22
Allowance Delta] Q _S is the determination of whether the reactive power loss increment Delta] Q or larger than _L is performed (S15). If allowance Delta] Q _S is greater than the reactive power loss increment Delta] Q _L, it is determined that the power system is stable, allowance of voltage stability of the power system on the display unit 50 (ΔQ _S -ΔQ _L) is displayed Is performed (S17).
If allowance Delta] Q _S is equal to or less than the reactive power loss increment Delta] Q _L, it is determined that the power system is unstable (S1
9).

FIG. 6 is an example of a power system diagram of a power system whose voltage stability is evaluated by the voltage stability evaluation device of the present invention. The power system has 13 generators G1 to G13.
And 13 substations M1 to M13, three electric power companies (company A to company C), and lines connecting them. Here, it is assumed that the voltage stability is evaluated when the line B is designated as a target line and the substation M4 of A is set as a monitoring target bus.

FIG. 7 is a circuit diagram showing the power system shown in FIG.
The voltage stability evaluation device of the invention is applied, and the voltage stability is
9 is a chart showing an example of an evaluation result. However, invalid
Increase in reactive power loss calculated by power loss calculation unit 20
Addition ΔQ_LIs 0.980 PU and the reactive power increase
ΔQ_GiTo the reactive power of the monitored bus used to determine
The predetermined amount of reactive power ΔQ to be added is 0.1 PU
And FIG. 7 shows the generator symbols G1 to G13 and
And the maximum reactive power output corresponding to the
The calculated reactive power possible output amount ΔQ_MiAnd reactive power
Increase ΔQ_GiAnd ΔQ_Mi/ Q_GiAre shown. Generator G
ΔQ of 5_Mi/ ΔQ_GiIs the minimum value of 17.26.
1.726 PU multiplied by ΔQ (= 0.1 PU)
Tolerance ΔQ _SIs the value of Therefore, in this case, ΔQ_S>
ΔQ_LTherefore, the power system was evaluated as stable and
Indicating part 50 shows a margin of voltage stability of power system 0.746P.
U is displayed.

The present invention can take the following modes. (A) In the present embodiment, the case has been described where the target line and the monitoring target bus are specified or set in advance.
A mode may be set each time the voltage stability of the power system is evaluated. In this case, each time the voltage stability of the power system is evaluated, it is possible to specify or set the target line and the monitoring target bus desired by the operator. (B) In the present embodiment, a case has been described in which the target line and the monitoring target bus are respectively specified or set at one location, but a configuration in which two or more locations are specified or set may be used. In this case, it is possible to evaluate the voltage stability of the power system under various conditions. (C) In the present embodiment, the case where the stability of the power system is evaluated every time the real connection state and the real power flow state are collected by the information collecting unit 10 has been described. In this case, the stability of the power system may be evaluated. In this case, it is possible to reduce the load on the computer by determining the timing for evaluating the stability of the system from the past results or the actual power flow state. (D) In the present embodiment, the case where the margin of the voltage stability of the power system is displayed on the display unit 50 has been described, but an alarm is issued when the margin of the voltage stability becomes a predetermined value or less. It may be a form or a form in which a system operation preset for the monitored bus is instructed. In the former case, the workload of the operator monitoring the margin of the voltage stability of the power system on the display unit 50 is reduced, and in the latter case, the operator further instructs the monitoring target bus to operate the system. Work load is reduced. (E) In the present embodiment, the case has been described where the real connection state and the real power flow state collected and stored by the information collecting unit 10 are used in the evaluation of the voltage stability. May be stored and analyzed over a long period of time to find a bus line and a time zone in which the voltage stability is likely to be unstable, and to provide a plan for measures for voltage stabilization of the power system.

[0036]

According to the first, fifth, sixth, and seventh aspects of the present invention, at least one of the lines constituting the power system is designated, and at least one of the buses constituting the power system is connected. When the monitoring target bus is set as a monitoring target bus, power transmission to the designated target line is assumed to be stopped, and a change in the amount of reactive power reaching the monitoring target bus due to a change in power flow before and after this is assumed. The reactive power loss increase amount is calculated, and the margin of the reactive power that can be supplied from the generator configuring the power system with respect to the change in the reactive power of the monitored bus in the power system after the power transmission is stopped is calculated. Is done. Then, the voltage stability is evaluated by comparing the increase amount of the reactive power loss and the margin amount. Therefore, since the process is relatively simple, it is possible to evaluate the voltage stability online, and it is possible to evaluate the practical voltage stability because the criteria for determination are clear.

According to the second aspect of the present invention, the information collecting means collects and stores the actual connection state, which is the actual connection state of the power system, and the actual power flow state, which is the actual power flow state, at a predetermined timing. The rating of the generator constituting the power system is stored by the rating storage means.
Then, by the reactive power loss calculating means, the post-power-supply power flow state, which is the power flow state after the power transmission is stopped, is calculated using the power flow calculating means, and the actual power flow state to the monitored bus and the power flow after the power transmission stop state are calculated. An increase in reactive power loss is calculated from the respective amounts of reactive power reached. Further, the surplus amount calculating means calculates the reactive power possible output amount of each generator using the generator rating and the actual power flow state, and disables the monitored bus in the actual power flow state in the power system after the power transmission is stopped. The power flow state when a predetermined amount of reactive power is increased in the power is calculated using the power flow calculating means, the reactive power increase amount for each generator is obtained, and the reactive power available output amount and the reactive power increase amount are calculated. The surplus amount is calculated using this. Therefore, the reactive power loss increase and the surplus are efficiently calculated, and
Is efficiently realized.

According to the third aspect of the present invention, the difference between the margin and the increase in the reactive power loss is displayed on the display as the margin of the voltage stability by the voltage stability evaluation means. Can be quantitatively grasped. According to the invention as set forth in claim 4, a value obtained by dividing the reactive power possible output amount by the reactive power increase amount for each generator is obtained by the margin amount calculating means, and the margin amount is determined for the generator having the smallest value. Since the calculation is performed, a voltage stability evaluation device that performs the strictest evaluation is realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a voltage stability evaluation device of the present invention.

FIG. 2 is a table showing input conditions and output items of power flow calculation.

FIG. 3 is a diagram for explaining a method of calculating a reactive power possible output amount of a generator.

FIG. 4 is a diagram for explaining a method of calculating a reactive power increase amount of a generator.

FIG. 5 is a flowchart of a process performed by the voltage stability evaluation device of the present invention.

FIG. 6 is an example of a power system diagram of a power system whose voltage stability is evaluated by the voltage stability evaluation device of the present invention.

FIG. 7 is a diagram to which the voltage stability evaluation device of the present invention is applied;
9 is a chart showing an example of a result of evaluating voltage stability.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 voltage stability evaluation device 10 information collection unit (information collection unit) 20 reactive power loss calculation unit (reactive power loss calculation unit) 21 margin calculation unit (margin calculation unit) 22 voltage stability evaluation unit (voltage stability evaluation) Means) 30 Track designation unit (track designation means) 31 Monitoring bus setting unit (Monitoring bus setting means) 40 Power flow calculation unit (Power flow calculation means) 41 Rating storage unit (Rating storage means) 50 Display unit (Display means)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5G066 AA09 AD01 AE07 AE09

Claims (7)

[Claims] At least one of lines constituting a power system
Line designation means for designating two lines as target lines, and monitoring target bus setting means for setting at least one bus of the buses constituting the power system as a monitoring target bus which is a bus to be monitored, A reactive power loss calculating means for calculating an increase in reactive power loss, which is an amount of change in the amount of reactive power reaching the monitoring target bus due to a power flow change before and after the transmission stop of the target line; and A margin calculating means for calculating a margin of reactive power that can be supplied from a generator constituting the power system with respect to a change in reactive power of the monitored bus, and comparing the reactive power loss increase with the margin. And a voltage stability evaluation means for evaluating the voltage stability. 2. An information collecting means for collecting and storing, at a predetermined timing, an actual connection state as an actual connection state of the power system and an actual power state as an actual power flow state, and a power flow calculation of the power system. And a rating storage means for storing the ratings of the generators constituting the power system, wherein the reactive power loss calculating means reads the power flow state after the power transmission stop, which is the power flow state after the power transmission stop. The reactive power loss increase is calculated from the amount of reactive power reached in the actual power flow state to the monitored bus and in the power flow state after the power transmission is stopped. A reactive power possible output amount for each generator is calculated using the rating and the actual power flow state of the generator, and a predetermined amount of the reactive power in the actual power flow state of the monitored bus in the power system after the power transmission is stopped. Calculating the power flow state when the power is increased by the power flow calculation means to obtain the reactive power increase amount for each generator, and calculating the margin using the reactive power possible output amount and the reactive power increase amount. The voltage stability evaluation device according to claim 1, wherein: 3. A display device for displaying a margin of voltage stability, wherein the voltage stability evaluation unit displays the difference between the margin and the increase in reactive power loss as a margin of voltage stability. The voltage stability evaluation device according to claim 1 or 2, wherein the voltage stability is displayed on a means. 4. The surplus amount calculating means obtains a value obtained by dividing the reactive power possible output amount by the reactive power increase amount for each generator, and calculates the surplus amount for the generator having the smallest value. The voltage stability evaluation device according to claim 2 or 3, wherein: 5. At least one of the lines constituting the power system
Two lines are specified, and at least one of the buses constituting the power system is set as a monitoring target bus, which is a bus to be monitored, and the monitoring target associated with a power flow change before and after the power transmission of the target line is stopped. An increase in reactive power loss, which is a change in the amount of reactive power reaching the bus, is calculated and supplied from a generator constituting the power system with respect to a change in reactive power of the monitored bus in the power system after the power transmission is stopped. A voltage stability evaluation method, comprising calculating a margin of reactive power to be obtained, and comparing the increase in reactive power loss with the margin to evaluate voltage stability. 6. At least one of the lines constituting the power system
One of the buses constituting the power system is set as a monitoring target bus which is a bus to be monitored, and the monitoring target associated with a power flow change before and after the power transmission of the target line is stopped. An increase in reactive power loss, which is a change in the amount of reactive power reaching the bus, is calculated and supplied from a generator constituting the power system with respect to a change in reactive power of the monitored bus in the power system after the power transmission is stopped. A voltage stability evaluation program which calculates a margin of reactive power to be obtained, and evaluates voltage stability by comparing the increase in reactive power loss with the margin. 7. At least one of the lines constituting the power system
One of the buses constituting the power system is set as a monitoring target bus which is a bus to be monitored, and the monitoring target associated with a power flow change before and after the power transmission of the target line is stopped. An increase in reactive power loss, which is a change in the amount of reactive power reaching the bus, is calculated and supplied from a generator constituting the power system with respect to a change in reactive power of the monitored bus in the power system after the power transmission is stopped. A computer-readable recording medium recording a voltage stability evaluation program, wherein a margin of the reactive power to be obtained is calculated, and the voltage stability is evaluated by comparing the increase in the reactive power loss and the margin. .