JPH08280135A - Voltage reactive power controller - Google Patents

Abstract

PURPOSE: To make it possible to control a reactive power generator for power systems by dividing a power system to calculate matching between a reactive power generating source and a reactive power consuming source within the power system. CONSTITUTION: Fed with data on a power system from a data reading device 102 through a communication line 258, a power system division calculating device 104 divides the power system into subsystems most suitable for voltage reactive power control. For each of the resultant subsystems, the amounts of reactive power consumed and generated are calculated, and the adequacy of reactive power balance is judged. As a result the system in question is dynamically divided into the subsystems, and reactive power is allotted with reactive power balance taken into account for each subsystem. This enables prevention of reverse control phenomena. This also makes it possible to perform total calculation at high speed and thus provide voltage reactive power control on- line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for calculating an optimum voltage reactive power distribution for a power flow state of an arbitrary time section.

[0002]

[Prior art]

(1) Edited by The Institute of Electrical Engineers of Japan, measures for maintaining voltage stability of power systems, Institute of Electrical Engineers of Japan Technical Report II-73, 43-45 (1979) The above literature is known as a known example of the voltage reactive power control method. Among these, there are (a) a method of using a judgment function, (b) a method of allocating at a margin ratio, and (c) a method of allocating at the minimum transmission loss. The method of allocating using the judgment function of (a) is to calculate the amount of change of the judgment function for all the adjustment devices in the target system, select the adjustment device that gives the largest decrease in the judgment function, and Do the operation. This process is repeated until the constraint condition of the monitoring point is satisfied. In the method (b), the deviation of the reference voltage of the voltage monitoring device in the electric power system is associated in advance with a group of generators for adjusting the deviation, and each unit within the group is associated with the deviation. The adjustment amount is calculated so that the same margin ratio is obtained within the defined reactive power adjustment range. In addition, the method of (c) allocating with the minimum transmission loss reduces the average value of the deviation of the voltage of each part of the system from the reference value, and the reactive power flow at the interconnection point approaches the reference value. Control the total value of reactive power.

(2) Japanese Unexamined Patent Publication No. 5-108177 The feature of the method of the known example (2) is that each voltage reactive power control device has a restriction on the number of operations, and a control target having a restriction on the number of operations is provided. By configuring the devices so as to perform control in consideration of the constraint value, the average frequency of use of each control device can be ensured, and the control followability is ensured when the demand changes suddenly.

[0004]

Among the above prior arts,
The method (1) (a) has a drawback that the number of calculation iterations for adjusting the voltage and the reactive power increases when the voltage and the reactive power change significantly. Further, in the method (1) and (b) of distributing with an equal margin ratio, it is necessary to change the reference voltage when the system configuration of the target power system is significantly changed, and this operation greatly increases the work. In addition, in the method of (1) (c) that allocates with minimum transmission loss, since only the adjustment of the reactive power output of the generator is the control variable, considering the actual operation of the power system, Transformer tap adjustments need to be included in the controlled variable.

Further, in the publicly known example (2), the above publicly known example is improved in that the number of operations of the same phase adjusting device is prevented from being concentrated in consideration of the number of operations of the phase adjusting equipment. Since the improvement measure in this known example changes the weighting coefficient of the evaluation function of the phase adjusting device, it is necessary to change the weighting coefficient for the evaluation function every time the system state changes or the control target device changes. is there. Therefore, the calculation efficiency is not improved, and there is a problem in using it for online control.

The voltage reactive power control device in the publicly known examples so far considers the voltage reactive power control device in all the target power systems as a control target, that is, the voltage is controlled by using a so-called overall system control concept. Reactive power control is performed. In this all-in-one method, the solution obtained by calculation may not match the actual operation guideline of the power system. For example, it is a case where the operation of the generator reactive power output farther from the voltage control bus bar having a higher operation sensitivity to the voltage than the phase adjusting device around the voltage control bus having a low operation sensitivity to the voltage is optimally selected. Similarly, in the known example (1), since the voltage sensitivity coefficient of each voltage reactive power control device is obtained for the entire system collectively, the phenomenon of device selection as described above occurs. for that reason,
In many cases, consistent voltage control is not performed, resulting in a control result that differs from actual operation.

In the present invention, the target system is dynamically divided into sub-systems, and reactive power is distributed to each sub-system while considering the reactive power balance to prevent the reverse control phenomenon in the entire system. The invention is to perform simple addition / subtraction / multiplication / division calculations other than power flow calculation, to execute the entire calculation at high speed, to realize voltage reactive power control online, and the process of selecting the reactive power control device is performed by the power system operator. It is also an object of the present invention to provide a voltage reactive power control device that is easy to understand.

[0008]

According to the present invention, this power system is divided with respect to a target power system, and a matching state between a reactive power generation source and a reactive power consumption source is determined in the divided power system. By calculating, the reactive power generator of the power system is controlled.

That is, in the present invention, the voltage-reactive power adjusting device, which has been required for the whole system until now, is divided into some partial systems for the target power system. In the publicly known examples up to now, there has been a publicly known example in which only a specific type of electric reactive power regulator having high voltage sensitivity is divided into partial systems (publicly known example (1) (b)), but in the present invention, this part is used. The system is divided into a substation of the main system and its subsystems, or a system with the same power supply as one unit. In this division method, when the demand and supply of reactive power cannot be balanced, fusion and division with adjacent sub-systems are repeated to perform optimum sub-system division. The reactive power balance is calculated for each of the divided partial systems in this way, and the optimum voltage reactive power adjusting device is calculated for each of the partial systems.

In order to calculate the optimum voltage reactive power regulating device to be controlled for each partial system, in addition to the algorithm used in the past, a case of a similar system condition is searched from past history data, and the past A method of selecting an optimum voltage reactive power control device based on the result is used. By combining this idea with a power flow state prediction support system for a few hours in the future, we have made it possible to deal with the system state that changes from moment to moment. Moreover, the result of the reactive power operating device and the power flow state at each time point were learned and used for the calculation of the optimum reactive power control device at the next time point.

[0011]

[Operation] After predicting the power flow state at a future time point, the entire target system is divided into a plurality of partial systems in a form suitable for each power flow state. By performing fusion and division of the target system while considering the amount of reactive power generation and consumption and dividing into optimum sub-systems and performing reactive power distribution calculation, consistent control that does not cause reverse control phenomenon in the entire system can be achieved. It will be possible. Further, the power flow state at the time of execution of the calculation is compared with the similar power flow state in the past history data, and the reactive power is distributed by reflecting the difference amount in the time section in the control state on the similar day. Here, the optimum distribution of reactive power is obtained while considering the margin of the voltage reactive power adjustment device. By this method, it is possible to perform high-speed processing because it is only necessary to perform simple calculations other than executing the power flow calculation.

[0012]

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 1 shows a power system voltage reactive power controller 1 according to the present invention.
It is a block diagram. The present invention relates to a target power system 101, a data reading device 102 that reads necessary data from the power system 101, a state estimation device 103 that estimates a likely system state at the time based on the read data, and a voltage reactive power control implementation. The power system partial system partitioning calculation device 104 as a pre-processing for performing the above, and the future system power flow state prediction device 1 for predicting the power system in the future by several hours from the state estimation device.
05, the reactive power optimal distribution calculating device 106, the device 1 for selecting a voltage reactive power control device to be operated for optimal reactive power distribution from the predicted power flow state obtained from the device
Based on the result of 06, a command is issued to the operation device, a reactive power distribution command device 107, an operation result is output, and an output device 108
Consists of

Details of each of the following devices will be described. In the data reading device 102, information is obtained from each facility through the communication line 251, and the target system is further contracted.
A process for storing the system information in a format like this is performed. The processing result in the device 102 is sent to the state estimation device 103 through the communication line 252. The state estimation device 103 is means for estimating a likely state in the power system at that time using a method represented by the following known example.

Lars Holten, Anders Gjelsvik, Sverre A
dam, FF Wu and Wen-Hsiung E. Liu, Comparison of
Diffeent Methods for State Estimation. IEEE Trans.
Power Syst., 3 (1988), 1798-1806. The estimation result of the device 103 is sent to the future system power flow state prediction device through the communication line 253. Here, it is a function of predicting the power flow state of the power system at a future time point based on the past total power demand, data on the generator, load data of each substation, and the result of the device 103. The details are described in detail in the following publicly known examples.

Nakajima, Okubo, Matsumoto, Ishida, Tamura, several hours ahead power flow state prediction system (DP)
F) System development, 1995 IEEJ National Convention, 13
96 (1995).

The electric power system partial system division calculation device 104 is a characteristic device of the present invention. The device 104 obtains the power system data from the data reading device 102 through the communication line 258, and the state estimation result obtained by the device 103 or the power flow state prediction result obtained by the device 105. Based on the above data, this device divides the power system for voltage reactive power control into optimum sub-systems. Details of the system division method performed by this device will be described with reference to FIG. First, the means 301 divides the target system into a system in which the main system substation and its subordinate system are units. An actual example of this division will be described with reference to FIG. In the example system of Fig. 4, the core substation is A
s / s to Cs / s. The other substations are subordinate substations. The means 301 divides the target power system of FIG. 4 into sub-systems 401, 402 and 403.

Next, the means 302 calculates the reactive power balance based on the reactive power consumption and the reactive power generation amount or the reactive power generation possible amount for each of the divided partial systems. After obtaining the reactive power balance by the means 302, the means 303 determines whether or not the reactive power balance is appropriate. The means 303 determines the suitability of the reactive power balance based on the following formula.

[0018]

## EQU00001 ## (Reactive power consumption amount) .ltoreq. (Reactive power generation amount or possible generation amount) (Equation 1) When the expression 1 is satisfied, the processing of the power system partial system division calculation device is ended. If not, a partial system that does not satisfy the formula 1 is selected, one of the adjacent partial systems is fused by the means 304, and the reactive power balance for the fused partial system is calculated by the means 305. For example, taking the power system of FIG. 4 as an example, when the reactive power balance of the partial system 402 is not appropriate, the partial system 401 and the partial system 402 are fused to calculate the reactive power balance of both partial systems. Next, the means 306 checks the reactive power balance after fusion. Here, if the above expression 1 is satisfied, the partial system division calculation process is terminated. When the expression 1 is not satisfied, the means 307 sets a fusion examination completed flag to the partial system fused by the means 304, and the means 308 divides the fused partial system by the means 304. Next means 30
At 9, it is confirmed whether or not the fusion examination completed flag is set for all the adjacent partial lines. If the flags are set for all the adjacent partial systems, the means 310 indicates that the system configuration needs to be changed, and the system division processing ends. If the flag is not set yet, the processing returns to the means 304 and continues the processing.

The results of the grid state predicting device 105 and the power grid sub grid dividing calculating means 104 are sent to the reactive power optimum distribution calculating device through the communication lines 254 and 255, respectively. Details of the reactive power optimal distribution calculation device will be described with reference to FIG.

First, the means 501 fetches the result obtained by the future system state prediction device 105 of FIG. Next means 502
At, the objective function for optimal voltage reactive power distribution is set. In this embodiment, as an example of the objective function, either the active power loss or the reactive power loss of the transmission line shown in Expression 2 and Expression 3 is used.

[0021]

[Equation 2]

[0022]

(Equation 3)

Next, the means 503 sets a constraint on the reactive power balance for each of the sub-systems divided by the device 104 in FIG. The constraint here is that the
Set the upper and lower limits for generated and consumed reactive power, the output upper and lower limit constraint curve for reactive power for generators, and the upper and lower limits for operation for transformer taps. Using the setting value here, the means 504 calculates the reactive power distribution for each partial system.

As an example of the reactive power distribution calculation, an optimal reactive power distribution method using the case-based method, which is one of the features of the present invention, will be described with reference to FIGS. 6 and 7. FIG. 6 is a flowchart showing an optimum reactive power distribution method using the case-based method. First, the means 601 performs initial setting for executing the calculation. The process here is an evaluation function value for each voltage reactive power adjusting device described later, and an initial setting of a threshold value for determining whether to actually control the operating device,
Furthermore, the amount of transmission loss calculated later is initialized. After this processing is completed, the means 602 calculates the transmission loss coefficient of each reactive power control facility. This coefficient means the amount of change in which the transmission loss decreases or increases when one unit of the phasing equipment that operates as a discrete variable, the reactive power output of the generator, and the transformer tap changes by one unit. The following documents are detailed for examples of the transmission loss coefficient.

[The Institute of Electrical Engineers of Japan, Electric Power System Voltage Stable Maintenance Measures,
IEEJ Technical Report II-73, 43-45 (197)
9).

Next, the means 603 executes the optimum reactive power distribution calculation. The details will be described with reference to FIG. 7. In the reactive power optimal distribution calculation of the present invention, data that is most similar to the power flow state of the time section from the past history data is searched using a certain similarity evaluation function, and the search result and the time section of the time section are searched. The target reactive power control device is set using the state quantity of the control variable of the voltage reactive power control device. The details will be described with reference to FIG. 7. A graph 701 in FIG. 7 is an example of a physical quantity that represents a power flow state in an arbitrary time section. In each graph, the vertical axis represents the predicted time change of each physical quantity, and the horizontal axis represents the passage of time. Graphs 721 to 724 are changes in the physical quantity in the past several hours until the time section corresponding to the system calculation, graph 7
11 to 714 are examples of the case where the history data of the past having the smallest similarity search index is the most similar.

The similarity search index here is calculated using the following formula.

[0028]

[Equation 4]

However, t: number of target time sections n: physical quantity as a guideline for voltage reactive power control for each sub-system (eg, transmission line active power flow, reactive power flow, substation load, etc.) Similarity search described above A method of selecting the reactive power adjusting device and determining the operation amount thereof when the result of the historical data is searched based on the index and the result of the graph 702 regarding the voltage reactive power control amount is searched is shown below. Here, the amount of difference between the transmission loss coefficient obtained for each of the voltage reactive power adjusting devices, the actual data at that time, and the search result data is used. The difference amount here is the difference between the search result at the time of executing the calculation and the actual result value obtained for each piece of equipment. In the example of the graph 702 in FIG. 7, graphs 731 to 734
Indicates the actual value, and the dotted lines in the graphs 741 to 744 indicate the search results. In this case, the uppermost graph means the difference amount between the graph 731 and the graph 741.
Based on this amount, the means 604 obtains an evaluation function for each voltage reactive power control equipment by the following formula.

[0030]

[Equation 5] (Evaluation function of equipment i) = (transmission loss coefficient) i × (difference amount between history data and actual data) i × (equipment allowance amount) (Equation 5) When performing voltage reactive power control It is desirable to select, as the control target device, a device having the largest control effect. Therefore, in the present invention, among the evaluation functions of the respective voltage reactive power control equipment obtained by the equation 5, the voltage reactive power adjusting equipment having the largest evaluation function is selected as the control target device (means 605).

Depending on the target power system, operating the voltage reactive power control device may not have the effect of reducing the target function. In order to omit the processing in that case, it is necessary not to issue the operation command when the evaluation function value is less than a certain value. This processing is performed by the means 606.
If the determination condition in the means 606 is satisfied, the means 607 calculates the power flow, the means 608 calculates the amount of power transmission loss, and determines the power flow state after the operation. This processing is executed through the means 609 and the means 610 as long as there is a facility to be adjusted that satisfies this state and the transmission loss decreases.

When the reactive power distribution calculation is completed for each partial system, the means 505 of FIG. 5 confirms whether or not there is a power flow constraint violation. When the means 505 determines that there is a constraint violation, means (507) and (508) use the above (formula 2) and (formula 3) to determine the transmission line with the maximum transmission loss. When the transmission loss is large, the voltage at both nodes of the transmission line often deviates from the reference value. Therefore, the voltage of the nodes at both ends of the power transmission line is checked. If the node voltage exceeds the reference value, the means 513 sets the node voltage to the reference value and executes the reactive power distribution calculation of the means 504. This processing is continued through the means 510 and 511 until there are no transmission lines to be considered. If there is a violation of equipment restrictions related to voltage reactive power and there is no abnormality in the voltage value of the node in the sub system, an alarm will be presented to the driver and a warning will be issued to investigate the fault occurring in the power system. To do.

As described above, the reactive power optimal distribution calculation device 10
The description of 7 ends. The device 107 issues an operation command to the actual device through the communication line 256 in FIG. 1 and outputs the result to the output device through the communication line 257.

As described above, this method dynamically divides the target system into sub-systems and distributes the reactive power while considering the reactive power balance for each partial system. Can be prevented. In addition, the present invention consists of simple addition, subtraction, multiplication and division calculations other than power flow calculation,
Since the whole calculation can be executed at high speed, it is possible to realize the voltage reactive power control online. Further, there is an advantage that the process of selecting the reactive power control device can be easily understood by the operator of the power system.

Further, in the above-mentioned embodiment of the present invention, the method of voltage reactive power control in the online is shown.
The present invention is not limited to this, and can be used in an offline state. For example, the data of the power system input by the data reading device shown in FIG. 2 is not stored in real time but is stored in a storage device in the control system in advance so that it can be used as a simulator of reactive power of the entire power system. That is clear.

[0036]

As described above, the present invention has the following effects.

The target power system is dynamically divided into sub-systems, and reactive power is distributed while considering the reactive power balance for each sub-system, so that the reverse control phenomenon in the entire system is prevented. Is possible. Further, the present invention consists of simple addition / subtraction / multiplication / division calculations other than the power flow calculation, and since the whole calculation can be executed at high speed, it is possible to realize the voltage reactive power control online. Further, there is an advantage that the process of selecting the reactive power control device can be easily understood by the operator of the power system.

[Brief description of drawings]

FIG. 1 is a diagram showing the features of the present invention.

FIG. 2 is an example of data types read by a data reading device.

FIG. 3 is a flowchart showing a process of dividing the entire target system into partial systems.

FIG. 4 is a diagram showing an example of a process of dividing the entire target system into partial systems.

FIG. 5 is a flowchart showing the flow of processing of the entire voltage reactive power optimal distribution method.

FIG. 6 is a flowchart showing detailed processing of a voltage reactive power optimal distribution method.

FIG. 7 is a diagram showing an example of a voltage reactive power optimal distribution method by selecting similar cases.

[Explanation of symbols]

101 ... Target electric power system, 102 ... Data reading device, 103 ... State estimation device, 104 ... Electric power system partial system division calculation device, 105 ... Future system power flow state prediction device,
106 ... Reactive power optimal distribution calculation device, 107 ... Reactive power distribution command device, 108 ... Output device, 201 ... Example of system constant production, 202 ... Example of generator output, bus load database reading, 251 ... From power system, A communication line for supplying the state quantity in the system to the data reading device, 252 ... A communication line connecting the data reading device and the state estimating device,
253 ... Communication line connecting state estimating device and future system power flow state predicting device, 254 ... Communication line connecting electric power system partial system dividing device and reactive power optimum distribution calculating device, 255 ...
The future system power flow state prediction device is a communication line connecting the reactive power distribution calculating device, 256 ... A communication line connecting the reactive power optimal distribution device and the reactive power distribution command device, 257 ... Connecting the reactive power distribution command device and the output device. Communication line, 258 ... Communication line connecting data reading device and power system partial system division calculation device, 301 ... Initial state of system division, 302, 3
05 ... Reactive power balance calculation device, 303, 306 ... Reactive power balance determination device, 304 ... Subsystem fusion means,
307, 309 ... Considered partial system determination processing, 308 ... Partial system dividing means, 310 ... Message output device, 401,
402, 403 ... Examples of partial system, 501 ... Data capturing device, 502 ... Target function setting means, 503 ... Reactive power balance setting device, 504 ... Reactive power distribution calculation device,
505 ... Constraint violation detection device, 506 ... Calculation continuation determination device, 507 ... Transmission loss calculation device, 508 ... Maximum loss occurrence transmission line detection device, 509 ... Transmission line both-end node constraint violation detection device, 510, 511 ... Calculation continuation determination device 512 ...
Alarm output device, 513 ... Reference voltage setting device, 601
... Initial setting device, 602 ... Transmission loss coefficient calculation device, 60
3 ... Reactive power optimal distribution calculating device, 604 ... Evaluation function calculating device, 605 ... Reactive power operating device setting device, 606 ... Calculation continuation judging device, 607, 611 ... Power flow calculating device, 60
8 ... Transmission loss calculation device, 609, 610 ... Calculation continuation determination device, 612 ... Transmission loss calculation device, 701 ... Graph showing time transition of reactive power distribution calculation input variable, 702 ... Time transition of reactive power distribution calculation control variable Showing the graph, 7
11 ... Graph showing time transition of substation active power load in past history data, 712 ... Graph showing time transition of substation reactive power load in past history data, 713 ...
Graph showing time transition of interconnection line effective power flow in past history data, 714 ... Graph showing time transition of interconnection line reactive power flow in past history data, 721 ... of substation active power load in actual data 722 is a graph showing time transition
… Graph showing time transition of substation reactive power load in actual data, 723… Graph showing time transition of interconnection active power flow in actual data, 724… Time of interconnection reactive power flow in actual data Graph showing transition, 731 ...
A graph showing the time transition of the amount of phase-modifying equipment used in the actual result data, 732 ... A graph showing the time transition of the tap ratio in the actual data, 733 ... A graph showing the time transition of the generator reactive power output in the actual data, 734 ... graph showing time transition of bus voltage in actual data, 741 ... graph showing time transition of phase adjusting equipment usage in past history data,
742 ... Graph showing time transition of tap ratio in past history data, 743 ... Graph showing time transition of generator reactive power output in past history data, 744 ... Time transition of bus voltage in past history data A graph that represents.

Claims (12)

[Claims] 1. A power system data fetching means for fetching a power system state of a power system to be controlled, a power system power flow state judging means for judging a power flow state of the power system using the power system data, and a power system to be controlled. Is used to calculate the matching state between the reactive power generation source and the reactive power consumption source in the divided power system, and the output from the power system partial system division means is used. And a reactive power distribution command output means for sending a control signal to the reactive power generator of the power system. 2. The voltage reactive power control device according to claim 1, wherein the power system partial system division calculation means divides the main system substation of the power system in units. . 3. The voltage reactive power control device according to claim 1 or 2, wherein the power system partial system division calculation means uses the reactive power demand amount and supply amount of each partial system to form a partial system. A voltage reactive power control device characterized by optimally dividing a target power system into a plurality of sub-systems while dividing and fusing. 4. The voltage reactive power control device according to claim 1, 2, or 3, wherein the power system partial system division calculation means retrieves a similar system state from past history data, and A voltage reactive power controller characterized by calculating an optimum distribution state using similar system states. 5. An active power, a reactive power with respect to a load amount and a power generation amount of a power system in an arbitrary time section, a system constant in the time section, an amount of use of a phase-modulating facility in the time section and its operation curve, and the time. Magnitude of bus voltage at substation in cross section, tap value of transformer, data reading device for reading the necessary data, state estimating device for estimating internal state of power system, current flow state obtained by the state estimating device A future system state prediction device for estimating a power flow state at a more future time point, a power system partial system division calculation device for dividing a target power system so that a reactive power generation source and a reactive power consumption source are balanced, Optimal reactive power distribution calculation device for optimally distributing the amount of reactive power generation to the power system from the future system power flow state prediction device, and the reactive power optimum distribution calculation device Results based on a voltage consisting of reactive power distribution command device for sending a control signal to disable the power generator reactive power controller. 6. The voltage reactive power control device according to claim 5, wherein the power partial system division calculation device divides the target system. 7. A voltage reactive power control system according to claim 5, wherein said power system sub-grid partitioning computing device divides the power system in units of trunk substations. . 8. The voltage reactive power control device according to claim 5, wherein the power system sub-system division calculation device divides or fuses the sub-systems based on the reactive power demand and supply of each sub-system. A voltage reactive power control method characterized by optimally dividing the entire target system into multiple sub-systems while performing. 9. The voltage reactive power control device according to claim 2, claim 3, or claim 4, wherein reactive power control is independently performed for each partial system of the power system divided by the power system partial system division calculation device. A voltage reactive power control method characterized by calculating a quantity. 10. The voltage reactive power control device according to claim 5, wherein the reactive power optimum distribution calculation device searches for a similar system status from past history data for the reactive power optimum distribution calculation, and the similar system status. A voltage reactive power controller characterized by calculating an optimum distribution result using. 11. The voltage reactive power control device according to claim 5, wherein the reactive power optimal distribution calculation device uses the device as a selection criterion of the voltage reactive power control device to be adjusted when determining the optimal reactive power distribution. Voltage reactive power control characterized by calculating each reactive power control amount using each equipment margin, transmission line loss coefficient, actual value at the time of calculation execution, and difference amount of similar date search results at that time method. 12. The voltage reactive power control device according to claim 5, wherein the reactive power optimal distribution calculation device stores the input and output data of the control execution record in the time section in a database and executes the control execution in the next section. A voltage reactive power control method characterized by being used for calculation.