WO2009142011A1

WO2009142011A1 - Decision device with minimum power transmission loss system, method, and program

Info

Publication number: WO2009142011A1
Application number: PCT/JP2009/002224
Authority: WO
Inventors: 村井雅彦; 小坂葉子; 小林武則; 小坂田由美子
Original assignee: 株式会社東芝
Priority date: 2008-05-20
Filing date: 2009-05-20
Publication date: 2009-11-26
Also published as: JP2009284614A; CN102037627B; JP5395367B2; CN102037627A

Abstract

Provided are a decision device with a minimum power transmission loss system, a method, and a program which can determine having lower power transmission losses than branch switching during a practical computation period. A “closed” open/close mechanism selection means (12) selects the set of the unselected n (n ³ 2) open/close mechanisms in the “open” state which should be in the “closed” state so that the mesh systems become one in the current system, and changes the mechanisms to the “closed” state. A flow calculation means (13) calculates the power flow of the mesh system created by changing to the “closed” state. An “open” open/close mechanism selection means (14) sequentially selects an open/close mechanism in the “closed” state where the transmitted current value becomes the minimum to be an open/close mechanism which should be in the “open” state in the power flow of the mesh system calculated by the flow calculation means (13), and changes the mechanism to the “open” state.

Description

Minimum transmission loss system configuration determination device, method and program

The present invention relates to an apparatus for determining a transmission loss of a distribution system, and more particularly, to a determination apparatus, a method, and a program for a minimum transmission loss system configuration capable of determining a system configuration that minimizes the transmission loss in a practical calculation time. .

Generally, the method of determining the system configuration that minimizes the transmission loss of the distribution system is as follows: “The distribution system is configured radially and there are capacity constraints on feeders and switches in the system”. Thus, a method for determining the open / close state of a switch provided in the distribution system so that the power transmission loss is minimized is known. An example of a method for determining the distribution system configuration that minimizes the transmission loss of such a distribution system will be described below with reference to FIGS.

FIG. 9A is a diagram showing a connection configuration example of a distribution system in which five switches 91 to 95 are radially arranged. Among the blocks indicating the switches, the “open” state blocks are blank. The blocks in the “closed” state are indicated by hatching. That is, in FIG. 9A, the

switches

91 and 94 are in the “open” state, and the

switches

92, 93, and 95 are in the “closed” state. FIG. 9B shows the load and the impedance of the section corresponding to the section numbers 9a to 9g of the distribution system in FIG. 9A. Here, in the connection configuration example of the distribution system in FIG. 9A, assuming that the section load is uniformly distributed in the section, the transmission loss in each section is expressed by the following equation (1).

That is, the transmission loss in each section of the distribution system configured radially as shown in FIG. 9A is obtained by substituting the load and impedance shown in FIG. Can be calculated. In order to determine a system configuration that minimizes the transmission loss in the connection configuration example of the distribution system in FIG. 9A, all the switches 91 to 95 are opened and closed so that the distribution system maintains a radiating state. The power transmission loss is calculated with respect to the state, and the switching states of the switches 91 to 95 are determined so that the total loss is minimized.

Here, FIG. 11 is a diagram showing all combinations of the switching states of the switches in such a radially distributed distribution system. That is, (a) to (h) of FIG. 11 respectively show eight system configurations with different switching states of the switches. FIG. 12 shows the result of calculating the power transmission loss corresponding to each system configuration (a) to (h) in FIG. According to FIG. 12, the minimum value of the power transmission loss is the power transmission loss value “56.267W” of the system configuration (f), and it can be seen that this system configuration (f) is a system configuration that minimizes the power transmission loss.

However, in an actual large-scale distribution system, applying this method of calculating transmission loss for all switch combinations of switches will result in an enormous number of combinations and transmission loss in practical calculation time. It was impossible to determine the distribution system configuration that minimizes the power distribution system. For this reason, in addition to the above-described method for calculating all combinations, a determination method for obtaining a system configuration that minimizes transmission loss by employing various methods has been proposed.

For example, a branch exchange method has been proposed as one of the system configuration determination methods for minimizing the transmission loss of such a distribution system (see Non-Patent Document 1). In this branch exchange method, in a radial distribution system, a switch in an “open” state is changed to a “closed” state to create one loop, and the power flow calculation of the created loop is performed. The system configuration in which the switch having the minimum passing current is set to the “open” state is obtained. Then, by repeatedly performing the process of obtaining the system configuration by such loop creation and power flow calculation for all the switches in the “open” state, among the obtained system configurations, the system configuration that minimizes the transmission loss is obtained. This is the extraction method.

Hereinafter, an example of a system configuration determination method that minimizes power transmission loss by the branch exchange method as described above will be described with reference to FIGS.

First, when the branch exchange method is applied to the distribution system of FIG. 9, a loop is created by closing the switch 91 in the “open” state, and the power flow calculation in this loop is performed. The current passing through 91 to 93 and 95 is calculated. The passing current of each of the switches 92 to 93, 95 maintaining the “closed” state is to close the switch 91 with respect to the passing current of the system configuration of FIG. 9 in which the switch 91 is in the “open” state. The calculation is performed by adding the current flowing through the switch 91.

Further, the passing current of the switch 91 can be calculated from the potential difference between both ends of the switch 91 in the “open” state in FIG. 9 by using Thevenin's law. The potential difference between both ends of the switch 91 can be obtained by calculating the voltage drop Vd [V] in each section by the following equation (2).

Further, the current flowing through the switch 91 by closing the switch 91 can be calculated by the following equation (3) using the Thevenin's law.

Here, FIG. 13 shows the passing current and the voltage drop in each section obtained by the above calculation for each of the switches 91 to 95 having the system configuration of FIG. That is, the potential difference of the switch 91 is determined from the voltage drop Vd [V] in each section shown in FIG.
ΔV = -0.42-(-0.05-0.125-0.225-0.35) = 0.33
It becomes. And from this potential difference obtained and equation (3), the current change caused by closing the switch 91 is
ΔI = 0.33 / (0.028 + 0.01 + 0.01 + 0.01 + 0.01 + 0.01) = 4.853 [A]
It becomes. Therefore, the passing currents of the switches 91 to 93 and 95 after the switch 91 is closed are as shown in FIG.

In the branch exchange method, the power transmission loss of the newly constructed radial distribution system is calculated by opening the switch that minimizes the passing current in the loop. That is, according to FIG. 14, the switch having the minimum passing current is the switch 91, and therefore the system configuration of the distribution system is the same in the operation of setting the switch 91 to the “open” state, and the transmission loss is It does not change.

Further, a similar process is performed on the switch 94, that is, by closing the switch 94 in the “open” state, a loop is created, and the power flow calculation in this loop is performed, so that each of the switches 92 to 95 is When an operation for calculating the passing current is performed, the passing current of the loop system is calculated as shown in FIG. Here, according to FIG. 15, the switch with the smallest passing current is also the switch 94, so that the system configuration of the distribution system is the same and the transmission loss does not change.

As can be seen from the above, when the branch exchange method is applied to the distribution system of FIG. 9, a loop is created with only one “open” switch at a time being “closed”, Since power flow calculation must be performed, iterative calculations are required to determine the system configuration of the distribution system that minimizes transmission loss. In addition, this is a local search method in which a narrow range in which switches in the “open” state are switched one at a time is searched as a neighborhood, and since the neighborhood range to be searched is narrow, the calculation result tends to fall into a local solution (local minimum) . For this reason, a system configuration in which the power transmission loss is a true minimum value as shown in FIG. 11F cannot be obtained.

The present invention has been proposed to solve the above-described problems, and its purpose is to determine a system configuration with a practical calculation time and smaller transmission loss than the branch exchange method. It is an object of the present invention to provide an apparatus, a method and a program for determining a minimum power transmission loss system configuration.

In order to achieve the above-described object, the present invention provides a minimum transmission loss system configuration determination device that determines a minimum transmission loss system configuration that minimizes a transmission loss among system configurations in which the switching state of the switch is changed. Therefore, it has the following technical features. That is, the minimum power transmission loss system configuration determining apparatus of the present invention first includes “closed” switch selecting means, “open” switch selecting means, power transmission loss calculating means, reduction determining means, updating means, and determining means. Here, the “closed” switch selection means selects two or more open switches from a plurality of switches to be closed so as to create one mesh system in the system configuration. It is means to do. The “open” switch selecting means should open the same number of closed switches as the number of switches selected by the “closed” switch selecting means so as to obtain a radial system configuration. It is a means to select. The transmission loss calculating means changes the open switch selected by the “closed” switch selecting means to the closed state, and the open / closed switch selected by the “open” switch selecting means. It is means for calculating the transmission loss of each system configuration obtained as a result of changing the device to the open state. The reduction determination unit is a unit that determines whether the transmission loss of the specific system configuration newly calculated by the transmission loss calculation unit is lower than the transmission loss of another system configuration calculated earlier. The updating unit is a unit that updates the specific system configuration as a minimum transmission loss system candidate when the reduction determination unit determines that the transmission loss of the specific system configuration is reduced. The determining means is means for determining the minimum transmission loss system configuration from the minimum transmission loss system candidates. In this determination means, the reduction determination means reduces any transmission loss of each system configuration calculated by the transmission loss calculation means from the transmission loss of the minimum transmission loss system candidate that is the latest update result. If it is determined that it is not, the minimum transmission loss system candidate is determined as the minimum transmission loss system configuration.

Further, the “open” switch selecting means sequentially selects a switch in a closed state with a minimum passing current among the switches in the mesh system. It is.

The “closed” switch selection means can select not only a plurality of open switches to be closed, but also a single switch in an open state. Further, a configuration in which the number of switches to be selected is changed by changing the number of switches to be selected by the “closed” switch selection unit, so that the number of switches to be selected is variable is also an aspect of the present invention. It is.

Further, the system includes an initial system generation unit that generates a plurality of initial systems by randomly changing the open / close state of the switch, and the “closed” switch selection unit includes each initial system generated by the initial system generation unit. A configuration in which a switch in an open state is selected so as to create one mesh-like system is also included as one aspect of the present invention.

According to the present invention as described above, a plurality of "open" state switches are changed to the "closed" state at the same time, and the same number of switches are set to the "open" state, whereby the branch exchange method described above Compared to the above, since it is possible to search in a wide range, it is possible to provide an apparatus, method and program for determining a minimum transmission loss system configuration capable of determining a system configuration with a smaller transmission loss.

The block block diagram of the determination apparatus of the minimum power transmission loss system structure which concerns on the 1st Embodiment of this invention. The figure which shows the processing flow of the determination apparatus of the minimum power transmission loss system structure which concerns on the 1st Embodiment of this invention. The figure (1) explaining the determination process of the minimum power transmission loss system structure by this invention. The figure (2) explaining the determination process of the minimum power transmission loss system structure by this invention. The block block diagram of the determination apparatus of the minimum power transmission loss system structure which concerns on the 2nd Embodiment of this invention. The figure which shows the processing flow of the determination apparatus of the minimum power transmission loss system | strain structure which concerns on the 2nd Embodiment of this invention. The block block diagram of the determination apparatus of the minimum power transmission loss system | strain structure which concerns on the 3rd Embodiment of this invention. The figure which shows the processing flow of the determination apparatus of the minimum power transmission loss system structure which concerns on the 3rd Embodiment of this invention. The figure which shows an example of a power distribution system. The figure which shows an example of calculation of the transmission loss of a distribution system. The figure which shows the some system structure based on the switching state of the switch of a power distribution system. The figure which shows the transmission loss of the several system structure based on the switching state of the switch of a distribution system. The figure (1) which shows the minimum transmission loss determination process of the distribution system by the branch exchange method which is a prior art. The figure (2) which shows the minimum transmission loss determination process of the distribution system by the branch exchange method which is a prior art. The figure (3) which shows the minimum transmission loss determination process of the distribution system by the branch exchange method which is a prior art.

[First Embodiment]
[Constitution]
Next, the configuration of the determination apparatus for the minimum transmission loss system configuration that minimizes the transmission loss of the distribution system according to the first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram illustrating the configuration of the minimum power loss system configuration determining apparatus according to the first embodiment.

This minimum power transmission loss system configuration determining apparatus includes a calculation means 1, an input means 2, a storage means 3, a display means 4, and an I / F means 5 as shown in FIG. The I / F unit 5 is connected to the power distribution system 7 via the power distribution system monitoring control device 6.

Here, the computing means 1 is specifically realized by a main memory of a computer, a program stored in the computer, a CPU controlled by the program, etc., and has processing means 10 to 17 as will be described later. . The input means 2 is an input device such as a mouse or a keyboard for inputting a signal corresponding to a user operation to the computer.

The storage means 3 stores in advance various system information data of the power distribution system necessary for the processing in the computing means 1 and also stores the calculation results by the computing means 1. Realized. In addition, the system information data of a power distribution system is information, such as connection information (connection structure of a power distribution system) of a distribution line, an impedance, the switching state of a switch, a load, etc., for example.

The display means 4 is a display device such as a display for displaying to the user the data input through the input means 2, the data stored in the storage means 3, and the calculation result processed by the calculation means 1. The I / F unit 5 is a communication interface that transmits and receives system information data and control data of the distribution system 7 via the distribution system monitoring and control device 6, and the received system information data is stored in the storage unit 3. The distribution system monitoring and control device 6 is a device that performs monitoring and control of the distribution system 7, and holds various data related to the planning, operation, and control of the distribution system 7.

The computing means 1 includes a data reading means 10, a power transmission loss calculating means 11, a “closed” switch selecting means 12, a power flow calculating means 13, an “open” switch selecting means 14, a power transmission loss reduction determining means 15, an initial stage. System comparison means 16 and loss minimization configuration update means 17 are provided.

The data reading means 10 is means for reading the system information data from the storage means 3, that is, the connection configuration of the distribution system, the open / close state of the switch provided in the system, and data on the load and impedance. In this specification, “system configuration” to be determined, that is, “system configuration of the distribution system” means the configuration of the distribution system including the switching state of the switch, and “connection configuration of the distribution system”. Means an installation connection configuration of the distribution system that does not include the open / close state of the switch.

The power transmission loss calculation means 11 calculates the power transmission loss in the system configuration changed by opening and closing the switch provided in the power distribution system 7. The “closed” switch selection means 12 selects n (n ≧ 2) switches that are changed from the plurality of switches in the “open” state to the “closed” state among the switches constituting the distribution system 7. select.

The power flow calculation means 13 is a means for calculating the power flow of the mesh system created by changing the n switches selected by the “closed” switch selection means 12 to the “closed” state.

The “open” switch selecting means 14 is a mesh-like system created by changing the n switches selected by the “closed” switch selecting means 12 to the “closed” state. Among the “closed” state switches to be configured, n switches to be changed to the “open” state are selected. As an example, the “open” switch selection means 14 is a switch that should open the switch with the smallest value of current passing through the power flow of the mesh system calculated by the power flow calculation means 13. Are selected sequentially.

The transmission loss reduction determining means 15 is a means for determining whether the transmission loss is reduced from the previous system configuration with respect to the new system configuration in which the switching state of the switch is changed. For example, it is determined whether the current power transmission loss calculated by the power transmission loss calculating means 11 is reduced as compared with the solution candidates that are sequentially updated.

When determining that the current transmission loss is lower than the solution candidate, the transmission loss reduction determining unit 15 stores the current transmission loss in the storage unit 3 as a new solution candidate. The initial system comparison unit 16 is a unit that determines whether the transmission loss of the solution candidate is lower than the transmission loss of the initial system.

The loss minimizing configuration updating unit 17, when the initial system comparison unit 16 determines that the transmission loss of the solution candidate is lower than the transmission loss of the initial system, the transmission loss of the solution candidate and the transmission loss This is a means for updating the system configuration that generates the minimum transmission loss and the system configuration and storing them in the storage unit 3.

[Action]
Next, in the determination apparatus for the minimum transmission loss system configuration having the configuration of FIG. 1, the determination procedure of the system configuration that minimizes the transmission loss will be described below with reference to the flowchart of FIG.

According to FIG. 2, first, in STEP 201, the data reading means 10 sends system information data such as data relating to the connection configuration of the distribution system from the storage means 3, the switching state of the switches provided in the system, and the load and impedance. And data to be used in the subsequent processing are prepared. Here, the system configuration used in the initial stage is the initial system configuration, and this is set as a solution candidate. In addition, since the distribution system used as the object of minimization of power transmission loss has a radial configuration, the initial system configuration has a radial configuration.

Here, in STEP 201, as an initialization process, the transmission loss calculation means 11 calculates the transmission loss of the solution candidate that is the initial system, and stores it in the storage means 3 as the initial transmission loss. The initial system configuration and the initial transmission loss stored in the storage unit 3 are adopted as the system configuration in the current distribution system, and serve as a reference for performing a system configuration update process described later.

In STEP 202, the “closed” switch selection means 12 is set to the “closed” state in the current system configuration, and has not yet been selected (unselected) n (n ≧ 2) “open” state. Select a combination of switches. Here, the set of n switches selected by the “closed” switch selection means 12 is selected so that one mesh system is created by closing the switch.

In addition, when the scale of the target distribution system for minimizing transmission loss is large, the number of combinations of n “open” switches in the distribution system increases, which may increase the calculation time. Is done. In such a case, the “closed” switch selecting unit 12 includes a limiting unit that limits the number of n switches to be selected. By this limiting unit, for example, the potential difference between both ends of the switch is large. The number of sets of switches can be limited in the order that includes the switches.

Here, when the “closed” switch selecting means 12 selects n “open” switches, the “open” switch is changed to the “closed” state on the model. In STEP 203, this “closed” switch is selected. The power flow of the mesh system created when the state is changed is calculated by the power flow calculation means 13.

In STEP 204, the “open” switch selection means 14 selects one switch to be set to the “open” state among the “closed” state switches of the created mesh system. Specifically, in the power flow of the mesh system calculated by the power flow calculation means 13 in STEP 203, the switch in the “closed” state in which the current value passing through is minimized is selected as the switch to be set in the “open” state. To do. In particular, a switch in the “closed” state that minimizes the passing current is selected as a switch that should be in the “open” state based on the capacity constraint of the transmission line.

When the “open” switch selecting unit 14 selects n “closed” switches, the “closed” switch is changed to an “open” state on the model. In STEP 205, this “open” switch is selected. The power flow of the new mesh system created when the state is changed is calculated again by the power flow calculation means 13.

Here, in STEP 205, based on the newly calculated power flow, the “open” switch selection means 14 selects the switch in the “closed” state in which the passing current value is minimum, and the selected switch The process of changing the device to the “open” state and calculating the power flow of the newly created mesh system by the flow calculation means 13 is repeated n times.

That is, among the created “closed” state switches of the mesh system, the “open” switch selecting means 14 selects n “closed” state switches one by one, and The calculation means 13 changes the selected switch to the “open” state, and calculates the power flow n times for the remaining mesh system.

In STEP 206, the transmission loss calculation means 11 calculates the transmission loss of the radial system reconfigured by the processing of STEPs 204 and 205 repeated n times. In STEP 207, the transmission loss reduction determination means 15 determines whether or not the current transmission loss of the radial system calculated by the transmission loss calculation means 11 is lower than the transmission loss of the solution candidate.

If the transmission loss of the current system configuration is lower than the transmission loss of the solution candidate (YES in STEP 207), in STEP 208, the transmission system loss reduction determination means 15 causes the current system configuration and transmission loss to be a new solution candidate and The transmission loss is stored in the storage means 3. On the other hand, when the transmission loss of the current system configuration is not lower than the transmission loss of the solution candidate (NO in STEP 207), the current system configuration is not stored as a solution candidate, and the process proceeds to STEP 209.

In STEP 209, the “closed” switch selecting means 12 has n “s” in different arrangements from the arrangement of the “open” state switches configured by the processing of STEPs 204 and 205 repeated n times. It is determined whether there is a set of switches in the “open” state. That is, it is determined whether there are n other “open” switch groups that have not yet been selected.

If there are other n “open” switch sets (YES in STEP 209), the process returns to STEP 202, and a new n “open” switch set is “closed” open / close. It is selected by the device selection means 12, and the subsequent processing is repeated. On the other hand, when there is no other set of n “open” switches (NO in STEP 209), the initial system comparison means 16 causes the transmission loss of the solution candidate in STEP 208 to be greater than the transmission loss of the initial system. It is determined whether it is reduced (STEP 210).

If it is determined that it is smaller than the initial transmission loss (YES in STEP 210), the solution candidate and the transmission loss are stored in the storage unit 3 by the loss minimizing configuration updating unit 17 as the initial system configuration and the initial transmission loss. The initial system configuration and the initial transmission loss are updated (STEP 211). When the initial system configuration and the initial transmission loss are updated by the loss minimization configuration updating unit 17, the processing from STEP 202 onward is repeated based on the updated initial system configuration and the initial transmission loss.

On the other hand, when it is not determined that the transmission loss of the solution candidate is smaller than the initial transmission loss, that is, when the transmission loss of the solution candidate is equal to or more than the initial transmission loss (NO in STEP 210), loss minimization is performed. The configuration updating unit 17 determines the current initial system configuration and initial transmission loss as the minimum transmission loss system configuration and minimum transmission loss, and displays the determined minimum transmission loss system configuration and minimum transmission loss on the display unit 4 and the I / F. The data is output through the means 5 (STEP 212), and the process is terminated. Thus, in the present embodiment, the loss minimization configuration updating unit 17 functions as a determining unit in the present invention.

[Example]
Next, referring again to FIGS. 9 and 11 showing an example of a radial distribution system, a specific example of the first embodiment will be described below based on FIGS. As shown in FIG. 2, since only two “open” state switches exist in FIG. 9A, n = 2.

In STEP 201, the data reading means 10 reads the power distribution system configuration (initial system configuration) as shown in FIG. 9A and the system information data as shown in FIG. 9B from the storage means 3 as initialization processing. Then, the transmission loss calculation means 11 calculates the transmission loss of the solution candidate which is the initial system configuration of FIG. 9, and obtains 57.567 [W] as shown in FIG. This power transmission loss is stored in the storage means 3 as the initial power transmission loss.

In STEP 202, the “closed” switch selection means 12 selects a combination of two “open” state switches that should be in the “closed” state in the system configuration of FIG. Two “open” switches are changed to the “closed” state. In STEP 203, as shown in FIG. 3, the power flow calculation means 13 calculates the power flow of the mesh system created when the state is changed to the “closed” state.

In STEP 204, the “open” switch selecting means 14 selects the switch 92 that minimizes the passing current, and the system configuration as shown in FIG. Is obtained. In STEP 205, the power flow calculation means 13 calculates the power flow of the new mesh system in FIG. 4 created when the state is changed to the “open” state.

By repeating the processing of STEPs 204 and 205 a total of two times (since n = 2), the switch 95 having the smallest passing current value is changed to the “open” state in the system configuration of FIG. A mesh system as shown in FIG. 11 (f) is created, and the power flow of the created system configuration is calculated by the power flow calculation means 13.

In STEP 206, the power transmission loss calculation means 11 calculates the power transmission loss of the newly configured system configuration, and as shown in FIG. 12, the power transmission loss 56.267 corresponding to the system configuration of FIG. [A] is obtained.

In STEP 207, the power transmission loss reduction determining means 15 determines whether or not the power transmission loss corresponding to the system configuration of FIG. 11 (f) calculated by the power transmission loss calculating means 11 is lower than the solution loss of the solution candidate. . Specifically, the power transmission loss reduction determination unit 15 includes the power transmission loss 56.267 [W] of the system configuration and the initial power transmission loss 57.567 [W] calculated by the power transmission loss calculation unit 11 in the initialization process of STEP 201. By comparing (see FIG. 10), it is determined that the current transmission loss is lower than the solution loss of the solution candidate. As shown in FIG. 12, there is no system configuration capable of reducing the transmission loss from this transmission loss 56.267 [W], so even when another set of “open” state switches is selected, There is no system configuration lower than the transmission loss of the system configuration in FIG.

Subsequently, since the current transmission loss is lower than the solution loss of the candidate solution (YES in STEP 207), in STEP 208, the transmission loss reduction determination means 15 newly sets this system configuration and transmission loss 56.267 [W]. Are stored in the storage means 3 as possible solution candidates and their transmission losses.

In STEP 209, the “closed” switch selection means 12 determines whether there are two “open” switch groups having different arrangements with respect to the system configuration of FIG. The If there are other two “open” switch groups (YES in STEP 209), the process returns to STEP 202 and two new “open” switch groups are “closed”. “Selected by the switch selection means 12, and the subsequent processing is repeated.

On the other hand, when there is no other set of two “open” switches (NO in STEP 209), the initial system comparison means 16 causes the transmission loss of the solution candidate in STEP 208 to be greater than the transmission loss of the initial system. It is determined whether it is reduced (STEP 210).

If it is determined that it is smaller than the initial power transmission loss (YES in STEP 210), the loss minimizing configuration updating unit 17 stores the solution candidate and the power transmission loss in the storage unit 3 as the initial system configuration and the initial power transmission loss. The initial system configuration and the initial transmission loss are updated (STEP 211). When the initial system configuration and the initial transmission loss are updated by the loss minimization configuration updating unit 17, the processing from STEP 202 onward is repeated based on the updated initial system configuration and the initial transmission loss.

On the other hand, when it is not determined that the transmission loss of the solution candidate is smaller than the initial transmission loss, that is, when the transmission loss of the solution candidate is equal to or more than the initial transmission loss (NO in STEP 210), loss minimization is performed. The configuration updating unit 17 determines the current initial system configuration and initial transmission loss as the minimum transmission loss system configuration and minimum transmission loss, and displays the determined minimum transmission loss system configuration and minimum transmission loss on the display unit 4 and the I / F. The data is output through the means 5 (STEP 212), and the process is terminated. That is, the system configuration in FIG. 11F is output as the minimum power transmission system configuration that minimizes the power transmission loss.

[effect]
According to the first embodiment as described above, a plurality of “open” state switches are changed to the “closed” state at the same time, and the same number of switches are set to the “open” state, thereby widening the search range. Therefore, it is possible to provide a determination apparatus, a method, and a program for determining a minimum transmission loss system configuration that can determine a system configuration that further reduces transmission loss and that can reduce the time required to determine the system configuration.

In the above embodiment, the “open” switch selecting means 14 selects one switch in the “closed” state to be set in the “open” state one by one, but the present invention is limited to this mode. Not what you want. That is, the present invention also includes an embodiment in which n switches that are in the “closed” state at a time are selected and changed to the “open” state.

[Second Embodiment]
[Constitution]
Next, the configuration of the minimum transmission loss system configuration determining apparatus that minimizes the transmission loss of the distribution system according to the second embodiment of the present invention will be described below with reference to FIG. FIG. 5 is a block diagram showing a configuration of a determination apparatus for a minimum transmission loss system configuration according to the second embodiment for minimizing transmission loss. Here, in FIG. 5, the same components as those in FIG.

In the second embodiment, in addition to the configuration of FIG. 1 in the first embodiment, a switch number changing means 18 is provided. The switch number changing means 18 changes the number of switches to be selected at one time by the “closed” switch selecting means 12. In particular, the switch number changing means 18 determines whether the number of selected switches is equal to n, which is a predetermined number of preset switches, and the number of selected switches is less than n. In this case, the number of switches to be selected at a time is increased by one up to n.

[Action]
Next, in the determination apparatus for the minimum transmission loss system configuration having the configuration of FIG. 5, the determination procedure of the system configuration that minimizes the transmission loss will be described below with reference to the flowchart of FIG. FIG. 6 is a diagram illustrating a system configuration determination flow that minimizes power transmission loss according to the second embodiment.

First, in STEP 601, as in the first embodiment, in STEP 201, the data reading means 10 relates to the connection configuration of the distribution system from the storage means 3, the switching state of the switch provided in the system, and the load and impedance. System information data such as data is read, and data to be used in the subsequent processing is prepared. Here, the system configuration used in the initial stage is the initial system configuration, and this is set as a solution candidate.

Also, as an initialization process, the transmission loss calculation means 11 calculates the transmission loss of the solution candidate that is the initial system, and stores it in the storage means 3 as the initial transmission loss. The initial power transmission system and the initial power transmission loss stored in the storage unit 3 are adopted as a system configuration in the current distribution system, and serve as a reference for performing a system configuration update process to be described later.

Here, in step 602, when selecting n (n ≧ 1) “open” state switches that have not yet been selected, the “closed” switch selection unit 12 should be in the “closed” state. The value is set to n = 1. Then, as in the first embodiment, the “closed” switch selection means 12 makes one “open” state (initially n = 1) that has not yet been selected and should be in the “closed” state. Select the switch.

As in the first embodiment, when the scale of the distribution system targeted for minimizing transmission loss is large, a set of n “open” switches in the current system configuration increases. Therefore, there is a concern about an increase in calculation time. In such a case, the “closed” switch selecting unit 12 includes a limiting unit that limits the number of n switches to be selected. By this limiting unit, for example, the potential difference between both ends of the switch is large. The number of sets can be limited in the order including switches.

When this “closed” switch selecting means 12 selects one “open” switch (initially n = 1), the “open” switch is changed to the “closed” state on the model. In STEP 603, the power flow calculation means 13 calculates the power flow of the mesh system created when the state is changed to the “closed” state.

In STEP 604, one of the switches in the “closed” state of the created mesh system is selected by the “open” switch selection means 14 to be in the “open” state. Specifically, in the mesh system power flow calculated in STEP 603 by the power flow calculation means 13, the switch in the “closed” state in which the passing current value is minimum is selected as the switch to be set in the “open” state. To do. In particular, a switch in the “closed” state that minimizes the passing current is selected as a switch that should be in the “open” state based on the capacity constraint of the transmission line.

When the “open” switch selecting means 14 selects one “closed” switch, the “closed” switch is changed to the “open” state on the model. In STEP 605, this “open” switch is selected. The power flow of the new mesh system created when the state is changed is calculated by the power flow calculation means 13. In STEP 606, the power transmission loss calculation means 11 calculates the power transmission loss of the reconfigured radial system. In STEP 607, the power transmission loss reduction determination means 15 calculates the current power transmission loss of the radial system calculated by the power transmission loss calculation means 11. However, it is determined whether or not it is lower than the transmission loss of the solution candidate.

When the transmission loss of the current system configuration is lower than the transmission loss of the solution candidate (YES in STEP 607), in STEP 608, the current system configuration and the transmission loss are changed to a new solution candidate and The transmission loss is stored in the storage means 3. On the other hand, when the transmission loss of the current system configuration is not lower than the transmission loss of the solution candidate (NO in STEP 607), the current system configuration is not stored as a solution candidate, and the process proceeds to STEP 609.

In STEP 609, there is one “open” switch group in which the “closed” switch selection means 12 is arranged differently from the arrangement of the “open” switch in the configured system configuration. Determine whether. That is, it is determined whether there is one other “open” switch group that has not yet been selected. In STEP 609, when n ≧ 2, the “closed” switch selecting means 12 opens and closes n “open” states of the system configuration configured by repeating the processes of STEPs 604 and 605 n times. It is determined whether there is a set of n “open” switches in a different arrangement from the arrangement of the appliances.

If there is another such set of “open” switches (YES in STEP 609), the process returns to STEP 602, and one new “open” switch set is “closed” open / close. It is selected by the device selection means 12, and the subsequent processing is repeated. On the other hand, when there is no other switch set in the “open” state (NO in STEP 609), the initial system comparison means 16 causes the transmission loss of the solution candidate in STEP 608 to be greater than the transmission loss of the initial system. It is determined whether it is reduced (STEP 610).

If it is determined that it is smaller than the initial transmission loss (YES in STEP 610), the solution candidate and the transmission loss are stored in the storage unit 3 by the loss minimizing configuration updating unit 17 as the initial system configuration and the initial transmission loss. The initial system configuration and its initial transmission loss are updated (STEP 611). When the initial system configuration and the initial transmission loss are updated by the loss minimization configuration update unit 17, the processing from STEP 602 is repeated on the basis of the updated initial system configuration and the initial transmission loss.

On the other hand, if it is not determined that the transmission loss of the solution candidate is smaller than the initial transmission loss, that is, if the transmission loss of the solution candidate is equal to or greater than the initial transmission loss (NO in STEP 610), in STEP 612, The switch number changing means 18 determines whether or not the number of switches selected by the “closed” switch selection means 12 is equal to a preset number of n (a preset number of preset switches).

If it is less than the preset number n, for example, if n ≧ 2 (NO in STEP 612), the switch number changing means 18 increases the number from n = 1 by 1, and then returns to STEP 602 again. Return and repeat the process. That is, the processing of STEPs 602 to 611 is repeated n times in order from 1 to the number of switches in the “open” state selected by the preset “closed” switch selection means 12.

In the processing of STEPs 604 and 605 in the case of n ≧ 2, as in the first embodiment, the “open” switch selection unit 14 minimizes the passing current value based on the calculated power flow. By selecting the switch in the “closed” state, the process is changed to the “open” state, and the power flow calculating means 13 calculates the power flow of the newly created mesh system n times.

In STEP612, when the switch number changing unit 18 determines that the number of switches selected by the “closed” switch selecting unit 12 is equal to the preset number n (YES in STEP612), the loss minimum The updated configuration update means 17 determines the current initial system configuration and initial transmission loss as the minimum transmission loss system configuration and minimum transmission loss, and displays the determined minimum transmission loss system configuration and minimum transmission loss on the display unit 4 and the I / I The data is output through the F means 5 (STEP 613), and the process is terminated.

[effect]
According to the second embodiment as described above, the number of switches that are changed from the “open” state to the “closed” state at a time can be increased sequentially from 1, so that the search range is expanded. As a result, for the problem that the calculation time is substantially increased, the minimum transmission loss can be calculated at high speed in the initial stage when the number of switches to be changed is small, and the number of switches to be changed has increased. In the stage, it is possible to gradually improve the degree of minimization of transmission loss.

The switch number changing means 18 in the above embodiment determines whether or not the number of switches selected by the “closed” switch selection means 12 is equal to the preset n, and this preset n The number of switches is increased when the number is less than one, but the present invention is not limited to this.

Specifically, in the present invention, when the transmission loss of the system configuration calculated by the transmission loss calculation unit 11 is determined not to be lower than the transmission loss of the solution candidate by the transmission loss reduction determination unit 15, Embodiment in which the switch number changing means 18 increases the number of switches to be selected by the “closed” switch selecting means 12 one by one when the system comparison means 16 determines that the initial transmission loss has not been reduced. Is included. That is, when the power transmission loss calculated by the power transmission loss calculation unit 11 is not reduced in the predetermined number of switches selected by the “closed” switch selection unit 12, the “closed” switch selection unit 12. By increasing the number of switches selected by, it becomes possible to search for a smaller transmission loss.

[Third Embodiment]
[Constitution]
Next, the configuration of the minimum transmission loss system configuration determining apparatus according to the third embodiment of the present invention will be described below with reference to FIG. FIG. 7 is a block diagram showing a determination apparatus for a minimum transmission loss system configuration according to the third embodiment for minimizing transmission loss. Here, in FIG. 7, the same components as those in FIG.

In the third embodiment, in addition to the configuration of FIG. 1 in the first embodiment, an initial system generation unit 19, an initial system selection unit 20, and a minimized configuration selection unit 21 are provided.

The initial system generation means 19 is a means for generating a plurality of initial system configurations having different system configurations from a certain initial system. The initial system selection means 20 is a means for selecting an initial system that has not yet been selected from a plurality of initial systems, and the minimized configuration selection means 21 is a solution candidate for minimizing transmission loss for each initial system configuration. It is a means for selecting the one with the smallest transmission loss from all the obtained system configurations.

[Action]
Next, in the determination apparatus for the minimum transmission loss system configuration having the configuration of FIG. 7, the determination procedure of the system configuration that minimizes the transmission loss will be described below with reference to the flowchart of FIG. In addition, FIG. 8 is a figure which shows the determination flow of the system | strain structure which concerns on 3rd Embodiment and has the minimum power transmission loss. Here, the description of the same processing as the flowchart of FIG. 2 is omitted.

First, in STEP 801, as in the first embodiment, the data reading unit 10 is configured to transmit data such as the connection configuration of the power distribution system from the storage unit 3, the open / close state of the switch provided in the system, and data regarding the load and impedance. System information data is read and data to be used in the subsequent processing is prepared. Here, the system configuration used in the initial stage is the initial system configuration, and this is set as a solution candidate.

In STEP 802, the initial system generation unit 19 creates a plurality of different system configurations for the read initial system, and the transmission loss calculation unit 11 calculates the initial transmission loss for each system configuration. In addition, the plurality of initial system configurations created by the initial system generation means 19 are, for example, closing a randomly selected “open” state switch with respect to the initial system, and in the configured mesh system, It is created by opening a randomly selected switch.

In STEP 803, the initial system selection unit 20 selects a new system configuration that has not yet been selected among the plurality of initial system configurations created by the initial system generation unit 19. Thereafter, by executing the same processing as the processing of STEPs 202 to 211 in FIG. 2 in the first embodiment, the minimum transmission loss and the minimum transmission loss system configuration calculated based on the selected initial system configuration are obtained. Can be derived (STEP 804-813).

In STEP 814, the initial system selection means 20 determines whether there is another initial system configuration that has not yet been subjected to power transmission loss minimization processing. If there is present (YES in STEP 814), the process proceeds to STEP 803. A new initial system configuration is selected.

When the initial system selection unit 20 determines that no other initial system configuration exists (NO in STEP 814), in STEP 815, the minimized configuration selection unit 21 minimizes the transmission loss for each initial system configuration. From all system configurations obtained as candidate solutions, select the system configuration that minimizes the transmission loss, determine the selected system configuration and its transmission loss as the minimum transmission loss system configuration and minimum transmission loss, and display them. The data is output through the means 4 and the I / F means 5, and the process is terminated.

[effect]
According to the present embodiment as described above, since a plurality of initial system configurations can be created in advance, it is possible to calculate the minimum transmission loss for each initial system configuration, and the transmission loss calculation process Can fall into a local solution. Therefore, a wide range can be set as a search target, and a system configuration with a smaller power transmission loss can be determined.

[Other Embodiments]
The present invention selects the initial system configuration means 19 for generating a plurality of initial systems having different system configurations and an initial system configuration that has not yet been selected from the plurality of initial system configurations according to the third embodiment. The initial system selection means 20 and the minimization configuration selection means 21 for selecting the system configuration with the minimum power transmission loss among the system configurations with the minimum power transmission loss calculated based on all the initial system configurations. Embodiments applied to the forms are also included.

Specifically, in the second embodiment, in STEP 601, the data reading unit 10 receives data such as the configuration of the power distribution system from the storage unit 3, the open / close state of the switch provided in the system, and data on the load and impedance. The system information data is read, and as an initialization process, the initial system generation unit 19 creates a plurality of different system configurations, and the transmission loss calculation unit 11 calculates the initial transmission loss for each system configuration.

Then, the initial system selection unit 20 selects a new system configuration that has not yet been selected from among the plurality of initial system configurations created by the initial system generation unit 19, and STEPs 602 to 612 are performed based on the initial system configuration. The process is executed. In STEP612, when the switch number changing unit 18 determines that the number of switches selected by the “closed” switch selecting unit 12 is equal to a preset n (predetermined threshold) (YES in STEP612) ), The initial system selection means 20 determines whether there is another initial system configuration that has not been subjected to the power transmission loss minimization process.

When it is determined by the initial system selection unit 20 that there is another initial system configuration that has not been subjected to the power transmission loss minimization process, the initial system selection unit 20 includes a plurality of items created by the initial system generation unit 19. By selecting a new system configuration that has not been selected from among the initial system configurations, the processing from STEPs 602 to 612 is repeated.

When the initial system selection unit 20 determines that no other initial system configuration exists, in STEP 613, the minimized configuration selection unit 21 is obtained as a solution candidate for minimizing the transmission loss for each initial system configuration. The system configuration that minimizes the transmission loss is selected from all the system configurations, the selected system configuration and the transmission loss are determined as the minimum transmission loss system configuration and the minimum transmission loss, and the display means 4 and the I / I The data is output through the F means 5 and the process is terminated.

DESCRIPTION OF SYMBOLS 1 ... Calculation means 2 ... Input means 3 ... Memory | storage means 4 ... Display means 5 ... I / F means 6 ... Distribution system monitoring control apparatus 7 ... Distribution system
9a to 9g ... Section number 10 ... Data reading means 11 ... Transmission loss calculation means 12 ... "Closed" switch selection means 13 ... Power flow calculation means 14 ... "Open" switch selection means 15 ... Transmission loss reduction determination means 16 ... Initial System comparison means 17 ... Loss minimized configuration update means 18 ... Switch number change means 19 ... Initial system generation means 20 ... Initial system selection means 21 ... Minimization configuration selection means 91 to 95 ... Switches

Claims

Among the system configurations in which the switching state of the switch is changed, a determination device for the minimum transmission loss system configuration for determining the minimum transmission loss system configuration that minimizes the transmission loss,
“Closed” switch selection means for selecting two or more open switches from a plurality of switches to be closed so as to create one mesh system in the system configuration;
“Open” switch selection means for selecting the number of switches in the closed state as many as the number of switches selected by the “closed” switch selection means to be opened so that a radial system configuration can be obtained. When,
The open switch selected by the “closed” switch selection means is changed to the closed state, and the closed switch selected by the “open” switch selection means is changed to the open state. Transmission loss calculating means for calculating the transmission loss of each system configuration obtained as a result,
A reduction determination unit that determines whether the transmission loss of the specific system configuration newly calculated by the transmission loss calculation unit is lower than the transmission loss of another system configuration calculated earlier;
When it is determined by the reduction determination means that the power transmission loss of the specific system configuration is reduced, an update unit that updates the specific system configuration as a minimum power transmission loss system candidate;
Determining means for determining the minimum transmission loss system configuration from the minimum transmission loss system candidates;
With
In the determination means, the reduction determination means reduces any transmission loss of each system configuration calculated by the transmission loss calculation means from the transmission loss of the minimum transmission loss system candidate that is the latest update result. When determining that the minimum transmission loss system configuration is not, the minimum transmission loss system configuration determining apparatus determines the minimum transmission loss system candidate as the minimum transmission loss system configuration.
2. The minimum power transmission loss according to claim 1, wherein the “open” switch selection unit sequentially selects a switch in a closed state with a minimum passing current among the switches in the mesh system. System configuration determination device.
3. The minimum power transmission according to claim 2, wherein the “open” switch selection means sequentially selects a switch in a closed state with a minimum passing current under a capacity restriction of a transmission line of the system. Loss system configuration determination device.
The apparatus for determining a minimum power transmission loss system configuration according to claim 1, further comprising a limiting unit that limits a selection number of switches in an open state selected by the "closed" switch selection unit.
Among the system configurations in which the switching state of the switch is changed, a determination device for the minimum transmission loss system configuration for determining the minimum transmission loss system configuration that minimizes the transmission loss,
“Closed” switch selection means for selecting a switch in an open state from a plurality of switches to be closed so as to create one mesh-like system in the system configuration;
Switch number changing means for changing the number of switches selected by the "closed" switch selecting means;
“Open” switch selection means for selecting the number of switches in the closed state as many as the number of switches selected by the “closed” switch selection means to be opened so that a radial system configuration can be obtained. When,
The open switch selected by the “closed” switch selection means is changed to the closed state, and the closed switch selected by the “open” switch selection means is changed to the open state. Transmission loss calculating means for calculating the transmission loss of each system configuration obtained as a result,
A reduction determination unit that determines whether the transmission loss of the specific system configuration newly calculated by the transmission loss calculation unit is lower than the transmission loss of another system configuration calculated earlier;
When it is determined by the reduction determination means that the power transmission loss of the specific system configuration is reduced, an update unit that updates the specific system configuration as a minimum power transmission loss system candidate;
Determining means for determining the minimum transmission loss system configuration from the minimum transmission loss system candidates;
With
In the determination means, the reduction determination means reduces any transmission loss of each system configuration calculated by the transmission loss calculation means from the transmission loss of the minimum transmission loss system candidate that is the latest update result. When determining that the minimum transmission loss system configuration is not, the minimum transmission loss system configuration determining apparatus determines the minimum transmission loss system candidate as the minimum transmission loss system configuration.
The switch number changing means, when it is determined by the reduction determining means that the transmission loss of the specific system configuration is not reduced more than the power transmission loss of another system configuration previously calculated, 6. The apparatus for determining a minimum transmission loss system configuration according to claim 5, wherein the number of switches selected by the switch selection means is increased.
An initial system generation means for generating a plurality of initial systems by randomly changing the switching state of the switch,
The “closed” switch selection unit selects a switch in an open state so as to create one mesh system in each initial system generated by the initial system generation unit. Item 6. The apparatus for determining the minimum power transmission loss system configuration according to Item 1 or 5.
Among the system configurations in which the switching state of the switch is changed, the minimum transmission loss system configuration determination method for determining the minimum transmission loss system configuration that minimizes the transmission loss,
“Closed” switch selection step for selecting two or more open switches from a plurality of switches to be closed so as to create one mesh system in the system configuration;
“Open” switch selection step for selecting the number of switches in the closed state equal to the number of switches selected in the “closed” switch selection step so that the switches are opened so as to obtain a radial system configuration. When,
The switch in the open state selected by the “closed” switch selection step is changed to the closed state, and the switch in the closed state selected by the “open” switch selection step is changed to the open state. Transmission loss calculation step for calculating transmission loss of each system configuration obtained as a result,
A reduction determination step for determining whether the power transmission loss of the specific system configuration newly calculated by the power transmission loss calculation step is lower than the power transmission loss of another system configuration calculated earlier;
When it is determined that the power transmission loss of the specific system configuration is reduced by the reduction determination step, an update step of updating the specific system configuration as a minimum power transmission loss system candidate;
A determination step for determining a minimum transmission loss system configuration from minimum transmission loss system candidates;
Including
In the determination step, the transmission loss of each system configuration calculated in the transmission loss calculation step is reduced more than the transmission loss of the minimum transmission loss system candidate that is the latest update result. A determination method of a minimum transmission loss system configuration, wherein, when it is determined that the minimum transmission loss system configuration is not determined, the minimum transmission loss system candidate is determined as a minimum transmission loss system configuration.
9. The minimum transmission loss according to claim 8, wherein the “open” switch selection step sequentially selects a switch in a closed state with a minimum passing current among the switches in the mesh system. System configuration determination method.
Among the system configurations in which the switching state of the switch is changed, the minimum transmission loss system configuration determination method for determining the minimum transmission loss system configuration that minimizes the transmission loss,
A “closed” switch selection step of selecting a switch in an open state from a plurality of switches to be closed so as to create one mesh-like system in the system configuration;
A switch number changing step for changing the number of switches selected in the “closed” switch selection step;
“Open” switch selection step for selecting the number of switches in the closed state equal to the number of switches selected in the “closed” switch selection step so that the switches are opened so as to obtain a radial system configuration. When,
The switch in the open state selected by the “closed” switch selection step is changed to the closed state, and the switch in the closed state selected by the “open” switch selection step is changed to the open state. Transmission loss calculation step for calculating transmission loss of each system configuration obtained as a result,
A reduction determination step for determining whether the power transmission loss of the specific system configuration newly calculated by the power transmission loss calculation step is lower than the power transmission loss of another system configuration calculated earlier;
When it is determined that the power transmission loss of the specific system configuration is reduced by the reduction determination step, an update step of updating the specific system configuration as a minimum power transmission loss system candidate;
A determination step for determining a minimum transmission loss system configuration from minimum transmission loss system candidates;
Including
In the determination step, the transmission loss of each system configuration calculated in the transmission loss calculation step is reduced more than the transmission loss of the minimum transmission loss system candidate that is the latest update result. A determination method of a minimum transmission loss system configuration, wherein, when it is determined that the minimum transmission loss system configuration is not determined, the minimum transmission loss system candidate is determined as a minimum transmission loss system configuration.
The switch number changing step is performed when the reduction determining step determines that the transmission loss of the specific system configuration is not reduced more than the power transmission loss of another system configuration previously calculated. The method for determining the minimum power transmission loss system configuration according to claim 10, wherein the number of switches selected in the switch selection step is increased.
Including an initial system generation step of generating a plurality of initial systems by randomly changing the switching state of the switch,
The “closed” switch selection step selects a switch in an open state so as to create one mesh system in each initial system generated by the initial system generation step. Item 11. The method for determining the minimum transmission loss system configuration according to Item 8 or 10.
A determination program for a minimum transmission loss system configuration that causes a computer to determine a minimum transmission loss system configuration that minimizes transmission loss among the system configurations in which the switching state of the switch is changed,
In the computer,
A “closed” switch selection process for selecting two or more open switches to be closed from a plurality of switches so as to create one mesh system in the system configuration;
“Open” switch selection process for selecting the number of switches in the closed state equal to the number of switches selected by the “closed” switch selection process so that the switches are opened so as to obtain a radial system configuration. When,
The switch in the open state selected by the “closed” switch selection process is changed to the closed state, and the switch in the closed state selected by the “open” switch selection process is changed to the open state. Transmission loss calculation processing for calculating the transmission loss of each system configuration obtained as a result,
A reduction determination process for determining whether the power transmission loss of the specific system configuration newly calculated by the power transmission loss calculation process is lower than the power transmission loss of another system configuration calculated earlier;
When it is determined by the reduction determination process that the power transmission loss of the specific system configuration is reduced, an update process for updating the specific system configuration as a minimum power transmission loss system candidate;
A decision process for determining the minimum transmission loss system configuration from the minimum transmission loss system candidates;
And execute
In the determination process, any of the transmission losses of each system configuration calculated by the transmission loss calculation process in the reduction determination process is lower than the transmission loss of the minimum transmission loss system candidate that is the latest update result. When determining that the minimum transmission loss system configuration is not, the minimum transmission loss system configuration determination program determines the minimum transmission loss system candidate as the minimum transmission loss system configuration.