JPS63242130A - Power system changing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Objective of the Invention 1 (Field of Industrial Application) The present invention is directed to a power system switching system that automatically performs system switching to restore a power outage section when an accident occurs in a power system. It is related to the device.

(Prior Art) Generally, when a system fault occurs in an electric power system, the power outage section is restored by system switching. This point will be explained using the power system shown in FIG. 9 as an example. That is, in FIG. 9, under normal conditions, the main substation A's circuit breaker CB11. Disconnector DS11B, disconnector D
S11L is closed, adjacent substation B interrupter 0821. The disconnector 0821m is open, the disconnector 0821B is in the open state, and power is being supplied from the main substation A to the power transmission 11L1. In this state, if an accident occurs in the power receiving system of the main substation A and the bus line BUSA of the main substation A becomes non-voltage, the power supply to the power transmission line L1 is cut off, and the power transmission line 111L1 is cut off.
The distribution substation system connected to the main transformers 811 and 312 will experience a power outage. At this time, the breaker C811 of the main substation A and the disconnector [)S
After opening 71L, disconnect switch DS21 of adjacent substation B
By turning on the L, L disconnector CB21, power is supplied from the adjacent substation B connected to the power supply system to the power transmission line L1, and the power outage is restored. The same applies to the power transmission line L2 side, and the main substation A's circuit breaker CB12. After opening the disconnector DS12L, by turning on the disconnectors DS31L, L, and C831 of the adjacent substation C, the power is transmitted from the adjacent substation C connected to the power supply system. Power is supplied to line 2 to restore the power outage. Note that the system configuration in Figure 9 is 1 bank 1
Although the line configuration is shown, the system configuration is generally 3 banks and 3 lines.

However, since the above-described system switching operation is performed under an emergency situation, there is a risk that the operator may mistakenly perform an operation other than a predetermined procedure. In addition, in the case of a total power outage accident at main substation A, there are an extremely large number of transmission lines on which such system switching operations must be performed, and operators must make sure that there are no errors in each operation. When performing these operations, it takes a considerable amount of time to complete all operations, which prolongs the power outage, and especially in the centers of large cities where important loads are concentrated, such power supply disruptions can cause social chaos. There is concern that this may cause (Problems to be solved by the invention) As described above, in the conventional system switching operation by an operator,
Not only can this be done incorrectly, but in the event of a total power outage at a main substation, it can take a long time to recover from the power outage.

An object of the present invention is to automatically perform system switching operations between the main substation and its adjacent substations in the event of a total power outage accident at the main substation, safely and reliably, and quickly restore the power outage section. The object of the present invention is to provide a power system switching device that can improve the reliability of power supply and improve services.

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, in the first invention, there is a common trunk substation on one end side and a common main substation is connected to the power supply system on the other end side. In an electric power system consisting of multiple transmission lines each having different adjacent substations, in which power is normally supplied from the main substation to each transmission line, the main substation Inputs are operation signals from a protective relay device installed at the main substation that detects system faults at the main substation, switching status signals of the switches of the main substation, and voltage presence/absence status signals of the bus and transmission lines. a central device;
A terminal device is installed at each adjacent substation and receives the open/close status signal of the switch of the adjacent substation and the voltage presence/absence status signal of the bus bar and power transmission line. When the central device detects a total power outage accident at the main substation, it outputs an open command to the switch of the main substation, and then each terminal device A start command signal is sent to the central device, and each terminal device uses the start command signal from the central device to
The present invention is characterized in that a closing command is output to a switch of an adjacent substation where each terminal device is installed.

Further, in the second invention, a first power transmission line has a common main substation on one end side and an adjacent substation connected to the power supply system on the other end side, and an adjacent substation connected to the power supply system. A power system consisting of a second power transmission line where each substation does not exist, and in normal times multiple transmissions are sent from the main substation! I! In the case where power is supplied to A central device that inputs signals and voltage presence/absence status signals of bus bars and transmission lines, and is installed in an adjacent substation.
Information for transmitting and receiving signals by connecting the terminal device which inputs the switching state signal of the switch of the adjacent substation and the voltage presence/absence state signal of the bus bar and power transmission line, and the central device and each terminal device separately. When the central device detects a total power outage accident at the main substation, it outputs an open command to the switch of the main substation on the first power transmission line, and connects the power receiving system of the main substation to the main substation. When the circuit breaker connected to the busbar of the main substation is not automatically opened, it outputs an opening command to it and then sends a start command signal to the terminal device, and the terminal device uses the start command signal from the central device to A closing command is output to the switch of the adjacent substation where the terminal device is installed, and then the central device outputs the closing command to the switch of the main substation at the first transmission Ntm. shall be.

(Operation) In the power system switching device of the first invention, when the central device detects a total power outage accident at the main substation, it opens the switch of the main substation and then sends a start command signal to each terminal device. Then, each terminal device receives this activation command signal,
Perform the closing operation of the switch of the adjacent substation where each terminal device is installed. As a result, for areas with power outage.

Power is switched from the main substation to the adjacent substations where each terminal device is installed, and the power outage section is restored.゛In addition, in the power system switching device of the second invention, when the central device detects a total power outage accident at the main substation, it opens the switch of the main substation on the first power transmission line, and switches the power receiving system of the main substation. If the circuit breaker connecting the main substation and the busbar of the main substation is not automatically opened, the circuit breaker is opened, and then a start command signal is sent to the terminal device. Then, the terminal device receives this activation command signal and closes the switch of the adjacent substation where the terminal device is installed, and then the central device operates the switch of the main substation on the first power transmission line. Do the following. As a result, power is supplied to the power outage section from the adjacent substation where the terminal device is installed via the busbar of the main substation, and the power outage section is restored.

(Example) The present invention will be described below with reference to an example shown in the drawings.

FIG. 1 is a block diagram showing a configuration example of a power system switching device according to the present invention. Note that in this embodiment, the ninth
A case will be described in which the present power system switching device is applied to a power system having the configuration shown in the figure.

In FIG. 1, 1 is a central device provided on the side of the main substation A, 2-1 and 2-2 are terminal devices provided in each of the adjacent substations B and C, and 3 is a central device II! 1 and each terminal installation! 2-1 and 2-2 are connected separately to send and receive signals. Here, the central device 1 is a protective relay bag @ 4 that detects a system fault at the main substation A.
Operation signal from 6. The switches (breaker CSII, disconnector OSIIS, disconnector D) are the system equipment 5 of the main substation A.
S11L, and interrupter CB12. Disconnector DS12B,
Open/close status signal 7 of disconnector DS12L) and bus line BL
JSA and feed'R line L1. The voltage presence/absence status signal 8 of L2 is inputted, and the following processes (, a) to (c) are performed to send the operation command signal 9 to the switch, which is the system equipment 5 of the main substation A. This is what is output. In addition, the terminal devices 2-1 and 2-2 are equipped with switches (interrupters CB21, disconnectors, DS21B.

Disconnector DS21L, breaker CB31, disconnector D
S31 B, disconnector DS31L) open/close status signal @11-
1.11-2. Oh, nihiff1llBUsB.

BUSC and power transmission 1i1L1. L2 voltage presence/absence status signal 1
2=1.12-2 respectively, and the following (d), (
After performing each process of e), the operation command signal 13-1.13-2 is output to the switch which is the system equipment 10-1.10-2 of the adjacent substations B and C.

(a) Determine whether or not the normal grid pattern is in the grid state considered for automatic switching (total shutdown! Normal grid state before the accident), and A system for determining whether or not a breaker to be tripped by the protective relay device 4 (a breaker in the power receiving system) is in an open state after a certain period of time has elapsed since the operation signal 6 of the device 4 was input. Configuration condition determination processing.

(b) The operation signal 6 of the protective relay bag W14 is input.

It is activated on the condition that the conditions determined by the system configuration condition determination process are satisfied and there is no bus bar (BUSA) voltage of the main substation A, and the switches of the main substation A (breakers CB11, DS11L, and breaker CB12.Disconnector DS12
Processing to output an open command to L).

(c) Due to the above opening command, the switches of main substation A (breaker CB11, disconnector DS11 L, and breaker CB
12. A start command signal is sent to each terminal device ff2-1.2-2 via the information transmission means 3 on the condition that the disconnector DS12L) is opened and there is no voltage on the power transmission lines (Ll, L2) of the main substation A. The process of sending out.

(d) The system status of adjacent substations B and C is changed from the adjacent substations B and C to transmission line L1. Determine the conditions as to whether the configuration has sufficient system capacity to supply power to L2 (for example, determine whether three transformers are operated in parallel (for example, Power transmission line L1.L2 is 3
Grid condition determination processing (determining whether all lines are in operation).

(e) A start command signal is input from the central unit @1, and the conditions determined by the system condition determination process are established.

And it is activated on the condition that there is no voltage on the transmission lines (Ll, L2) of the adjacent substations B and C, and the switches of the adjacent substations B and C (breaker CB21, disconnector DS21L, and breaker CB, 31. Disconnection: Process of outputting the input command to DS31L). 1. Figure 2 shows the above-mentioned (a) to
An example of the functional blocks of the central unit @1 and each terminal device 2-1, 2-2 for realizing each process in (e) is shown.

Next, the operation of the power system switching device configured as described above will be described using the flowcharts shown in FIGS. 3 and 4. In addition, FIG. 3 is a flow diagram showing the processing contents in the central device 1,
FIG. 4 is a flowchart showing the processing contents in each terminal device 2-1 and 2-2.

In Figure 1, under normal conditions, breaker CB of main substation A
11. Disconnector 0811B and disconnector DS11L are closed, and adjacent substation B's breaker CB21° and disconnector DS21L are open.
Further, the disconnector DS21B is in a closed state, and power is being supplied from the main substation to the power transmission line L1. Similarly, breaker CB12. of main substation A. Disconnector DS12B and DS12L are closed, and breaker CB51 of adjacent substation C
, the disconnector DS31L is open, the disconnector DS31B is closed, and power is being supplied from the main substation A to the power transmission line L2.

In such a state, if a total power outage occurs at the main substation A due to an accident in the power receiving system, the central equipment 1 receives the operation signal 6 from the protective relay device 4. Start by inputting the automatic cutoff signal of the breaker of the power receiving system and the no-voltage signal of the bus BUSA, and turn on the breaker CBI of the main substation A.1.
Output an open command to CBI 2. After confirming that these are open, disconnect switch DSIIL of main substation A is
.

A release command is output to DS12L, and after these releases are confirmed, power transmission line L1. After confirming that there is no voltage on L2, a start command signal is sent to the terminal devices 2-1, 2-2 of adjacent substations B and C via the information transmission means 3. On the other hand, each terminal device 2-
1.2-2 is started by a start command signal from the central device 1, and the bus lines BUSB and BUSC have voltage, and the sending Wl line L1
．． After confirming that there is no voltage in 12, disconnect the disconnectors DS21L and D.
A closing command is output to S31L, and after confirming these closings, the disconnectors CB21. CB5
1, and after these inputs are confirmed, the voltage distribution of the power transmission 11L1.12 is confirmed on the central device 1 side, and a series of switching operations is completed. This caused the power outage section, namely main transformers S11 and 812.82
For the distribution substations connected to 1 and 822, power is supplied from the main substation A to the adjacent substations B and C where each terminal equipment f12-1.2-2 is installed. The system will be switched over and the power outage section will be restored.

As described above, in the power system switching device of this embodiment, when a power outage accident occurs at the main substation A, the power outage occurs on the power transmission line L1. It becomes possible to automatically switch the power supply to L2 from the adjacent substations B and C connected to the power supply system. In addition, since the open/close status of system equipment and the presence/absence of system voltage are checked automatically according to predetermined procedures at each stage of the system switching operation, there is no risk of operational errors occurring during system switching. System switching can be performed safely, reliably, and quickly without any problems. As a result, it is possible to improve the reliability of system switching operations for restoring power outage sections, shorten power outage time, and minimize the area of power outage. When the device is applied, the effect is extremely large.

In addition, in the above explanation, the transmission lines subject to system switching include:
When there are adjacent substations B and C that are both connected to the power system at the terminal on the opposite side of the main substation A (power transmission line)
However, as another example, an example in which there is a power transmission line 1 (load transmission line) with no adjacent substation connected to the power supply system at the terminal opposite to the main substation is shown in the drawing below. Explain with reference to.

FIG. 5 shows an example of the configuration of a power system that is subject to system switching according to this embodiment, and the same parts as in FIG. 8 are denoted by the same reference numerals. In FIG. 5, the power system consists of a first power transmission line L1 with a common trunk substation A at one end and an adjacent substation B connected to the power supply system at the other end.
, and second power transmission lines L3 and 14 connected to the power supply system and having no adjacent substations, respectively.

Also, CB13. CB14 has 2 power transmission lines 13 for each
．． The circuit breakers D813B and D813L, D814B and D814L of the main substation A at 14 are also connected to the second power transmission line L3. Disconnectors 831 and S32 of main substation A in L4 S41 and S42 are connected to the second power transmission line L3. The main transformers are respectively connected to L4.

Furthermore, the power system switching device according to the present embodiment also has the above-mentioned first
It has the same configuration as the figure, and the following (a) to (
A central device 1 that performs each of the processes in c) and (f) is installed in the main substation A, and a terminal device (hereinafter referred to as the terminal device 2) that performs each of the processes in (d) and (e) below is installed in the main substation A. Substation B
The only difference is that it is provided only in

(a) Determine the condition as to whether the normal system pattern is in the system state targeted for automatic switching (normal system state before the occurrence of a total power outage accident), and operate the protective relay device 4. After a certain period of time has passed since signal 6 was input,
A system configuration condition determination process that determines a condition as to whether or not a breaker to be tripped by the protective relay device 4 (a breaker in the power receiving system) is in an open state.

(b) The operating signal 6 of the protective relay device 4 is input.

The conditions determined by the above system configuration condition determination process are satisfied.

And it is activated on the condition that there is no busbar (BUSA) voltage of main substation A, and the switch (breaker CB11゜disconnector DS11) of main substation △ on the first power transmission line (Ll)
Processing to output an open command to L).

(c) The condition is that the switch (breaker CBI1, disconnector DS11 L) of the main substation A is opened by the above opening command, and that there is no t2 voltage on the first power transmission line (Ll) of the main substation A. , a process of sending an activation command signal to the terminal device 2 via the information transmission means 3;

(d) The system status of adjacent substation B is determined from the adjacent substation B side by the first and second transmission lines L1 and L3. Determine the conditions as to whether the configuration has a sufficient number of grid customers to supply power to L4 (for example, determine whether three transformers are operated in parallel), (Determination of whether all three lines of power transmission IL1 are in operation)
System condition judgment processing.

(e) A start command signal is input from the central station 1, and the conditions determined by the system condition determination process are established.

Processing that is activated on the condition that there is no voltage on the power transmission line (Ll) of the adjacent substation B, and outputs a closing command to the switches (breaker CB21, disconnector DS21L) of the adjacent substation B.

(f) The switch of the adjacent substation B (breaker CB21, disconnector DS21L) is closed by the above closing command, and on condition that the voltage of the first transmission line (Ll) of the main substation A is present, the switch of the adjacent substation B is closed. A process of outputting a immersion command to the switch (breaker CB11, disconnector DS11L) of the main substation A on the power transmission line (Ll) of No. 1.

In addition, FIG. 6 shows an example of functional blocks of the central device 1 and the terminal stomach 2 for realizing each of the above-mentioned processes (a) to (e).

Next, the operation of the power system switching device configured as described above will be described using the flow diagram shown in FIG. 6. In addition, the 6th
The figure shows the processing contents in the central device 1 and the terminal device @2.

In Figure 5, during normal times, breaker CB of main substation A
11. Disconnector DS11B and disconnector DS11L are closed, and the adjacent substation B's interrupter CB21° and disconnector DS21L are open.
Further, the disconnector D821B is in a closed state, and power is being supplied from the main substation A to the first power transmission line L1. Similarly, breaker CB1'3 of main substation A. Disconnector DS1
3B.

Disconnector DS13L is closed, and breaker CB14. of main substation A is closed. The disconnector DS14B and the disconnector D814L are in a closed state, and power is being supplied from the main substation A to the second power transmission lines L3 and L4, respectively.

Under these conditions, if a total power outage occurs at the main substation A due to an accident in its power receiving system, the central unit 1 will act as a protective relay! 4. Operating signal from 6. It starts by inputting the automatic cutoff signal of the breaker of the power receiving system and the no-voltage signal of the bus BUSA, and outputs an open command to the breaker CB11 of the main substation A on the first power transmission line L1. After these openings were confirmed, the main substation A was also opened.
An open command is output to the disconnector DS11L. in this case,
Breakers CB13 and CB of main substation A on second transmission lines L3 and L4 14. The disconnectors DS13L and DS14L remain closed, and the second power transmission lines L3 and L4 are connected to the bus line BUSA of the main substation A. On the other hand, after these openings are confirmed, if the secondary side breaker CB1 of the main transformer T1 is not automatically cut off, it is opened, and then the secondary side breaker DS1T of the main transformer T1 is opened. Then, bus B of main substation A
Separate LJSA from the accident area. The subsequent processing from sending the startup command signal to the terminal @station 2 of the adjacent substation B until the end of the processing of the terminal device 2 is the same as that shown in FIGS. 3 and 4 described above. After completing the processing of the terminal equipment @2 and confirming the presence of voltage on the first power transmission line L1, the central equipment 1 connects the main substation A bus (BtJSA) 1! After confirming that there is no pressure, turn on the disconnector DS11L of the first power transmission line L1,
Furthermore, the breaker CB11 of the first power transmission line L1 is turned on,
After these inputs are confirmed, the presence of voltage at the main substation A bus 1 (BUSA) is confirmed on the central equipment 1 side, and a series of switching operations is completed. This causes the power outage section, that is, the main transformers 811 and S12. S31 and 832
．． For the distribution substations connected to 8416 and 842, the power supply is switched from the adjacent substation B, where the terminal device 2 is installed, to the main substation A mother II (BtJSA). , the restoration range of the power outage section can be expanded.

On the other hand, as in the embodiments shown in FIGS. 5 to 7 above, there is an adjacent substation to which the power system is connected from adjacent substation B to the other end of the main substation A via the bus BtJSA. When power is supplied to second transmission lines L3 and L4 that are not connected to the adjacent substation, the sum of the loads on the second transmission lines L3 and 14 and the load on the first transmission line L1, which is directly connected to the adjacent substation, is Since the condition is that the power transmission capacity is equal to or less than the power transmission capacity of B, in the above-described embodiment, the switching operation is possible based on the amount of normal load. However, when load fluctuations are large and may exceed the transmission capacity of adjacent substation B, the load flow is transferred to instrument current transformer C as shown in Figure 8.
T11. CT13°CT14, potential transformer PT, measuring device M 1 .

M3. M4 was used to measure the 8th transmission WIilL1. immediately before the total power outage occurred at the main substation A. Measured value of tidal current of L2°L3 PL1. PL21PL3 are stored in the central device 1. And adjacent′! ! For the power transmission capacity Pes of L'R station B, PBs-PLt <PL 2 +PL! Pe 9-P
When L t >PL 2 Pa 5-PLl > PL 3 , the power transmission line L3. Since it is impossible to supply power to both L4 and L4, priorities are assigned in advance to transmission lines L3 and L4 based on the importance of the loads, and the one with the highest layer order is routed from adjacent substation B to the main substation. Power is supplied via A's mother IBUCA. By doing as described above, it is possible to finely limit the range in which power failure recovery is not possible, and to perform system switching operations while preventing problems such as overload from occurring for the system within the power failure recovery range.

[Effect of the invention] As explained above, according to the present invention, all P of the main substation
In the event of a P power line accident, system switching between the main substation and its adjacent substation is automatically performed to safely, reliably, and quickly restore the outage section, thereby improving the reliability of power supply and service. It is possible to provide a power system switching device that can

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the power system switching device according to the present invention, FIG. 2 is a filtering block diagram showing processing contents of the central device and terminal device in the same embodiment, and FIGS. 3 and 4 is a flowchart for explaining the operation in the same embodiment, FIG. 5 is a configuration diagram showing an example of a power system subject to grid switching according to another embodiment of the present invention, and FIG. FIG. 7 is a flow diagram for explaining the operation in the same example; FIG. 8 is a configuration diagram showing a modification of the embodiment shown in FIG. 5; FIG. 9 is a configuration diagram showing an example of a power system that is subject to system switching. DESCRIPTION OF SYMBOLS 1... Central device, 2.2-1.2-2... Terminal device, 3... Information transmission means, 4... Protective relay device, 5...
...System li equipment, 6...Operation signal of protective relay @4,
7... Circuit breaker, open/close status signal of disconnector, 8... Voltage presence/absence status signal of bus bar, power transmission line, 9... Operation command signal of circuit breaker, disconnector, 10-1.10 -2... System equipment, 11-1.11-2... Interrupter. Open/close state signal of disconnector, 12-1.12-2... Voltage presence/absence state signal of bus bar, power transmission line, 13-1.13-2... Breaker. Disconnector operation command signal, A...Main substation, B, C...
・Adjacent substation, T1. T2. T3.811゜312
．． 821.822. S31.832°S41. S42・
...Main transformer, Ll, 12. L3゜L4...Power transmission line, CB1. CBI 1. CB12°CB13. CB14
．． CB21.0B31... Breaker, DSl T, D
Sl 1 B, 0812B, CB13B, D814B,
DSIIL, D812L. DS13L, DS14L, CB21B, D831B, C
B21 L, CB31 L...Disconnector, BUSA...
・Bus bar of main substation A, B U S B +' B U
S C...Bus bars of adjacent substations B and C, CTI 1.
CT13°CT14...Measuring current transformer, PT...Measuring transformer, Ml, M3. M4...Measuring device. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 9 Figure 3 Figure 4 Figure 7 □i to Figure 6

Claims (2)

[Claims] (1) A power system consisting of multiple power transmission lines with a common main substation at one end and different adjacent substations connected to the power system at the other end. When power is supplied from the main substation to each power transmission line, an operating signal from a protective relay device installed on the main substation side and used to detect a system fault at the main substation. , a central device having each of the following means (a) to (c) and each of the adjacent substations receives the switching state signal of the switch of the main substation and the voltage presence/absence state signal of the bus bar and transmission line as input. The following (d) and (e)
What is claimed is: 1. A power system switching device comprising: a terminal device having each of the means; and an information transmission means for separately connecting the central device and each terminal device to send and receive signals. (a) Determine the condition as to whether the normal system pattern is in the system state targeted for automatic switching, and after a certain period of time has elapsed since the operation signal of the protective relay device is input, A system configuration condition determining means for determining whether or not a breaker to be tripped by a relay device is in an open state. (b) The operation signal of the protective relay device is input, the condition determined by the system configuration condition determining means is satisfied, and the switch of the main substation is activated on the condition that there is no bus voltage of the main substation. Means to output an open command to. (c) Sending a start command signal to each terminal device via the information transmission means on the condition that the switch of the main substation is opened by the opening command and there is no voltage on the transmission line of the main substation. means. (d) System condition determining means for determining whether the system status of the adjacent substation is configured to have sufficient system capacity to supply power from the adjacent substation to the transmission line. . (e) A start-up command signal is input from the central device, and the system is activated on the condition that the conditions determined by the system condition determining means are met and there is no transmission line voltage of the adjacent substation, and the adjacent substation is opened/closed. A means of outputting a loading command to the device. (2) A first power transmission line with a common trunk substation at one end and an adjacent substation connected to the power system at the other end, and no adjacent substation connected to the power system In a power system configured with second power transmission lines, in which power is normally supplied from the main substation to each transmission line, the second power substation is installed on the main substation side, and The following (a) to ( A central device having each of the means of c) and (f), which is provided at the adjacent substation, and receives as input the open/close state signal of the switch of the adjacent substation and the voltage presence/absence state signal of the bus bar and the power transmission line, performs the following: It is characterized by comprising a terminal device having each of the means (d) and (e), and an information transmission means for separately connecting the central device and each terminal device to send and receive signals. power system switching device. (a) Determine the condition as to whether the normal system pattern is in the system state targeted for automatic switching, and after a certain period of time has elapsed since the operation signal of the protective relay device is input, A system configuration condition determining means for determining whether or not a breaker to be tripped by a relay device is in an open state. (b) The protection relay device is activated on the condition that an operation signal is input, a condition determined by the system configuration condition determination means is satisfied, and there is no bus voltage of the main substation, and the first power transmission line Means for outputting an open command to the switch of the main substation. (c) On the condition that the switch of the main substation is opened by the opening command and there is no voltage on the first power transmission line of the main substation, send a start command signal to the terminal device via the information transmission means. means of sending. (d) Conditions as to whether the system status of the adjacent substation is such that it has sufficient system capacity to supply power from the adjacent substation to the first and second transmission lines. System condition determining means for determining. (e) A start-up command signal is input from the central device, and the system is activated on the condition that the conditions determined by the system condition determining means are met and there is no transmission line voltage of the adjacent substation, and the adjacent substation is opened/closed. A means of outputting a loading command to the device. (f) The switch of the adjacent substation is closed by the said closing command, and on the condition that the first transmission line voltage of the said trunk substation is present, the switch of the trunk substation on the first transmission line is closed. A means of outputting commands.