JP5094062B2 - Short-circuit current reduction system and short-circuit current reduction method for power transmission and distribution system - Google Patents

Description

  The present invention relates to a short-circuit current reduction system and a short-circuit current reduction method for a transmission / distribution system that improve the reliability of the transmission / distribution system by reducing the short-circuit current of the transmission / distribution system.

  The power system that supplies the power generated by the power station to the customer is a power system that uses the high-voltage that is generated by stepping up and down the generated three-phase alternating current at an ultra-high voltage substation, primary substation, secondary substation, etc. Power transmission system, and a power distribution system that sends power to consumers with a voltage obtained by stepping down the high voltage of the power transmission system at the distribution substation. In these power transmission and distribution systems, three-phase alternating current is output from the power plant and substation (power generation substation) via the bus, and transmission lines (branch lines, connection lines, etc.) called branch lines and connection lines are used. The power is supplied to various loads of consumers by transmitting power to the load line). In this case, a double bus system that is generally excellent in reliability is widely used as the bus.

  FIG. 7 is a connection diagram showing a configuration example of a conventional power transmission / distribution system employing such a double bus system. This power transmission / distribution system includes, for example, an A bus 6A and an Oto bus 6B to which a high voltage of 110 KV is supplied. 1A and 2B are provided with a double bus structure, and reference numerals 13A to 13O are switches connected to the A bus 6A, reference numerals 14A to 14O are switches connected to the B bus 6B, and reference numerals 15A to 15A. 15O is a circuit breaker connected between a pair of corresponding switches (for example, 13A and 14A, 13B and 14B, etc.). And the 1st line | wire is connected via each circuit breaker 15B-15O connected to the different bus | bath for every area | region where the grid connection line and load line which are power transmission lines for supplying electric power to a consumer are supplied. Two lines, 1L and 2L, are drawn. In the drawing, symbols A to D indicate the names of areas to which power is supplied. In this way, if multiple lines are drawn as grid interconnections and load lines from different buses for each region of the supply destination, even if the function of one bus is stopped due to an accident or the like, the remaining buses are connected. By using it, it is possible to supply power to consumers without causing a power outage.

In the transmission / distribution system adopting the double bus configuration as described above, a bus protection device is provided to detect an accident occurring between the bus connection breaker provided in the bus connection line and the current transformer. (For example, refer to Patent Document 1).
JP-A-8-237857

  By the way, when a short-circuit accident occurs for some reason in the power transmission / distribution system, a large short-circuit current flows in the power transmission / distribution system. By detecting this short-circuit current and breaking the circuit breaker provided in the power transmission / distribution system, The power transmission and distribution system is protected from short circuit accidents. Hereinafter, an example of an accident occurring in one of the B line and the C connection line will be described with reference to the configuration of FIG. 7. For example, a short circuit accident has occurred in the B line and the C connection line as load lines to which a high voltage of 110 KV is supplied. Then, the B line breakers 15H and 15I and the C connection lines 15J and 15K are blocked by the action of a current transformer and a protection relay (not shown), thereby protecting the power transmission and distribution system from a short circuit accident.

  However, if the short-circuit capacity of the system increases due to system expansion or system change, and a near-end three-phase short-circuit current that exceeds the rated breaking current of the circuit breakers 15H, 15I and 15J, 15K flows, Since there is a possibility of damage, the power transmission / distribution system cannot be protected from a short circuit accident. Here, the reason why the near-end three-phase short-circuit current is particularly large is that the electrical resistance of the transmission line becomes smaller at the near end. Therefore, in such a case, change the transmission / distribution system to another system to reduce the short-circuit current, or change the circuit breakers 15H, 15I and 15J, 15K to those with larger maximum rated currents, for example The one for 110 KV is replaced with the one for 220 KV.

  However, when the power transmission / distribution system is changed to another system as in the former case, there arises a problem that a decrease in system reliability is inevitable. On the other hand, when replacing the latter circuit breaker with one with a higher rated breaking current, not only will the replacement cost associated with the replacement of the circuit breaker be necessary, but a decrease in system reliability during the replacement period should be avoided. The problem that it is not possible arises.

  Moreover, in the busbar protection device as described in the above-mentioned Patent Document 1, there is no disclosure about a countermeasure when a short-circuit current exceeding the rated breaking current of the circuit breaker flows.

  Therefore, the present invention reduces the short-circuit current of the transmission / distribution system that can improve the system reliability of the transmission / distribution system and reduce the cost of replacing the breaker even when the short-circuit current exceeds the rated breaking current of the circuit breaker. The object is to provide a system and a method of reducing short circuit current.

In order to achieve the above object, the invention according to claim 1 supplies power to a power transmission / distribution system from a power substation via a bus, and exceeds a rated breaking current of a load line breaker provided in the power transmission / distribution system. A short-circuit current reduction system for a power transmission / distribution system that reduces the short-circuit current when a short-circuit current is generated in the power transmission / distribution system, the circuit breaker control controlling the load line circuit breaker provided in the power transmission / distribution system and means, connected to the circuit breaker control means, the power transmission and distribution two conditions occurs when the three-phase short-circuit fault of the three-phase short-circuit fault occurs at close end of the load line breaker of the system are established at the same time Near-end three-phase short-circuit fault detection means for detecting that a short-circuit current is a three-phase short-circuit fault that exceeds the rated breaking current of the load line breaker, and grid interconnection controlled by the breaker control means Wire breaker and said breaker A breaker control means controlled by a control means, wherein the breaker control means includes a three-phase short circuit fault detecting means for detecting a short circuit current exceeding a rated break current of the load line breaker. When a phase short-circuit accident is detected, control is performed to shut off at least one of the bus bar breaker and the grid interconnection breaker.

  According to a second aspect of the present invention, in the short-circuit current reduction system for a power transmission and distribution system according to the first aspect, the bus has a double bus configuration.

  According to a third aspect of the present invention, in the short circuit current reduction system for a power transmission / distribution system according to the first or second aspect, the system interconnection line provided with the system interconnection line breaker comprises a plurality of lines. .

According to a fourth aspect of the present invention, power is supplied from a power substation to a power transmission / distribution system via a bus, and a short-circuit current exceeding a rated circuit breaker current of a load line breaker provided in the power transmission / distribution system is the power transmission / distribution. A short-circuit current reduction method for a power transmission / distribution system that reduces the short-circuit current when it occurs in the system, the circuit breaker control means for controlling the load line breaker in the power transmission / distribution system, and the circuit breaker control means connected, short-circuit current interrupting said load line when the two conditions that have occurred in the generation and the three-phase short-circuit fault of the three-phase shorting accidents nearest end of the load line breakers are established at the same time of the transmission and distribution system Near-end three-phase short-circuit fault detecting means for detecting a three-phase short-circuit fault exceeding the rated breaking current of the breaker, a grid-connected line breaker controlled by the breaker control means, and the breaker control Busbar communication shielding controlled by means The breaker control means, when the three-phase short-circuit accident in which the short-circuit current exceeds the rated breaking current of the load line breaker is detected by the closest-end three-phase short-circuit accident detection means, Control which interrupts | blocks at least one of a bus-line connection circuit breaker and a grid connection line circuit breaker is performed.

  According to a fifth aspect of the present invention, in the short circuit current reduction method for a power transmission / distribution system according to the fourth aspect, when the bus has a single bus configuration and the system interconnection has a plurality of lines, When the terminal three-phase short circuit accident detection means detects the three-phase short circuit accident, the circuit breaker control means controls the circuit interconnection breaker to be disconnected.

  According to a sixth aspect of the present invention, in the method for reducing a short-circuit current of the power transmission and distribution system according to the fourth aspect, when the bus has a double bus configuration and the system interconnection has a plurality of lines, When the near-end three-phase short-circuit accident detecting means detects the three-phase short-circuit accident, the circuit breaker control means basically controls to shut off the bus bar breaker.

  According to a seventh aspect of the present invention, in the short circuit current reduction method for a power transmission / distribution system according to the sixth aspect, when the closest three-phase short-circuit fault detecting means detects the three-phase short-circuit fault, the circuit breaker control means Thus, it is possible to control so as to shut off the grid interconnection breaker.

  According to the invention described in claim 1, the short-circuit capacity of the system increases due to system expansion, system change, etc., and a three-phase short-circuit accident at the near end is a condition in which the short-circuit current exceeds the rated circuit breaker current of the circuit breaker. When detected, at least one of a busbar breaker and a grid interconnection breaker whose opening operation is controlled by the breaker control means is provided. Therefore, after detecting the condition that the short-circuit current exceeds the rated breaking current of the load line breaker, the breaker control means controls to shut off at least one of the bus connection breaker and the system interconnection breaker. Because the short-circuit current can be reduced, even if the short-circuit current exceeds the rated breaking current of the load line breaker, the system reliability of the power transmission and distribution system is improved and the load line breaker replacement cost is reduced. be able to.

  According to the invention described in claim 2, in the power transmission / distribution system of the double bus configuration, even when the short-circuit current exceeds the rated breaking current of the load line breaker, the system reliability of the power transmission / distribution system is improved and the load line The circuit breaker replacement cost can be reduced.

  According to the third aspect of the present invention, in the transmission / distribution system in which the grid connection line is composed of a plurality of lines, the system reliability of the transmission / distribution system is improved even when the short-circuit current exceeds the rated breaking current of the load line breaker. In addition, the load line breaker replacement cost can be reduced.

  According to invention of Claim 4, after providing a circuit breaker control means, a near-end three-phase short-circuit fault detecting means, a busbar connection circuit breaker, and a system interconnection line breaker in the power transmission and distribution system, the near-end three-phase After the condition that the short-circuit current exceeds the rated breaking current of the load line breaker is detected by the short-circuit accident detection means, the breaker control means controls to shut off at least one of the bus connection breaker and the grid-connected line breaker Thus, the short circuit current is reduced. Therefore, even when the short-circuit current exceeds the rated breaking current of the load line breaker, the system reliability of the power transmission and distribution system can be improved and the load line breaker replacement cost can be reduced.

  According to the fifth aspect of the present invention, when the bus bar has a single bus configuration and the grid connection line is composed of a plurality of lines, the circuit breaker control means controls to shut off the grid connection line breaker. Can reduce the short-circuit current.

  According to the sixth aspect of the present invention, when the bus is composed of a double bus and the system interconnection is composed of a plurality of lines, the circuit breaker control means controls to basically shut off the bus connection breaker. By doing so, the short circuit current can be reduced.

  According to the seventh aspect of the present invention, when the near-end three-phase short-circuit accident detecting means detects a three-phase short-circuit accident, the circuit breaker control means can be controlled to shut off the system interconnection line breaker. By doing so, the short-circuit current can be reduced.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

  FIG. 1 is a schematic configuration diagram illustrating a short-circuit current reduction system 10 for a power transmission and distribution system according to an embodiment of the present invention. This short circuit current reduction system 10 of the power transmission / distribution system includes a circuit breaker control means 1 for controlling various circuit breakers provided in the power transmission / distribution system of the substation and a three-phase short circuit accident at the closest end of the load line circuit breaker. Near-end three-phase short-circuit fault detecting means 2 for detecting the power, system-connected circuit breaker 3 whose opening operation is controlled by the circuit breaker control means 1, and load line interruption whose opening operation is controlled by the circuit breaker control means 1 And a bus bar breaker 4 whose opening operation is controlled by the circuit breaker control means 1.

FIG. 2 is a connection diagram illustrating a configuration example of a power transmission / distribution system to which the short-circuit current reduction system 10 for the power transmission / distribution system according to the present embodiment is applied. This power transmission / distribution system has, for example, a double-bus configuration of 1st and 2nd buses provided with a first bus 2A and a second bus 6B to which a high voltage of 110 KV is supplied, and each bus 6A and 6B is provided between each bus 6A and 6B. It is connected via a plurality of switches 13A-13O and switches 14A-14O. However, a breaker 15A for 110 KV bus communication is connected between the switches 13A and 14A. From the connection point between the switches 13B and 14B, for example, the first line 1L of the A branch line is drawn out as a system interconnection line that supplies power to the bus via the circuit breaker 15B, and the switches 13C and 14C A second line 2L of the A branch line is drawn out from the connection point to the A branch line through the circuit breaker 15C. Similarly, for example, the first line 1L of the A connection line is connected from the connection point between the switches 13D and 14D via the circuit breaker 15D, and from the connection point between the switches 13E and 14E via the circuit breaker 15E. The second line 2L of the A connection line is drawn out.
Similarly, the first line 1L of the D line is connected from the connection point between the switches 13L and 14L via the circuit breaker 15L, and the D line is connected from the connection point between the switches 13M and 14M via the circuit breaker 15M. Of the second line 2L. Similarly, the first line 1L of the D heating power line is connected from the connection point between the switches 13N and 14N via the circuit breaker 15N, and the first line 1L is connected from the connection point between the switches 13O and 14O via the circuit breaker 15O. The second line 2L of the thermal power line is drawn out.

  Further, from the connection point of the switches 13H and 14H, for example, a first line 1L of B line is used as a load line which is a transmission line for supplying power from a bus to a consumer and a distribution substation via a circuit breaker 15H. The second line 2L of the B line is drawn from the connection point between the switches 13I and 14I via the circuit breaker 15I. Similarly, the first line 1L of the C connection line is connected from the connection point between the switches 13J and 14J via the circuit breaker 15J, and the C line is connected from the connection point between the switches 13K and 14K via the circuit breaker 15K. The second line 2L of the communication line is drawn out.

  The first line 1Tr of the interconnection Tr is connected from the connection point between the switches 13F and 14F via the circuit breaker 15F, and the connection Tr is connected from the connection point between the switches 13G and 14G via the circuit breaker 15G. Of the second line 2Tr.

  As shown in FIG. 3, the first and second lines 1L and 2L drawn out as the system interconnection line or load line from the A bus line 6A and the Oto bus line 6B via the circuit breakers 15B to 15O are protected as shown in FIG. The relay method is applied. This protection relay system includes a protection relay 9, and a power transmission line 7 (first line) for supplying power to a bus, a customer, and a distribution substation for a bus 6 (corresponding to a bus A 6A or an Oto bus 6B). 1 L or 2 L (corresponding to the second line 2 L) is drawn, and each transmission line 7 has a breaker CB that opens and closes these transmission lines and a large current flowing through the transmission line 7. A current transformer CT is provided for current transformation to a small current (for example, 5 A) suitable for the protection relay 9. On the other hand, a transformer PT for transforming the high voltage to a low voltage (for example, 110 V) suitable for the protective relay 9 is provided on the bus 6. The signal detected by the current transformer CT and the signal detected by the transformer PT are input to the protection relay 9. The protection relay 9 is provided with a pallet 5A, and the circuit breaker CB is also provided with a pallet 5B, and each of the pallets 5A and 5B is connected to a DC power source.

  In the power transmission / distribution system including the protection relay 9 as described above, if a short circuit accident occurs in the power transmission line 7 drawn from the bus 6 for some reason, a current larger than the normal value flows in the power transmission line 7. It is detected by the current transformer CT and transmitted to the protection relay 9. As a result, the protective relay 9 operates to close the pallet 5A, whereby the pallet 5B of the circuit breaker CB is closed and a circuit breaker tripping relay (not shown) operates to block the circuit breaker CB. Therefore, since the bus 6 and the power transmission line 7 are disconnected, the power transmission and distribution system can be protected from a short circuit accident. However, in the configuration as described above, when a large short-circuit current that exceeds the rated breaking current of the circuit breaker CB flows, the circuit breaker CB stops functioning and cannot be handled.

  Therefore, in the present invention, when the near-end three-phase short-circuit accident detection means 2 in the short-circuit current reduction system 10 of the power transmission and distribution system according to the present embodiment of FIG. Is a load line that exceeds the rated breaking current of the circuit breaker, for example, it is provided on the B line and the C connection line in FIG.

  As described above, the short circuit current exceeds the rated breaker current of the circuit breaker. The occurrence of a three-phase short-circuit accident. Since the two conditions that the three-phase short-circuit accident occurred at the near end of the circuit breaker are satisfied at the same time (known), the near-end three-phase short-circuit accident detection means 2 detects the near-end three-phase short-circuit accident. After that, the circuit breaker control means 1 controls the bus line breaker 15A or the grid interconnection breakers 15B to 15E and 15L to 15O in FIG. Will be able to. This eliminates the need to change the transmission / distribution system to another system or replace the circuit breaker with one with a larger maximum rated current as before, improving the system reliability of the transmission / distribution system. The circuit breaker replacement cost can be reduced.

  As described above, when detecting the near-end three-phase short-circuit accident detecting means 2 using the near-end three-phase short-circuit accident detecting means 2, as a method for detecting the close-end end accident, for example, an undervoltage relay is used. That is, by setting the set value in the vicinity of “0” V in advance using the undervoltage relay, when the set value becomes the reference value or less, the undervoltage relay is operated and Consider an accident at the edge. Moreover, as a method of detecting a three-phase short-circuit accident, for example, a distance relay is used. That is, it is assumed that a three-phase short-circuit accident has occurred by performing a red-white phase, white-blue phase, red-blue phase operation using a distance relay.

  Here, after detecting the near-end three-phase short-circuit accident, the selection of whether to control to shut off either the busbar breaker 15A or the grid connection breakers 15B to 15E, 15L to 15O The availability depends on the configuration of the bus or the configuration of the grid interconnection as follows.

  (1) When installing in a substation where the bus has a single bus configuration and there are two or more grid interconnection lines, the grid interconnection is cut off.

(2) When installing at a substation with 1 or 2 double bus configuration and 2 or more grid interconnection lines, basically disconnect the bus connection breaker. However, a switching switch for selecting either the bus connection breaker or the grid interconnection breaker is provided so that the grid interconnection breaker can also be selected. In the following cases, a grid interconnection breaker is selected.
1. When there is a power outage on one bus in a double bus configuration.
2. When the bus configuration is changed so that it is no longer a double bus configuration of A and B.

  Next, a method for reducing the short-circuit current of the power transmission and distribution system based on the above conditions will be described with reference to FIG. In FIG. 2, when the near-end three-phase short-circuit accident detecting means 2 detects, for example, a close-end three-phase short-circuit accident of the circuit breaker 15H of the first line 1L of the B line as the load line (1)). Since the power transmission / distribution system in FIG. 2 has a double bus configuration and two or more grid interconnections, the circuit breaker control means 1 determines that the above condition (2) is satisfied, and automatically activates the bus line breaker 15A. (2)) so as to shut off automatically. Alternatively, when one of the main bus 6A or the second bus 6B is out of power, or when it is no longer in the double bus configuration of the first A and the second B, the circuit breaker control means 1 is the above (2) -1 or (2) It is determined that the condition of -2 is satisfied, and control (2) -1) is performed so as to automatically shut off the grid connection line 15B. Then, B line 1L, which is an accident power transmission line, is interrupted (3)). Even if the bus bar breaker 15A is cut off as described above, it does not affect the trip of other lines and supply trouble.

  According to the short-circuit current reduction method of the power transmission / distribution system as described above, in the case of the control methods 1) to 2) above, before the 110 KV bus bar breaker 15A is cut off, the power supply was 43.4 KVA as an example. The short circuit current can be reduced to 36.4 KVA after the busbar breaker 15A is shut off.

  Next, with reference to FIG. 4, a schematic sequence will be described with reference to FIG. 4 for a shut-off operation when a near-end three-phase short-circuit accident occurs in the short-circuit current reduction system 10 of the power transmission and distribution system according to the present embodiment. In addition, as described above, an example in which selection of the busbar breaker and the grid interconnection breaker is possible will be described. FIG. 5 shows an example of a trip circuit for a load line breaker, and FIG. 6 shows an example of a trip circuit for a bus line breaker.

  First, in the transmission / distribution system, a near-end three-phase short-circuit occurred (for example, 1 in Fig. 2), which is a condition that the short-circuit current exceeds the rated breaker current of the circuit breaker. When detected by the accident detection means 2, this detection information is output from the AND gate 11A and input to the AND gate 11B. Here, when the transfer interruption device “use” switch is operated and the use information is input to the AND gate 11B, the AND gate 11B outputs the detection information to be input to the AND gates 11C and 11D. Next, when information for selecting a bus contact breaker is input to the AND gate 11C by the circuit breaker selection SW (changeover switch), the AND gate 11C turns the bus contact breaker (for example, 2 in FIG. 2)). The circuit breaker control means 1 outputs a “cut” command for breaking. As a result, the busbar communication circuit breaker (for example, the circuit breaker 15A) is automatically disconnected.

  On the other hand, when information for selecting the system interconnection line breaker is input to the AND gate 11D by the circuit breaker selection SW, the AND gate 11D is connected to the system interconnection line breaker (for example, 2 in FIG. 2) -1) The circuit breaker control means 1 outputs a “cut” command for interrupting the circuit. As a result, the grid connection circuit breaker (for example, circuit breaker 15B) automatically breaks.

  Next, when “OFF” information of the bus bar breaker and “Bus line breaker” “selection” information are input to the AND gate 11G, the bus bar breaker “OFF” information is output from the AND gate 11G. Input to the gate 12A. Similarly, when the grid connection line breaker “OFF” information and the grid connection line breaker “selection” information are input to the logical product gate 11H, the grid connection line breaker “OFF” information is obtained from the logical product gate. 11H and input to the OR gate 12A. Next, the output of the AND gate 11B is input to the AND gate 11E via the inverter 16 and also to the AND gate 11F. On the other hand, transmission line relay (Ry) operation information is input to the AND gate 11E, input to the AND gate 11F, and the output of the OR gate 12A is output to the AND gate 11F. Next, the outputs of the logical product gate 11E and the logical product gate 11F are input to the logical sum gate 12B. Accordingly, the OR gate 12B outputs from the circuit breaker control means 1 an “off” command for interrupting the accident power transmission line circuit breaker. As a result, the accident power line breaker automatically shuts off.

  According to the method of reducing the short-circuit current by the short-circuit current reduction system 10 of the transmission / distribution system according to the present embodiment as described above, the circuit breaker control means 1 and the closest three-phase short-circuit accident detection means 2 are provided in the transmission / distribution system. And the bus connection circuit breaker 4 and the grid connection circuit breaker 3 were detected, and the condition that the short-circuit current exceeded the rated breaking current of the load line breaker was detected by the near-end three-phase short-circuit accident detection means 2 Thereafter, the circuit breaker control means 1 performs control so as to cut off at least one of the bus bar breaker 4 and the grid connection line breaker 3 to reduce the short-circuit current. Therefore, even when the short-circuit current exceeds the rated breaking current of the load line breaker, the system reliability of the transmission / distribution system can be improved and the breaker replacement cost can be reduced.

  Although the embodiment of the present invention has been described above, the specific configuration is not limited to the present embodiment, and design changes and the like within the scope not departing from the gist of the present invention are included in the present invention. It is. For example, in the power transmission / distribution system, a short circuit accident occurred in a specific area of the grid connection line drawn from the bus. However, the short circuit accident may occur in either the transmission line or the distribution line. Because there is, the place can be applied to the whole transmission and distribution system. In general, when a short-circuit accident occurs, a short-circuit current increases in a power transmission / distribution system in which many generators are installed. Therefore, by applying the present invention to such a power transmission / distribution system, a great effect can be obtained. be able to.

The schematic block diagram which shows the short circuit current reduction system of the power transmission and distribution system which concerns on embodiment of this invention. The connection diagram which shows the structural example of the power transmission / distribution system to which the short circuit current reduction system of the power transmission / distribution system which concerns on embodiment of this invention was applied. The block diagram which shows the protection relay system of the general power transmission / distribution system applied to the short circuit current reduction system of the power transmission / distribution system which concerns on embodiment of this invention. The schematic sequence shown about the interruption | blocking operation | movement at the time of the near-end three-phase short circuit accident occurrence in the short circuit current reduction system of the power transmission and distribution system which concerns on embodiment of this invention. The block diagram which shows the load line circuit breaker trip circuit example in the short circuit current reduction system of the power transmission and distribution system which concerns on embodiment of this invention. The block diagram which shows the example of a bus | bath connection circuit breaker trip circuit in the short circuit current reduction system of the power transmission and distribution system which concerns on embodiment of this invention. The connection diagram which shows the structural example of the conventional power transmission / distribution system.

Explanation of symbols

1 Circuit breaker control means 2 Near-end three-phase short-circuit detection means 3 Grid connection circuit breaker 4 Bus connection breaker 5A Protection relay pallet 5B Breaker pallet 6 Bus 6A A bus 6B Oto bus 7 Transmission line (system) Interconnection line / load line)
DESCRIPTION OF SYMBOLS 8 Load line circuit breaker 9 Protection relay 10 Short circuit current reduction system of transmission / distribution system 11A-11H AND gate 12A, 12B OR gate 13A-13O Switch 14A-14O Switch 15A-15O Breaker 16 Inverter

Claims (7)

When power is supplied to the power transmission / distribution system from the power substation via the bus, short-circuit current that exceeds the rated breaking current of the load circuit breaker provided in the power transmission / distribution system is short-circuited. A short-circuit current reduction system for a power transmission and distribution system that reduces current,
Circuit breaker control means for controlling the load line circuit breaker provided in the power transmission and distribution system;
The circuit breaker is connected to the control unit, short-circuit when the power transmission and distribution two conditions occurs when the three-phase short-circuit fault of the three-phase short-circuit fault occurs at close end of the load line breaker of the system are established at the same time Near-end three-phase short-circuit accident detection means for detecting that the current is a three-phase short-circuit accident exceeding the rated breaking current of the load line breaker ;
A grid interconnection breaker controlled by the breaker control means;
A bus bar breaker controlled by the breaker control means;
With
When the three-phase short-circuit accident in which the short-circuit current exceeds the rated breaking current of the load line breaker is detected by the near-end three-phase short-circuit accident detection means, A short-circuit current reduction system for a power transmission / distribution system, wherein control is performed to cut off at least one of the system interconnection line breakers. The bus comprises a double bus configuration;
The short circuit current reduction system of the power transmission and distribution system according to claim 1. The system interconnection line provided with the system interconnection line breaker consists of a plurality of lines,
The short-circuit current reduction system for a power transmission / distribution system according to claim 1 or 2. When power is supplied to the power transmission / distribution system from the power substation via the bus, short-circuit current that exceeds the rated breaking current of the load circuit breaker provided in the power transmission / distribution system is short-circuited. A method for reducing a short circuit current in a power transmission / distribution system that reduces current,
It said transmission and distribution line, said a circuit breaker control means for controlling a load line circuit breaker is connected to the circuit breaker control means, the three-phase short circuit and said load line the three-phase short circuit fault accident of the power transmission and distribution system Proximity end three-phase short-circuit detecting that the short-circuit current is a three-phase short-circuit accident that exceeds the rated breaking current of the load line circuit breaker when the two conditions that occurred at the closest end of the circuit breaker are satisfied simultaneously An accident detection means, a grid interconnection breaker controlled by the breaker control means, and a bus line breaker controlled by the breaker control means are provided, and the breaker control means includes the proximal end When the three-phase short-circuit accident in which the short-circuit current exceeds the rated breaking current of the load line breaker is detected by the three-phase short-circuit accident detection means, at least one of the bus connection breaker and the grid interconnection breaker is cut off Control Short-circuit current method of reducing transmission and distribution system, characterized in.   When the bus is composed of a single bus and the grid connection line is composed of a plurality of lines, when the nearest-end three-phase short-circuit accident detecting means detects the three-phase short-circuit accident, the circuit breaker control means 5. The method for reducing a short-circuit current in a power transmission and distribution system according to claim 4, wherein control is performed so that the system interconnection breaker is shut off.   In the case where the bus has a double bus configuration and the grid connection line is composed of a plurality of lines, the circuit breaker control means when the nearest-end three-phase short-circuit fault detecting means detects the three-phase short-circuit fault. 5. The method for reducing a short circuit current in a power transmission / distribution system according to claim 4, wherein the control is basically performed so as to cut off the bus bar breaker. When the near-end three-phase short-circuit accident detecting means detects the three-phase short-circuit accident, the circuit breaker control means can be controlled to shut off the grid interconnection line breaker. The short circuit current reduction method of the power transmission and distribution system according to claim 6.

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