JPH0591670A - Operating system for transformer - Google Patents

Abstract

PURPOSE:To provide an operating system for transformer in which a plurality of transformers can be operated in parallel and only a failed distribution line can be isolated positively during parallel operation. CONSTITUTION:Buses 2, 2 for a plurality of transformers 1 are interlinked through a semiconductor device 3. Each distribution line 4 is provided with a fault current detecting section 6 and when the fault current exceeds a predetermined level with the semiconductor device 3 being turned ON, the semiconductor device 3 is turned OFF by a supervisory control section 7 before the circuit breaker 5 for each distribution line 4 is turned OFF.

Description

Detailed Description of the Invention

The present invention relates to a transformer operating system in a distribution substation having a plurality of transformers.

[0002]

2. Description of the Related Art As shown in FIG. 6, in a distribution substation having two or more transformers 20, each transformer 20 has a plurality of distribution lines 21.
In the normal operation state, the secondary side busbars 22, 22 of each transformer 20 are interconnected by the busbar breaker 23 in the off state. However, when the power demand increases in the summer, for example, the load sharing among the transformers 20 becomes unbalanced, and the utilization factor of the transformers may decrease. Therefore, in such a case, in order to improve the supply reliability and equalize the load sharing, it is conceivable that the busbar breaker 23 is turned on and a plurality of transformers 20 are operated in parallel.

However, in such a distribution system that performs parallel operation of transformers, when a short-circuit accident occurs in the distribution line 21, a fault current that is much larger than a case in which a plurality of transformers 20 are used alone is present. Will flow toward the accident point, which may exceed the breaking ability of the distribution line breaker 24 installed in each distribution line 21, and the distribution line breaker 24 operated in this state. In case of distribution line breaker 24
May be damaged. Therefore, if the fault current exceeds a predetermined value, a method of not operating the distribution line circuit breaker 24 may be considered, but in that case, the circuit breaker 25 on the primary side of the transformer is used.
Had to be operated to suppress the accident current, and there was a problem that the supply of electric power to a large number of distribution lines 21 was stopped and the power outage area was wide.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and improves the reliability of supply and smoothes the load sharing among transformers by using a plurality of transformers in parallel. It is an object of the present invention to provide a transformer operation system that can be performed and can reliably operate only the distribution line breaker of any distribution line when an accident occurs.

[0005]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, has a structure in which the secondary side busbars of a plurality of transformers are interconnected via a semiconductor device and distributed to each distribution line. A detection unit is provided for detecting a failure of the electric wire, and the semiconductor device described above is provided on the distribution line when the fault current detected by the detection unit exceeds a predetermined value when the semiconductor device is on. It is characterized in that a monitoring control unit for turning off the semiconductor device is provided before the electric wire breaker is turned off.

[0006]

According to the present invention, by turning on the semiconductor device provided between the secondary side busbars of a plurality of transformers, the load sharing between the transformers can be balanced. Even if one transformer stops due to an accident, the remaining transformers can continue power distribution. Also, when the semiconductor device is turned on and parallel operation occurs, an accident occurs in any distribution line, and when it is determined that the fault current detected by the detection unit exceeds the breaking capability of the distribution line breaker, the monitoring control unit Turns off the semiconductor device before the breaker for the distribution line. Therefore, the fault current that flows toward the fault point is only the current that flows from one transformer, and then the circuit breaker for the distribution line can be used for interruption. Immediately after the breaker for the distribution line is turned off, the semiconductor device may be turned back on and the parallel operation may be started.

[0007]

The present invention will be described below in more detail with reference to the embodiments shown in the drawings. In FIG. 1, 1 and 1 are two transformers,
Reference numerals 2 and 2 denote busbars of the transformers 1 and 1, and these busbars 2 and 2 are interconnected via a semiconductor device 3 capable of high-speed disconnection instead of the conventional busbar circuit breaker. A plurality of distribution lines 4 are connected to each of the buses 2 and 2, and each distribution line 4 is provided with a distribution line breaker 5 and a detection unit 6 located on the load side thereof. 7 is the detection unit 6
The monitor control unit 8 receives a signal from the semiconductor control unit 8 and the semiconductor control unit 8 is connected to the monitor control unit 7.

The semiconductor device 3 used in the present invention is one in which semiconductor elements 9 such as thyristors are connected in antiparallel as shown in FIG. 2, and by connecting some of them in series and in parallel, the breakdown voltage is increased. It is possible to increase the capacity, reduce the load on the semiconductor element 9, and improve the reliability of the device.

The above-mentioned detection unit 6 has the function shown in the block diagram of FIG. 3, and outputs a signal from the output circuit to the monitoring control unit 7 when the fault current flowing through the distribution line 4 exceeds a predetermined value. .. Here, the level of the predetermined value is set to be equal to or lower than the rated breaking current of the circuit breaker 5 for the distribution line. A conventional current transformer and relay may be used for the detection unit 6.

Next, the operation of the system of the present invention will be described.
First, the semiconductor device 3 is turned off during normal operation,
As mentioned above, it is turned on when the power demand increases,
A plurality of transformers 1, 1 are operated in parallel. Now, in this state, when an accident occurs in any one of the distribution lines 4, the accident current is detected by the detection unit 6, and the monitoring control unit 7 judges the level of the accident as shown in the flow sheet of FIG.

If the semiconductor device 3 is on and the fault current detected by the detector 6 exceeds a predetermined value, the distribution line breaker 5 provided on the distribution line 4 is turned off. First, the monitoring controller 7 turns off the semiconductor device 3. As a result, each of the transformers 1 and 1 shifts to the independent operation, so that the current only flows from the transformer 1 on one side to the fault point, and the fault current decreases. In this state, the distribution line breaker 5 provided on the distribution line 4 in which the accident has occurred is turned off to interrupt the accident current. If the fault current does not exceed the predetermined value, the monitoring controller 7 does not turn off the semiconductor device 3 but turns off only the circuit breaker 5 for the distribution line to shut off the fault current. After the circuit breaker 5 for the distribution line is turned off and the fault current is cut off in this manner, the monitoring controller 7 immediately turns on the semiconductor device 3 and restarts the parallel operation.

As described above, the level of the predetermined value of the fault current at which the monitoring controller 7 turns off the semiconductor device 3 is set to be equal to or lower than the rated breaking current of the distribution line breaker 5. Assuming that this level is 12.5kA, which is the short-circuit current value of general distribution lines.
Then, the distance from the substation outlet and the short-circuit current value at that point are calculated and graphed in FIG. According to this figure, the short-circuit current (fault current) flowing through the distribution line 4 is 1 when an accident occurs within 0.3 km from the substation.
It will exceed 2.5 kA, and in the case of an accident farther than that, the value will be 12.5 kA or less due to the impedance of the distribution line. Therefore, in most accidents, it is understood that the distribution line breaker 5 can separate the distribution line in which the accident has occurred without operating the semiconductor device 3.

[0013]

As described above, according to the transformer operation system of the present invention, since a plurality of transformers can be operated in parallel, the facility utilization rate can be improved, and one transformer can be used. Even if the power plant stops due to a failure, etc., it is possible to continue the power distribution without interruption by the remaining transformer. Further, according to the present invention, even when an accident occurs in a distribution line during the parallel operation of a plurality of transformers, only the distribution line can be separated and the power failure range can be minimized. Further, according to the present invention, since the semiconductor device is turned off only when the fault current exceeds a predetermined value, unnecessary operation can be eliminated. Furthermore, the operation system of the transformer of the present invention can make the most of the conventional equipment and reduce the equipment cost.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a semiconductor device.

FIG. 3 is a block diagram showing a function of a detection unit.

FIG. 4 is a flow sheet showing the operation of the system of the present invention.

FIG. 5 is a graph showing the relationship between the distance from the substation to the accident occurrence point and the magnitude of the accident current.

FIG. 6 is a circuit diagram showing a conventional power distribution system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transformer 2 Bus 3 Semiconductor device 4 Distribution line 5 Distribution line breaker 6 Detecting unit 7 Monitoring control unit 8 Semiconductor control unit

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[Procedure amendment]

[Submission date] October 13, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (2)

[Claims] 1. The secondary side busbars of a plurality of transformers are interconnected via a semiconductor device, and each distribution line is provided with a detection section for detecting a failure of the distribution line. Monitoring that turns off the semiconductor device before the breaker for distribution line provided on the distribution line turns off when the fault current detected by the detection unit exceeds a predetermined value while the semiconductor device is on A transformer operation system characterized by having a control unit. 2. The operating system for a transformer according to claim 1, wherein the monitoring controller turns on the semiconductor device after the breaker for the distribution line is turned off.