JP3017551B2 - Distribution line protection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for protecting a distribution line for preventing a distribution line from being disconnected by a fault current when a short-circuit fault current due to a lightning strike or a ground fault short-circuit fault current flows in the distribution line. It is.

[0002]

2. Description of the Related Art A circuit breaker and an OCR (overcurrent relay) of a circuit breaker have been conventionally provided in a distribution substation in order to protect a system in the event of a short circuit accident or a ground short circuit accident in a distribution line. is set up. However, since the OCR of this circuit breaker has a slow operation characteristic so that it operates after the OCR of the customer circuit breaker operates,
During the operation of the circuit breaker, the distribution line is disconnected due to the arc of the accident current, resulting in a problem that a long-time power failure occurs.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and, when a fault occurs in a distribution line or a ground fault short-circuit, the fault current is cut off at a high speed, and disconnection due to the fault current arc is prevented. It is an object of the present invention to provide a method for protecting distribution lines that can be prevented.

[0004]

Means for Solving the Problems To solve the above problems,
The distribution line protection method of the present invention,
The fault current exceeds the specified value in the distribution line on the secondary side of the ACB
Occasionally, ignoring the OCR operating characteristics of customer circuit breakers,
Thyristor type opening
The thyristor-type opener is installed in parallel with the distribution line.
Always shut off the circuit breaker and wait for a lightning strike
It is characterized by the following.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the illustrated embodiments. In FIG. 1, reference numeral 1 denotes a distribution substation, 2 denotes a circuit breaker provided in the distribution substation 1, 3 denotes a distribution line on the secondary side of the circuit breaker 2, and 4 denotes a customer interruption provided in a customer premises. It is a vessel. In the present invention, the distribution line 3 on the secondary side of the circuit breaker 2
A thyristor-type switch 5 for forcibly short-circuiting is provided in parallel with the distribution line 3. The thyristor-type switch 5 is normally off, but is turned on at a high speed when an accident current is detected to forcibly short-circuit the accident current to protect the system.

FIG. 2 is a graph showing the operating characteristics of the thyristor switch 5 in the form of a graph in which the vertical axis represents time and the horizontal axis represents current. As can be seen from this graph, although the circuit breaker 2 and customer breaker 4 of the distribution substation 1 are taking timed coordination made to have a delay in the operation time according to the magnitude of the current, the thyristor type Example The switch 5 has a vertical operating characteristic so that it operates immediately when the fault current exceeds a predetermined value (here, 500 A). For this reason, when the fault current exceeds a predetermined value, the operating characteristics of the OCR of the customer circuit breaker 4 are ignored, that is, the thyristors are ignored ignoring time coordination.
The switchgear 5 is turned on.

[0007] In general, this type of protection device is usually operated at all times so that it can be operated at any time.
The protection device used in the present invention is always stopped,
It is operated only during a lightning strike and is in a standby state . This point also has a great feature of the present invention.

[0008]

Next, the operation of the protection device will be described with reference to FIG. The protection device used in the present invention is always stopped, but at the time of a lightning strike, the protection device is operated and enters a standby state. In this state, if an accident due to lightning strike occurs on the premises of the customer or on the distribution line 3 connecting the customer and the substation as shown in FIG. 1, a CT (not shown) attached to the distribution line 3
Detects the current value, and the current value is a predetermined value (here, 500 A)
If it exceeds, it is judged as an accident.

As a result, the thyristor switch 5 of the protection device is immediately turned on ignoring the operation characteristics of the OCR of the customer circuit breaker 4, and the turned-on state is maintained within a predetermined time, for example, about 100 msec. This allows the thyristor type opening of the fault current.
It is cut off by the switch 5 and protects the distribution line 3 from fusing by the arc at the fault point. And then thyristor opening and closing
The container 5 is opened. In this state, if the arc is not extinguished and an accident current still flows through the distribution line 3, the protection device cannot operate because the protection device cannot cope with it, and the operation of the protection substation 1 is stopped as before. The circuit breaker 2 is turned off to start a timed accident point search.

On the other hand, the arc at the accident point is eliminated by the high-speed operation of the thyristor switchgear 5, and the thyristor switchgear is again activated.
When the fault current is no longer detected in the distribution line 3 also opens the vessel 5, becomes a successful disconnection prevented by the protective device, thereafter it becomes possible to start the fault point probe while continuing normal power transmission.

As described above, according to the present invention, when it is detected that an accident current has flown in the distribution line 3 when the protection device is in a standby state , the customer circuit breaker 4 The thyristor-type switch 5 operates immediately, ignoring the operating characteristics of the OCR. For this reason, power transmission to customers other than the customer in which the accident occurred is also stopped, and a power outage occurs. However, this power outage time is instantaneous for about several cycles, and since the protection device of the present invention is operated only at the time of a lightning strike, the substantial effect of this can be greatly reduced.

The protection device used in the present invention simplifies the operation characteristics of the thyristor switch 5 ignoring time-coordination as described above, so that the protection device can be constructed economically. Furthermore, since this protection device is operated only during a lightning strike, damage to the protection device is small, and the number of maintenance operations can be greatly reduced.

[0013]

As described above, according to the present invention, when a short-circuit accident due to a lightning strike or a ground-fault short-circuit accident occurs in a distribution line, the fault current can be cut off at a high speed to protect the system. It has advantages such as the simplification of the equipment and the reduction of the cost and the number of maintenance work.Therefore, as a protection device for distribution lines that has solved the conventional problems, it greatly contributes to the development of industry. is there.

[Brief description of the drawings]

FIG. 1 is a system diagram illustrating a protection device used in the present invention.

FIG. 2 is a graph showing operating characteristics of a thyristor switch according to the embodiment of the present invention.

FIG. 3 is a block diagram showing the operation of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distribution substation 2 Breaker 3 Distribution line 4 Customer breaker

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02H 3/08-3/52 H02H ⁷ /22-7/30

Claims (1)

(57) [Claims] To 1. A secondary side of the circuit breaker of the substation distribution line, things
When the current exceeds a predetermined value, the OCR
Ignoring the operating characteristics of
Install a short-circuit thyristor switch in parallel with the distribution line.
The thyristor switch is always stopped,
Maintaining distribution lines characterized by being in a standby state during a lightning strike
Protection method.