JPS60174011A - Reclosing system - 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] [Field of Application of the Invention] The present invention relates to a grounding method for promptly re-closing a circuit after removing a fault in a power transmission line, and particularly relates to a method for reducing the current capacity of a grounding switch. Regarding.

[Background of the Invention] - Conventional earthing switches have been used primarily to reduce the voltage induced from operating lines into idle lines, and to protect people during maintenance of idle lines. For this reason, high speed, current capacity, etc. were not particularly an issue, and only reliability was required.

On the other hand, in ultra-high voltage systems, the re-closing time after an accident is removed is as long as 6 seconds, and in consideration of system stability and time coordination with back-up protection relays, a grounding system using a grounding switch is adopted. It is necessary to make the re-closing time within 2 seconds.

In this grounding method, the faulty phase is immediately grounded after disconnecting from the power supply, and the grounding current is calculated assuming the power transmission line distance is 250km and the power transmission power is 189W.
- In the example, b-phase 111! In a ground fault, it is approximately 60 OA, and in a 3-wire ground fault that connects two circuits, it is 20 OA in the phase with the minimum current and 200 OA in the phase with the maximum current. In this way, especially in the case of multiple faults, there will be a large difference in the grounding current of each phase. or,
There is a large difference in current between the earthing switches at the sending end and the receiving end. There are also large differences in the types of accidents. Therefore, when determining the current capacity of the earthing switch, -C is:
It was necessary to cover all of these cases and safely operate the earthing switch at the maximum imaginable current, and it was necessary to provide a large-capacity device.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a re-closing system which compensates for the above-mentioned drawbacks and which enables a grounding switch with a small current capacity necessary for high-speed re-closing.

[Summary of the invention]

Regardless of the type of accident, the earthing switches at both ends of the transmission line should be closed for each phase, then opened after a certain period of time, and then reclosed. By repeating this for each phase, the large current that would flow through the earthing switch in the conventional method when the fault spans two or more phases can be suppressed to the earthing switch current equivalent to a single-wire earthing fault. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. Electrical stations GI and G- exchange power through their respective buses B+ and Bt, and through power transmission lines LI and L*. Transmission line Lr, point p of L , , 1.1! If an accident occurs on transmission line L1. Breaker CB+ at both ends of L snow
-CB- is opened, and then the earthing switch SW+~S
After closing Wa, reducing the recovery voltage, and reducing the secondary arc current, open the earthing switch 8% to 8W,
Close circuit breaker CB+-eBa. If this flow n is expressed as a phase-to-ground fault in line 1 and line 2, bb'2-line ground fault, and a total ground fault, it will appear as shown in Fig. 2. Here, the subscript indicates the phase, that is, conventionally, the accident was simultaneous with the accident, that is,
The earthing switch was opening and closing and the circuit breaker was closing at the same time. For this reason, UHV 250km, 2 lines.

Considering the time of 18GW power transmission, the current passing through the earthing switch reaches as much as 1700A. On the other hand, if the earthing switch is closed, opened, and reclosed for each phase as shown in FIG. 3, the current will be about 700A. In this way, by processing each phase, the capacity of the earthing switch can be reduced to 215.

The current flowing in the ground phase is determined by electrostatic induction and electromagnetic induction, but generally the electromagnetic induction component is large, so we focus only on this fraction. When the 1st line phase and the 2nd line b' phase are grounded at the same time, the circuit can be treated in the same way as the 1st phase grounding during 1 line power transmission.
Shown as shown.

In other words, the current I that peaks at the voltages Vo and Vs at both ends of the transmission line
The voltage Vr determined by the mutual induction M correlated with L is passed along one line,
Inductance L with earth as the return path.

The current It divided by Flows into the earthing switch. In contrast,
When only one phase of one line is grounded, the voltage VF determined from the voltages Vo and Vs at both ends of the transmission line and the mutual induction of the current IL%, as shown in Fig. 5, is the same as above, but the b phase In the case where only the ground phase is grounded, the inductance related to the ground phase increases to L,' due to the influence of the line on the b' phase side.

Therefore, the current IP' flowing through the earthing switch decreases.

〔Effect of the invention〕

According to the present invention, the current capacity of the earthing switch can be reduced to f: 215 simply by changing the operation sequence of the earthing switch, so the economic effect is extremely large.

In addition, by adopting this method, one fault phase is grounded using one earthing switch, and then the circuit is opened.
The earthing switch can be used to earth and open the other phases. In this way, since one grounding switch can be used for multiple phases, the number of installed grounding switches can be reduced, and the economic effect is extremely large.

[Brief Description of the Drawings] Figure 1 is a system diagram showing the features of the present application, and Figure 2 is a system diagram showing the features of the present application.
Figure 3 is a sequence diagram showing the opening/closing and reclosing status of a conventional earthing switch. Figure 4 is a sequence diagram showing the opening/closing and reclosing status of the earthing switch of the present application. Figure 4 is a sequence diagram showing the opening/closing and reclosing status of a conventional earthing switch. Figure 5 shows the circuit when only one phase is grounded. Mountain, G3... Electrical station, B+, Bs... Bus bar, L+
, Lx...Air voltage, M...Mutual induction, IL...
-Current, Vr...ground phase voltage, IF, IF'...ground switch current, L*+L*'...indicates interftance. Agent Patent Attorney Akio Takahashi □#1

Claims (1)

[Claims] 1. In a system equipped with a circuit breaker and a grounding switch at both ends of the transmission line, the fault phase of the transmission line is disconnected from the power supply, and then the transmission line is grounded, and after a certain period of time has elapsed. A re-closing method that is characterized by providing a time difference in the operation of the earthing switch in the method of opening and re-closing the ground. 2. In the first claim, regardless of the type of accident,
For each phase of the accident, the earthing switch is closed, the earthing switch is opened,
A reclosing method characterized by reclosing the circuit. 3. In the first claim, regardless of the type of accident,
A re-closing method characterized by closing the grounding switch for all fault phases, and sequentially opening and re-closing the ground switch for each fault phase.