JPS59188326A - Transmission line protecting relaying unit - 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] The present invention relates to a power transmission line protection relay device for a power system.

Conventionally, failure detection relays used in this type of protection device include undervoltage relays and overcurrent relays for each phase for short circuit failures, and zero-phase overcurrent relays for ground fault failures. In the power system diagram of FIG. 1, 1 is an undervoltage relay, 2 is an overcurrent relay for each phase, 6 is a zero-phase overcurrent relay, and 4 is a breaker that must be disconnected in the event of a failure.

Next, the operation of the conventional failure detection relay device shown in FIG. 1 will be explained. When a system failure occurs in a power transmission line, taking a single-phase system as shown in FIG. 2(a) as an example, the current I of the failed phase increases and the bus voltage V decreases.

FIG. 2(b) shows how the line voltage changes.

This current ■ is detected by the current transformer CT, and the overcurrent relay 2
In addition, the undervoltage relay 1 is activated due to a drop in the line voltage V, whereby a system failure can be detected and the circuit breaker 4 is disconnected.

However, due to the increase in the short-circuit capacity of the system, if a fault current that exceeds the breaking current of the circuit breaker occurs, the fault cannot be removed even if four circuit breakers are removed.

Therefore, a current limiting device (hereinafter referred to as CL) is installed on the transmission line side of the breaker.
(abbreviated as D) may be installed.

CLD has capacitor 5, reactor 6,
When the passing current is small, the capacitor 5 and the reactor 6 perform LC series resonance, and the impedance is almost zero. However, when the passing current becomes large and the voltage across the capacitor 5 becomes large, the nonlinear element 7 This allows the current to be bypassed and an impedance for the reactor to be inserted, making it possible to limit the current.

If such a CLD is installed on a power transmission line, the current will not increase much even in the event of a system failure. For this reason, the conventional overcurrent relay 2 may not be able to detect a failure, and the undervoltage relay 1 may also be unable to operate because the drop in bus voltage V is small, as shown in FIG.

An object of the present invention is to provide a power transmission line protection relay device that protects power transmission lines by applying a voltage balance relay as a failure detection relay for a CLD installation system as described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power transmission line protection relay device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 5, reference numeral 9 is a voltage balancing relay which operates only when the voltage Z at both ends (~ and (B)) of the CLD 8 is compared and the voltage at the line side end (B) drops.

The configuration of the voltage balancing relay 9 is well known and will therefore be omitted.

Next, the operation Z of the embodiment having such a configuration will be described.

The line voltage distribution at the time of a system fault at line F point is as shown in Figure 4, and since the impedances at both ends (N and (B) of the CLD 8 are greatly different), the fault can be detected reliably by the voltage balancing relay 9. It is possible to issue a command to trip the breaker 4.

In addition, in the case of a failure at the bus bar side end (N), the voltage across the CLD130 (
There is no difference in A) and (BJ), and the voltage balancing relay 9 does not operate unnecessarily, making it ideal for protecting power transmission lines.

It is clear that a distance relay, a phase comparison relay, a current differential relay, etc. can be considered as the main relay to be combined with this voltage balance relay for failure detection.

As described above, according to the power transmission line protection relay device of the present invention, CL
Even if D is installed on a power transmission line, we use a voltage balancing relay that operates by comparing the voltage between both terminals of the CLD, so we can reliably detect line faults and prevent faults on the bus side. It also has the advantage of not causing unnecessary malfunctions.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional failure detection relay;
Figures (a) and (b) are explanatory diagrams showing power transmission line failure and voltage distribution at the time of failure, respectively, Figure 3 is a CLD circuit configuration diagram, and Figure 4 is the voltage at the time of transmission line failure when CLD is installed. An explanatory diagram showing the distribution, and FIG. 5 is a circuit diagram of a failure detection relay according to an embodiment of the present invention. 1...Undervoltage relay, 2...Each phase current relay,
6... Zero-phase overcurrent relay, 4... Breaker, 5...
・Capacitor, 6...Reactor, 7...Nonlinear element, 8...-CLD, 9...Voltage balance relay. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 (a)

Claims (1)

[Claims] A transmission line protection relay device that installs a line sum current limiting device, detects a line failure, and energizes a breaker, comprising a voltage balancing relay that detects a voltage difference between both ends of the current limiting device, the voltage balancing relay A power transmission line protection relay device characterized in that a failure on the line side is determined based on an output signal of.