JP2642349B2 - Transmission line protection relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transmission line protection relay device for protecting a transmission line of a power system from a near-point three-phase ground fault or the like.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional transmission line protection relay device described in, for example, Denki Shoin, “Protection Relay System” pages 64-68 issued on February 25, 1974. PS is the power supply of the power system, L is the protected transmission line, F is the near-point three-phase ground fault, CT is the current transformer, PT is the voltage transformer of the protected transmission line L, _If is the fault current, E is The secondary voltage of the voltage transformer PT, 52 is a circuit breaker. Further, reference numeral 1 denotes a distance relay (hereinafter, simply referred to as a distance relay) having a phase characteristic of a moe characteristic as shown in FIG. The mo-characteristic distance relay is a kind of directional relay with voltage suppression, and has a characteristic that it has inherent directionality and requires less unnecessary operation.

FIG. 7 is a time chart for explaining the operation of the transmission line protection relay device of FIG.

In the time chart of FIG. 7, representative values are used for the operation time and the return time of the distance relay 1 and the circuit breaker 52.

 Next, the operation will be described.

(B) if near point 3-phase ground fault F during operation of the protected transmission line L occurs, first, an input failure voltage of the distance relay 1, the distance relay 1 as shown in E _f in FIG. 6 It is set to a value smaller than the static operation limit voltage, for example, about 0.1V.

Since the distance relay 1 has a memory function of storing a sound voltage before the occurrence of a failure, when a three-phase ground fault F occurs, a voltage change due to the failure is detected by the secondary voltage E of the voltage transformer PT. Work.

The distance relay 1 that has detected the three-phase ground fault F is, for example, 40
Although it operates in ms, it simultaneously outputs a trip command to the circuit breaker 52 and opens the circuit breaker 52 to remove the fault F.
FIG. 7 (a) shows how the characteristics of each part change.

(B) When the protected transmission line L in which the near-point three-phase ground fault F has occurred is turned on by the circuit breaker 52, the grounding breaker of the protected transmission line L is closed, that is, the closest point 3 FIG. 7 (b) shows how the input fault voltage _Ef and the fault current _If change when the circuit breaker 52 is turned on while the phase-to-ground fault F is occurring. Input fault voltage E _f of distance relay 1
Is about 0.1 V as in the case of FIG. 7A.

However, in this case, since the memory function of the distance relay 1 does not operate, the distance relay 1 cannot operate,
Therefore, the near point three-phase ground fault F cannot be removed.

[Problems to be solved by the invention]

Since the conventional transmission line protection relay is configured as described above, the near-point three-phase ground fault during operation can be detected and removed, but the near-point three-phase ground due to forgetting to operate the grounding disconnector, etc. When a power transmission line in which a fault has occurred is turned on, the fault cannot be detected and cannot be removed, and the time-limited trip is rescued by another protection relay (not shown). Not only is it significantly increased, but also it is not possible to ensure the stability of the system.

The present invention has been made in order to solve the above-described problems. Even when a breaker of a protected transmission line is turned on in a state in which a near-point three-phase ground fault has occurred, the present invention can be performed at a high speed. It is an object of the present invention to obtain a highly reliable transmission line protection relay capable of eliminating a device trip and failure.

[Means for Solving the Problems] The transmission line protection relay device according to the present invention introduces the three-phase voltage from the transmission line voltage transformer and the output voltage of at least one phase of the bus voltage transformer as inputs to the distance relay. In addition, a distance relay having a maximum value voltage of both of them as a distance measurement voltage and an output of a current transformer of the protected transmission line as a distance measurement current is provided to operate the circuit breaker.

(Operation)

In the distance relay of the transmission line protection relay according to the present invention, even when the circuit breaker of the transmission line is open, at least one phase output voltage of the bus voltage transformer is introduced, so that the near-point three-phase ground fault is provided. Even if the circuit breaker of the transmission line is turned on while a failure has occurred, the one-phase memory circuit of the distance relay functions, and the distance relay operates to remove the failure.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 5, the same parts as those in FIG. 5 are denoted by the same reference numerals. In FIG. 1, BUS is a bus of the system from which the protected transmission line L is drawn out, and PT _B is at least a bus connected to the bus BUS. The bus voltage transformer for one phase, 2 uses the input of the current transformer CT as the distance measuring current, and outputs the voltage from the voltage transformer PT of the protected transmission line L
At least one phase of the phase voltage and the bus voltage transformer PT _B, for example, by introducing the output voltage of the A-phase, the maximum value voltage of both the distance relay to the distance measuring voltage.

Next, the operation of the present invention will be described below with reference to the time chart of FIG.

(B) Near-point three-phase ground fault F during operation of protected transmission line L
When this occurs, the operation in this case is the same as that of the conventional distance relay device.
That is, the three-phase output voltages E _A , E _B , E _C of the voltage transformer PT of the protected transmission line L are introduced into the distance relay 2 together with the output voltage E _{A (BUS)} of the bus voltage transformer PT _B , the a-phase voltage transformer PT _B maximum value is ranging voltage E _a and E _{a (BUS).} However, since E _A = E _{A (BUS)} before and during the failure, the input of the distance relay 2 is the same as that of the conventional device, and the distance relay 2 operates at a high speed similarly to the conventional device due to the memory function. Then, a trip command is issued to the circuit breaker 52. Accordingly, the circuit breaker 52 is opened, and the near point three-phase ground fault F is removed.

 The operation in this case is shown in FIG.

(B) When the circuit breaker 52 of the protected transmission line L in which the near point three-phase ground fault F has occurred is turned on, according to the present invention, while the circuit breaker 52 is open, the protected transmission line L Even if the voltage E _A from the voltage transformer PT is zero,
Bus voltage transformer PT healthy voltage from _B to phase A (E _{A (BUS))} because is input into the distance relay 2, wherein E _A and E _{A (BUS)}
Even if the breaker 52 of the protected transmission line L in which the near-point three-phase ground fault F has occurred is turned on, the maximum value of the ranging voltage becomes EA _(BUS) , as in the case of the fault during operation. , Distance relay 2
Operates at high speed by the function of memory function
The phase-to-ground fault F is removed.

Also, again, the distance measuring voltage of the A-phase distance relay 2 is the output E _A of the bus voltage transformer PT _{B (BUS)} after removal.

In the above embodiment has been described applied to keep the circuit constituting the output E _{A (BUS)} constantly distance relay 2 of bus voltage transformer PT _B of A-phase, as is apparent from the above description, The reason that the output E _{A (BUS) of the} A-phase bus voltage transformer PT _B is required is only the time from when the distance relay 2 operates until the circuit breaker 52 is opened immediately before the circuit breaker 52 is turned on. Therefore, for example, even if the circuit configuration is as shown in FIG. 3 and the circuit is operated according to the time chart shown in FIG.

In FIG. 3, reference numeral 52A denotes an auxiliary contact of the circuit breaker configured to be closed prior to the main contact of the circuit breaker 52, and 3 denotes a one-shot for generating a pulse output of a fixed time width, for example, 150 ms. Multi-circuit (gate means),
Gate circuit (gate _means), E _{A (G)} is the output of the bus voltage transformer PT _B controlled by a gate circuit 4.

In the time chart of FIG. 4, the auxiliary contact 52A of the circuit breaker 52 closes, for example, 40 ms before the main contact, and energizes the one-shot multi-circuit 3.

One-shot multivibrator circuit 3 outputs a pulse of, for example 150 ms, the pulse output period only the gate circuit 4 is generated, thereby the bus output E _{A (BUS)} of bus voltage transformer PT _B.

Therefore, even in the case of this embodiment, even when the circuit breaker 52 is turned on in the state where the near-point three-phase ground fault F has occurred in the protected transmission line L, the distance relay 2 remains high due to its memory function. Speed operation.

[Effects of the Invention] As described above, according to the present invention, the bus voltage detected by the bus voltage transformer is input, and only when the auxiliary contact is closed, the voltage is constant after the auxiliary contact is closed. Time and gate means for outputting the input bus voltage are provided, and the distance relay compares the output of the gate means with the output of the transmission line voltage transformer, and the larger output is used as the ranging voltage. Is configured to detect the occurrence of the near-point three-phase ground fault using the output of the power source as the ranging current, so that the circuit breaker is accidentally turned on when the near-point three-phase ground fault occurs in the protected transmission line. However, the distance relay uses the voltage of the bus detected by the bus voltage transformer as the ranging voltage, and detects the occurrence of the near-point three-phase ground fault before the circuit breaker is actually turned on. Processing can be started, and as a result Since the trip speed of the breaker can be increased, there is an effect that damage to the protected transmission line is suppressed to a minimum and the stability of the system can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a transmission line relay device according to one embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of FIG. 1, FIG. 3 is a block diagram of another embodiment, 4
FIG. 5 is a time chart for explaining the operation of FIG. 3, FIG. 5 is a block diagram of a conventional transmission line relay device, FIG. 6 is an example of phase characteristics of the distance relay of FIG. 5, and FIG. 5 is a time chart for explaining the operation of FIG. 52 is a circuit breaker, 52A is an auxiliary contact of the circuit breaker, L is a protected transmission line, CT is a current transformer, PT is a voltage transformer, PT _B is a bus voltage transformer, 2 is a distance relay, and 3 is a one-shot multi The circuit 4 is a gate circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A current transformer, which is provided on a bus side of a circuit breaker of a protected transmission line and detects a current flowing through the protected transmission line, and is provided on a transmission line side of the circuit breaker of the protected transmission line,
A transmission line voltage transformer that detects the voltage of the protected transmission line, a bus voltage transformer that detects the voltage of the bus, and when the circuit breaker is turned on, closes before the circuit breaker is turned on. The auxiliary contact of the circuit breaker and the bus voltage detected by the bus voltage transformer are input, and only when the auxiliary contact is closed, a certain time after the closing of the auxiliary contact, the input bus A gate means for outputting a voltage, and comparing the output of the gate means with the output of the transmission line voltage transformer, the larger output is used as the ranging voltage, while the output of the current transformer is used as the ranging current. A transmission line protection relay device comprising: a point three-phase ground fault; and a distance relay that trips the circuit breaker when a near-point three-phase ground fault is detected.