JPS6285633A - Checking circuit of protective relay - 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 Industrial Application] The present invention relates to a divine intention detection circuit for a protective relay device that responds to time changes in an input signal from a power system.

[Conventional technology]

A protective relay device detects an accident state or a dangerous state of a power transmission line or power equipment, outputs a trip signal to a breaker using an operation judgment circuit, and disconnects the accident section from the power system. 6. Protective Relay Device If the system malfunctions, the normal section will be disconnected from the power grid, causing major damage.
A protective relay device generally includes a main detection relay and a fail-safe relay such as a current change width relay, voltage change width relay, or power change width relay, and is a redundant relay that outputs a final trip under conditions where both operate together. is being planned. Also,
An automatic inspection function is provided to check whether each relay operates properly in the event of an accident.

The automatic inspection of the conventional current change range relay will be explained below with reference to FIGS. 4 and 5.

In general, the current variation range relay 1 generates an operational output when the input current changes by more than a predetermined set value, and employs the configuration shown in FIG. 4, for example. That is, a current input signal and a delay circuit 2 that delays this current input signal by a delay time TD.
It has a determination circuit 3 which inputs an output signal of , and outputs a motion determination signal when the difference between the two human force signals is equal to or greater than a motion determination value.

Usually, this delay time TD is a time equivalent to several cycles of the current input signal, but below, it will be explained using a time equivalent to one cycle as an example. For this reason, the output of the 1 judgment circuit 3 only continues for a short time, so a time-limited return circuit TDD (hereinafter referred to as TDD) is used as a circuit to extend the output to about 2 seconds.
) is provided. Further, an inspection control circuit 4 is provided which applies an accident simulation signal It to the current input signal during automatic inspection, and outputs a clear signal to clear the TDD output after the inspection is completed. The inspection control circuit 4 also has a mechanism for returning the current change range relay 1, which is in the output lock state during inspection, to the normal protection state in response to a clear signal.

Next, the normal operation of the automatic inspection of the current change width relay 1 will be explained using FIG. 5 (,).

In order to compare the current input signal with a delayed signal delayed by one cycle, the current change width relay 1 generates an output from the determination circuit 3 during one cycle period at the start of the automatic inspection and one cycle period at the end of the inspection. The output of the determination circuit 3 is delayed by the TDD during inspection, but is cleared by a clear signal output from the inspection control circuit 4 after TOFF for a certain period of time after the inspection is completed. As a result, the current change range relay 1 quickly returns to the normal protection state. 1 hour T. When setting the FF, it is necessary to set the current change width after clearing to be larger than the delay time TD so that L No. 1 does not operate again.

[Problem that the invention seeks to solve]

The operation when an accident occurs in the power system during automatic inspection of the current change range relay 1 will be explained using FIG. 5(b). If a fault occurs in the power system during automatic inspection, this fault current is superimposed on the current input signal and input to the relay 1. During automatic inspection, one inspection is executed in the same manner as described above.

However, at the time TOFF after the automatic inspection, the current change width relay 1 enters the normal protection state due to the clear signal, but the fault in the power system continues.

Even if we compare the current signal with delay time TD and the current input signal,
No current change occurs. Therefore, the current change width relay does not operate.

Therefore, if an accident that occurs during automatic inspection continues even after the inspection is completed, there is a drawback that the protective relay device will lose its function entirely.

[Means for solving problems]

Means for solving the problem will be explained with reference to FIG.

A first delay circuit 12A delays an input signal IL obtained from the power system via a transformer by a first delay time, and inputs the input signal processing signal and delays the input signal IL by a first delay time and a protection switch. Compare the input signal processing with the second delay circuit 12B that delays the second delay time that is larger than the sum of the inspection times of the electrical equipment, and one of the output signals of the first and second delay circuits L2A and 12B. A determination circuit 13 that generates an operation output when there is a difference greater than or equal to the operation determination value of the protective relay device, and a first delay circuit 12 that generates an operation output when the protective relay device is normally operated and inspected.
The output signal of A is input to the judgment port 'J613, and the second delay time is approximately equal to the first delay time after the inspection is completed.
An off-duty inspection circuit for a protective relay device comprising a switching circuit 14 for switching an output signal of a delay circuit 12B to a determination circuit 13.

[For production]

In the normal protection state of a protective relay device, the electrical input signal and
The output of the determination circuit to be compared with the output of the first delay circuit is selected by a switching circuit.

When the automatic inspection is executed, a 1-inspection simulation input signal is applied to the protective relay device, and the operation is determined by the determination circuit.

During the automatic inspection, the protective relay device is in an operational lock state, but immediately returns to the protected state after the automatic inspection is completed. Here, from the end of the automatic inspection to a time approximately equal to the first delay time, the second delay circuit, which has a second delay time greater than the sum of the first delay time and the automatic inspection time, is operated. Switch to output. As a result of the above, immediately after automatic inspection, the second delay circuit compares the electrical input signal with the electrical input signal before automatic inspection. Therefore, changes in electrical input can be detected.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 2 and 3. A protective relay device that responds to time changes will be explained using a current change range relay as an example. The current change width relay 11 includes a first delay circuit 12A that inputs current information of the power system as a current input signal via a current transformer, and a determination circuit 13.
and a second delay circuit 12B. A switching circuit 14 is provided to input the outputs of the first and second delay circuits 12A and 12B and input one of them to the determination circuit 13. This switching circuit 14 selects the first delay circuit 12A during normal and inspection of the current change width relay 11, and selects the first delay circuit 12A from the end of inspection.
During a time equal to the delay time of A, the second delay circuit 12B is temporarily selected and switched. A TDD is connected to the output of the determination circuit 13 to output a relay output signal in order to generate a continuous signal. In addition, an inspection control circuit 15 is provided which has a function of applying an accident simulation signal to the current input signal during automatic inspection, a function of outputting a clear signal to clear the TDD output, and a function of locking the relay output signal during automatic inspection. It is.

The determination circuit 13 inputs the electrical input signal and the output signal of either the first or second delay circuit, which is switched by the switching circuit 14, and determines whether the current change width is greater than or equal to the operation determination value of the current change width relay 11. If there is a difference, an operation determination signal is output. The first delay circuit 12A is selected by the switching circuit 14 and connected to the determination circuit 13 when the current change width relay 11 is in a normal protection state.

The delay time To of this first delay circuit 12A is usually a time corresponding to several cycles of the current input signal.

- The delay circuit 12B of the force cylinder 2 is selected by the switching circuit 14 and connected to the 1 determination circuit 13 from the end of the automatic inspection until the first delay time TD. The delay time T3 of the second delay circuit 12B is greater than the sum of the first delay time To and the automatic inspection time TA.

Next, the automatic inspection time TA, the first and second delay times T
D+ TS for 4 cycles of electrical input signal each.

The normal operation of automatic inspection will be explained using FIGS. 3(a) and 3(b) as times corresponding to 1 cycle and 5 cycles. When the automatic inspection is started, the 1-inspection control circuit 15 outputs the accident simulation signal I for 4 cycles, and this signal I is generated when the load current 1. Judgment circuit 1
3 is input to delay circuits 12A and 12B. At this time, since the first delay circuit 12A is connected to the determination circuit 13 by the switching circuit 14, the determination circuit 13. An operating output is generated for one cycle from the start of automatic inspection. The output of this determination circuit 13 becomes a signal stretched by TDD. However, at the end of the automatic inspection, that is, after four cycles have elapsed from the start of the inspection, it is cleared by a clear signal from the inspection control circuit 15, and the locked state of the relay output signal during the automatic inspection is released. At this time, the switching circuit 14
The second delay circuit 12[1 is connected to the determination circuit 13.

The determination circuit 13 compares the electrical input signal after inspection with the electrical input signal from 5 cycles before, which was delayed by the second delay circuit 12B, so no output is produced. In other words, at the end of the automatic inspection, a protection state using the second delay circuit 12B is entered.

After the automatic inspection ends, after the first delay time TD and between the start of the automatic inspection and the second delay time TS, the switching circuit 14 connects the first delay circuit 12A to the determination circuit 13 again. Switch. From now on, it will enter a protection state using the first delay circuit 12A.

Next, with reference to FIG. 3(b), an explanation will be given of the effect when a fault current is superimposed on the electrical input signal due to a power system fault during automatic inspection. During automatic inspection, due to the same effect as above,
Inspections are performed. After the automatic inspection is completed, the second delay circuit 12B compares the electrical input signal with the electrical input signal from five cycles before the automatic inspection, so the determination circuit 13 detects a difference. As a result, a relay output signal is output, and the current change range relay operates even in the event of an accident in the power system during automatic inspection.

Although the current variation range relay has been described as an example, the present invention can be similarly implemented for relays that respond to changes in electrical signals introduced from the power system, such as voltage variation range relays and power variation range relays. Further, the same function can be applied to a digital relay using a microcomputer or the like by providing the same function.

〔Effect of the invention〕

After the automatic inspection is completed, by switching to the second delay circuit that compares the electrical input signal before the automatic inspection.

To provide a 64 inspection circuit for a protective relay device that operates even in the event of a power system accident during automatic inspection.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an automatic inspection circuit for a protective relay device according to the present invention, FIG. 2 is a block diagram of an automatic inspection circuit for a current variation range relay according to an embodiment of the present invention, and FIG. FIG. 4 is a block diagram showing the automatic inspection circuit of a conventional protective relay device. FIG. FIG. 3 is a time chart diagram showing the action during automatic inspection. L2A, 12B... Delay circuit 13... Judgment circuit 14... Switching circuit Fig. 1 Fig. 2 Fig. 3 (Q-) Fig. 3, b Fig. 4 Fig. 5 (0L) Fig. 5 Figure Cb)

Claims (1)

[Scope of Claims] A first delay circuit that delays an input signal obtained from a power system via a transformer by a first delay time; A second delay circuit that delays the relay by a second delay time that is greater than the sum of the inspection times of the relay device, and one of the output signals of the first and second delay circuits is compared with the input signal, and the protection is performed. A determination circuit that generates an operational output when there is a difference greater than or equal to the operation determination value of the relay device; and an output of the first delay circuit during normal and inspection of the protective relay device is input to the determination circuit, and the inspection is completed. 1. An inspection circuit for a protective relay device, comprising: a switching circuit that switches the output signal of the second delay circuit to be later input to the determination circuit for a time substantially equal to the first delay time.