JPS5947528B2 - Slight ground fault selection relay method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slight ground fault selective relay system for quickly handling multi-line faults in a multi-line distribution line.

When a ground fault occurs on a power distribution line, the ground fault direction relay will operate, allowing the fault line to be discovered.
However, if a slight ground fault occurs that causes the ground fault directional relay to operate, or if the ground fault directional relay is defective and does not operate despite the ground fault, the conventional The usual method is to manually turn off and turn on the circuit breaker for each line while checking the zero-phase voltmeter.

On the other hand, in order to replace such a manual operation with an automatic one, automatic control using a re-closing relay for the input operation has also been carried out.

In other words, the one using a reclosing relay is a multi-circuit distribution line f
In this case, when a slight ground fault occurs, the ground fault overvoltage relay has a zero-phase voltage of V.

When it is detected, the slight ground fault selection relay operates.
Every time you step forward one line, you lock the line to start re-closing, then cut off that line, and the next time you move forward one step, lock the start-up to re-close that line, and then lock the start of re-closing to the previous line. A system is adopted in which the faulty line is released, and when the faulty line is reached, the faulty line is memorized and the faulty line is selected and detected while the re-closing activation of the relevant line is locked.

Therefore, in the above method, in the case of two or more small ground faults, that is, a multi-line fault, the healthy circuit is not reclosed after the first faulty circuit is discovered, so the circuit breaker is turned on after the reclosed time, and the remaining circuits are closed. Zero-sequence voltage V from fault line t.

To see the occurrence of E, the zero-sequence voltage V remains for a long time until the next cycle begins.

This continued, creating a security problem.

SUMMARY OF THE INVENTION An object of the present invention is to shorten the duration of zero-sequence voltage in the event of a multi-line fault, thereby providing a slight ground fault selective relay method that can handle early faults.

The feature of this invention is that after a ground fault is detected, the lines are sequentially cut off after a certain period of time has elapsed, and at the same time, the activation of the recloser relay of the line is locked and the recloser of the previous line is activated. If the lock is released and the ground fault disappears during the sequential cutoff, the subsequent cutoff operation is stopped and the activation of the re-closing relay for that line remains locked, and the ground fault is detected after the cycle time has elapsed. If a ground fault is detected again in any of the above cycles, the re-closing relay that is locked at start-up should be unlocked from the higher-ranked line every cycle. Immediately after the next period
There is a point f where the cutoff operation is repeated sequentially.

The present invention will be explained below with reference to FIGS. 1 and 2.

In Fig. 1, F1 to F5 are lines, CB1 to CBS
and 79F1 to 19F5 are circuit breakers and reclosing relays corresponding to lines F1 to F51, T is a grounding transformer, and zero-sequence voltage V is generated in the tertiary winding f when a line is grounded.

A ground fault overvoltage relay 64f is provided. The control circuit 10 is activated by the operation f of the relay 64.

The output of the control circuit 10 is a breaker (, 'Bl~CB5f sequential cutoff command, re-closing relay 79F1~79
This is a start lock command and a lock release command for F5f.

FIG. 2 is a block diagram of the control circuit 10, and 11 is a contact point of a ground fault overvoltage relay 64, which is designed to close when a ground fault occurs in any one of the plurality of lines to be detected.
It's happening.

Reference numeral 12 denotes a starting circuit consisting of a 79717071 circuit that inverts when the contact 11 is closed for a certain period of time (for example, 3 seconds), and the inversion f causes the pulse generation circuit 1
The oscillator 13 generates a single pulse and the oscillator 13 generates clock pulses at fixed time intervals, and these single pulses and clock pulses serve as starting and stepping pulses for a selection output circuit 20i, which will be described later.

14 is a counter that measures the O-clock pulse, and 16 is V.

(Zero-phase voltage) pulse generation circuit 17 is a cycle setting circuit for setting the count value of the counter 14. If the 0-tally switch R8W is set to, for example, the terminal T1f, the counter 14 is set for the time T1. When a pulse corresponding to f is counted up (for example, 95 seconds) or when a zero-phase voltage is generated, a reset pulse is sent to the counter 14f.

18 is ■. An OR circuit 19 is an impedance input to which pulses and reset pulses are input.

To explain the operation next, if a ground fault occurs in lines F3 and F5, the zero-sequence voltage V.

occurs, and the ground fault overvoltage relay 64 operates.

Therefore, when the contact 11 closes, the starting circuit 12 is activated, and the selection output circuit 20 is activated by the pulse from the starting pulse generating circuit 15 and the clock pulse from the oscillator 13, and starts stepping.

Therefore, at intervals of approximately 1 second per line (stepping interval), a command to activate and lock the reclose relay of each line is given in a predetermined order, and then a command to close or disconnect the breaker is issued. When the relay activation lock command is given, the activation lock of the re-closing relay immediately before the relay step is simultaneously released.

Since the re-closing relay is activated by this unlocking, the re-closing relay is re-closed after a predetermined time (approximately 60 seconds).

Also, during this operation, the zero-phase voltage V.

disappears and the ground fault overvoltage relay returns, immediately cancels subsequent line cutoff commands, and continues to lock the activation of the recloser relay only for the line for which the previous cutoff command was issued. do.

Therefore, at the time when line F3 is cut off, line breaker CB3 of line F3 has not yet been reclosed, and therefore line F59 is cut off, resulting in zero-sequence voltage V.

disappears, contacts 11 open, and inverter 19 is inverted, so selection output circuit 20 stores the locked state of reclose relay 79F5.

As described above, the circuit breakers ('Bl to eB4 are sequentially reclosed by the corresponding recloser relays 19F1 to 79F41).

Therefore, when the line F3 is reclosed, the zero-sequence voltage V again.

occurs and contacts 11 are closed.

Therefore V. A pulse is generated from the pulse generation circuit 16, which resets the counter 14 via the period setting circuit 1T, and the selection output circuit 2.0 is activated again via the OR circuit 18, and the breaker (,' They are cut off sequentially starting with Bl.

Then, when the cutoff 5CB3 is cut off, the zero-sequence voltage disappears, so the inverter 19 is inverted, and the selection output circuit 20 stores the locked state of the recloser relay 79F3.

Next, the period time (T, : 9
5 seconds), a count-up signal is given to the selection output circuit 201 from the period setting circuit 17 through the OR circuit 18. At this time, if the selection output circuit 20f signal is given from the inverter 19, that is, the count-up signal is zero. Phase voltage V.

If this has not occurred, the locked state memory of the re-closing relay 79F of the high-rank line F5 is released.

On the other hand, the counter 14 continues to count after the previous count amplifier, and when it counts up again, the signal from the inverter 19 and the signal from the period setting circuit 17-OR circuit 18, as described above, cause the recloser relay 19F3 to be in the locked state. The memory is cleared and the count up of the counter 14 is waited.

Then, the count-up signal, the signal from the inverter 19, and the memory contents of the selection output circuit 20 are compared, and if it is confirmed that the contents are not stored, the selection output circuit 20 inverts the starting circuit 12 to return to the initial state f. Bring it back.

As described above, according to the method of the present invention, the zero-sequence voltage V occurs during line disconnection.

If disappears, the cut-off operation is stopped sequentially, and after the cycle time has passed, the zero-sequence voltage is returned to V.

Compared to the conventional method, the method of the present invention immediately repeats the sequential cut-off operation from the start-up state and selectively detects two or more ground fault lines from F. Once the sequential cut-off operation stops, the zero-sequence voltage becomes V again.

If this occurs, the zero-phase voltage V will be reduced immediately after the operating time (approximately 3 seconds) of the ground fault overvoltage relay 64 has elapsed to repeat the sequential shutoff from the starting state.

The duration time can be shortened, which is advantageous in terms of security.

Moreover, it has the effect of shortening the accident handling time.

Furthermore, it can be used in combination with the existing re-closing relay for automatic shutoff.
Since there is no need to separately prepare a device for controlling input, there is an advantage that the configuration of the device for carrying out the present invention is simple and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a single line diagram to which the present invention is applied, and FIG. 2 is a block diagram showing the configuration of a control circuit for implementing the present invention. 64...Ground fault overvoltage relay, 10...
Control circuit, 12... Starting circuit, 13...
・Oscillator, 14... Counter, 15...
- Starting pulse generation circuit, 16... Vo pulse generation circuit, 17... Period setting circuit, 18...
...OR circuit, 19...Inverter, 20...
...Selection output circuit.

Claims (1)

[Claims] 1. A re-closing relay installed on each circuit of a multi-circuit distribution line, a ground fault overvoltage relay for detecting a ground fault in each circuit, and a breaker for each circuit will issue a shutdown command in sequence. In the device E, which has a control circuit that issues an activation lock command and a lock release command to the re-closing relay E, the circuits are sequentially cut off after a certain period of time has elapsed after the ground fault overvoltage relay detects a ground fault. After locking the activation of the re-closing relay of the current line, release the activation lock of the re-closing relay of the previous line, and if the ground fault disappears during the sequential disconnection, stop the subsequent disconnection operation. The activation of the reclosing relay for that line remains locked, and if no ground fault is detected after the period of time has elapsed, the reclosing relay whose activation is locked is unlocked from the higher-ranked line every 1 synchronous period. In addition, if a ground fault is detected again even after the above-mentioned interruption period, the circuit immediately enters the next period after a certain period of time and repeats the cut-off operation sequentially. Slight ground fault selection relay system.