JPS59188325A - 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 [Technical Field of the Invention] The present invention relates to a protective joint device that transmits and collects electrical quantities of each terminal and detects failures.

[Technical background of the invention and its problems]

There are various types of relay devices that protect conventional power systems, but the current differential FM carrier protection relay device uses a transmission method that uses an FM modulation method (frequency modulation method) to detect the instantaneous current of each terminal. The values are transmitted and collected to each other, and in the case of an external failure or normal conditions, the total current will be zero, so the relay will not operate, and in the case of an internal failure, the total current will be 2 times the difference 'current corresponding to the fault point current. There is a method that operates a magnetic relay.

An example of such a transport protection relay device will be described with reference to FIGS. 1 and 2.

In FIG. 1, the A end and the B end (not shown) are interconnected by a power transmission line 1, and a current transformer 2 is provided at each terminal. 3 is a directional ground fault relay, which responds to a ground fault by inputting the zero-sequence current of the power transmission line 1 and the neutral point current 2 of the main transformer (not shown). Reference numeral 4 denotes a current differential relay, which responds to the current difference for each phase (ratio phase, S phase, T phase) at the A end and the B end. 5 is an input transformer, 6 is a transmitting section, 7 is a receiving section, and 8 is a determination circuit. The current at the A end detected by the input transformer 5 is subjected to PM modulation in the transmitting section 6, and then transmitted to the carrier terminal station device 9. ,
The signal is transmitted to the B end via the radio device 10, and the Giryu-go signal at the B end is received by the radio device 1o, and is input to the receiving section 7 via the carrier terminal device 9, where it is F'M demodulated. Ru.

The determination circuit 8 detects the current difference between the A terminal and the B terminal, and has operating characteristics in the shaded area in FIG. Reference numeral 11 denotes a constant monitoring circuit which inputs the own terminal current and the other terminal current, and monitors defects such as gain fluctuations of the current differential relay 4 by utilizing the fact that the differential current is always zero.

In Figure 3, the sword is a slight ground fault breaker circuit.

3a, 4a, and 31a are output circuits for a directional ground fault relay 3, a current differential relay 4, and a failure detection relay 31 to be described later.

32 is an AND circuit which outputs the AND of the output signals of the output circuits 3a and 4a. 33 is a delay circuit.

The output signal of the AND circuit 32 is delayed by a set time T1.

34 is a NOT circuit, which inverts the output signal of the output circuit 31a. 35 is an AND circuit, and a delay circuit 33
The AND of the output signals of the NOT circuit 34 and the trip signal is output as 1-.

In FIG. 4, 11a is an output circuit of the constant monitoring circuit 11, and 40 is a delay circuit, which delays the output signal of the output circuit 1.13 by a set time T2. Reference numeral 31 denotes a defect detection relay, which responds to the output signal of the delay circuit 40.

Now, if a slight ground fault occurs on the power transmission line L, the A and B ends
A difference occurs between the currents at the ends, the current differential relay 4 at the A end operates, and a signal of logic level rlJ is output from the output circuit 4a. Further, the directional ground fault relay 3 operates by inputting the zero-sequence current of the slight ground fault and the neutral point current of the transformer, and outputs a signal rlJ from the output circuit 3a.

In addition, due to the difference in current between A terminal and B terminal,
The constant monitoring circuit 11 operates, and the output circuits 11 a to rl
J is output. The outputs of output circuits 3a and 4a are both "
l'', the output of the AND circuit 32 becomes rlJ
After the set time T□, the output of the delay circuit 33 becomes "L".
becomes. At this time, if it is set so that T+ < T2, the AND condition of the AND circuit 35 is satisfied and a trip command is given to a breaker (not shown).

As described above, in order to improve the reliability of the current differential relay 4, the constant monitoring circuit 11 is provided to constantly monitor that there is no differential current in the system. Therefore, the constant monitoring circuit is sufficiently operated by the difference current generated in a slight ground fault in the protected area. By the way, in the case of a normal accident, it is possible to shut off the breaker at straw speed using another cutoff circuit.

In the case of a slight ground fault, the circuit will be cut off after the set time T1. On the other hand, the constant monitoring circuit 11 shown in FIG. 4 operates, and if this operation continues for the set time Tt, the defect detection relay 31
works. As the defect detection relay 31 operates, the output of the output circuit 31a in FIG. ing. In other words, the slight ground fault is cut off after the current differential relay 4 and the directional ground fault relay operate.

After the set time T, a trip command is given to the breaker, but the fault detection relay 31 appears between the slight ground fault breaker circuit.
may be locked by the output of the output circuit 31a, making it impossible to interrupt a slight ground fault.

A case in which such a slight ground fault cutoff becomes impossible will be explained with reference to FIGS. 5 and 6.

FIG. 5 shows a two-terminal power system, in which the A end and the B end are interconnected by power transmission lines 51 and 52. Also, each terminal A, H
The above-mentioned transport protection relay devices 53 and 54 are installed. Here, the A end is the power supply end, and the B end is the non-power end.

Note that 55 is a power supply behind the A terminal.

If a slight ground fault occurs at point F1 at the near end of the B end type, a fault current greater than the setting value of the directional relay 3 at each end A and B will flow, and the current difference at both the incoming end and the B end @ relay 4 and the directional ground fault relay 3 operate simultaneously, and after the set time T1, the breaker is closed.

However, if a slight ground fault occurs at the point F2, which is closest to the A end, a fault current 'FA l FB flows as shown by the solid line. These currents become fault currents flowing through the directional ground fault relay 3 at the A end due to the line impedance relationship. The directional ground fault relay at the B end can operate only after the breaker at the A end is tripped and the fault current ■FB shown by the dotted line flows. Therefore, as shown in FIG. 6, for the A terminal, the current differential relay 4 and the directional ground fault relay 3 operate simultaneously, and before the failure detection relay 31 operates, the delay circuit okara outputs "l". ” occurs, so the circuit breaker is tripped, but until the breaker at the A terminal is tripped, the fault current is less than the setting value of the directional ground fault relay 3, and a directional ground fault occurs. a Electric appliance 3 does not work. on the other hand,
The constant monitoring circuit 11 operates at the same time as the accident occurs, and after the set time T2, the failure detection relay 31 operates and the output circuit 31 a
The output of is rlJ.

Therefore, when the output of the delay circuit 33 becomes "1",
The output of the output circuit 31a is Ill, and the output of the not circuit 34 is "0", and the slight earth fault cutoff circuit I is locked, no trip command is output, and the slight ground fault cutoff becomes impossible.

In such a device, if a slight ground fault occurs at point F2 in Figure 5, the directional ground fault relay 3 at F4 will operate after the A-terminal breaker is tripped. This had the disadvantage that it was impossible to cut off the connection.

[Purpose of the invention]

The present invention has been made to eliminate the above-mentioned drawbacks, and prevents unnecessary locking by a constant monitoring circuit in the event of a slight ground fault.
The purpose of the present invention is to provide a protection connecting/forming device that can reliably interrupt slight earth faults.

[Summary of the invention]

In order to achieve the above object, the present invention provides a current difference # relay 4 that responds to the current difference between its own end and the opposite end.

A directional ground fault relay 3 that operates when a fault current exceeding a set value flows, and a constant monitoring circuit Bll that monitors the current differential relay by utilizing the fact that the current difference is always zero and operates due to a failure. , the logical product of the failure detection relay 31 that operates on the condition that the operation of this constant monitoring circuit Bll continues for 1 vJTz at the time of setting, and the output signals of the current differential relay 4 and the directional ground fault relay 3.

and a first AND circuit 32 which takes the output signal of the first AND circuit for a set time T which is shorter than the set time T2.

A first delay circuit 33 that delays the output signal of the first delay circuit, a second AND circuit 35 that inputs the output signal of the first delay circuit, and the output signal of the directional ground fault relay according to the time difference between the operation of the current differential relay and the directional ground fault relay. and the logical product of the second delay circuit 70 that delays by the set time T within a range shorter than the set time T, the inverted signal of the output signal of this second delay circuit, and the output signal of the failure detection relay. An unnecessary lock prevention circuit 74 is provided which supplies an inverted signal to the input of the second AND circuit, so that when the output of the first delay circuit becomes logic level "1", the output of the unnecessary lock prevention circuit is always logical level
I try to work with the moon.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIGS. 7 to 9.

In FIG. 7, 4a is an output circuit of the current differential relay 4, and as shown in FIG. Outputs a level “1” signal.

, 3a is an output circuit of the directional ground fault relay 3, which outputs a signal of logic level rlJ when a fault current exceeding a set value flows and the directional ground fault relay 3 operates. Reference numeral 32 denotes an AND circuit, which performs the AND of the output signals of the output circuits 3a and 4a. The wings are delay circuits.

The output signal of the AND circuit is delayed by a set time T. A delay circuit 70 delays the output signal of the output circuit 3a of the directional ground fault relay 3 by a set time T3. 71 is a NOT circuit which inverts the output signal of the delay circuit 70.

Reference numeral 72 denotes an AND circuit, which takes the logic of the output signal δ of the NOT circuit 71 and the output signal of the output circuit 31a of the defect detection relay 31. A NOT circuit 73 inverts the output signal of the AND circuit 72. In this way, the knot circuit 71, the AND circuit 72, and the knot circuit 73 constitute an unnecessary lock prevention circuit 74. 35 is an AND circuit, which provides a trip signal to the breaker when the output signals of the delay circuit 33 and the NOT circuit 73 both become [l].

Next, the operation of this embodiment will be explained.

If a slight ground fault occurs at point F2 in Figure 5,
As shown in FIG. 8, the current differential relay 4 and the directional ground fault relay 3 operate simultaneously, and the output circuits 3a and 4a
The output of is "1". The output of the delay circuit 33 reaches Ill after a set time T1 from the occurrence of the accident. Also, the delay circuit 70
The output becomes T after the accident occurs, and later becomes rlJ. In other words, after T3 after the occurrence of the accident, the output of the delay circuit 70 is "1".
Therefore, the output of the NOT circuit 71 is "0", the output of the AND circuit 72 is also "0", the output of the NOT circuit 73 is rlJ, and the gate of the AND circuit 35 is opened to time the output signal of the delay circuit 33. ing.

Thereafter, after T1, the output of the delay circuit 33 becomes "1", and at this point a trip command is given to the breaker from the AND circuit 35, and the breaker is tripped.

In addition, at the B end, as shown in Fig. 9, a directional ground fault relay 3
When the breaker at the A terminal is tripped and a fault current exceeding the set value starts flowing, the output of the output circuit 3a is delayed from the output of the output circuit 4a.
It becomes ll. The output of the delay circuit 33 is further output for a set time T1.
Later became Ill. Further, the output of the delay circuit 70 becomes rlJ after a set time T3 from the operation of the directional ground fault relay 3, and at that time, the output of the not circuit 7I becomes "0". The output of the output circuit 31a is r after the set time T2 from the occurrence of the accident.
It becomes lJ. Therefore, when the output of the delay circuit 33 becomes rlJ, the output of the AND circuit 72 is "0", the output of the NOT circuit 73 is "l", and the AND circuit Okara trip command is given to the breaker, and the breaker A trip takes place.

The setting time T3 of the Hiko delay circuit 70 is the output circuit 31 a.
Before the output of the delay circuit 70 becomes "1", the output of the delay circuit 70 becomes "1".
'', that is, the sum of the time difference between the operations of the current differential relay 4 and the directional ground fault relay 3 and the set time T3 may be set to be shorter than the set time T2.

Therefore, according to this embodiment, even if the operation of the directional ground fault relay γ lags behind the operation of the current differential relay, unnecessary locking due to the operation of the constant monitoring circuit 1 can be prevented, and the slight ground fault can be interrupted. can be done reliably.

〔Effect of the invention〕

According to the present invention, as described above, it is an object of the present invention to provide a protective relay device that can prevent unnecessary locking by a constant monitoring circuit in the event of a 2-north road accident and can reliably interrupt a slight ground fault.

[Brief explanation of the drawing]

Figures 1, 3 and 4 are block diagrams showing the conventional F Mm transmission protection relay device, Figure 2 is a characteristic diagram showing the operation of the current differential relay in Figure 1, and Figures 5 and 4 are block diagrams showing the conventional F Mm transmission protection relay device. FIG. 6 is a circuit diagram and time chart showing the operation of the device shown in FIG. 1, FIG. 7 is a configuration diagram showing an embodiment of the present invention, and FIGS. 8 and 9 are operation of the device shown in FIG. 7. It is a time chart showing. 3... Directional ground fault relay, 4... Current differential relay,
DESCRIPTION OF SYMBOLS 11... Constant monitoring circuit, 32... First AND circuit, 33... First delay circuit, A... Second AND circuit, 70... Second delay circuit. 74...Unnecessary lock prevention circuit. (7317) Agent Patent attorney Kensuke Norichika (one idiot) Figure I A Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] A current differential relay that responds to the difference in current obtained at one end and the other end of the power system; a directional ground fault relay that operates when a fault current exceeding a set value flows; A constant monitoring circuit that monitors the current differential relay using the fact that the current difference is zero and operates in the event of a failure; and a failure detection relay that operates on the condition that the constant monitoring circuit continues to operate for a set time T2. a first AND circuit that takes the logical product of the output signals of the current differential relay and the directional ground fault relay; and a first AND circuit that delays the output signal of the first AND circuit by a set time T1 shorter than the set time T2. with a delay circuit. a second AND circuit inputting the output signal of the first delay circuit; and the output signal of the direction ground fault tsnt device M11. a second delay circuit that delays by a set time T within a range where the sum of the time difference between the operation of the current 4D relay and the directional ground fault relay is shorter than the set time T2; and the output of this second delay circuit. A protection switching device comprising: an unnecessary lock prevention circuit that supplies, as an input to the second AND circuit, a signal obtained by inverting a signal and a signal obtained by inverting the logical product of the output signal of the failure detection relay.