JPH01259717A - Protective relay - Google Patents

Abstract

PURPOSE:To prevent erroneous function, by holding the first stage function of a shortcircuit distance relay due to close point fault through AND operation of an output from a failsafe relay functionable only upon system fault and an output from the first stage of the shortcircuit distance relay. CONSTITUTION:Upon occurrence of shortcircuit or inner close point fault, the first stage element of a shortcircuit distance relay produces an H output based on a memory voltage only during several cycles. Upon function of an overcurrent relay 4, an H output is produced and an AND gate 13 produces an H output. At this time, a shortcircuit overcurrent relay 2 and a shortcircuit under voltage relay 3 function, while a NAND gate 6 produces an L output to set a FF7 thus bringing an OR gate 8 to H. The shortcircuit overcurrent relay 4 is in H state and an AND gate 9 produces an R output. Then an ON delay timer 9 is started and a stand-by trip command is fed through on OR gate 12. Consequently, even if the relay 1 produces H output during several cycles due to fault of PD secondary line, AND 13 conditions are not satisfied because the relay 4 is in L state and thereby the FF7 is not set. By such arrangement, mis-trip is prevented.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Field of Industrial Application) The present invention is a distance relay device applied to backup protection of power transmission lines, which does not malfunction even in the event of a PD failure such as a PD secondary circuit disconnection. The present invention relates to a protective relay device that can reliably eliminate internal short-circuit accidents in a protection system.

(Prior Art) In a protection system that protects power transmission lines in two lines, main protection and back-up protection, when life insurance m malfunctions, the back-up protection performs a time-limited trip in time coordination with the main protection. Furthermore, when the main protection is not in use, the first-stage backup protection element is generally tripped instantaneously to perform accident removal at high speed.

In a backup protection relay system using a distance relay, in the event of a short-circuit accident at a close point inside the relay installation point, the system voltage becomes zero or a small accident voltage close to it. A memory circuit has been added to store several cycles of data, ensuring reliable operation even in the event of a near-point accident.

However, as mentioned above, as a countermeasure against main protection failure,
When the first stage element of the distance relay is set to time-limited operation, in the event of a short-circuit accident, the memory circuit retains the pre-failure system voltage for only a few cycles, so the time period exceeding the first stage element time-limited timer setting value, Since it is necessary to hold the first stage element output, a short circuit distance relay first stage output holding circuit is provided in the protection sequence section.

Below, the second example of a protective relay device with a conventional holding circuit is shown.
This will be explained using figures.

Figure 2 shows a tripping block diagram of the short-circuit distance relay first stage element, 1 is the short-circuit distance relay first stage element, 2 is the short-circuit overcurrent relay, 3 is the short-circuit under-pressure relay, and 4 is the system A short-circuit overcurrent relay that operates only in the event of an accident. 5 is a condition where the protective relay device is not used.

6 is N A N D logic, 7 is a flip-flop, 8 and 12 are OR logic, 9 and 11 are AND logic, 10
indicates an on-delay timer.

In Fig. 2, when an internal short-circuit accident occurs and the system voltage becomes zero or a small value close to it, the short-circuit distance relay No. 1 - Membrane element 1 uses a built-in memory circuit to
The output is output only for a few cycles, and the short-circuit overcurrent relay 2 and short-circuit undervoltage relay 3 detect an accident and operate, so the NAND, ? ! The output of the logic circuit 6 becomes 1101+, and the flip-flop 7 is turned on.

At this time, if the main protective relay device malfunctions and the accident continues, the short circuit overcurrent relay 2 and the short circuit undervoltage relay 3 will continue to operate, so the R(
The reset) terminal remains at uOu, and the flip-flop 7 continues to operate even if the memory voltage of the short-circuit distance relay disappears and the output of the first stage element 1- becomes "0".

Therefore, the output of the OR logic 8 becomes "1" and the output of the short-circuit overcurrent relay 4 becomes "1", and the output of the AND logic 9 continues to be #III until the fault is removed. Here, in the main protection use state, the logic of condition 5 of not using the main protection relay device is i
t O+? Therefore, AND logic 11 is LL OII
Therefore, the on-delay timer 10 becomes effective.

Therefore, the AND logic 9 starts the on-delay timer 10, and after the settling time, the rr 1 rr high output OR logic 12 becomes ll I II and outputs a breaker trip command.

Next, when the main protection relay device is not used, the main protection relay device non-use condition 5 is “1” logic, so the AND logic 9 is set to II.
When it comes to I JT, A N D logic 11 instantly changes to LL L.
II, a tripping command is instantaneously output via the OR logic 12, and the first stage instantaneous tripping becomes possible.

After the trip command is output, the fault is removed, so the short-circuit overcurrent relay 2 and the undervoltage relay 3 are restored, and the N A
ND logic 6 becomes rt l u, and short-circuit distance relay first stage element 1 has also returned, so flip-flop 7
is reset.

By the way, when a PD failure occurs due to a disconnection in the PD 2nd cycle, when the PD normal voltage becomes zero voltage, the short circuit distance relay 1st stage element 1 outputs an unnecessary output for several cycles due to the memory voltage, and the undervoltage relay 3 becomes activated. , and when the short-circuit overcurrent relay 2 is operating due to the current, N
AND logic 6 becomes 11 Q II and flip-flop 7 is set. In this state, when an external accident occurs, the short-circuit overcurrent relay 4, which is a fail-safe relay, operates, and the AND logic 9 of the OR logic 8 (II II I) and the high output short-circuit overcurrent relay 4 becomes "1". At this time, if the main protection is not used, the condition 5 for not using the main protection relay is 1 (I II), so AND logic 11 instantly becomes LL I I + high output, OR logic 12
There is a risk of accidentally outputting a trip command via the

(Problem to be Solved by the Invention) As described above, in a holding circuit as a measure against a close point accident of the first stage element of a short-circuit distance relay, the output of the first stage element is erroneously held when a PD fails.

In such a situation, if an external accident were to occur, there was a possibility of a mistrip.

Therefore, the present invention prevents the short-circuit distance relay first-stage element holding circuit from erroneously performing a holding operation even when the PD is defective due to secondary disconnection or disconnection, and prevents mistrips due to external accidents when the PD is defective. It is an object of the present invention to provide a holding relay device that can reliably trip a breaker in the event of an internal close-end accident.

[Structure of the invention]

(Means for Solving the Problems) The protective relay device of the present invention is a protective relay device in which the output of a distance relay applied to backup protection of a power transmission line is provided with an output holding circuit in response to a short-circuit accident at a close point. , an output holding circuit is provided that holds the output under the condition that the distance relay first stage element output and the fail-safe relay output that operates in the event of a fault in the transmission line system are both held, and holds the output until the fault is removed. .

Here, the fail-safe relay includes an overcurrent relay, a current variation width relay, etc. 6 (Function) The present invention is a fail-safe relay that operates only in the event of a short-circuit distance relay first stage element output and a system fault.

For example, by maintaining the operation of the first stage element of the distance relay due to a short-circuit accident based on the AND condition of the output of the short-circuit overcurrent relay, backup cutoff by the short-circuit first stage is performed.

(Example) Hereinafter, an example will be described with reference to the drawings. FIG. 1 shows an example of a tripping block diagram of the first stage element of the short-circuit distance relay according to the present invention. The same parts as in FIG. Let's talk about that part. In FIG. 1, 13 indicates AND logic,
In the event of a short-circuit internal close point fault, the short-circuit distance relay is activated by several cycles of memory voltage, and its first stage element 1 outputs "1" until the memory voltage disappears, and the over-current relay 4 is activated by the fault current. Therefore, AND logic 1
3 becomes "1" output.

Also, at this time, the short circuit overcurrent relay 2 and the short circuit undervoltage relay 3 operate, so the output of the NAND logic 6 is "0".
”, the flip-flop 7 is in the set state, and its output causes the OR logic 8 to output at 1 u and the short-circuit relay 4 to output “’1”, so the AND logic 9
outputs “1”. Therefore, at this time, if the main protection is malfunctioning in the main protection use state, the on-delay timer 10 is activated by the output of the AND logic 9, and the subsequent tripping command is outputted via the OR logic 12. Then, as the accident is removed by the subsequent tripping, the short-circuit overcurrent relay 2 and the short-circuit undervoltage relay 3 are restored.
NAND logic 6 outputs “1”.

Since the short-circuit distance relay first stage element 1 has also returned, the flip-flop 7 is reliably reset.

Next, considering the case of PD failure such as PD secondary disconnection, PD2
When the next voltage drops from the PD health voltage to zero voltage, the short-circuit distance relay responds unnecessarily for several cycles due to the memory voltage, and the output of the first stage element 1 becomes "1", but it only operates in the event of a system fault. Since the short-circuit overcurrent relay 4 is inactive, the AND logic 13 remains at the 110 I+ output and the flip-flop 7 is not erroneously set.

As mentioned above, the flip-flop is set by the AND condition of the short-circuit overcurrent relay output, which operates only in the event of a system fault, and the short-circuit distance relay 1st stage output, so the PD
Even when the PD lightning voltage is lost in the event of a failure, the flip-flop will not be set by mistake.

In addition, in the above explanation, it was explained that the first stage operation is maintained by ANDing the short circuit overcurrent relay and the short circuit distance relay first stage output, but as a fail-safe relay, instead of the short circuit overcurrent relay, the current change width is You can get the same effect by using a relay.

〔Effect of the invention〕

As explained above, according to the present invention, the fail-safe relay output that operates only in the event of a system fault and the first short-circuit distance relay
Since the 1st stage operation of the short-circuit distance relay due to a close point fault is maintained by AND with the stage output, the unnecessary response of the 1st stage element in the event of a PD failure is not maintained, so errors caused by an external accident in the event of a PD failure are avoided. It is possible to provide a protective relay device that can prevent tripping and can reliably perform breaker exception in the event of an internal close point accident.

[Brief explanation of the drawing]

FIG. 1 is a tripping block diagram of a short circuit distance relay first stage element according to the present invention, and FIG. 2 is a tripping block diagram of a conventional short circuit distance relay first stage element. 1...Short circuit distance relay 1st stage element 2...Short circuit overcurrent relay 3...Short circuit insufficient '6 Pressure relay 4...Short circuit overcurrent relay 5...Life insurance 5 relay-11 device non-use condition 6 ...NA
N I) Circuit 7...Flip-flop circuit 8.12...OR circuit 9, 1], 13...A N I) Circuit 10...
・On-day timer agent Patent attorney Nori Chika Ken Yudo Daishimaru Ken 5 Figure 2

Claims (1)

[Claims] In a protective relay device in which the output of a distance relay applied to backup protection of a power transmission line is provided with an output holding circuit in response to a short-circuit accident at a close point, the first stage element output of the distance relay operates in the event of an accident in the transmission line system. 1. A protective relay device characterized by comprising an output holding circuit that holds the output under conditions where both the fail-safe relay output and the fail-safe relay output hold until the fault is removed.