JPH05191917A - Control method for inactive terminal of current differential protection relay - Google Patents

Abstract

PURPOSE:To disable a breaker to trip unnecessarily when the breaker is activated in a current differential protection relay. CONSTITUTION:A current differential protection relay is provided with an inactive terminal control system at each terminal to protect a multi-terminal transmission line. The relay comprises a first relay 5 which does not any input form an inactive terminal by the inactive terminal control when there is any terminal which is at halt, and then, executes a determination; a second relay 6 which latches inputs from all the terminals irrespective of the presence of any inactive terminals, and then, executes a determination; a circuit 7 which executes an inner determination instantaneously when the first relay 5 and second relay 6 are activated together; and the circuits 9 and 10 which execute an inner determination after a given period of time when the first relay 5 is activated, but the second relay 6 is not activated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a quiescent end of a current differential protection relay device.

[0002]

2. Description of the Related Art A current differential relay detects an accident point current from a current value of each terminal, and not only a two-terminal transmission line but also
It can also be applied to multi-terminal transmission lines. For that purpose, it is necessary to transmit the current waveform of each terminal to the other terminal, and in the digital relay system, the instantaneous value data of each terminal current is converted into a digital amount and encoded, and the PCM (Pulse Code Modulator-
transmission) to the other end in the transmission direction. A digital current differential relay is configured by a microcomputer that collects the current data of each terminal transmitted in this way and performs a determination process. For this reason, sampling the data at each terminal of the transmission line to extract the data at the same time on each terminal, and by adding this data, an accurate difference current can be obtained without operations such as transmission delay compensation. There is. There are two methods for sampling synchronization: one that simultaneously samples each terminal current based on the synchronization signal generated at the signal terminal station, and one that has a sampling synchronization function built into the relay side. Only the latter will be described using 6.

In FIG. 6, an input converter 31 receives a system electric quantity i _L via a current transformer CT-1 at an A terminal, is introduced into an analog input unit 32, and is sampled via an analog filter 33. The hold circuit (S / H) 34 and the analog / digital converter (A / D) 35 convert the data into digital data at every predetermined sampling synchronization, and the system bus
It is introduced into the transmission control unit 37 and the arithmetic unit 41 via 36. In the transmission control unit 37, the parallel / serial conversion circuit (P / S) 38 transmits data to the other end via the transmission device. The data at the other end is received by the serial / parallel conversion circuit (S / P) 39 via the transmission device and introduced into the arithmetic unit 41 via the system bus 36. The sampling synchronization control circuit (SYNC) 40 samples the sample and hold circuit (S / H) 34 so that the sample and hold circuit (S / H) 34 and the serial / parallel conversion circuit (S / P) 39 are synchronized with each other. Control timing. The arithmetic unit 41 adds the data of the digital converter (AD) 35 and the data of the serial / parallel converter 39, and when the difference current is the set value or more, the breaker C
Issue a command to trip B-1.

FIG. 7 shows a transmission format for transmitting information of each terminal used in the PCM transmission system, which is an example applied to the 60 Hz system. 1 super frame (1
6.67ms) consists of 900 bits. 1 frame-75 bits consists of 6 bits for frame sync signal, 36 bits for instantaneous value data of each terminal current (12 bits for 3 phases), 12 bits for control signal (control signal) It sends on / off information of the circuit breaker, inspection command information, synchronization control signal, etc.) and a CRC check signal (Cyclic Redandancy Check). The CRC check signal is a method generally used for detecting a code error in communication. In this example, an error in a received signal is detected, and a single-shot failure of a bit is surely detected. Further, the control signal controls the frame synchronization and the sampling synchronization, and detects the defect when the synchronization is not achieved. CRC above
When a code error or synchronization failure is detected in the check, it is generally determined that the received data is bad, and the device is locked and an alarm is displayed. Further, even when the power is turned off, the control signal cannot be sent, so that the received data is determined to be defective.

FIG. 8 shows the case of the terminal A in a conventional pause end control circuit. 12 is a CF detection circuit (received data defect detection circuit), 13 is a CB (breaker) disconnection detection circuit at the B end, 14 and 15 are NOT circuits, and when the CF detection circuit 12 detects a defect, the NOT circuit 14 outputs 0 , CB
When the disconnection detection circuit 13 detects the disconnection, the NOT circuit 15 outputs 0. 16 and 17 are AND circuits, the output 1 of the NOT circuit 14
In this case, the AND circuit 16 outputs 1 when the CB disconnection detection circuit 13 detects disconnection, and the AND circuit 17 outputs 1 when disconnection is not detected. Reference numeral 18 is an F / F circuit (flip-flop circuit). When the input terminal S is 1 and R is 0, the output terminal Q is output 1 and it is determined that the B terminal is idle. Input terminal S is 0, R is 1
In this case, the output terminal Q becomes output 0 and it is determined that the terminal B is in operation.
When both the input terminals S and R are 0, the output terminal Q holds the previous value. 3 is a B terminal current zero control condition, and when the Q output 1 of the F / F circuit 18 is 1, it is judged that the B terminal is idle, and the B terminal received current data is controlled to zero. 19 is a NOT circuit F / F
When the output of Q of 18 is 1, the output becomes 0. Reference numeral 20 is an AND circuit, which is detected by the CF detection circuit 12, and is in operation at the B end, and is an F / F circuit.
When the output of 18 is 0, the output is 1. Reference numeral 21 is a transmission failure detection circuit, which outputs 1 from the AND circuit 20 when the reception data at the B end is defective.
If so, it is determined that the transmission is defective and the device is locked.

FIG. 9 shows a conventional internal determination circuit for the A terminal. 1 is an A-terminal current input I _a taken in through the analog input unit 32 of FIG. 6, 2 is transmitted from the B-terminal, and B-terminal current input I _b taken in through the transmission control unit 37 is 3 The condition is satisfied when it is determined that the B end is stopped under the B end current zero control condition of No. 8. 4 is a switching control circuit of the B-end current input I _b, in the B-end operational output I _b O which is switching control without controlling the B-end current input I _b is the same as I _b. When the B-terminal current zero control condition 3 in the B-terminal pause is satisfied, the switching control circuit 4 controls the B-terminal current input I _b to zero. Therefore, the output I _b O becomes zero. 5 is a current differential relay, performs internal fault determined by differential principle captures I _a and I _b O. Here, the determination formula of the current differential relay will be described. Actually, the ratio characteristic and the phase characteristic are taken into consideration, but they are omitted here because they are not particularly relevant in the present invention. (Determination expression of the current differential relay) I _a + I _b O> internal fault determination I _a + I _b O <pre settles I _k detection sensitivity here determined when an external fault or normal when the I _k when I _k The given constant. From the above, the sizes of I _b and I _b O are the same during the operation at the B end, but when the B end is idle, the switching control circuit 4 controls the I _b O to zero, so that the current differential relay 5 is not supplied. Only I _a will be input.

[0007]

FIG. 10 is a diagram for explaining the problems of the prior art. Fig. 10 (a) shows the case where an accident occurred inside the protection section when both ends were in the CB. The accident currents I _A and I _B will flow into the accident point F. At this time, the currents I _a and I _{b at} both ends are taken into the current differential relay 5 of FIG. 9 via CT-1 and CT-2. Since both I _a and I _b are flowing inward, the differential currents are I _a and I
_{When b} becomes the added value, I _a + I _b > I _k , and the current differential relay 5 makes an internal accident determination and outputs an operation output. FIG. 10 (b) shows the case where the A end CB is inserted and the B end CB is turned off. At this time, currents (tidal currents) I _A and I _B do not flow,
Since both the differential currents I _a and I _b O become zero, I _a + I _b O
<I _k , and the current differential relay 5 does not operate. Figure 10
(c) is a case where the B end CB insertion operation is performed from the state of FIG. 10 (b). Normally, if both ends are in the CB on state, the pause control is not performed, so that the current differential relay 5 in FIG. Since for this case I _a a I _b O reverse phase, current differential relay 5 becomes I _a + I _b O is zero becomes inoperative. However, as shown in Fig. 10 (c), Fig. 10 (b)
Immediately after the B end CB input operation is performed in the state of, a time delay occurs from the B end CB input until the B end suspension control is released, as shown in the time chart of FIG. This is because there is a time delay from the entry of the CB main contact to the entry of the CB auxiliary pallet and the processing time for the protection device to take in. For this reason, the currents I _A and I _B (tidal current or external fault current) flow into the power transmission line due to the input of the CB at the B end.
Only the input of I _a at the A end is taken in. At this time I _a
Is larger than I _k , the current differential relay 5 outputs an operation output.

Even if the current differential relay 5 outputs an operation output immediately after the B terminal CB is turned on, a fail-safe relay is provided in the protection device. When both operation outputs are ANDed, CB is pulled. Because I am considering to remove it,
Don't immediately follow the trip. However, if an external accident occurs at this time, or if there is no B-terminal bus voltage, the fail-safe relay is also operating, so CB is unnecessarily tripped. Especially important transmission lines are usually provided with an automatic reclosing function, and it is considered that the CB is turned on as quickly as possible after the accident of the transmission lines is eliminated to maintain the continuity of the grid and eliminate the power supply failure. .. However, when the CB is turned on by the automatic reclosing circuit, it is in a weather condition such that lightning falls on the power transmission line, and when the CB is turned on, there is a concern that it may overlap with the occurrence of an external accident. Furthermore, it is possible that an accident occurred on another transmission line due to lightning. Unnecessary tripping of the CB in this situation is unacceptable to eliminate supply disruption. The present invention has been made to solve the above problems, and an object of the present invention is to provide a dormant end control system for a current differential protection relay device in consideration of avoiding unnecessary tripping of CB when CB is turned on. I am trying.

[0009]

In order to achieve the above-mentioned object, the present invention is a system for controlling a quiescent end of a current differential relay provided at each terminal in order to protect a multi-terminal transmission line. In this case, the first relay that makes a decision without taking in the input of the pause end by the pause end control and the second relay that makes a decision by taking inputs of all terminals without performing the pause end control regardless of the presence or absence of the pause end. It is composed of relays, and when the first relay and the second relay are both operating, it makes an internal determination instantly, and when the first relay is operating and the second relay is not operating, it makes an internal determination after a certain period of time. To do.

[Function] When an internal accident immediately after entering the CB, the internal accident is instantly judged, and at the time of an external accident, the internal judgment is made after a certain period of time when the rest end is released. It has become possible to prevent tripping.

[0010]

Embodiments will be described below with reference to the drawings. Figure 1
FIG. 3 is a configuration diagram of an embodiment for explaining a dormant end control system of a current differential protection relay device according to the present invention. In FIG. 1, the same parts as those in FIG. 9 are designated by the same reference numerals and the description thereof will be omitted. In the figure, 6 is a current differential relay added this time, which is directly connected to the current inputs 1 and 2 at the A and B ends, and one of the outputs is connected to an AND circuit 7 and the other to a NOT circuit 8. It The output of the current differential relay 6 is input to the other input of the AND circuit 7, and the output of the current differential relay 5 is input to the other input of the AND circuit 9. The output of the AND circuit 9 is input to the OR circuit 11 via the time delay operation circuit 10, and at the same time, the output of the AND circuit 7 is also input to the OR circuit 11. The output of the OR circuit 11 becomes the internal accident determination output. The determination formula of the current differential relay 6 described above is the same as that of the current differential relay 5 already described.
Further, the time limit of the time delay operation circuit 10 is set to be longer than the time from when the B terminal CB is input to when the B terminal pause is released.

FIG. 2 is a time chart for explaining the operation. The operations of FIGS. 10 (a) and 10 (b) are omitted because they are similar to those of FIG. 9, and a description will be given immediately after the B end CB insertion operation is performed from the state of FIG. 10 (b). As already explained in the prior art, C
Since there is a time delay from the main contact input of B to the release of the B end stop, even if the current differential relay 5 takes in only the A end I _A input and outputs the operation output, the current differential relay 6 is set to the B end stop. Inputs of I _A and I _B are taken in regardless. Here, if I _B has a phase opposite to I _A ,
It remains inoperative. Therefore, the AND circuit 7 is not established, and the time delay operation circuit 10 is started by the AND circuit 9, but the current differential relay 5 is restored because the time delay operation circuit 10 is released from the B end stop before the time is up. AND circuit 9
Is not established, no internal accident judgment is made. In the circuit of the present invention, the time-delay operation circuit 10 internally determines after a certain time that if the CB of the B terminal is arranged on the bus bar side of CT as shown in FIG. 3, an accident occurs between CB and CT. This is because even if the occurrence occurs, the accident cannot be removed without removing the CB of the A terminal. Therefore, as shown in FIG. 3, when it is not necessary to consider that CB is arranged on the bus side from CT,
It is possible to omit the circuits of reference numerals 8 to 11.

FIG. 4 is a block diagram of another embodiment. In FIG. 4, the same parts as in FIG. In this embodiment, an internal accident determination is instantaneously performed when an internal accident occurs immediately after the CB is entered, and when an external accident occurs, an internal determination is made after a certain time after the suspension edge is released.
In addition to the input of the conventional device, the AND circuit 15 has a current zero control 3
Is input from the delay time operation recovery circuit 13 and the NOT circuit 14. Further, the AND circuit 16 receives the current differential relay 6, the B-side normal operation 12 and the output of the current zero control 3. The output of each AND circuit 15, 7, 16 is the OR circuit 17
It becomes an internal accident judgment output via. Therefore, if both the current differential relays 5 and 6 operate by making an internal judgment, A
The condition of the ND circuit 7 is satisfied, and the internal accident is instantly judged. Further, when the current differential relay 5 is operating and the current differential relay 6 is not operating, when the fixed time period of the time delay operation recovery circuit 13 has passed since the B-terminal zero current control condition 3 was canceled, AN
The D circuit 15 determines an internal accident via the OR circuit 17. With the above configuration, in the case of FIGS. 10A and 10B, the same operation as in the case of FIG. 9 is performed. This is clear from the time chart of FIG.

Next, FIG. 10 (b), which is a problem in the conventional device
Immediately after performing the B end CB entry operation from the state of, the following is performed. That is, even if a time delay occurs from the main contact of the CB to the release of the B end suspension, even if the current differential relay 5 takes in only the A end I _a input and outputs the operation output, the current differential relay 6 is in the B end suspension. since the input unrelated I _a and I _b are taken, stuck in the inoperative if the state of the I _b antiphase to I _a. Therefore, the AND circuit 7 does not work. Further, in the AND circuit 15 as well, N is set during the recovery time limit of the time-delaying operation recovery circuit 13 after canceling the pause at the B end.
When locked by the OT circuit 14 and then released from the B end stop, the current differential relay 5 also recovers, so the AND circuit
15 is not established and no internal accident judgment is made. The time limit of the time delay operation recovery circuit 13 is coordinated with the time limit of the current differential relay 5.

When an accident occurs at point F in FIG. 3, the current differential relays 5 and 6 do not operate, so this device does not make an internal determination, and a busbar protection device installed at the end B causes a C at the end B.
B is tripped. For this reason, the B end is stopped and the B end current zero control condition 3 is satisfied, and the switching control circuit 4 controls the B end current to zero. As a result, only the A-terminal current is input to the current differential relay 5 to operate. At this time, since the lock by the NOT circuit 14 is delayed only for the operation time limit of the time delay operation recovery circuit 13, the AND circuit 15 is established during this time, and the internal determination can be performed via the OR circuit 17. AND in the circuit of this device
The internal judgment circuit by the circuit 15 is provided so that when the CB of the B terminal is arranged on the bus side of CT as shown in FIG. 3, even when an accident occurs at the point F between CB and CT. A
This is because the accident cannot be removed without removing the CB of the terminal.

However, when the CB as shown in FIG. 3 is not arranged on the bus bar side of CT, reference numerals 8, 13, 14,
The 15 circuits can be omitted. The condition 12 is established when the terminal B is operating normally and the reception data in FIG. 8 is not good or the device is not being tested. Normal operation refers to a state in which normal input is normally taken in, unless the current input is abnormal due to a defective transmission line or during maintenance and inspection. The AND circuit 16 makes an internal accident determination while the B end current zero control condition and the B end normal operation condition 12 are satisfied. This is because when the fault current flows only to the B terminal side immediately after the B terminal CB is turned on, the operation of the current differential relay 5 that controls the B terminal current to zero is delayed until the suspension control is released. It is provided in order to make internal judgment.

[0016]

As described above, according to the present invention, when an internal accident occurs immediately after the breaker is turned on, the internal accident is judged instantaneously, and when an external accident occurs, the internal judgment is made after a certain time after the rest end is released. Therefore, it is possible to perform reliable pause end control without fear of tripping the breaker unnecessarily due to the release delay of the pause control immediately after the operation of turning on the breaker.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment illustrating a pause control method according to the present invention.

FIG. 2 is a time chart for explaining the operation of FIG.

[Fig. 3] A circuit breaker is installed on the bus side of CT,
The block diagram which shows the state which the accident generate | occur | produced on the bus-bar side from CT.

FIG. 4 is a configuration diagram of another embodiment.

5 is a time chart for explaining the operation of FIG.

FIG. 6 is a block diagram of a digital type current differential relay.

FIG. 7 is a transmission format of a transmission method.

FIG. 8 is a conventional idle end control circuit diagram.

FIG. 9 is a circuit example diagram of a conventional pause edge control system.

FIG. 10 is a diagram showing each case of rest edge control.

FIG. 11 is a time chart for explaining the operation of the conventional method.

[Explanation of symbols]

 1, 2 Current input 3 Zero current control condition 4 Switching control circuit 5, 6 Current differential relay 7, 9, 15, 16 AND circuit 8, 14 NOT circuit 10, 13 Time delay operation circuit 11, 17 OR circuit 12 B terminal normal Operating condition

Claims (2)

[Claims] 1. A current differential protection relay device provided with a quiescent end control system provided at each terminal for protecting a multi-terminal transmission line, and when there is a quiescent end terminal, the quiescent end is controlled by the quiescent end control. A first relay that makes a determination without taking in the input of the input, and a second relay that makes a decision by taking in the input of all terminals without performing the pause end control regardless of the presence or absence of the pause end.
A circuit that makes an internal determination instantly when both the first relay and the second relay are operating, and an internal determination after a certain period of time when the first relay is operating and the second relay is not operating. A quiescent end control system for a current differential protection relay, which is equipped with a circuit. 2. A current differential protection relay device provided with a dormant end control system provided at each terminal to protect a multi-terminal transmission line, and if there is a dormant end terminal, the dormant end is controlled by the dormant end control. A first relay that makes a determination without taking in the input of the first relay, and a second relay that makes a determination by taking in the input of all terminals without performing the pause end control regardless of the presence or absence of the pause end. And the second relay are both operating, a circuit that makes an internal determination instantly, and when the first relay is operating and the second relay is not operating, an internal determination is made after a certain period of time from the release of the pause end control. A quiescent end control system for a current differential protection relay device, comprising a circuit and a circuit for instantaneously making an internal judgment by the operation of a second relay when the quiescent end control terminal is operating normally.