JP2006320075A - Digital protective relay system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To swiftly remove an accident in a section in a relevant line without waiting until an accident in the adjacent line (rear side) even when multiple accidents occur in both the two lines of a one-end non-power supply system constructed of two parallel lines. <P>SOLUTION: A digital protective relay system includes: a ground directional distance relay 11 provided in each phase of a power system; an undervoltage relay 12 provided in each phase of the power system; and a front accident detection relay 16 that determines the direction of an accident from the phase relation of current-voltage in each phase of the power system or the phase relation of current-voltage of a symmetrical component. When rear two-line ground fault accident occurs, the output of the ground directional distance relay 11 is locked by the operation of the undervoltage relay 12. When a front accident occurs, locking by the undervoltage relay 12 is released by the operation of the front accident detection relay 16 to enable the operation of the ground directional distance relay 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital relay device, and more particularly to a digital protective relay device that can quickly eliminate an accident in its own section in a multiple accident including a rear accident.

  Conventionally, the transmission line protection method of the ultra-high voltage, direct grounding system in Japan is generally treated as a fixed power terminal assuming that both terminals have a power supply capable of supplying the positive phase. However, depending on the region, there may be a system configuration in which one terminal serves as a power supply end and the other terminal serves as a non-power supply system or a variable power supply terminal due to restrictions on the installation location of the power plant.

  In the case of a system configuration in which one end is treated as a non-power source system or a variable power source end, the protection system is also affected. For example, it has long been known that when a two-wire ground fault occurs behind a ground fault direction distance relay, direction discrimination does not work (for example, see Non-Patent Documents 1 and 2). For this phenomenon, as shown in Non-Patent Document 3, a technique to which a malfunction prevention function called an undervoltage lock method is added is generally applied even now.

  FIG. 10 is a logic sequence diagram depicting the malfunction prevention function by the undervoltage lock method described in Non-Patent Document 3 in an easy-to-understand manner. In FIG. 10, 11a, 11b, and 11c calculate the fault impedance from the voltage and current of each phase of the input power system, compare with the settling impedance, and determine whether or not there is an internal fault in the transmission line protection section from the comparison result. This is a ground fault distance relay that operates.

12a, 12b, and 12c prevent the circuit breaker from being erroneously cut off by the operation output of the ground fault direction distance relays 11a, 11b, and 11c in the event of a two-wire ground fault behind the ground fault direction distance relays 11a, 11b, and 11c. This is an undervoltage relay provided for the purpose. Reference numerals 13a, 13b, and 13c denote AND circuits for inputting operation outputs of the ground fault direction distance relays 11a, 11b, and 11c of the respective phases. Then, after the outputs of the undervoltage relays 12a, 12b, and 12c of each phase are inverted through the negation circuits 14a, 14b, and 14c, one phase sequence is provided at the gate terminals of the AND circuits 13a, 13b, and 13c. Enter with a delay. That is, the output of the negative circuit 14b is input to the gate terminal of the AND circuit 13a, the output of the negative circuit 14c is input to the gate terminal of the AND circuit 13b, and the output of the negative circuit 14a is input to the gate terminal of the AND circuit 13c. This prevents the circuit breaker from being erroneously cut off by the operation outputs of the ground fault direction distance relays 11a, 11b, and 11c. The outputs of these AND circuits 13a, 13b, and 13c are given as a three-phase cutoff command to a circuit breaker tripping circuit (not shown) via an OR circuit 15.
Susumu Kobayashi "Protective Relay Technology" 1st edition, 1st edition, Denki Shoin, published on October 15, 1972, pages 383-385, Yoshihide Hase, Michio Masui “Protective Relay Technology”, February 15, 1979, 1st edition, 1st edition, Tokyo Denki University Press, P.287-288 986 “Response of ground fault direction relay in normal phase non-power supply system”, Electrical Engineering Society of Japan 1973, Ichiro Mikami, Koichi Kitaura, Akio Furuya, Kenji Suzuki, Katsumi Nakamura

  However, it has been found that even in the case of a ground fault direction distance relay provided with an undervoltage relay for preventing malfunction as shown in FIG. 10 described above, it may take time to remove the accident depending on the aspect of the accident.

  For example, in a parallel two-line system in which one terminal shown in FIG. 11 is a positive phase power supply terminal and the other terminal is a non-power supply, a two-wire ground fault (bc phase) on the 1L side and a one-wire ground fault on the 2L side When multiple accidents (phase b) occur across both lines, ground fault distance relays 11b and 11c and undervoltage relays 12b and 12c operate on the 1L side, and the gate of the AND circuit 13c opens and passes through the OR circuit 15. A three-phase cutoff command is immediately output, and a two-wire ground fault (b, c phase) can be removed at high speed.

  However, since the ground fault direction distance relay 11b and the undervoltage relays 12b and 12c operate on the 2L side, the AND circuits 13a to 13c do not open the gate, the three-phase cutoff command is not issued, and the one-wire ground fault ( b phase) cannot be removed at high speed. As a result, on the 2L side, the 1L side 2 wire ground fault of the adjacent line is removed, and the c phase undervoltage relay 12c is removed and then removed. Therefore, the malfunction prevention measure described in Non-Patent Document 3 has a problem that the accident removal on the 2L side is delayed.

  The present invention has been made in view of the above-described problems. Even in the case of a double-line multiple power failure in a parallel two-line single-ended non-power supply system, an accident in its own section can be promptly performed without waiting for the removal of the adjacent line (rear side) accident. It is an object of the present invention to provide a ground fault direction distance relay that can be removed.

  In order to achieve the above object, the present invention inputs the voltage and current of each phase of the power system, calculates the fault impedance from the voltage and current, compares it with the settling impedance, and from the comparison result, the transmission line protection section Determine the direction of the accident based on the ground fault direction distance relay that determines whether it is an internal accident, the undervoltage relay that operates by detecting the undervoltage of each phase of the power system, and the phase relationship between the voltage and current obtained from the power system A forward fault detection relay to perform, lock the output of the ground fault direction distance relay by the operation of the under voltage relay, release the lock by the under voltage relay by the operation of the front accident detection relay, It is characterized in that an accident removal command is output by making the operation of (1) effective.

  According to the present invention, the forward accident detection relay is added to the lock circuit by the ground fault distance relay for the positive phase non-power supply countermeasure, thereby enabling the lock function by the undervoltage relay in the rear accident and the undervoltage relay of the forward accident. Accident removal is possible without restrictions, and accident removal can be performed at high speed in various aspects of accidents.

Embodiments of the present invention will be described below with reference to the drawings. Note that the same parts as those in FIGS. 10 and 11 are denoted by the same reference numerals.
FIG. 1 is a power system diagram in which the digital protection relay device according to the present embodiment is installed. In this power system, one terminal S is a positive-phase power supply terminal, the other terminal R is a non-power supply terminal, and the two terminals S and R are two parallel lines including a first line transmission line 1L and a second line transmission line 2L. Connected. Since the present invention relates to the response of the digital protection relay devices Ry1 and Ry2 that protect the first line transmission line 1L and the second line transmission line 2L installed on the power supply terminal S side, the digital of the non-power supply terminal R The protective relay device is not shown.

  The digital protection relay devices Ry1 and Ry2 are supplied with a terminal current I taken from the current transformers CT1 and CT2 and a terminal voltage V taken from an instrument transformer (not shown). These current I and voltage V are converted into digital data through a filter, a sample hold circuit, and an A / D converter, and then a protective relay arithmetic program required by the present invention by a digital arithmetic processing unit such as a CPU, for example, direction It is calculated based on the calculation program for the distance relay, the undervoltage relay, and the forward accident detection relay. The calculation result is output as a circuit breaker trip signal through the interface circuit.

FIG. 2 is a malfunction prevention circuit for positive-phase non-power supply countermeasures for the ground fault direction distance relay in the digital protective relay Ry1 installed on the power supply terminal S side of the first line transmission line 1L.
2, 11a, 11b, and 11c are ground fault direction distance relays similar to those described in FIG. 10, and their outputs are input to AND circuits 13a, 13b, and 13c, respectively. 12a, 12b, and 12c are undervoltage relays for preventing the ground fault direction distance relays 11a, 11b, and 11c from malfunctioning in the event of a rear two-wire ground fault, as described with reference to FIG. Reference numeral 16 denotes a newly provided forward accident detection relay having a function of determining the direction of the accident by introducing, for example, a positive phase amount of current and voltage and determining the phase of both.

  The outputs of the undervoltage relays 12a, 12b, and 12c are inverted by the negation circuits 14a, 14b, and 14c, and then input to the OR circuits 17a, 17b, and 17c. The output of the forward accident detection relay 16 is commonly input to the OR circuits 17a, 17b, and 17c. A delayed phase OR circuit output is input to the gates of the AND circuits 13a, 13b, and 13c. For example, the output of the b-phase OR circuit 17b is output to the gate of the a-phase AND circuit 13a, the output of the c-phase OR circuit 17c is output to the gate of the b-phase AND circuit 13b, and the output of the c-phase AND circuit 13c is a The output of the phase OR circuit 17a is input.

  In this way, the undervoltage relays 12a to 12c are operated by forming an OR circuit with the forward accident detection relay 16 and the negative circuits 14a to 14c for inverting the outputs of the undervoltage relays 12a to 12c, so that the undervoltage relays 12a to 12c operate. Even if the lock function by is activated, when it is determined that the forward accident detection relay 16 is a forward accident, the lock function by the undervoltage relay is released and the outputs of the ground fault distance relays 11a to 11c are permitted. Can do. The outputs of the AND circuits 13a, 13b, and 13c pass through the OR circuit 15 and a three-phase cutoff command is output.

FIG. 3 is a diagram showing a symmetrical distribution circuit at the time of a power system failure. This symmetrical branch circuit differs depending on the accident aspect (3φS, 2φS, 2φG, 1φG) shown in FIG.
FIG. 4 is a vector diagram showing the state of each phase electric quantity at the time of the accident appearance that occurred in front of the installation point of the digital protective relay Ry1 (Ry2). (A) is a three-phase short circuit accident (3φS), ( B) is a BC phase 2-wire short-circuit accident (2φS), (C) is a BC-phase 2-wire ground fault (2φG), and (D) is an A-phase 1-wire ground fault (1φG) current of each phase. FIG. 5 is a voltage vector and positive phase voltage and current vector diagram.

FIG. 5 is a characteristic diagram of the forward accident detection relay 16. As can be seen from this characteristic diagram, the forward accident detection relay 16 can reliably detect an accident ahead of the relay installation point due to the phase relationship between the positive phase amount voltage V ₁ and the positive phase amount current I ₁ .

Next, the operation of the present embodiment will be described.
FIG. 6 shows a three-phase short circuit accident (3φS) ahead of the relay installation point of the first line transmission line L1 in a two-line transmission system in which one end is a positive phase power supply end and the other end is a non-power supply end in the event of an accident. It is a figure which shows a situation when single accidents, such as a BC phase 2 wire short circuit accident (2 (phi) S), a BC phase 2 wire ground fault accident (2 (phi) G), and an A phase 1 line ground fault accident (1 (phi) G), have occurred.

  In the digital protection relay device Ry1 shown in FIG. 2, in the case of such a single accident ahead in the protection direction, the ground fault direction distance relays 11a to 11c and the front accident detection relays 16a to 16c operate in any accident aspect. Therefore, even if the undervoltage relays 12a to 12c operate, the output of the ground fault direction distance relay is not blocked. For this reason, the digital protection relay device Ry1 installed in the first line transmission line 1L can output the three-phase cutoff command and eliminate the accident.

  FIG. 7 shows a three-phase short-circuit accident (3φS), a BC-phase two-wire short-circuit accident (2φS), a BC-phase two-wire ground fault (2φG), and an A-phase one-wire ground fault behind the installation point of the digital protective relay Ry1. It is a figure which shows a condition when single accidents, such as an accident (1phiG), have occurred.

  In the case of this rear accident, since only the zero-phase current is supplied from the non-power supply end, the forward accident detection relays 16a to 16c do not operate in any accident aspect. Moreover, even if any of the ground fault direction distance relays 11a to 11c malfunctions, the lock function works effectively by the operation of the underphase relays 12a to 12c of the lagging phase to prevent malfunction. As a result, the response of the digital protection relay device Ry1 does not malfunction as usual.

  FIG. 8 shows a front accident at the installation point of the digital protection relay devices Ry1 and Ry2, that is, a front multiple accident ((3φS), (2φS), (2φG), and (1) It is a figure which shows the state which 1phiG)) generate | occur | produced.

  In the case of this forward multiple accident, the fault phase ground fault direction distance relays 11a to 11c and the forward accident detection relay 16 operate, so the bc phase ground fault on the first line transmission line 1L side and the second line transmission line 2L side The undervoltage relays 12a to 12c are unlocked even in the case of a b-phase accident or an uncommon phase both-line 1-line ground fault. For this reason, the digital protective relay Ry2 can validate the output of the ground fault direction distance relay without waiting for the return of the undervoltage relay due to the accident removal of the adjacent line (back side) as in the prior art. As a result, as in the case of the digital protective relay Ry1, it is possible to quickly eliminate the accident within the self section.

FIG. 9 is a diagram showing a state at the time of a front / rear multiplex (progress) accident.
In FIG. 9, when the front accident precedes the front / rear multiplex (progress) accident, the three-phase interruption by the ground fault distance relays 11a to 11c is possible while the front accident detection relay 16 is output. is there.

  In addition, when a rear accident precedes, the lock function by the undervoltage relay becomes effective in the same way as in the conventional case, and no erroneous interruption occurs. On the other hand, when an accident current that can be detected by the forward accident detection relay 16 flows on the front accident side, the outputs of the ground fault direction distance relays 11a to 11c can be validated, and the accident current that can detect the accident is If not, the accident will be removed after the back accident is resolved.

In this way, in the event of a rear accident, the lock function by the undervoltage relay is made effective as before, and in the event of a forward accident, the forward accident detection relay responds to prevent the undervoltage relay from being locked. It is possible to solve the problem of removing the forward accident after waiting for the accident to be removed.
In the embodiment described above, the positive phase electric quantity is used for identifying the accident direction. However, the present invention is not limited to the normal phase electric quantity, and each phase electric quantity or the reverse phase electric quantity is used. Also good.

The electric power system diagram in which the digital protection relay device of this invention is installed. The block diagram of the ground fault distance relay malfunction prevention circuit for the positive phase non-power supply countermeasures provided with the forward accident detection function which concerns on embodiment of this invention. The figure which shows the symmetrical distribution circuit at the time of an electric power system failure. The figure which shows the accident aspect at the time of a forward accident. The characteristic figure of a forward accident detection relay. The figure explaining the response at the time of a single forward accident. The figure explaining the response at the time of a back accident. The figure explaining the response at the time of a forward multiple accident. The figure explaining the response at the time of the front and back multiplex (progress) accident. The malfunction prevention circuit diagram of the ground fault distance relay provided with the undervoltage relay for the malfunction prevention measure at the time of the conventional 2-wire ground fault accident. The figure which shows the multiple accident aspect of a parallel 2 line system | strain for demonstrating a prior art.

Explanation of symbols

  Ry1, Ry2 ... digital protective relay, CT1, CT2 ... current transformer, 11a-11c ... ground fault distance relay, 12a-12c ... undervoltage relay, 13a-13c ... AND circuit, 14a-14c ... negative circuit, 15 ... OR circuit, 16 ... forward accident detection relay, 17a to 17c ... OR circuit.

Claims (4)

Input the voltage and current of each phase of the power system, calculate the fault impedance from the voltage and current, compare with the settling impedance, and determine the ground fault direction distance from the comparison result to determine whether there is an internal fault in the transmission line protection section A relay,
Undervoltage relay that operates by detecting undervoltage of each phase of power system,
With a forward accident detection relay that determines the accident direction based on the phase relationship between the voltage and current obtained from the power system,
By locking the output of the ground fault direction distance relay by the operation of the undervoltage relay, by releasing the lock by the under voltage relay by the operation of the forward accident detection relay, to enable the operation of the ground fault direction distance relay, A digital protection relay device configured to output an accident elimination command.   2. The digital protective relay device according to claim 1, wherein the forward accident detection relay performs an accident direction determination based on a phase relationship between a positive-phase voltage and current.   2. The digital protective relay device according to claim 1, wherein the forward accident detection relay determines an accident direction based on a phase relationship between a voltage and a current of each phase.   2. The digital protective relay according to claim 1, wherein the forward accident detection relay performs an accident direction determination based on a phase relationship between a voltage and a current having a reverse phase amount.

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