JPS63287322A - Relay for detecting ground fault section in distribution line - Google Patents

Abstract

PURPOSE:To separate fault section without interrupting power supply to sound sections by producing two types of signals with different timing according as a ground fault occurs on power source side or load side of a section switch. CONSTITUTION:A zero phase current detector 81 and a zero phase voltage detector 82 are arranged at each installing point of section switch. Detected values are taken into CPU85 which judges whether ground fault has occurred at power source side or load side based on the levels and the phases of zero phase current and voltage. When ground fault has occurred at power source side, signals OB, IA having different timings are produced while when ground fault has occurred at load side, signals OA, IB having different timings are produced. Then the signals are operated logically in order to detect fault section quickly and separate the fault section without interrupting power supply to sound sections.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects whether or not a ground fault is within a protected area when a ground fault is detected in a high-voltage distribution line, and causes a power outage in a healthy area. This invention relates to a relay that detects the direction in which a ground fault occurs in order to separate the faulty section from other healthy sections.

[Conventional technology]

In order to improve the reliability of power supply, conventionally, when an accident occurs on a distribution line, sectional switches are turned on one after another to automatically detect the faulty section, disconnect the faulty section, and then switch on the sections after the faulty section. The so-called DM method is adopted, in which power is reversely transmitted and distributed to other healthy sections.

FIG. 5 is a block diagram of a power distribution system using the DM system. In the DM system distribution system, circuit breaker 1-1 of substation SS
~1-5, Normally closed section switch 2-1~2-8.3-1゜4
-1.5-1.5-2, Normally open section switch 2 for reverse transfer flexibility
-9°2-10.2-11. Distribution lines a, b, c, d, e, f, g that are transmitted by the circuit breaker 1-1
, h.

1. Consists of an accident detection device 9 and control devices 7-1 to 7-15 for detecting accident sections of the respective section switches.

Conventionally, in the control method described in, for example, Japanese Patent Publication No. 57-43021, when an accident occurs on the distribution line d, an accident detection signal is used to activate the circuit breaker 1-1 of the substation SS.
tripped, and after waiting for circuit breaker 1-1 to restart, section switches 2-1, 2-2 were closed in sequence from the power supply side, and then section switch 2-3 was used to close the fault section. The fault zone d is determined by tripping the circuit breaker 1-1 again.

As a result, power supply reliability has been improved by reducing and shortening the one-hour accidental power outage range.

Problems to be Solved by the Invention] However, in the case of this conventional method, the circuit breaker 1-1
After tripping, the fault section is detected by reopening circuit breaker 1-1, and power is transmitted only to the healthy section by closing circuit breaker 1-1 again, and the sections a and b on the power supply side of the fault section are connected.

Power is transmitted to C11 from distribution line 1-1, and then load 1
Distribution line 1 is installed in sections e, f, g, and h of 111.
-4. From 1-5, it was necessary to provide reverse transportation flexibility. In the above method, sections a, b, c, other than accident section d,
e, f, g.

As for power outages h and l, they are also causing problems in stable power supply due to long-term power outages.

In recent years, with the advancement of OA and FA, and the transformation into a highly information-oriented society, even a short power outage has a large impact on society, resulting in higher quality products.

There is a growing demand for highly reliable power supplies.

This demand cannot be met with the functionality and performance of the conventional DM system, which involves one or two short power outages from the occurrence of an accident to the distribution of power to healthy sections, and requires the development of a new accident handling method. There is.

The present invention has been made in view of such social demands, and is designed to quickly detect an accident zone and generate a ground fault direction signal for determining whether or not it is within a protected zone. The purpose is to provide relays.

[Means for solving problems]

In order to achieve this purpose, the relay for detecting a ground fault fault section of a distribution line of the present invention is applicable to a distribution substation busbar, a distribution circuit breaker, a fault detection device 1 section switch, and a normally open relay for performing reverse power interchange power transmission. In a power distribution system consisting of sectional switches and wires that connect them, when an accident occurs on the power supply side, based on the level and phase of the zero-sequence voltage and zero-sequence current of the high-voltage distribution line at the installation point of the sectional switch. Signal IA that turns on
.

Signal I8. which turns on when there is an accident on the load side. Similarly, signal 04 turns on when there is an accident on the load side and turns on before the signal 8 operates, and signal 04 turns on when there is an accident on the power supply side and turns on before the signal IA operates. The present invention is characterized in that it is configured to generate four signals, ie, signals OB.

Embodiments] The present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 4 is a block diagram showing a part of the configuration of a distribution line accident section detection system to which the present invention is applied. In the figure, IOA and IOB are substations of different systems, respectively.
-1. ..., 20-3 is a normally closed sectional switch that is normally turned on for the transmission 7 from the substation 10A.

Reference numeral 20-4 is a normally open section switch that is normally open, but is turned on whenever power transmission from another substation 10B, that is, reverse power interchange transmission is required. Each section switch 20-1 to 20-
4 includes controllers 30-1 to 30-4 that control the closing of each switch and have a function of automatically detecting and disconnecting the fault section when sequentially closing, an overcurrent detector, a ground fault direction relay, and a master station. By monitoring the zero-sequence current and zero-sequence voltage of the distribution line at the point where the sectional switch is installed, the system is equipped with a communication circuit with Relay slave stations 40-1 to 40-4 having a function of detecting whether the controller 30-1
- 30-4 and relay slave stations 40-1 to 40-4 to close and open each section switch 20-1 to 20-4. The master station 50 and each relay slave station 40-1 to 40-4 are connected by a communication and transfer input cable 60, and the relay slave stations at adjacent section switch installation locations are
They are connected by a ground fault section detection cable 70.

FIG. 1 shows an example of the configuration of relay slave stations 40 installed in each of the section switches 20-1 to 20-4. A zero-phase current transformer ZCT, a zero-phase voltage detector ZPD, and an overcurrent detection current transformer CT for overcurrent locking are installed on the distribution line. Waveform shaping circuit 81. The zero-phase voltage detection/waveform shaping circuit 82 and the overcurrent detection/waveform shaping circuit 83 are manually operated. The output lci of these circuits 81, 82, and 83 is output as a digital signal for digital processing by a microcomputer. Each signal is input to the CPU 85 through the input interface 84 . The CPU 85 detects the levels of the zero-sequence current and zero-sequence voltage, and uses the phase of the zero-sequence current and zero-sequence voltage to determine whether a ground fault is occurring on the power supply side for each section switch installation location. It determines whether it is on the load side and outputs this as a ground fault occurrence direction signal. below,
A for the power supply side for a certain sectional switch.

The load side will be called B.

In this embodiment, the ground fault occurrence direction signals include a direction signal ■□ indicating that the ground fault is on the A side, and a direction signal 111 . Four signals are output as energizing signals for each relay: a direction signal OA indicating that it is not on the A side, and a direction signal O6 indicating that it is not on the B side. Here, IA and OR
, In and OA are signals that are output under the same conditions, but the latter is set to have a lower operating level than the former, and the sensitivity is set so that it operates faster. . In Figure 1, 86 is the CPU
, 85 is a ROM that stores operating programs, 87 is a human output interface, and 88 and 89 are controllers 30, respectively.
A switch open signal and a switch close signal are respectively provided from the CPU 85 via an input/output interface 87 to a switch open circuit and a switch close circuit built in the switch.

90 is a logic circuit for detecting a ground fault section; 91 is a rewritable ROM, which is a nonvolatile external memory for storing operating level setting values such as zero-sequence current and zero-sequence voltage; and 92 is a pair of This is a communication circuit that communicates with the master station via a communication line and outputs a normally open sectional switch closure command signal in the event of a ground fault. The ground fault section detection logic circuit 90 performs ground fault section detection by transmitting and receiving its own ground fault direction signal and the ground fault direction signal of an adjacent section switch, and issues a ground fault section detection signal.

FIG. 2 shows a method of connecting a relay slave station equipped with such a function of outputting a ground fault signal.

Here, connections of relay circuits in three section switches 20-1 to 20-3 connected to the second section of the power distribution line are shown. Each relay slave station is connected by a pair of signal cables 70. Paying attention to the connections in the second section, the B side signal of section switch 20-1, section switch 20-2
The input side signal of the section switch 20-3 and the A side signal of the section switch 20-3 are connected by a relay sequence circuit. In this circuit, FAI and Pst (+ = 1.2.3) each indicate a DC constant current power supply. When a DC constant current power source is installed on an actual distribution line, the distance between sectional switches is 1 to 2 km.

Signal transmission and reception over such long distances is greatly affected by the resistance of the signal line, and in general constant voltage power supplies, problems occur due to voltage drop sections. Therefore, in this embodiment, a constant current power supply is used to supply a constant current even if the resistance of the signal line increases, so that signals can be reliably exchanged.

If a ground fault occurs in the second section of the distribution line, as explained in the block diagram of Fig. 1, the relay slave station 40-1 of the sectional switch 20-1 will detect the fault in the B direction. Therefore, relay contacts 1111 and O
A+ closes. At the same time, regarding section switch 20-2, since the accident occurred in six directions, IA2 and 0112
closes. Furthermore, regarding the relay slave station of the section switch 2o-3, tA3 and OR3 are similarly closed. Contact 11
+1. IA2 and IA3 are closed, trip relays for each section switch T B I I T A 2 and IA
3 is excited by the constant current power supplies Pad, PA2 and pa3, and the section switches 20-1, 20-2 and 20-
3 is released. In this case, if any one of contacts 1811 1A2 and IA3 closes, trip relay T B
+, TA2 and TAj are all excited,
Power supplies PBl+ PA2 and PA3 are each set to be able to supply excitation current to all of the trip relays.

Generally, the power supplies FBI and FAI are set so that they can simultaneously supply the excitation current of the trip relay in the relay circuit in which these power supplies are inserted.

Next, assuming that a ground fault has occurred in the first section of the distribution line, in this case, the fault is on the A side of the sectional switch 20-1, and the -3), it is still an accident on the A side.

Therefore, in the relay slave station of section switch 1120-1, relay contacts +A, , 1 and 0Ill are closed, and for section switch 20-2, IA2 and OB 2 are closed, and furthermore, section switch 20-3's Regarding relay slave stations, TA3 and ○R3 are closed. At this time, as explained earlier, the O contact is set to have higher sensitivity and operate faster than the I contact, so the contacts IA2 and I
Contact On + will close before A3 closes.

Therefore, even if contacts rA2 and IA3 are subsequently closed, the power supply circuit of the relay circuit is short-circuited, so that
Prelays TRI, TA2 and TA3 are not energized.

Therefore, the section switches 20-2 and 20-3 will not be opened. On the other hand, the section switch 20-1 is opened by closing the contact IAI.

In this way, only the section switch connected to the section where the ground fault occurred is opened, and other sections, that is, healthy sections, are not affected.

The above operation can be expressed as a logical formula as follows.

(In + + IA2 + Iks)・(Oat +
OAm 10A3) In addition, the operation status of direction signals in response to accidents in each section is as follows.

A power distribution system that uses the relay of the present invention to achieve uninterrupted power in a healthy section by reverse power interchange prior to disconnection of the faulty section will be described. In the explanation of Figure 2,
If a ground fault occurs in the second section, the sectional switch 20-
1. 20-2 and 20-3 are open, and power transmission from the power supply side seems to be stopped in the third section, but the third section and the fourth section, which is the B side of the section switch 20-3, In this case, prior to disconnection of the faulty section, interchange power transmission from other power distribution systems will be carried out.

As shown in Fig. 3, when a ground fault occurs in the second section, the relay slave stations of the sectional switch 20-1 are connected to the relay slave stations of the normally open sectional switches 21-1 and 21-2. , the setting is made so that a closing command signal is transmitted through the communication line 60 (see FIG. 4). As a result, the normally open section switch 21
-1 and 21-2 are turned on to perform reverse power interchange power transmission for the third section and the fourth section. Then, as described above, the section switches 20-1, 20-2 and 20-3 are opened to separate the second section. Generally, when a ground fault occurs, the circuit breaker in that system shuts off, but by closing the normally open section switch and disconnecting the fault section within the circuit breaker's trip time, for example, 1 second. , it becomes possible to disconnect the accident section without tripping the circuit breaker.

Therefore, even if a ground fault occurs, it is possible to continue power distribution without causing a power outage to the healthy section X.

According to statistics, 80-90% of power outage accidents are ground faults.
Since short circuit accidents are rare, by implementing uninterruptible measures against ground fault accidents as in the present invention, it is possible to eliminate power outages in healthy sections in response to most accidents.

[Effects of the Invention] As described above, in the present invention, when a ground fault occurs, four ground fault occurrence direction signals are output for separating the fault section. By using this signal, it becomes possible to detect the accident section, and it is possible to quickly carry out reverse power transfer or disconnection of the accident section after the occurrence of an accident. Therefore, the quality of power supply can be improved.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an embodiment of the present invention, Figure 2 is a circuit diagram showing the configuration of a fault section detection circuit using the relay of the present invention, and Figure 3 is a diagram of a power distribution system incorporating the relay of the present invention. FIG. 4 is a block diagram showing a part of the configuration of a distribution line fault section detection system to which the present invention is applied, and FIG. 5 is a block diagram of a conventional DM type power distribution system. 10A, IOB: Substation 20-1 to 20-3: Division switch 20-4: Normally open division switch 30-1 to 30-4: Earth fault direction relay 40-1 to 40
-4: Relay slave station 50: Master station 60: Ground fault section detection cable 81: Zero-phase current detection/waveform shaping circuit 82: Zero-phase voltage detection/waveform shaping circuit 83: Overcurrent detection/waveform shaping circuit 84, 87 :I/O interface 85 :CP
U86: ROM88: Switch opening circuit 89: Switch closing circuit 90: Ground fault section detection logic circuit 91: ROM

Claims (1)

[Claims] 1. Distribution substation busbar, distribution circuit breaker, fault detection device,
In a power distribution system consisting of a sectional switch, a normally open sectional switch for performing reverse power interchange transmission, and the wires that connect them, the level of zero-sequence voltage and zero-sequence current of the high-voltage distribution line at the installation point of the sectional switch. and the phase, the signal I_A is turned on when there is a fault on the power supply side, the signal I_B is turned on when there is a fault on the load side, and the signal I_B is turned on when there is a fault on the load side. Signal I_
It is characterized by a configuration in which four signals are generated: a signal O_A that is turned on before the signal I_A operates, and a signal O_B that is turned on when there is an accident on the power supply side and is turned on before the signal I_A operates. A relay for detecting ground fault fault sections of distribution lines.