RU2536168C2 - Method for determining place of occurrence of single phase-to-earth fault for overhead transmission lines in networks with insulated neutral - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method consists in control of voltage on buses of a distributing device and installation on supports of overhead transmission lines of recorders for signalling of current flow of single phase-to-earth fault; with that, phase voltage is controlled on buses of the distributing device; recorders are provided with a control and signalling unit (CSU), a current-limiting resistor and a high-voltage thyristor controlled with signals shaped with CSU, which are individual for each support of the overhead transmission line; with that, fact of current flow of single phase-to-earth via the support of the overhead transmission line is signalled as per a nature of variation of phase voltage on the buses of the distributing device, which is determined by individual repeated short-time shunting of the current-restricting resistor by means of a controlled high-voltage thyristor.

EFFECT: improving electric power supply reliability of consumers.

2 dwg

Description

The invention relates to electrical networks and is intended to identify supports with a single-phase earth fault (OZZ) overhead power line (VLEP) in distribution networks with insulated neutral.

A known method of determining supports with earth faults in distribution networks with isolated neutral, which consists in fixing the current of a double earth fault in the outgoing line with a stable OZZ. According to this method, when a zero sequence voltage appears on the buses, indicating the occurrence of an SCR, one of the phases is switched on to earth through a current-limiting resistance. With an increase in current at any connection, it is identified as a connection with an OZZ and a shutdown is performed. According to this method, OZZ current recorders are installed on the VLEP supports, providing visual alarm, upon detection of which the visiting team determines the support and repairs it (RF patent No. 2317624) [1].

The disadvantage of this method is to reduce the reliability of power supply to consumers by disconnecting the connection. Disabling VLEP for the entire time the OZZ is detected contradicts the logic of using networks with isolated neutral, according to which the OZZ is not an emergency mode and does not require immediate disconnection of consumers. In addition, for the detection of indicating indications of registrars installed on the VLEP pylons, departure of attendants is necessary.

The objective of the invention is to increase the reliability of power supply to consumers by automating the process of finding support with OZZ and reducing the time of violation of power supply to consumers.

This problem is achieved due to the fact that in the known method for determining the occurrence of a single-phase earth fault for overhead power lines in networks with isolated neutral, which consists in monitoring the voltage on the busbars of the switchgear and installing recorders on the VLEP supports for signaling the flow of current OZZ, according to the invention, they are controlled phase voltage on the buses of the switchgear, the recorders are equipped with a control and signaling unit (BCS), current-limiting resistance a phenomenon and a high-voltage thyristor, controlled by signals generated by the BCS, individual for each VLEP support, while the fact that the OZZ current flows through the VLEP support is signaled remotely, by the nature of the phase voltage change on the busbars of the switchgear, due to individual repeated short-time shunting of the current-limiting resistance by means of a controlled high-voltage thyristor.

The operation of the invention is illustrated by drawings, in which Fig. 1 shows a single-line electrical diagram of a distribution network, and Fig. 2 is a circuit diagram of an OZZ current flow recorder.

The single-line electrical circuit of the distribution network contains: a power transformer 1, a voltage measuring transformer (VT) 2, an insulation monitoring device (UKI) 3, a switchgear (RU) 4, two outgoing feeders f.1 and f.2, supports with current flow recorders ZNZ.

The circuit diagram of the ZNZ current flow recorder contains: VLEP I1-I3 support insulators, a control and signaling unit (BCS) 5, a high-voltage thyristor 6, a current-limiting resistance 7.

The proposed method works as follows.

When the insulation of the support is broken, voltage appears on the grounding conductor. BCS 5 generates a signal consisting of a series of consecutive pulses aimed at opening and closing the high-voltage thyristor 6. The high-voltage thyristor 6, when opened, shunts the current-limiting resistance 7. The voltage between the ground and undamaged phases increases. When closing the high-voltage thyristor 6, the shunt disappears, the circuit occurs through the current-limiting resistance 7, the phase voltage relative to the ground decreases. The combination of openings, temporary pauses and closures is individually programmed for each BCS and is not repeated on any support.

For each device, the program is set in such a way that first there is the number of pulses indicating the feeder number, then a pause, then the number of pulses indicating the support. Impulses are indicated by a sign (+), pauses (-).

Remote fixation of the flow of current OZZ is carried out by an ultrashort pulse, which is a specialized microprocessor controller. Having counted the number of voltage surges and pauses between them, the USP calculates the feeder and support with damaged insulation, after which the service personnel of the transformer substation are notified with hardware alarm equipment, or when the USP is equipped with tele-signaling devices, a signal is transmitted to the control room.

For example, in case of an OZZ on a support No. 1 of the first feeder, the combination has the form: + - +.

When OZZ, on the support No. 7/1 of the second feeder: ++ - +++++++ - +, two throws indicate the second feeder, after a pause seven throws indicate the number of the support, the second pause is a branch on the seventh support, the last throw - number after the branch.

The proposed method allows you to remotely and reliably determine the occurrence of a single-phase earth fault in networks with isolated neutral, which allows you to abandon the traditional, field search emergency elements of high-voltage lines and quickly eliminate all technological defects and violations on high-voltage lines associated with OZZ, which contributes to a significant increase reliability of power supply to consumers through networks with isolated neutral.

Claims (1)

The method of determining the occurrence of a single-phase earth fault (OZZ) for overhead power lines (VLEP) in networks with isolated neutral, which consists in monitoring the voltage on the buses of the switchgear and installing on the poles of the VLEP registrars for signaling the flow of current OZZ, characterized in that they control the phase voltage on the buses of the switchgear, the recorders are equipped with a control and signaling unit (BCS), current-limiting resistance and a high-voltage thyristor controlled by ignalami formed BCS, individual for each support VLEP, wherein the flow of the fact VLEP PTG bearing current signal for remotely changing the nature of the phase voltage busbar of the switchgear, caused by the individual intermittent shunting current limiting resistance managed by a high-voltage thyristor.

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