SU970540A1 - Device for longitudinal differential protection of power transmission line - Google Patents

Description

The invention relates to electrical engineering, in particular to devices for * longitudinal differential protection of a power line.

Known longitudinal differential protection of the power line, containing connecting wires, and two half-sets installed at the ends of the protected line and containing a current filter connected to line current transformers, an intermediate transformer, a differential relay, a control unit 'and an isolation transformer C1J') The disadvantage of this device is the impossibility of using it to disconnect the line from the web. parties during short circuiting on substation buses, line breaker failure and operation of the device for redundancy in case of circuit breaker failure (CBD).

Closest to the proposed is the longitudinal differential protection of the power line, containing connecting wires And two half-sets installed at the ends of the line and containing a current filter connected to the line current transformers, an intermediate \ transformer, a differential relay ^ control unit, an isolation transformer and an intermediate relay, a winding which is connected to the output of the residual current device, and the disconnecting contacts into the circuit of the connecting wires.

This device allows you to ensure the deviation of the line from all sides with a short circuit on the substation tires, failure of the line switch and the operation of the URO [2].

A disadvantage of the known device is the need to withdraw from the action of the control unit during the operation of the CBD, which reduces the reliability of the longitudinal differential protection and complicates its scheme.

The purpose of the invention is to increase the reliability of the longitudinal differential protection of the power line.

This goal is achieved by the fact that in the device for longitudinal differential-phase protection of the power line, containing connecting wires and two half-sets, each of which contains a measuring and reacting unit, including a current filter, an intermediate transformer and a differential relay, moreover, the input of the measuring-reacting unit is designed to be connected to line current transformers, and the output is functionally connected to an isolation transformer, a control unit 5 connected to an isolation transformer a transformer, an intermediate relay, the winding leads of which are designed to be connected to the output circuits of the redundancy device 10 in case of circuit breakers failure, the intermediate relay is equipped with switching contacts connected between the output of the measuring and reacting unit, and the primary winding of the isolation transformer 15, and the disconnecting contacts connect unipolar the outputs of the measuring-reacting block and the primary winding of the isolation transformer, and jq shorting - bipolar conclusions.

The drawing shows a schematic diagram of a device.

The device contains two half-sets 1 and connecting wires 2. Each half-set contains a measuring and reacting block 3, which includes a current filter, an intermediate transformer and a differential relay ^ connected to current transformers 4 installed on the protected line 5. The output of the measuring and reacting block is connected to the primary winding of the isolation transformer 6 through the switching contacts with the loss-free switching 7 of the intermediate-35 relay 8, the winding of which is connected to the output of the unit 9 UROV installed on substation tires 10.. The control transformer 11 is also connected to an isolation transformer. Switching contacts 7 provide a change in the polarity of the connection of the output of the measuring and responding unit to the isolation transformer when the residual current device trips, which is perceived by the protection as an emergency mode, triggering the protection and disconnecting the line from all sides.

The device operates as follows.

, For all short circuits;

not accompanied by a failure of the switch and the operation of the residual current device, the output of the measuring and reacting unit 3 is connected to the primary winding of the isolation transformer 6 through switching contacts 7 with the same polarity. In this case, the device operates as a well-known longitudinal differential55 unit protection.

In the event of a short circuit on the busbars of the substation 10 and a failure of the line circuit breaker, the URF unit is activated, supplying a signal to the winding of the intermediate relay ¹ 8. The relay is activated and by its switching contacts 7 changes the polarity of the output of the measuring and reacting unit 3 to the primary winding of the isolation transformer b, which It is perceived by protection as a short circuit in the protection zone and provides a disconnection of the line from all sides.

The proposed device, having increased reliability ^ in comparison with the known ones, provides reliable shutdown of the line from all sides during a short circuit on the substation tires ^ failure of the line switch and operation of the CBD.

Claims (2)

transformer and differential relay, the input of the measuring and reacting unit is designed to be connected to line current transformers, and the output is functionally connected to an isolating transformer, a control unit connected to an isolating transformer, an intermediate relay, the winding pins of which are intended to be connected to output circuits m backup device in case of failure of the switches, the intermediate relay is energized by switching contacts connected between the output of the measuring-response unit and the primary The main winding of the isolation transformer, moreover, the opening contacts interconnect the unipolar outputs of the measuring response unit and the primary winding of the insulating transformer, and the shorting leads of different polarities. The drawing shows a schematic diagram of the device. The device contains two semi-sets 1 and connecting wires 2. Each semi-set contains a measuring-responding unit 3, including a current filter, an intermediate transformer, and a differential relay connected to current transformers 4 installed on the protected line 5. Output of the measuring-responding unit connected to the primary winding of the isolation transformer 6 via switching contacts with continuous switching 7 of intermediate relay 8, the winding of which is connected to the output of the breaker failure protection unit 9 installed on substation tires 10.. The control unit 11 is also connected to the isolating transformer. The switching contacts 7 provide a change in the polarity of the connection of the output of the measuring-response unit to the isolating transformer when the breaker actuates, which is perceived as emergency mode, triggers the protection and turns off the line from all sides. The device works as follows. Driving all short-circuits x that are not accompanied by a failure of the switch and the LEVEL operation, the output of the measuring unit 3 is connected to the primary winding of the insulating trans Φ) Armature 6 through a switch of KonT1 & KTA 7 with the same polarity. The device thus works as a known longitudinal differential protection. In case of short circuit on buses of substation 10 and failure of the line breaker, the Breakdown Unit is activated, giving a signal to the winding of the intermediate relay 8. The relay operates and its switching contacts 7 changes the polarity of connecting the output of the measuring-responsive block 3 to the primary winding of the isolation transformer 6, which is perceived by the protection as a short circuit in the protection zone and ensures disconnection of the line from all sides. The proposed device, possessing increased reliability compared to the known ones, ensures reliable disconnection of the line from all sides during short circuiting on substation buses, Q line breaker failure, and LEVER operation. Apparatus of the Invention A device for longitudinal differential protection of a line electr-. Reducers containing connecting wires and two half sets, each of which contains a measuring-responsive unit, including a current filter, an intermediate transformer and a differential relay, the input of the measuring-reacting unit being connected to line current transformers, and the output is functionally connected to an isolating transformer , a control unit connected to an isolating transformer, an intermediate relay, the winding leads of which are intended to be connected to the output circuits of the cut device in case of failure of switches, characterized in that, in order to increase reliability, the intermediate relay is equipped with switching contacts connected between the output of the measuring and reacting unit to the primary winding of the isolation transformer, and the opening contacts are interconnected by one-pole output terminals of the measuring-responding the block and the primary winding of the isolation transformer, and the closing opposite-polar outputs. Sources of information taken into account in the examination 1. Instructions before installing and checking the longitudinal differential protection of lines DZL-1. M., Energie, 1972, p. З-г-5. 2. Guidelines for relay protection. Backup devices in case of 35-500 kV breakers failure. Energy, issue. 6, 1966, p. 7 D i " V " -fi