SU561250A1 - Device for differential protection of parallel power lines - Google Patents

Description

one

The proposed differential protection of parallel power lines can be used in electrical installations, in particular, for relay protection of parallel power lines of small length.

Known transverse differential protection 1 and differential-phase high-frequency; protection 2.

Prototitt of this device. Bp ets longitudinal differential protection of lines of type D31L-1 3J.

Considering that basically these lines are performed in double-circuit design, the main disadvantage of such protections is the requirement to install on each side of parallel lines at least two protection packages when using also two pairs of communication lines between adjoining substations, which increases the cost of using Such sewn, and the use of cross sewn eliminates the presence of basic protection when one of the lines is disconnected.

The object of the present invention is to simplify the device by combining the half-sets of longitudinal cpc protection to reduce their number and the number of auxiliary communication wires while maintaining the protection in the disconnection mode of one of the power lines.

This goal is achieved by additionally adding additional balanced turnouts to the difference of individual currents of each line, connected to specified current transformers through extractors, a magnetoelectric (polarized) relay, connected through the specified coupling capacitor and an isolating transformer to a semi-set longitudinal differential protectors, their repeaters, and a capacitor connected in parallel to the communication wires through, the contacts of the indicated repeaters.

The drawing shows a differential protection device ..

Semi-set, 1 differentiated $ 1 differential protection 1 is included for the sum of parallel currents; AT

The secondary circuit of its isolating transformer 2 and the separation capacitor 3 is connected to the coil of a sensitive magnetoelectric relay 4, and the balanced relay 5 is connected to the difference of rectified individual currents of each line. From operational circuits of protection 1, the contacts of both relays are fed in pairs with interlocking coils of relay repeaters 6 and 7, which are separated by a closing contact from the same operational circuits 8. The capacitor 8 is connected to the communication cable 9 the same repeater relays 6 and 7, which also close the disconnecting circuit of the corresponding switch of power lines, on the opposite side of which to the cable O, a similar protection half set is connected.

If a short circuit occurs on any of the parallel protected power lines, both semi-sets of longitudinal differential protection 1 are triggered. Depending on which of the parallel lines is damaged, balanced relay 5 closes the corresponding power supply circuit of the repeaters 6 or 7. As a result which causes the protection to trip, the switch that feeds the damaged line.

If a short circuit occurs at the end of one of the lines, when the difference of the currents does not ensure the operation of the balanced relay 5, then in such cases a similar relay is guaranteed to work on the opposite side. When a balanced relay 5 of the opposite half-set triggers with a corresponding repeater 6 or 7, a separate capacitor 8 is connected with a certain polarity to the wires of a communication cable 9, the discharge pulse of a separate capacitor 8 to separation capacitors 3 on both sides causes their directional operation the magnetoelectric relays 4, which actuate the corresponding relay repeaters 6 or 7, thereby unambiguously determining that the damaged line was pushed from the point of short circuit.

The magnetoelectric relay 4 from the direct current of the control circuit does not work, since its circulation is excluded by the coupling capacitor 3, and from the alternating current protection of the relay 4 is tuned by the inertia of its operation and the sensitivity of the pickup setting. In the disconnection mode of one of the lines, the protection of the balanced relays 5 against the load current or short-circuit current is unambiguously oriented to disconnect the active line if it is damaged. , In case of external short circuit, the half-sets of the longitudinal differential protection 1 do not fail, the balanced relays 5 are also removed, therefore the protection in general does not work.

When two-sided power is supplied when DSCHIH1 of substations is dug, the protection operates mainly without any delay, except for the dead zones of the GOT balanced relays, where the cascade action of the relay equipment of one side occurs after it triggers on the other side, when the delay time is minimal. power supply at the substation with no power supply, a cascade protection action occurs after the switch is disconnected from the power side by the differential protection or back-up protection of the side without the source otkom aamykanii close to this side, that it is quite possible under the conditions of maintaining the stability of rabo1y generators and consumers. As a result, it would be necessary to operate all possible modes of operation of parallel power lines with a minimum number of semi-sets and communication cables.

The proposed invention is suitable for use in power systems that have parallel power lines for a short distance.

Claims (3)

1. Fedoseev A. M. Osnovy Relay cross-sectional differential protection is sewn, SEI, 1961 .. 2. Differential-phase high-frequency protection - in the reference book on relay protection, SEI, 1963. 3. Kuptsov V.M. Instructions on the adjustment and verification of the longitudinal differential protection of the lines DZL-1, Energii, 1972.