SU1365221A1 - Arrangement for protecting against inter-phase shorts in a three-phase power line - Google Patents

Description

(21) 3771172 / 24-07

(22) 07.13.84

(46) 07.01.88. № 1

(71) North-West Branch of the All-Union State Design and Survey and Research Institute of Energy Systems and Electric Networks Energostroyproject

(72) G.A. Eskin and E.N. Pršisovsky (53) 621.316.925 (088.8)

(56) Fedoseev A.M. Relayn protection of electrical systems.- M .: Energie, 1976, p.213, fig.4-26.

In the same place, p.452, fig.9-386.

(54) DEVICE FOR PROTECTION AGAINST INTERMEDIATE SHORT CIRCUIT OF A THREE-PHASE ELECTRICAL TRANSMISSION LINE

(57) The invention relates to electrical engineering. The purpose of the invention is to increase the reliability of power line protection with one-sided power by increasing the sensitive protection when short-circuited by a low-power transformer of a branch substation. This is achieved by the fact that a second power relay, Y., is introduced. Both the power direction 9 and IO relays or the negative sequence filter relays 11 are activated in the network, which switch off the intermediate relay 12 with their contacts. This relay starts the time relay 13, which turns on the switch. sensible relay and gives the command to turn off the device 4 il.

Sh

W

Hff Sb / ffjffcvff / ne jf S FIG.

on the power side - M Upl Sin (cf + 20

The relays 9 and 10 of the power direction react to a change in the phase angle between current and voltage and are set up in such a way that they do not work to a certain (boundary) angle between current and voltage, and when this angle passes, they begin to work.

When the first and second power direction relays 9 and O are working together, the zone of action is within the boundary angles, for example 45-160.

In the event of a short circuit on the supply line or behind the transformer 5 or 4 branch substations, the current vector passes into the angle range between 45 and 90, both relays 9 and 10 of the power direction trigger and close the circuit to trip protection

one

The invention relates to the field of relay protection and can be used to protect power lines from phase-to-phase short-circuits of scientific research institutes behind low-power transformers of branch stations.

 The purpose of the invention is to increase the reliability of power line protection by increasing the sensitivity of protection during a short circuit behind a low-power transformer of the answering substation.

Figure 1 shows a schematic diagram of a transmission line with response substations; figure 2 - diagram of the current circuit protection; FIG. 3 is a circuit of protection voltage circuits; in fig. 4 is a diagram of the operational protection circuits.

The device for protection of the transmission line against phase-to-phase short-circuits comprises a transmission line 1, a supply substation 2, a branch substation with two-wound transformers 3 and 4, a branch substation with a three-winding transformer 5, switches 6, current transformers 7, voltage transformers 8, the first and second relays 9 and 10 of the power directions and the filter-relay 11 of the negative sequence current, the intermediate relay 12, the time relay 13, the actuator 14 relays and the overlay 15. The power direction relay 9 has the characteristics ISTIC srabatshani type M U, IpSin (), and the relay 10

.

AND

Iq

- 20

3652212

In other modes, for example, when generating engine power in the event of damage to the supply part of the system, one or both of the relays 9 and 10 of the power direction do not trigger and block the protection.

As a starting body with two-phase short circuits behind transformers 4 and 5, a coupler is. A reverse sequence current relay 11, for example, of the RTF-1 or RT-2 type is provided in the KRB-126 device.

This relay does not respond to load currents and does not work in case of three-phase short-circuits and therefore it can be received with any degree of sensitivity over current.

In order to prevent the protection shields from starting up of the load motors of the branch substations, the protection time delay (time relay 13) is longer than the duration of the start-up of the indicated motors in the most unfavorable conditions.

Device to protect the transmission line from phase-to-phase short circuits works as follows.

In case of short circuits in the network or behind transformers 3,4 or 5, depending on the type of short circuit, both relays 9 and 10 of the power direction or the reverse-order filter-relay 11 operate and switch on intermediate relay 12 with their contacts. This relay starts relays 13 with its contacts time, which closes its contact with a predetermined time delay and through a pointer relay. I4 and pad 15 sends a command to turn off switch 6, thereby achieving its goal.

25

thirty

35

40

45

Claims (1)

Invention Formula Device for protection against phase-to-phase short-circuit of a three-phase transmission line, containing the first power direction relay with the characteristic of operation of type M Up I., Sint | - 45) and with current and voltage coils, reverse current filter-relay, intermediate relay, time relay, indicating relay and pad with outputs for their inclusion in the corresponding circuits, contact of the reverse-sequence current relay is included in the coil circuit of the intermediate relay, the contact of which is included in the coil circuit of the time relay, and the contact of the latter through the coil of the indicating relay and the pad, connected in series, is included in the disconnection circuit of the protected power line, which differs from Ensuring the reliability of power line protection by increasing the sensitivity of protection in case of a short circuit behind a low-power transformer of the branch substation, a second power direction relay with a type M response characteristic was additionally introduced into it. S 671 6 365221 u - is, four , 0 Up IpSin (if + 20), the current coils of the first and second power direction relays are connected in series with their outputs and included in the current circuit of one phase, the input terminals of the reverse-order filter relay are included in the current circuits of the three phases of the protected line, the voltage coils of both the power direction relays are connected to each other in parallel and, with their switches, are connected to the voltage circuit of the same phase in which their current coils are connected, in addition, the contacts of the first and second power direction relays are connected in series and in lyucheny parallel to said relay contact-filter feedback current. (rig.1 ig.2 f (dffyii / ff ZOSHCH1 / mo / /