RU1811639C - System for protecting transformer (autotransformer) and its high voltage bus arrangement - Google Patents

Description

The invention relates to electrical engineering, in particular to relay protection of equipment of stations and substations. The system is intended as the main protection of the transformer (autotransformer) from internal damage and short circuits on the busbar between the high voltage terminals of the transformer and current transformers installed on the circuit breakers on the high voltage side.

The purpose of the invention is the expansion of the range of differential protection of the transformer with the inclusion of busbars of higher voltage and ensuring the selectivity of its action, under short circuit. in the transformer and on the bus.

In FIG. Figures 1, 2 and 3 respectively show a single-line connection diagram of the proposed transformer protection system and its high voltage bus, a circuit diagram of the operational circuits of the protection system and an explanatory diagram of the connection of the windings and contacts of the differential current relays.

The protection system of the transformer, and its busbar 2 high voltage, containing the differential protection unit of the transformer 1, including current transformers 3, 4, 5, 6, installed on all sides of the transformer 1, to the secondary windings of which are connected differential current relay 7 with make contacts 8 which are connected in parallel to the serial circuit with the winding of the first indicator relay 9 with the make contact 10 and the windings of the output intermittent relays 11 with the make contacts 12 and 13, this circuit is connected between the pin by the sources of the operating current source 14, two autoreclosing prohibition circuits 15 of the circuit breakers 16 and 17 of the higher voltage side, the alarm circuit 18 when damaged in the transformer, including the make contact 10 of the first indicator relay 9, the alarm circuit 19 when damaged on the high voltage bus, block reverse directional current protection, including current transformers 20 built into the high voltage terminals of transformer 1, and a voltage transformer (not shown) mounted on high voltage buses, to the secondary the reverse winding power direction relay is connected to the windings of these transformers with a follower relay with a closing contact 21, and the current transformers on the higher voltage side are designed to be installed in the circuit of the switches 16 and 17 of the high voltage busbar and the first intermediate relay 22 with a closing .contact 23 and two NC contacts: 24 and 25, the second intermediate relay 26 with a delay in operation with two NC contacts 27 and 28, the second indicator relay 29 with circuit contact 30 and opening contact 31, while the series-connected make contact 12 of one output intermediate relay 11 and the winding of the second intermediate relay 26 with a delay in operation are connected to the source 14 of the operational current, the series-connected make contact 13 of another output intermediate relay 11, make contact 21 relays is a repeater of the reverse direction power direction relay, in parallel with which the closing contact 23 of the first intermediate relay 22 is connected, w winding of the first relay relay 29 and the winding of the first intermediate relay 22 are connected to the operating current source 14, the make contact 27 (28) of the second intermediate relay with a delayed response and the make contact 24 (25) of the first intermediate relay 22 are connected in series to each AR inhibit circuit 15 circuit breakers 16 and 17 of the higher voltage side, in series with the make contact 10 of the first indicator relay 9, the opening contact 31 of the second indicator relay 29 is connected to the signal circuit 18 in case of damage in the transf rmator, make contact 30 of the second indicator relay 29 is connected to circuit 19

alarm in case of damage on bus 2 of the highest voltage. In FIG. 1 also shows switches 32 and 33 on the middle and lower voltage side of the transformer,

The protection system works as follows,

If damaged in transformer 1

the differential current relays 7 are activated, the contacts 8 of these relays are closed and the indicator relay 9 and the output intermediate relays-11 are triggered. In this case, commands are issued to turn off the switches 16, 17, 32 and 33 through the closing contacts (not shown in Fig.) Of the output intermediate relays 11. When the contacts 12 of the relay 11 are closed, the voltage is supplied to the winding of the intermediate relay 26. After the deceleration times relay 26 closes its contacts 27 and 28 in circuits 15 of the automatic reclosure inhibit circuit breakers 16 and 17 on the higher voltage side (the automatic reclosure inhibit circuits of switches 32 and 33 on the medium and low voltage sides are not shown in Fig.) .. When contact 10 of the indicator relay 9 occurs Picking the transformer damage signal circuit 18.

In case of damage on busbar 2 of the higher voltage, the relay 7.9 and trips. 11 and the closing of the contacts of these relays, as well as the operation of the reverse direction power direction relay and its repeater relay. When the contacts 13 of the output relay. 11 and contacts 21 of the repeater relay, the relay 29 and the intermediate relay 22 are activated.

contacts 24 and 25 of the intermediate relay 22 are open circuit 15 of the automatic reclosure prohibition of switches 16 and 17. When the contacts 21 of the indicator relay 29 are opened, the alarm signal circuit 18 in the transformer 1 is opened, and when the contacts 30 of the relay 29 are closed, the alarm signal circuit 19 on the bus 2 is closed higher voltage. .

When the contacts 23 relay 22

 its self-retention is ensured in case of a return to the initial position of the reverse direction power relay-relay and its repeater relay in case of a possible transition of asymmetric fault on the bus to three-phase.

Thus, the invention allows to expand the protected area of the differential protection of the transformer and provides selectivity of protection when short-circuit in the transformer and on the bus.

SUMMARY OF THE INVENTION A system for protecting a transformer (autotransformer) and its high voltage bus, comprising: a differential transformer protection unit including current transformers,

. mounted on all sides of the transformer, to the secondary windings of which are connected differential current relays with make contacts, which are connected in parallel to the serial circuit with the winding of the first indicator relay with make contact and windings of the output intermediate relays with make contacts, indicated circuit included between the findings of the source operational

.current, two automatic automatic restart (AR) inhibit circuits of the high voltage side circuit breakers, alarm circuit in case of damage in the transformer, including the make contact of the first indicator relay, alarm circuit for

Damage to the high voltage bus, reverse directional current protection unit, including current transformers integrated in the transformer higher voltage terminals, and a voltage transformer mounted on high voltage buses, a power direction relay is connected to the secondary windings of these transformers of the reverse sequence with a repeater relay with a closing contact, with the exception of the fact that, in order to expand the protected zone of the differential protection of the transformer with for prison in error iovki higher voltage and ensuring selectivity of its effect at short

short circuit in the transformer and on the bus, current transformers on the higher voltage side are designed to be installed in the circuit of the high voltage bus switches and additionally, the first intermediate relay with NO and two NC contacts is introduced, the second intermediate relay with a delay for tripping with two NO contacts, the second indicator relay with make and break contacts, while connected in series. The make contact of one output intermediate relay and the winding of the second the daily relay with a deceleration to the operation are connected to the source of operational current, serially connected the make contact of the other output intermediate relay, the make contact of the relay-repeater relay power direction reverse sequence, in parallel with which is made the make contact of the first intermediate relay, the winding of the second indicator relay and the winding of the first intermediate relay connected to a source of operational current, serially connected make contact of the second intermediate p with a deceleration of operation and the opening contact of the first intermediate relay are included in each ARB inhibit circuit of the higher voltage side circuit breakers, the opening contact of the second indicating relay is included in the alarm circuit in case of damage in the transformer in series with the closing contact of the second indicating relay, the closing contact of the second indicating relay is turned on to the alarm circuit in case of damage on the busbar of the higher voltage.

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