Relay protection method for clearing dead zone fault of transformer

Abstract

The invention relates to a relay protection method for clearing a dead zone fault of a transformer. The method comprises the following steps: setting the following conditions under the trip control of the dead zone fault at one side of the transformer: I, a breaker at the side of the transformer is located at an open position; II, phase-A current or phase-B current or phase-C current at the side of the transformer exceeds a set value, or zero-sequence current exceeds the set value or negative-sequence current exceeds the set value; delaying for a constant value when the two conditions are totally satisfied, and then, starting a transformer differential protection trip master exit loop, and starting breakers at all sides of the transformer, thereby rapidly clearing the dead zone fault of the transformer; and immediately returning when any of the two conditions is not satisfied, and interrupting the transformer differential protection trip master exit loop.

Description

technical field [0001] The invention belongs to the control technology of electric power transmission and distribution network, and relates to a relay protection method for fault removal in the dead zone of a transformer. Background technique [0002] GB / T14285-2006 "Technical Regulations for Relay Protection and Safety Automatic Devices" stipulates that the transformer should be equipped with longitudinal differential protection as the main protection and electrical protection such as backup protection for transformer overcurrent caused by external phase-to-phase short circuit and grounding short circuit, Among them, the backup protection for responding to phase-to-phase short circuit includes composite voltage overcurrent protection and phase-to-phase impedance protection, and the backup protection for responding to grounding short circuit includes zero-sequence current protection and grounding impedance protection. These backup protections are equipped with different back...

AI Technical Summary

Problems solved by technology

Since the fault is outside the protection range of the transformer longitudinal differential protection, although the backup protection or other protection (such as busbar protection) on the fault side operates to trip the circuit breaker on the side of the transformer, the fault still exists. The protection action or the backup protection action of this side is used to trip the general outlet circuit of the transformer and trip the circuit breaker on the power side of the transformer to finally remove the fault. In this case, the time to remove the fault is generally longer; Since the short-circuit current does not reach the start-up value, the fault cannot be removed. Only when the transformer is burned to the point that the short-circuit current reaches and exceeds the protection start-up value can the backup protection on the power supply side of the transformer be activated to remove the fault.

Although the invention patent ZL200810201305.3 "Relay Protection Method for Eliminating Transformer Dead-zone Faults" proposes a scheme to trip the circuit breakers on the other side of the transformer after judging the dead-zone fault, the time to remove the fault is still a little long, and it is only suitable for 110kV transformers

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