Relay protection method for dead-zone faults of voltage transformers on basis of starting at switching positions and sealed current transformers TA

Abstract

The invention relates to a relay protection method for dead-zone faults of voltage transformers on the basis of starting at switching positions and sealed current transformers TA. The relay protection method includes setting four conditions during tripping control for the dead-zone faults on certain sides of the voltage transformers; enabling the differential protection current transformers TA on the certain sides of the voltage transformers to withdraw after time delay elapses if the conditions are met; accessing the transformer differential protection current transformers TA on the sides of the voltage transformers after the time of 0s elapses if an optional condition is not met. The first condition includes that local-side backup protection current elements for removing side circuit breakers of the voltage transformers are started; the second condition includes that the side circuit breakers of the voltage transformers are located at opening positions; the third condition includes that primary pulse T-time opening protection is started if the first condition and the second condition are met; the fourth condition includes that A-phase or B-phase or C-phase currents of the certain sides of the voltage transformers reach starting values or zero-sequence currents Io or negative-sequence currents I2 reach starting values. The relay protection method has the advantages of simple action principle, high reliability and capability of quickly removing the various voltage grades of dead-zone faults of various sides of the voltage transformers.

Description

technical field [0001] The invention belongs to the control technology of electric power transmission and distribution network, and relates to a transformer dead zone fault relay protection method based on switch position starting and closing TA. 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 equ...

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 fixed value, the fault cannot be removed. Only when the transformer is burned to the point where the short-circuit current reaches and exceeds the start-up value of the backup protection can the backup protection on the power supply side of the transformer be activated to remove the fault.

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