Method for determining incomplete phase of circuit breaker by using phase difference between port voltages

Abstract

The invention discloses a method for determining incomplete phase of a circuit breaker by using phase difference between port voltages. The method comprises the following steps of measuring three-phase voltages on two sides of the circuit breaker by using a circuit breaker protecting device; respectively calculating fundamental wave phase difference between voltages on two sides of the circuit breaker and effective values; determining the incomplete phase of the circuit breaker when the phase voltages on the two sides of the circuit breaker are greater than nominal voltage by 80%-90% and the port voltage of a certain phase or the phase difference between the port voltages of the two phases is greater than a set angle; and alarming or tripping after a short delayed time (t). By the method, the problem that the traditional negative-sequence current criterion cannot identify incomplete phase during incomplete phase of the circuit breaker under the condition of light load can be solved. Moreover, the method is suitable for a three-phase linkage circuit breaker without the aid of a joint with three different phases.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power systems, and in particular relates to a method for judging the non-full phase of a circuit breaker by using the phase difference between port voltages and a corresponding relay protection device or monitoring device. Background technique [0002] At present, the non-full-phase protection of circuit breakers widely used in the field is generally composed of three-phase inconsistent contacts and negative sequence current criteria. Very small, it is difficult to exceed the negative sequence current setting value, and it is impossible to judge that the circuit breaker is not in full phase. Generator machine-side circuit breakers are generally three-phase linkage, do not provide three-phase inconsistent contacts, and cannot adopt traditional non-full-phase protection. There have been many accidents in the field where one-phase tie rod of the machine-side circuit breaker broke and cause...

AI Technical Summary

Problems solved by technology

[0003] The main purpose of the present invention is to provide a method for judging the non-full phase of the circuit breaker at the generator end by using the phase difference between the port voltages, which does not depend on the magnitude of the negative sequence current, and solves the problem of non-full phase of the circuit breaker under light load. It solves the problem that the negative sequence current criterion cannot be identified in the past. In addition, because the method of the present invention does not require three-phase inconsistent contacts of the circuit breaker, it also solves the non-full-phase discrimination problem of the three-phase linkage circuit breaker

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