Fault indicator grounding fault judgment method

Abstract

The invention relates to a fault indicator grounding fault judgment method which includes the steps: firstly, setting an asymmetric current source for transmitting characteristic signals when a grounding fault happens; secondly, acquiring current signals on a circuit by a fault indicator, performing primary discrete Fourier transform for the current signals acquired by each cyclic wave, and obtaining fundamental wave current values of the current signals on the circuit; thirdly, taking fundamental wave current values I1 of n2 cyclic waves to form sequences a, performing primary discrete Fourier transform for the sequences a by each n2 cyclic wave, and obtaining fundamental wave current values I2 of the sequences a; fourthly, sequentially taking the fundamental wave current values I2 of n3 sequences a to form sequences b, and updating the sequences b every time T in a first-in first-out mode; fifthly, judging grounding faults of the fundamental wave current values in the sequences b. According to the technical scheme, the fault indicator grounding fault judgment method can overcome the shortcomings of the prior art, and selectivity, reliability and accuracy of single-phase grounding fault detection are ensured.

Description

technical field [0001] The invention relates to the technical field of single-phase ground fault detection in electric power systems, in particular to a method for judging the ground fault of a fault indicator. [0002] Background technique [0003] In small current grounding systems, the detection and location of single-phase ground faults have always been a technical difficulty in ensuring the normal operation of distribution networks. Accurately find out the section of the single-phase ground fault, which can avoid unnecessary switching operations on non-faulty areas and maintain the continuity of power supply. Since the fault indicator can indicate and report single-phase grounding and short-circuit faults, the fault section can be found by observing the status change of the fault indicator. Currently, single-phase-to-ground fault detection based on fault indicators mainly relies on changes in grid parameters. However, due to the characteristics of the low-current gro...

AI Technical Summary

Problems solved by technology

However, due to the characteristics of the small current grounding system, when a single-phase grounding fault occurs, the fault signal itself is weak and is subject to electromagnetic interference and harmonic pollution.

This not only leads to distortion of the obtained signal, but also directly affects the selectivity, reliability and accuracy of single-phase-to-earth fault detection

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