Single-phase grounding fault line selection method based on relativities of wavelet characteristic quantities after fault

Abstract

The invention relates to a single-phase grounding fault line selection method based on the relativities of the wavelet characteristic quantities after a fault. The method includes the following steps:a circuit measurement terminal acquiring the data of 8 paths of signals in the course of two sampling cycles after a fault, wherein the signals include three-phase and zero-sequence currents and voltages; performing wavelet transformation on the data in the course of two sampling cycles to obtain one group of waveform characteristic quantities; analyzing the voltages and the currents by using different wavelet algorithms, obtaining a total of 6 groups of waveform characteristic quantities, analyzing the relativity of each group of characteristic quantities, and comparing the relativity with asetting value; and if the number of the circuits is greater than a set number and the result does not conform to the setting value, determining that an outlet has a single-phase grounding fault. According to the invention, the method has the following beneficial advantages: the method herein makes determinations by using multiple wavelet analysis algorithms, avails the high sensitivity of the wavelet algorithms to discontinuities, can avoid wrong determination which might be caused due to the use of only one wavelet algorithm, and can accurately determine that the outlet has a single-phase grounding fault by analyzing the relativities of the characteristic quantities.

Description

technical field [0001] The invention relates to the field of distribution of electric power systems, in particular to a method for line selection of single-phase grounding faults in a low-voltage distribution network. Background technique [0002] Most of the medium and low voltage distribution networks in my country adopt the low current grounding method, and single-phase grounding faults are prone to occur during long-term operation. Single-phase-to-ground fault is the most frequent type of fault in distribution network. With the development of modern cities and the continuous expansion of power systems, the number of outgoing lines has greatly increased, and the capacitive current of the system has greatly increased. After a fault occurs, the fault current is also much larger than before. Insulation protection, resulting in damage to power facilities, endangering the safe operation of the entire system. Therefore, when a single-phase ground fault occurs in the distribut...

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Problems solved by technology

Due to the complexity of fault conditions, and the influence of line structure parameters, nonlinear characteristics of transformers, electromagnetic interference and other factors, the spectrum characteristics, energy distribution and attenuation characteristics of fault transient zero-sequence currents are very different, so the distribution network has been lacking Reliable single-phase ground fault line selection method, traditional methods cannot comprehensively analyze and cause line selection difficulties

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