Method for locating single-phase grounding fault by adopting transient state travelling wave and injection method

Abstract

The invention relates to a method for locating a single-phase grounding fault by adopting a transient state travelling wave and an injection method, which is suitable for locating a single-phase grounding fault of a low-current grounding system. The method solves the defects of a single fault locating method, thereby improving the fault locating accuracy. The method comprises the following steps of: (1) sampling a zero sequence voltage, and calculating and judging whether the zero sequence voltage exceeds a setting threshold value or not; if the zero sequence voltage exceeds the setting threshold value, showing that an electricity grid has a single-phase grounding fault, and then executing the following steps; (2) judging a fault phase according to the voltage change law in a system single-phase fault, then obtaining a phase voltage at the fault moment, and comparing the obtained phase voltage with 0.8up, wherein up is a system phase voltage peak value; (3) if the wavelet analysis is carried out on a transient state travelling wave signal, determining the time delta t for the travelling wave to go to and fro between a fault point and a generatrix once, thereby calculating the distance from the fault point to the generatrix; (4) and if a fault circuit is selected, cutting the power of the fault circuit, injecting a pulse signal to the fault signal, carrying out wavelet transform, detecting the reflected wave of the fault point, thereby obtaining delta t, and then calculating the distance from the fault point to the generatrix.

Description

technical field [0001] The invention relates to a single-phase grounding fault location method of a transient traveling wave and injection method in a small current grounding system. Background technique [0002] At present, the single-phase ground fault location methods of small current grounding system mainly include traveling wave method, S injection method and so on. Among them, the traveling wave positioning method only uses the transient traveling wave signal in a short period of time at the initial stage of the ground fault, and the fault development in the later stage of the ground fault has no influence on the transient traveling wave signal at the beginning, so the traveling wave positioning method is effective in instantaneous grounding, intermittent It is effective in the case of arc light grounding, etc. At the same time, the traveling wave method is not affected by factors such as transition resistance and line asymmetry, and is applicable to various lines. Ho...

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Problems solved by technology

[0003] Technical problem: The purpose of this invention is to provide a single-phase ground fault location method using transient traveling wave and injection method, which is suitable for single-phase ground fault location in small current grounding systems. This method solves the shortcomings of the single-fault location method and improves The accuracy of fault location

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