Single-phase grounding fault line selection method applied to flexible grounding system

Abstract

The invention discloses a single-phase grounding fault line selection method applied to a flexible grounding system. The method comprises three steps of fault time positioning, transient characteristic signal extraction and faulty feeder discrimination, and specifically comprises the steps of 1) carrying out wavelet packet decomposition on a zero sequence voltage signal of a neutral point, and taking a time point corresponding to a modulus maximum point as the actual fault time; 2) selecting feeder zero-sequence current signals of 1 / 4 and 3 / 4 periods before and after the actual fault time, carrying out wavelet packet decomposition and reconstruction, and extracting transient characteristic waveforms; and 3) calculating a comprehensive gray T-shaped correlation coefficient of the transientcharacteristic waveform of each feeder, and comparing the comprehensive gray T-shaped correlation coefficient with a threshold value to determine a faulty feeder. According to the method, the relevance of the dynamic change trend of the overhead line and the dynamic change trend of the cable is effectively reflected, the misjudgment caused by the difference between the capacitance values of the cable and the overhead line to the ground is reduced, the requirements of a flexible grounding system for the rapidity and accuracy of line selection are met, and the method has feasibility and practical value.

Description

technical field [0001] The invention relates to the field of power systems, in particular to a single-phase ground fault line selection method applied to a flexible ground system. Background technique [0002] As an important part of the power system, the distribution network is closely related to users. In recent years, with the continuous development of distribution network topology and the increasing number of cables used, the resonant grounding method has been difficult to meet the requirements of fast arc suppression. In order to solve this problem, relevant scholars put forward the concept of flexible grounding. Flexible grounding means that on the basis of traditional resonant grounding, when a single-phase grounding fault occurs, the power electronic device is used for compensation, and the current at the grounding point is suppressed to be close to 0 in a short time, so as to realize the complete extinguishment of the fault arc. Existing flexible grounding schemes...

AI Technical Summary

Problems solved by technology

[0008] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a single-phase ground fault line selection method applied to the flexible grounding system to solve the shortcomings of the existing distribution network line selection method applied to the flexible grounding system

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