Line Selection of Single-phase Grounding Clustering Method in Resonant Grounding System

Abstract

The invention relates to a resonant grounding system fault line selection method with clustering achieved by means of time-frequency matrix singular values. The resonant grounding system fault line selection method comprises the steps that empirical mode decomposition is carried out on the transient-state zero-sequence current waveform of each circuit and the transient-state zero-sequence current waveform of a bus after a fault occurs to obtain a plurality of IMF components; Hilbert conversion is carried out on the IMF components to obtain a two-dimensional Hilbert gray-scale time-frequency spectrogram of transient-state zero-sequence currents; a time-frequency matrix of the transient-state zero-sequence current waveforms is constructed by means of HHT band-pass filtering; singular value decomposition is carried out on the time-frequency matrix to obtain a series of singular values which can reflect time-frequency characteristics of the waveforms, and the singular values serve as the characteristic quantity of transient-state zero-sequence currents of each circuit and the bus; vague C mean value clustering is carried out on the singular values to select a fault line. According to the resonant grounding system fault line selection method, influence of distributed capacitance and currents of a sound long line is avoided when a short line breaks down, and accurate line selection can be achieved under the conditions of high resistance grounding, noise interference, arc faults and the like.

Description

technical field [0001] The invention relates to the field of relay protection of an intelligent power distribution system, in particular to a line selection method of a single-phase grounding clustering method for a resonant grounding system. Background technique [0002] When a single-phase ground fault occurs in the resonant grounding system, since the neutral point is grounded through the arc suppression coil, a low-impedance short-circuit loop cannot be formed, and the path can only be formed through the line-to-ground capacitance, so the fault current is higher than the neutral point after being compensated by the arc suppression coil. The ungrounded one is still small, and the three-phase line voltage remains symmetrical, which does not affect the continuous power supply to the load, so it is not necessary to trip immediately. According to the "Power System Safety Regulations", it can run with a fault for 1 to 2 hours. However, the non-faulted phase voltage rises to th...

AI Technical Summary

Problems solved by technology

[0004] Most of the line selection criteria used in the existing resonant grounding system fault line selection method adopt the manual experience threshold method, which cannot achieve intelligent fault line selection; and it is difficult to accurately select the line for high-impedance ground faults and short line faults

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