Fault line selection method for resonant grounding system using fuzzy k-means clustering

Abstract

The invention relates to a resonant earthed system fault line selection method utilizing fuzzy K-means clustering. The resonant earthed system fault line selection method comprises the following steps of 1 performing stretching transformation treatment on transient-state zero-sequence current of each line to improve similarities of transient-state zero-sequence currents of non-fault lines; 2 dividing the transient-state zero-sequence currents of all of lines according to a certain time period, performing subsection phase plane transformation to obtain Euclidean distances from all of phase points of the transient-state zero-sequence current of each section to determinacy points x and y on a phase plane so as to extract local features of the transient-state zero-sequence currents of all of subsections and obtain feature matrixes of global features of all of lines; 3 performing normalization processing on elements in the feature matrixes to improve comparability; 4 utilizing a fuzzy K-means clustering method to perform clustering on the normalized feature matrixes, dividing the transient-state zero-sequence currents of all of lines into two categories and the lines independently included in one category are fault line. The method improves the automation degree and line selection margin.

Description

technical field [0001] The invention relates to the technical field of relay protection for intelligent power distribution systems, in particular to a fault line selection method for a resonant grounding system based on waveform stretching transformation and fuzzy K-means clustering. Background technique [0002] The resonant grounding system has the advantages of improving the power supply reliability of the system, reducing the accident rate of lightning damage, and resisting electromagnetic interference of communication equipment. It is widely used in medium-voltage distribution networks. The probability of single-phase grounding faults in resonant grounding systems is very high, generally accounting for more than 80% of the total faults. If it is an instantaneous ground fault, the fault can be eliminated by itself; if it is a permanent ground fault, the system can continue to operate for 1 to 2 hours without affecting the continuous power supply of the system. Because t...

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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 high-impedance ground faults and short line faults. There is also a lack of research on whether the proposed line selection criterion is still valid when a single-phase ground fault occurs after the distribution network is connected to other equipment

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