A single-phase ground fault line selection method and device

Abstract

The invention provides a single-phase ground fault line selection method, which comprises the following steps: separately acquiring transient zero-sequence currents of a half cycle after M lines is changed suddenly; acquiring a magnitude cross-correlation coefficient matrix G by a dynamic time bending distance algorithm; adopting plus or minus 1 to characterize the positive and negative polarity of the transient zero-sequence current, generating the transient zero-sequence current polarity coefficient matrix C of each line, and obtaining the polarity cross-correlation matrix H according to thepolarity coefficient matrix C of each line; combining the magnitude cross-correlation matrix G and the polarity cross-correlation matrix H to obtain a comprehensive cross-correlation matrix Q; usingthe comprehensive cross-correlation matrix Q as an input of a fuzzy C-means clustering, dividing the zero sequence current into two categories by the fuzzy C-means clustering, and selecting the faultline according to the category of each line. The invention also provides a single phase ground fault line selection device. The method and the device disclosed by the invention have less operation time, high accuracy and strong versatility.

Description

technical field [0001] The invention relates to a single-phase ground fault line selection method and device. Background technique [0002] The medium and low voltage distribution network usually refers to the power network with a voltage level of 35kV and below, which has a wide distribution range, a complex structure, and is closely connected with users. When a permanent single-phase ground fault occurs, since the line voltage remains symmetrical, it can continue to run for 1-2 hours, but the non-fault phase voltage increases during this process, which may easily cause breakdown at the weakened insulation and cause fault expansion, so it must be quickly Select the faulty line and cut it off. In the prior art, the dynamic time warping distance (DTW) algorithm is used for line selection, but the existing DTW algorithm still has certain defects, such as the number of paths increases with the increase of the number of data points, resulting in a greatly prolonged algorithm ru...

AI Technical Summary

Problems solved by technology

When a permanent single-phase ground fault occurs, since the line voltage remains symmetrical, it can continue to run for 1-2 hours, but the non-fault phase voltage increases during this process, which may easily cause breakdown at the weakened insulation and cause fault expansion, so it must be quickly Select the faulty line and remove it

In the prior art, the dynamic time warping distance (DTW) algorithm is used for line selection, but the existing DTW algorithm still has certain defects, such as the number of paths increases with the increase of the number of data points, resulting in a greatly prolonged algorithm running time; if X The abnormality of the first data point of the sequence leads to the shortest distance between all data points of the Y sequence and the point, so that the DTW path appears "many-to-one, one-to-many", that is, the local path slope is too steep or too gentle, resulting in a gap between the two sequences. The difference between the DTW and the actual is large, which reduces the correlation between the two and affects the accuracy of line selection

On the other hand, due to the complex fault situation and the influence of external interference factors, the fault current waveform is distorted and the polarity jumps. Therefore, the DTW algorithm is used alone for line selection. Due to insufficient consideration of factors, the accuracy of line selection is greatly affected by external interference.

Images