Small current line selection method using correlation analysis

Abstract

The invention discloses a small current line selection method using correlation analysis. The method comprises following steps of first, starting a line selection device, then recording more zero-sequence current sampling data, that is, recording sampling data of each line zero-sequence current of one cycle before a fault and ten cycles after a fault; second, for each line fault zero-sequence current, deducting sampling data of the first cycle before a fault from sampling data of the first cycle after the fault correspondingly, then deducting sampling data of the tenth cycle after the fault correspondingly; and third, obtaining a transient pure fault component of a zero-sequence current, then performing correlation analysis by using the transient pure fault component of the zero-sequence current rather than the zero-sequence current, so as to realize fault line selection. The method can detect a fault line by analyzing similarity of line zero-sequence currents, and selects a line accurately and rapidly.

Description

technical field [0001] The invention relates to the technical field of a small current line selection method using correlation analysis, in particular to a small current line selection method using correlation analysis. Background technique [0002] When a single-phase ground fault occurs in a small-current grounded power grid, the charge and discharge of the ground capacitance of the healthy line are similar, so the zero-sequence current of the healthy line has a strong similarity. Due to the existence of the additional zero-sequence voltage source, the zero-sequence current waveform of the fault line is the most different from that of other lines. Therefore, the faulty line can be detected by analyzing the similarity of the zero-sequence current of each line. [0003] Existing line selection technologies only use part of the useful information of faults, so they all have certain limitations and cannot be applicable to all fault situations. In the past three years, the re...

AI Technical Summary

Problems solved by technology

However, if you rely too much on mathematical analysis tools and ignore the thorough analysis of the fault characteristics itself, the solution to the problem is tantamount to sacrificing the basics. The current line selection device uses zero-sequence voltage to start the line selection program, and many single-phase ground faults It is a gradual process. The zero-sequence voltage exceeds the limit after the initial transient process of the fault occurs for a period of time. At this time, the recorded waveform does not meet the premise of fault transient signal line selection. The possibility of misselection, therefore, an improved technology is urgently needed to solve this problem existing in the prior art

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