Fault line selection method based on phase current transient characteristic

Abstract

The method discloses a fault line selection method based on a phase current transient characteristic. The method comprises the following steps of S1, continuously measuring a distribution line outlet zero sequence voltage value and determining whether a power distribution network generates a grounding fault; S2, processing collected phase current data, extracting a transient phase-current sudden-change amount of each line, and carrying out interphase pairwise correlation analysis so as to obtain an interphase minimum correlation coefficient rhok min; S3, carrying out spectral analysis on each line fault phase current and calculating a gravity frequency fkg; S4, carrying out normalization processing on a fault characteristic quantity and acquiring normalization values, establishing a two-dimensional coordinate system based on the normalization values, and determining each line fault characteristic coordinate point; and calculating a fault characteristic distance dk between each line fault characteristic coordinate point and a reference point (0, 0) so as to determine a bus fault. The method possesses advantages that a principle is simple; practicality is high; an anti-interference capability is good; accuracy is high and so on.

Description

technical field [0001] The invention mainly relates to the technical field of distribution network grounding, in particular to a fault line selection method based on phase current transient characteristics. Background technique [0002] The distribution network is an important part of the power system and is closely related to users. The diagnosis and repair time of distribution network faults will directly affect the quality of power supply. Research in this area has always been one of the key points in distribution network protection. The 10kV power distribution system in cities in my country often adopts the grounding method of the neutral point through the arc suppression coil to reduce the influence of the instantaneous single-phase grounding fault and the transient arc on the system. However, this grounding method makes the fault current small and the fault line selection has a certain difficulty. [0003] At present, the line selection method based on transient signal...

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Problems solved by technology

The second method is based on wavelet analysis. This method takes advantage of the good localization advantages of wavelet analysis in both time domain and frequency domain. However, wavelet analysis is not adaptive and is easily affected by factors such as wavelet basis functions and decomposition scales. Impact

[0004] From the above analysis, it can be seen that the existing ground fault protection methods do not analyze the transient characteristics of faults deeply enough, and most of them compare the amplitude and phase of transient signals from different angles to determine the fault line, and the fault detection accuracy is relatively low. low, it is difficult to select the protection judgment setting value; and due to the influence of interference, the influence of transition resistance, the diversity of operation modes, etc., it may even cause protection malfunction or refusal

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