Ground fault line selection method based on high-frequency component correlation

Abstract

The invention discloses a ground fault line selection method based on high-frequency component correlation. The method comprises the following steps: S1) monitoring a zero sequence voltage value of an exit of each power distribution line in real time, and if the zero sequence voltage value is larger than a limit value, judging a power distribution network has a ground fault, and collecting zero sequence current of each line; S2) carrying out denoising processing on the zero sequence current of each line to obtain a pure fault component ; S3) carrying out EMD decomposition on the pure fault component to obtain various transient frequency components, and then, through instantaneous frequency analysis, removing a power frequency component and extracting a corresponding high-frequency transient component; and S4) carrying out pairwise correlation analysis on the high-frequency transient component of each line to obtain a correlative coefficient matrix M, and solving integrated correlation coefficient [rho]i of each line. The ground fault line selection method has the advantages of simple principle, high anti-interference capability and high protection precision and the like.

Description

technical field [0001] The invention mainly relates to the technical field of distribution network grounding, in particular to a grounding fault line selection method based on high-frequency component correlation. Background technique [0002] my country's distribution network widely adopts the neutral point non-effective grounding method. This operation can effectively improve the reliability of power supply. And the reliability is poor, and the line selection accuracy is generally low. [0003] Existing methods for line selection based on steady-state signals mainly include zero-sequence current ratio-amplitude-phase method, negative-sequence current method, harmonic method, etc. Generally speaking, the main difficulty of the steady-state method is that the fault current is weak, and it is easily affected by factors such as grounding mode and arc suppression coil overcompensation. Therefore, the reliability of the measured signal is not high, and even misjudgments and miss...

AI Technical Summary

Problems solved by technology

[0004] The existing transient ground fault protection methods are not deep enough to analyze the transient characteristics of the fault. Most of them only make a general analysis of the transient characteristics from different angles, and lack of comprehensive analysis.

Among them, the typical ones are: ①Using the zero-sequence current line selection method, but when the zero-sequence current contains a strong DC component, the waveform distortion caused by the saturation of the current transformer is likely to cause the problem of line selection failure. Therefore, if it is not dealt with , will cause misjudgment of line selection

② Use wavelet analysis for line selection, but wavelet analysis is not self-adaptive, and is easily affected by factors such as wavelet basis functions and decomposition scales

③ Use the characteristic frequency band to select the line, but because the frequency component of the transient quantity is affected by various factors such as network parameters and fault time, the distribution of the characteristic frequency bands of the transient quantity of different lines is not always completely consistent

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