Method for online detection of high impedance grounding fault of distributing line

Abstract

The invention discloses a method for online detection of a high impedance grounding fault of a distributing line and belongs to the field of electric power system protection and control. According to the method, the zero-sequence voltage waveform within two to three periods after the high impedance grounding fault occurs is detected, the harmonic frequency spectrum of the waveform contains the fault information of high impedance grounding, and the method can be used for online detection of the high impedance grounding fault. The method comprises the steps of acquiring the zero-sequence voltage harmonic wave of the secondary side feeder line of a transformer, determining the fault feature harmonic frequency (between 1000 Hz and 5000 Hz usually) according to the topological structure of the line, and judging whether the high impedance grounding fault occurs on the line by detecting the amplitude and frequency of the harmonic wave. The method is especially suitable for small current grounding systems not over 10kV, and only zero-sequence voltage signal acquisition and analysis are needed. Compared with existing judging methods, the method has the advantages that information acquisition can be conducted more conveniently, sensitivity is higher, the high impedance grounding fault can be effectively distinguished from other working conditions and fault types, the occurrence of miss trip and incorrect trip is reduced, and identification is more accurate.

Description

technical field [0001] The invention belongs to the field of power system protection and control, and in particular relates to a detection method for high-resistance grounding faults of low-voltage (6-10kV) power distribution lines in small-current grounding systems. technical background [0002] Single-phase ground fault is a common fault in power system, which is not serious hazard itself, but it is very easy to cause more serious accidents. It is found from the field fault recording analysis that a considerable part of all phase-to-phase faults develops from single-phase grounding faults. 6~10kV distribution lines are close to users, and the surrounding environment is complex, and high-resistance ground faults are prone to occur. Therefore, online monitoring and detection methods for distribution lines are of great research value. The line generally adopts a low-current grounding system. When a single-phase high-resistance grounding fault occurs in the system, the short-...

AI Technical Summary

Problems solved by technology

6~10kV distribution lines are close to users, and the surrounding environment is complex, and high-resistance ground faults are prone to occur, so the online monitoring and detection methods for distribution lines are of great research value

It has a high accuracy rate for high-resistance ground faults with a fault current above 5A, but the application range of this scheme is based on transmission lines with a voltage level of 110kV and above, and it is difficult to use for distribution lines

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