Identification method of characteristic harmonics of high-resistance grounding faults in distribution lines

Abstract

The invention relates to a method for distinguishing and identifying high-resistance grounding fault characteristic harmonics from harmonics generated under other working conditions, and belongs to the field of power system protection and control. During the operation of the line, other fault types such as: three-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, and harmonics generated during load switching will interfere with the identification of high-impedance faults. This method collects the high-order harmonics of the zero-sequence voltage of the line in real time, and uses the FFT method to obtain the harmonic spectrum, and distinguishes them according to the different frequency points and amplitudes of the characteristic harmonics in the identification process. This method is especially suitable for small current grounding systems of 10kV and below, and only needs to collect zero-sequence voltage signals for analysis. Compared with the existing identification methods, the information collection is more convenient, the sensitivity is higher, and it can be effectively distinguished from other normal working conditions and other fault types, and the high-resistance fault can be more clearly identified without being affected by other interference.

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 the power system, which itself does not have too serious harm, but it is easy to cause more serious accidents. From the analysis of field fault recordings, it is found that a considerable part of phase-to-phase faults is developed from single-phase grounding faults. For this type of fault, conventional protection does not work, and the short-circuit current is small, making it difficult to identify and locate, making it difficult to detect the fault at the initial stage. When the harmonics in the zero-sequence voltage and current signals of the faulty line are used as the criterion, the fault differentiation and identification are ofte...

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