Single-phase earth fault line selection method on basis of EEMD (ensemble empirical mode decomposition) and energy method for resonance earthed power distribution network

Abstract

The invention relates to a single-phase earth fault line selection method on the basis of an EEMD (ensemble empirical mode and decomposition) and energy method for the resonance earthed power distribution network. The single-phase earth fault line selection method includes firstly determining a start moment of faults, subjecting zero-sequence current of outgoing lines of 1 / 2 power frequency periods before and after the start moment of the faults respectively to EEMD, taking out high-frequency IMF component and residual component of current respectively, and solving the sum of energy of the high-frequency IMF component and the residual component of the lines respectively, acquiring energy weight coefficient of the lines and judging faulted elements by analyzing and comparing the energy weight coefficient. The single-phase earth fault line selection method is unaffected by transitional resistance and is high in interference resistance, and manual operation during fault judgment is omitted; when various types of single-phase earthed faults occur, the fault elements can be accurately judged.

Description

technical field [0001] The invention relates to a line selection method for a single-phase ground fault of a resonant ground distribution network, in particular to a line selection method for a single-phase ground fault of a resonant ground distribution network based on EEMD and an energy method. Background technique [0002] With the development of cities and the continuous increase of power system capacity, when a single-phase short-circuit fault occurs in the distribution network, the fault current is many times larger than before. In severe cases, arc overvoltage will occur in the system, and its value is 2.5~ 3 times, it seriously threatens the insulation of the system, and it is very easy to expand the scope of failure. In order to limit the magnitude of the current at the short-circuit point and prevent the above-mentioned hazards, the neutral point resonant grounding operation mode is widely used in the distribution network. In the resonant grounding distribution ne...

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Problems solved by technology

Among them, for the wavelet analysis method, the line selection accuracy is high, but the decomposition result of the wavelet transform is determined by the predetermined basis function, so the wavelet transform cannot perform adaptive decomposition according to the characteristics of the signal; the first half-wave method is susceptible to transition resistance Injected signal tracking method is also susceptible to the influence of transition resistance. When the transition resistance is large, the signal is very weak, and the injected signal is susceptible to interference. Although the pulling method has been improved, it still needs manual operation. , the time to identify the fault is still long; for the fifth harmonic component method, because the content of the fifth harmonic is much smaller than that of the fundamental wave, and it is easily affected by the fifth harmonic source of the load and the transition resistance, in practical application The effect is not ideal

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