Single-phase-to-ground fault line selection method for small current

Abstract

A single-phase-to-ground fault line selection method for small current comprises the following steps of first determining a signal sampling period, using an A/D converter to collect the zero-sequencevoltage of a bus and the zero-sequence current of feeders of the system, monitoring the zero-sequence voltage of the bus in real time, and starting a line selection algorithm when the zero-sequence voltage is greater than a set voltage; performing smoothing pre-treatment on the transient zero-sequence current spectrum of each of the extracted feeders, carrying out empirical wavelet transform decomposition to extract an intrinsic mode function that best characterizes the original signal, calculating energy relative entropies by using the amplitude of the signal obtained after Hilbert transform,selecting the line with the largest relative entropy as the fault candidate line, determining that the line with the largest relative entropy is faulty if the line with the largest relative entropy is larger than the sum of the relative entropies of the line with the second largest relative entropy and the line with the third largest relative entropy, and otherwise determining that the bus is faulty. The single-phase-to-ground fault line selection method is accurate in line selection and good in real-time performance without being affected by the neutral point grounding mode, the fault distance, the initial fault angle or the transition resistance fault condition.

Description

technical field [0001] The invention belongs to the technical field of intelligent state detection of power systems, and in particular relates to a line selection method for small current single-phase grounding faults. Background technique [0002] Rapid economic development has also increased the requirements for reliable operation of the power system, and the stability of the power supply of the power system directly affects the safety of society. If failure is inevitable, how to quickly eliminate the failure after the failure becomes a key research issue. The distribution network can be divided into two types according to the different grounding methods of the neutral point, namely the small current grounding system and the large current grounding system. In order to ensure continuous power supply, the distribution network below 66kV in my country mostly uses a small current grounding system. [0003] The statistical results show that the probability of power outage aft...

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Problems solved by technology

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a small current single-phase ground fault line selection method to solv

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