Single-phase ground fault detection method suitable for neutral-point small-resistance grounding distribution network

Abstract

The invention discloses a single-phase ground fault detection method suitable for a neutral-point small-resistance grounding distribution network. Based on the obvious difference between the ratio ofa differential value of the zero-sequence current to a differential value of the zero-sequence voltage in a faulty line and the counterpart ratio in a non-faulty line, zero-sequence voltage of a bus and zero-sequence current of a feeder line are collected to calculate the waveform similarity of the lines; then, whether a single-phase ground fault occurs in the lines or not is judged according to the waveform similarity, a faulty line and a non-faulty line can be correctly judged, the influence of transition resistance is small, and the method has good applicability to linear fault resistance and non-linear fault resistance and is not influenced by the polarity of a mutual inductor; moreover, the acquisition and processing of the zero-sequence voltage signal are added only on the basis of the traditional acquisition of the zero-sequence current signal, so that the engineering realization is easy.

Description

technical field [0001] The invention relates to the technical field of single-phase ground fault detection, in particular to a single-phase ground fault detection method suitable for a neutral point small resistance ground distribution network. Background technique [0002] With the rapid development of the city, the urban land is increasingly tight, and the transmission network of the distribution network of large and medium-sized cities is mainly composed of cable lines. Due to the large ground capacitance of the cable line, the capacitive current brought by it in the event of a single-phase ground fault is difficult to be compensated by the arc suppression coil, and the arc ground overvoltage and the difficulty of identifying the fault line also limit the arc suppression coil grounding. way of application. The small resistance grounding system has been more and more widely used in the distribution network of large and medium-sized cities in my country because of its adva...

AI Technical Summary

Problems solved by technology

It can be seen that the sensitivity of the existing step-by-step zero-sequence current protection is greatly affected by the transition resistance, and cannot meet the requirements of high-impedance ground fault detection

Some substations also adopt a zero-sequence protection scheme, but it is difficult to verify the polarity of the transformer, and the effect is not ideal

Although the fault current of a high-resistance ground fault is small, the high temperature generated by the grounded high-voltage line and the fault arc may cause great harm to nearby people and the surrounding environment, and even cause personal safety accidents; at the same time, if anyone Since the fault current always exists, it will further damage the insulation, cause more serious faults, and expand the fault range

[0004] At present, the detection methods for high-resistance grounding faults mainly focus on the use of waveform distortion and harmonics generated by nonlinear arcs, but when the nonlinear characteristics of the fault are not obvious, these methods may fail

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