Single-phase earth fault line selection device and method for small-current grounding system

Abstract

The invention discloses a single-phase earth fault line selection method for a small-current grounding system. The method comprises the following steps: an intelligent controller is used for judging and determining that a capacitor with a fixed capacitance value and a resistor with a fixed resistance value are respectively put into a neutral point grounding branch for a preset duration by a cut-off switch after a single-phase earth fault happens to the small-current grounding system according to a three-phase voltage signal of a bus collected by a voltage transformer; a plurality of current transformers are respectively used for collecting current signals of a plurality of to-be-tested lines within the preset duration and transmitting the current signals to the intelligent controller through a data collection device; the intelligent controller is used for respectively analyzing the phase variable quantity and the amplitude variable quantity of a zero-sequence current of the plurality of to-be-tested lines according to the current signals; and the intelligent controller is used for comparing the phase variable quantity and the amplitude variable quantity of the zero-sequence current of the plurality of to-be-tested lines, and selecting the line with the maximum phase variable quantity and amplitude variable quantity as a fault line.

Description

technical field [0001] The invention relates to the technical fields of relay protection and distribution network, in particular to a single-phase ground fault line selection device and method for a small current grounding system. Background technique [0002] In the medium-voltage power distribution system, in order to improve the reliability of power supply, the neutral point non-effective grounding method is adopted, and the arc-suppression coil grounding method is usually used to compensate the current of the line-to-ground capacitance, but it brings difficulties in line selection for single-phase grounding faults. The problem. If the faulty line cannot be selected and cut off in time, it will easily lead to the spread of faults and power outages. [0003] At present, many methods have been proposed for fault line selection, including power component method, injection method, disturbance method, harmonic method and so on. However, due to various reasons such as complex...

AI Technical Summary

Problems solved by technology

However, due to various reasons such as complex actual site conditions, difficult control, and unobvious fault characteristics, the efficiency of line selection is still not high, and power outages caused by single-phase ground faults occur from time to time

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