Single-phase fault judging method for small-current grounding system of overhead line

Abstract

The invention relates to a single-phase fault judging method for a small-current grounding system of an overhead line. The single-phase fault judging method comprises the following steps of: respectively installing a fault indicator on a phase A, a phase B and a phase C of the same site of the overhead line, wherein each fault indicator is in wireless communication with the other two fault indicators by virtue of a wireless communication module; detecting the voltage and current information of the phase, and judging whether the phase has small-current grounding faults or not by virtue of each fault indicator; if the phase is judged to have small-current grounding faults, acquiring voltage information of the phase of the other two fault indicators by virtue of the wireless communication module; judging whether the voltage of other two phases is higher than the normal value or not, if higher, judging that the phase has true small-current grounding faults and sending the small-current grounding fault information of the phase to a communication terminal by virtue of the communication module, otherwise, not sending the small-current grounding fault information.

Description

technical field [0001] The invention relates to the field of fault detection of overhead transmission lines, in particular to a method for detecting, judging and locating single-phase faults of small current grounding systems of overhead lines. Background technique [0002] The medium voltage distribution network widely adopts the neutral point non-effectively grounded operation mode, and the probability of ground faults is very high, especially the overhead lines, which are often affected by ground faults. When the system is single-phase grounded, the grounding current is very small, only a few amps to tens of amps, and the power supply of the system is not interrupted. However, due to the existence of ground faults, hidden faults in the line are caused, which seriously affect the normal power transmission. and grid security. Therefore, it is very important to detect and locate single-phase faults in the small current grounding system of overhead lines in time. [0003] F...

AI Technical Summary

Problems solved by technology

At present, there are active methods and passive methods for detecting single-phase ground faults based on fault indicators. Passive methods include fifth harmonic method, capacitive current pulse amplitude method, first half-wave method, etc. Active methods include signal injection However, various judgment methods only detect and judge the faulty phase, and do not combine the non-faulty phase, so they cannot distinguish between real single-phase ground faults and non-true single-phase ground faults, so the false alarm rate is high

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