Transient current projection component polarity comparison-based fault line selection method

Abstract

The invention discloses a transient current projection component polarity comparison-based fault line selection method. When a zero sequence voltage amplitude value of a bus exceeds a fixed value, zero sequence currents of all feed line outlet openings of a power distribution network are collected, transient components of the zero sequence currents of all the feed line outlet openings and transient components of zero sequence voltage of the bus are extracted, transient zero sequence currents of all the feed line outlet openings are projected onto transient zero sequence voltage of the bus, and a faulty line is determined according to a projection component polarity relation. A feed line of which transient current projection component polarity is opposite to transient current projection component polarity of other candidate feed lines is chosen as a faulty feed line; when all the candidate feed lines are the same in transient current projection component polarity, the bus is the faulty line. The transient current projection component polarity comparison-based fault line selection method can help solve a difficult fault line section problem in a small current grounding system when a high resistance earth fault occurs, and the transient current projection component polarity comparison-based fault line selection method can be widely applied.

Description

technical field [0001] The invention relates to the technical field of distribution network fault detection, in particular to a fault line selection method based on polarity comparison of transient current projection components. Background technique [0002] Since the medium-voltage distribution network directly faces users, and single-phase grounding accounts for about 80% of the total distribution network faults, the reliable detection of single-phase grounding faults has a significant impact on power supply reliability. In China and continental Europe, most of the medium-voltage distribution network adopts the grounding method of the arc suppression coil, which is the so-called resonant grounding system. When a single-phase ground fault occurs, it is not necessary to remove the fault immediately, which is conducive to improving the reliability of power supply. However, due to the weak fault current and other reasons, it is difficult to identify the ground fault line. In ...

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Problems solved by technology

The main difficulty of this method is that the line selection device needs to be connected to the three-phase current signal and is greatly affected by TV / TA transmission errors (such as unbalance)

[0005] For small current grounding systems, the power frequency current itself has no obvious fault characteristics and cannot be directly used for fault detection (the active component of power frequency current is theoretically feasible, but the content is small and easily affected by TV / TA transmission characteristics, and there are great difficulties in practical use ), other technical solutions must be sought

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