Single-phase earth fault line selection method for neutral point ungrounded power distribution network containing parallel multi-circuit lines

Abstract

The invention discloses a single-phase earth fault line selection method for a neutral point ungrounded power distribution network containing parallel multi-circuit lines. The method mainly comprisesthe following steps of: firstly, judging whether a single-phase earth fault occurs or not through the zero-sequence voltage of a power distribution network; when a fault occurs, detecting the zero-sequence current of the starting end of each line (taking each group of parallel multi-circuit lines as one line), and taking the vector sum of the zero-sequence currents of the lines as a criterion; determining a suspected fault line according to the zero-sequence characteristics; if the suspected fault line is a parallel multi-circuit line group, calculating the vector sum of zero-sequence currentsat the two ends of the lines in the parallel multi-circuit line group, and determining the line with the maximum vector sum amplitude and the negative direction in the group as a fault line; and if the suspected fault line is a non-parallel multi-circuit line, determining the line as a fault line. A single-phase earth fault line selection method for a neutral point ungrounded power distribution network containing parallel multi-circuit lines is realized, the influence of unbalanced current can be overcome, the line selection is accurate, the power failure range is reduced, and the safety andreliability of the power distribution network are improved.

Description

technical field [0001] The invention belongs to the technical field of power system automation, and in particular relates to a single-phase ground fault line selection method for a neutral point ungrounded distribution network containing parallel double-circuit lines or multiple circuit lines. Background technique [0002] Single-phase ground fault line selection in distribution network has always been a difficult point in relay protection. When a single-phase-to-ground fault occurs in the distribution network, the fault characteristics are complex, there are many types of faults, and the fault components are relatively small, which seriously affects the accuracy of ground fault line selection. For this reason, a large number of power workers have also proposed some line selection methods based on the characteristics of zero-sequence components after a ground fault. These line selection methods mainly include: the line selection method based on the zero-sequence current qua...

AI Technical Summary

Problems solved by technology

If the single-phase ground fault of the distribution network occurs on the above-mentioned parallel double-circuit line or multi-circuit line, the existing line selection method can not effectively solve the influence of unbalanced current in the parallel double-circuit line or multi-circuit line, and when the parallel When a single-phase ground fault occurs in one of the double-circuit or multi-circuit lines, it is impossible to quickly and accurately select the faulty line, and all parallel double-circuit or multi-circuit lines can only be powered off for inspection, which seriously interferes with the production work of users or life

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