Method for judging direction of two-phase-to-ground short-circuit faults in double-circuit lines paralleled on the same pole

Abstract

The invention discloses a two phrase grounding short circuit fault direction discriminating method of double circuit lines on the same tower. The two phrase grounding short circuit fault direction discriminating method of double circuit lines on the same tower measures the three-phrase voltage, zero-sequence voltage and the zero-sequence current of a single-circuit line in double-circuit lines on the same tower. Launching judging evidence is formed by the phrase angle relationship between the zero-sequence current and the zero-sequence voltage so that whether a fault occurs in the protected circuit line can be discriminated. A polarized voltage is obtained by subtracting two fault phrase voltages from the zero-sequence voltage. A relay protection judging evidence is formed by the phrase angle relationship between the zero-sequence current and the polarized voltage so that whether a positive direction fault or an opposite direction fault occurs in the protected circuit line can be accurately discriminated. According to the two phrase grounding short circuit fault direction discriminating method of double circuit lines on the same tower, a relay protection judging evidence is formed by the phrase angle relationship between the zero-sequence current and the polarized voltage, so that impacts of zero-sequence mutual inductance between lines to protecting dynamic performances can be eliminated theoretically, the fault direction can be actually discriminated, and relay protection malfunction happening when the opposite direction fault occurs in the protected circuit line can be effectively prevented.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for judging the direction of a two-phase-to-ground short-circuit fault of a parallel double-circuit line on the same pole. Background technique [0002] The double-circuit line paralleled on the same pole has a small footprint, low cost, and stable and reliable operation when connected to the grid. It has become a common transmission line connection method in the power system. After a two-phase-to-ground short-circuit fault occurs in the first circuit of the parallel double-circuit line on the same pole, the zero-sequence current flowing through the faulty line generates an induced zero-sequence voltage on the adjacent line through the zero-sequence mutual inductance between the lines, and the induced zero-sequence voltage The zero-sequence directional element will misjudge the normally operating protected line as a faulty line, causing the...

AI Technical Summary

Problems solved by technology

After a two-phase-to-ground short-circuit fault occurs in the first circuit of the parallel double-circuit line on the same pole, the zero-sequence current flowing through the faulty line generates an induced zero-sequence voltage on the adjacent line through the zero-sequence mutual inductance between the lines, and the induced zero-sequence voltage The zero-sequence directional element will misjudge the normally operating protected line as a faulty line, causing the zero-sequence directional element to malfunction. , due to the influence of the induced zero-sequence voltage, the zero-sequence directional element often malfunctions, causing the normal operation line to be cut off by mistake, which has a very negative impact on the safe and stable operation of the power grid.

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