Method for judging the direction of single-phase grounding faults in double-circuit lines paralleled on the same pole

Abstract

The invention discloses a single-phase grounding fault direction discriminating method of double-circuit lines on the same tower. The single-phase grounding fault direction discriminating method of double-circuit lines on the same tower measures the fault phase voltage, zero-sequence voltage and the zero-sequence current of a single-circuit line in double-circuit lines on the same tower. A compound polarized voltage is obtained by subtracting the fault phase voltage from the zero-sequence voltage. A direction judging evidence can be formed by a phase angle relationship between the zero-sequence current and the compound polarized voltage, so that a positive direction fault or an opposite direction fault happening in the protected circuit line can be actually discriminated. According to the single-phase grounding fault direction discriminating method of double-circuit lines on the same tower, the direction judging evidence is formed by utilizing the phase angle relationship between the zero-sequence current and the compound 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 single-phase grounding faults of double-circuit lines paralleled 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 single-phase ground fault occurs in the primary line of the double-circuit line paralleled on the same pole, the zero-sequence current flowing through the faulty line generates an induced zero-sequence voltage on the connected line through the zero-sequence mutual inductance between the lines. Affected by the induced zero-sequence voltage, The zero-sequence directional element will misjudge the normally operating protected line as a faulty line, resulting in misoperation...

AI Technical Summary

Problems solved by technology

After a single-phase ground fault occurs in the primary line of the double-circuit line paralleled on the same pole, the zero-sequence current flowing through the faulty line generates an induced zero-sequence voltage on the connected line through the zero-sequence mutual inductance between the lines. Affected by the induced zero-sequence voltage, The zero-sequence directional element will misjudge the normally operating protected line as a faulty line, resulting in misoperation of the zero-sequence directional element, especially when a single-phase high-resistance grounding fault occurs in the primary line of the parallel double-circuit line on the same pole, the induced Due to the influence of zero-sequence voltage, the zero-sequence directional element often malfunctions, resulting in the removal of normal operating lines by mistake, which has a very negative impact on the safe and stable operation of the power grid

Images