Double-circuit line different phase overline grounding fault direction decision method

Abstract

The invention discloses a double-circuit line different phase overline grounding fault direction decision method, which comprises the following steps of calculating a direction decision coefficient according to the characteristic that voltage drop from a protection installation part of an I circuit transmission line of a double-circuit parallel transmission line to a single-phase grounding fault point can be equivalent to voltage drop of a positive resistance-inductance element, and the voltage drop from the protection installation part of the I circuit transmission line of the double-circuit parallel transmission line to the single-phase grounding fault point can be equivalent to voltage drop of a negative resistance-capacity element when a different phase overline grounding fault occurred in a negative direction of the double-circuit parallel transmission line; deciding a double-circuit line different phase overline grounding fault direction according to the positive and negative of the direction coefficient. According to the method provided by the invention, only single-terminal single circuit transmission line electrical quantity is used without introducing another circuit transmission line electrical quantity, a double-circuit line different phase overline grounding fault direction decision result is not affected by the electric power system operation mode, and the method has stronger adaptive capacity when the electric power system operation mode is changed greatly.

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 double-circuit line with non-identical phase-crossing grounding faults. 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 non-identical phase cross-line grounding fault occurs on a 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 connected line through the zero-sequence mutual inductance between the lines, and is affected by the induced zero-sequence voltage. The sequence directional element will misjudge the normally operating protected line as a faulty line, resulting in misoperation of the ze...

AI Technical Summary

Problems solved by technology

After a non-identical phase cross-line grounding fault occurs on a 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 connected line through the zero-sequence mutual inductance between the lines, and is affected by the induced zero-sequence voltage. The 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 the double-circuit line with the same pole and a double-circuit line with the same name passes through a high-impedance grounding fault, the induced zero-sequence Due to the influence of voltage, the zero-sequence directional element often malfunctions, resulting in the normal operation line being cut off by mistake, which has a very adverse effect on the safe and stable operation of the power grid.

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