Location method of non-identical phase cross-line ground fault in double-circuit line

Abstract

The invention discloses a double-circuit line non-same-phase overline earth fault locating method. A fault phase voltage, a fault phase current and a zero-sequence current at the protection installation position of a circuit line of a first same-tower double circuit double-circuit line are measured, lumped parameters are adopted for modeling, a zero-sequence current of a circuit line of a second same-tower double circuit double-circuit line is calculated, a zero-sequence compensating current of the circuit line of the first same-tower double circuit double-circuit line is calculated, position relative coefficient amplitudes of points on the circuit line of the first same-tower double circuit double-circuit line and a non-same-phase overline earth fault point are sequentially calculated with a one-dimensional search method, then the characteristic that the position relative coefficient amplitude at the position of the non-same-phase overline earth fault point is minimum is adopted, accurate distance measurement on a double-circuit line non-same-phase overline earth fault is achieved, influences of the inter-line zero-sequence mutual inductance, the transition resistance and a load current on the fault distance measurement accuracy are eliminated, and fault distance measurement dead zones are avoided when the double-circuit line non-same-phase overline earth fault happens at a positive-direction outlet.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a double-circuit line non-identical phase cross-line grounding fault location method based on the position relative coefficient amplitude decrease characteristic. Background technique [0002] Divided from the electrical quantity used for distance measurement, fault location methods can be divided into two categories: double-ended ranging and single-ended ranging. The double-terminal fault location method is a method to determine the fault location of the transmission line by using the electrical quantity at both ends of the transmission line. It needs to obtain the electrical quantity of the opposite end through the channel, so it is highly dependent on the channel, and it is also vulnerable to the double-terminal sampling value in actual use. Synchronization effects. The single-ended ranging method is a method that only uses the voltage and curre...

AI Technical Summary

Problems solved by technology

The traveling wave method utilizes the transmission properties of fault transient traveling waves for distance measurement. It has high precision and is not affected by the operation mode and excessive resistance. application

The impedance method uses the voltage and current after the fault to calculate the impedance of the fault loop, and performs distance measurement according to the characteristic that the length of the line is proportional to the impedance. When measuring terminal faults, the distance measurement accuracy is seriously affected by the transition resistance of the fault point and the zero-sequence mutual inductance between lines.

There is zero-sequence mutual inductance between double-circuit lines on the same pole, and the zero-sequence mutual inductance will affect the zero-sequence compensation coefficient, which will lead to large errors in the ranging results of the impedance method

If a single-phase high-resistance grounding fault occurs on a parallel double-circuit line on the same pole, due to the comprehensive influence of the zero-sequence mutual inductance and high transition resistance between the lines, the ranging result of the impedance method often exceeds the full length of the line or has no ranging result, and cannot provide accurate fault information Location information makes it difficult to inspect line faults, which is not conducive to rapid troubleshooting and rapid restoration of line power supply

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