Method for locating ground faults of non-identical phase-to-phase-to-wire double-circuit lines based on binary search

Abstract

The invention discloses a method for locating a non-homonymic phase overline earth fault of a double-circuit line based on binary search. The method includes the steps that firstly, fault phase voltage, fault phase current and zero-sequence current of the protection installing position of a I-circuit line of the double-circuit line on the same pole are measured, lumped parameter modeling is adopted, zero-sequence current of an II-circuit line of the double-circuit line on the same pole is calculated, zero-sequence compensating current of the I-circuit line of the double-circuit line on the same pole is calculated, the non-homonymic phase overline earth fault of the double-circuit line is accurately located by the adoption of a binary search method and through the characteristic that a relative coefficient of the positions in front of and behind the non-homonymic phase overline earth fault point is abruptly changed into a value smaller than 0 from a value larger than 0, the influences of interline zero-sequence mutual inductance, transition resistance and load current on fault locating accuracy are eliminated, high capacity for resisting the influences of the transition resistance and the load current is achieved, and no fault location dead zones exist when the non-homonymic phase overline earth fault of the double-circuit line is generated at a protection positive direction outlet.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for distance measurement of non-identical phase-cross-line grounding faults of double-circuit lines based on binary search. 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 current data at one end of the tran...

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 there is no ranging result, which cannot provide accurate fault information Location information makes line fault inspection difficult, which is not conducive to rapid troubleshooting and rapid restoration of line power supply

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