Direct sampling and direct tripping communication mode-based double-circuit line single-phase earth fault positioning method

Abstract

The invention discloses a direct sampling and direct tripping communication mode-based double-circuit line single-phase earth fault positioning method, which comprises the steps: measuring the fault phase voltage, fault phase current and zero-sequence current of the circuit line I at the protection installation place of a common-tower double-circuit line, measuring the other two normal phase voltages, measuring the zero-sequence current of the circuit line II, and calculating the fault phase voltage when the circuit line I works normally by utilizing the two normal phase voltages of the circuit line I; starting from the protection installation place of the common-tower double-circuit line, sequentially calculating the phase angle that the fault phase voltage at each point of the circuit line I precedes the fault phase voltage when the circuit line I works normally in a fixed step length increment manner, and realizing the precise positioning of single-phase earth fault of the double-circuit line by virtue of the characteristic that the ratio of previous voltage to later voltage at the fault point has step change relative to the phase angle. According to the positioning method, the voltage before line fault does not need to be memorized, a voltage holding loop before the line fault does not need to be set; the influence of transition resistance, load current and interline zero-sequence mutual inductance on fault range accuracy is eliminated.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for locating a single-phase grounding fault of a double-circuit line based on a direct mining and jumping communication mode. 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 tr...

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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