A single-ended distance measurement method for non-identical phase-cross-line grounding faults of double-circuit lines

Abstract

The invention discloses a single-ended distance measuring method for a double-circuit line non-same-name phase crossover line ground fault. According to the method, fault phase voltage, fault phase current and zero sequence current at the protection installation position of a circuit line I of double circuits on the same tower are firstly measured, zero current of the circuit line II of the double circuits on the same tower is calculated, zero compensation current of the circuit line I of the double circuits on the same tower is calculated, the phase angle of the fault phase voltage, injected into the zero sequence current of a non-same-name phase crossover line ground fault point in a leading mode, at the protection installation position of the circuit line I of the double circuits on the same tower, is calculated, and the accurate distance measuring on the double-circuit line non-same-name phase crossover line ground fault is achieved by the utilization of the trigonometric function amplitude value characteristics of the vector relation among all electrical quantities of a single end after the double-circuit line non-same-name phase crossover line ground fault. In this way, Influences on the fault distance measuring accuracy by zero sequence induction, transition resistance and load current between the lines are eliminated, the capacity for resistance to transition resistance and load current is achieved, and it is guaranteed that no fault distance measuring dead zones exist when the double-circuit line non-same-name phase crossover line ground fault happens on an outlet in the forward direction.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a single-end ranging method for double-circuit line non-identical phase cross-line grounding faults. 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 transmission line to determine the f...

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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