SV network sampling-based double-circuit line single-phase earth fault distance measurement method

Abstract

The invention discloses an SV network sampling-based double-circuit line single-phase earth fault distance measurement method which is used for measuring the fault phase voltage mutational volume, the fault phase current mutational volume, the zero-sequence current and the other two normal phase voltages of an I-circuit line at the protection mounting position of a double-circuit line on the same pole, and measuring the zero-sequence current of a II-circuit line; calculating the fault phase voltage when the I-circuit line operates normally, sequentially calculating the positioning vector function of each point on the I-circuit line of the double-circuit line on the same pole until the full length of the I-circuit line of the double-circuit line on the same pole, and selecting the distance between the point with the smallest positioning vector function value on the I-circuit line of the double-circuit line on the same pole and the protection mounting position of the double-circuit line on the same pole as the fault distance. According to the method, the voltage of the circuit before the fault does not need to be remembered, and a voltage protection loop of the circuit before the fault does not need to be set; the influence of the zero-sequence mutual inductive impedance among the lines, the transition resistance and the load current on the precision of measurement of the fault distance is eliminated, and no fault distance measurement dead zone exists in protecting the single phase grounding fault of the outlet single-circuit line.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for measuring the single-phase grounding fault distance of a double-circuit line based on SV network sampling. 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...

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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