Single-end distance measurement method for line single-phase ground faults against the influence of transition resistance and load current

Abstract

The invention discloses a transition resistance and load current resisting line single-phase earth fault single-terminal location method. The transition resistance and load current resisting line single-phase earth fault single-terminal location method includes measuring fault-phase voltages, fault-phase currents, fault-phase negative-sequence currents and a zero-sequence current at a power transmission line protection mounting position; computing the line distance from a single-phase earth fault point to a power transmission line protection setting position; subtracting the line distance from the single-phase earth fault point to the power transmission line protection setting range from the power transmission line protection setting range to obtain the fault distance from the power transmission line protection mounting position to the single-phase earth fault point. The transition resistance and load current resisting line single-phase earth fault single-terminal location method has the advantages that the power transmission line single-phase earth fault single-terminal location is implemented by the aid of single-terminal electric quantities, and the location precision is unaffected by transition resistance or load currents, and is high; a searching mode is adopted in the method, the problem of false roots of an equation solving method and the problem of incapability of realizing convergence of an iterative method are solved, and the practicality is high.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for single-end single-end distance measurement of line single-phase grounding faults against the influence of transition resistance and load current. Background technique [0002] According to the division of electrical quantity sources, fault location methods are mainly divided into double-ended location methods and single-ended location methods. The double-terminal ranging method uses the electrical quantities at both ends of the transmission line to locate faults. It needs to obtain the electrical quantities at the opposite end through the data transmission channel, which is highly dependent on the data transmission channel. UHV AC transmission lines are often long-distance transmission lines, and the laying of data transmission channels required for distance measurement requires a large amount of additional investment. Therefore, the si...

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Problems solved by technology

The traveling wave method utilizes the transmission properties of fault transient traveling waves to perform single-ended fault location. It has high precision and is not affected by the operation mode and excessive resistance. However, it requires a high sampling rate, requires a special wave recording device, and has high application costs.

The impedance method uses the voltage and current after the fault to calculate the fault loop impedance, and performs single-ended fault distance measurement according to the characteristic that the line length is proportional to the impedance. It is simple and reliable, but the distance measurement accuracy is seriously affected by factors such as transition resistance and load current, especially When the transition resistance is large, the ranging result of the impedance method will seriously deviate from the real fault distance, and even the ranging failure will occur.

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