Voltage Measurement Method of Single-phase-to-ground Fault Point of Transmission Line

Abstract

The invention discloses a method for measuring voltage at a single-phase earth fault point of a power transmission line. The method comprises the steps as follows: fault phase voltage, a fault phase negative-sequence current, a fault phase current and a zero sequence current in a power transmission line protection installation position are measured; a real part of the ratio of the fault phase voltage to the fault phase negative-sequence current is calculated; a real part of the ratio of the power transmission line voltage drop per unit length to the fault phase negative-sequence current is calculated; and the fault phase negative-sequence current is multiplied by the difference between the real part of the ratio of the fault phase voltage to the fault phase negative-sequence current and the real part of the ratio of the power transmission line voltage drop per unit length to the fault phase negative-sequence current, so that the voltage at the single-phase earth fault point of the power transmission line is obtained. According to the method, the accurate measurement of the voltage at the single-phase earth fault point of the power transmission line is realized by virtue of the single-ended electrical capacity, the measurement accuracy is not influenced by a fault position, transition resistance and a load current, the algorithm principle is simple, the calculation capacity is small, and the measurement real-time performance is high.

Description

Technical field [0001] The invention relates to the technical field of power system relay protection, in particular to a method for measuring the voltage at a single-phase ground fault point of a transmission line. Background technique [0002] Real-time measurement of the voltage at the single-phase ground fault point of the transmission line is helpful to grasp the impact of single-phase ground fault on the thermal and dynamic stability of the transmission line in time, and provide a reliable decision basis for ensuring the safety of the transmission line and the stable operation of the power grid. [0003] Through real-time measurement of the voltage at the single-phase ground fault point of the transmission line, the low, medium and high resistance ground fault types of the transmission line can be diagnosed online according to the voltage amplitude of the single-phase ground fault point, which provides a reference basis for the fault inspection of the transmission line. Troubl...

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Problems solved by technology

[0004] However, the field of relay protection technology has not yet proposed a measurement method that can accurately calculate the voltage at the single-phase ground fault point of the transmission line, and cannot provide reliable decision-making for timely grasping the influence of the single-phase ground fault on the thermal and dynamic stability of the transmission line It is also unable to provide scientific basis for the diagnosis of low, medium and high resistance ground fault types of transmission lines.

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