Realizing single-phase high-resistance grounding fault relay protection method of transmission line by using single-end current

Abstract

The invention discloses a method for realizing relay protection of a single-phase high-resistance earth fault of a power transmission line by using single-ended current magnitude. The method comprises the steps of measuring a fault phase current instantaneous value of each sampling moment at a current transformer mounting position of the power transmission line; selecting two adjacent cycle fault phase current sampling values to form a protection criterion; detecting the degree of asymmetry of the fault phase current waveform and the existence of a discontinuous region; judging whether the power transmission line has a single-phase high-resistance earth fault if the protection criterion is accepted; and sending an action tripping signal to trip breakers at the two ends of the power transmission line. According to the method, the relay protection of the single-phase high-resistance earth fault of the power transmission line is realized by using the single-ended current magnitude, the action performance is not affected by transition resistance and load current, and correct reliable action can be realized in case of single-phase high-resistance earth fault of the power transmission line. According to the method, only the single-ended current magnitude is required to be used, the voltage data is not required to be used, and the action performance is not affected by secondary loop breakage of a voltage transformer.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for realizing single-phase high-resistance grounding fault relay protection of transmission lines by using single-end current. Background technique [0002] The additional impedance generated by the transition resistance will seriously affect the action performance of the impedance distance protection. If the additional impedance generated by the transition resistance is resistive and inductive, it is easy to cause the impedance distance protection to refuse to operate when there is a fault in the protection zone of the transmission line; beyond. [0003] High / super / extreme voltage AC transmission lines are often also heavy-duty transmission lines. Heavy-load currents will cause impedance distance protection to malfunction or refuse to operate. The impact of heavy-load current on the performance of impedance distance protection cannot be i...

AI Technical Summary

Problems solved by technology

[0002] The additional impedance generated by the transition resistance will seriously affect the action performance of the impedance distance protection

If the additional impedance generated by the transition resistance is resistive and inductive, it is easy to cause the impedance distance protection to refuse to operate when there is a fault in the protection zone of the transmission line; go beyond

[0003] High / super / extreme voltage AC transmission lines are often also heavy-duty transmission lines. Heavy-load currents will cause the impedance distance protection to malfunction or refuse to operate. The influence of heavy-load currents on the performance of impedance distance protection cannot be ignored.

Under the condition of overload transmission, the line has no faults. The measured impedance of the traditional distance protection will seriously deviate from the actual measured impedance due to the influence of the overload current, which will easily lead to the misoperation of the traditional distance protection, resulting in the expansion of the power grid blackout range, and even causing a large number of load transfers to threaten the normality of the line. operation, causing a huge security risk to the grid security

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