Longitudinal zero-sequence protection method of voltage-compensated power transmission line

Abstract

The invention discloses a longitudinal zero-sequence protection method of a voltage-compensated power transmission line, and solves the problem of low zero-sequence protection sensitivity during a high-resistance grounding fault in a protection region. The longitudinal zero-sequence protection method comprises the following steps of inputting zero-sequence voltage compensation (a product of a zero-sequence current and half impedance of the whole line of the power transmission line) when a phase included angle Theta<2> between a voltage phase and a current phase of a negative sequence of one end conforms that Theta<2> is larger than 175 degrees but smaller than 325 degrees; judging whether an internal fault or an external fault occurs when the compensated zero-sequence voltage amplitude 3U<0>' is larger than 0.5V and a phase included angle Theta<0>' between the zero-sequence voltage phase and the zero-sequence current phase after compensation conforms that Theta<0>' is larger than 175 degrees but smaller than 325 degrees; and sending out an allowable trip signal to an opposite end of the power transmission line, sending out a trip command to a fuse at an end and simultaneously sending out the allowable trip signal to the opposite end when opposite end protection conforms to the abovementioned condition, so that the fuse at the end can be switched off by the fuses at the two ends when the internal fault occurs. By the longitudinal zero-sequence protection method, the problems of false action of a protection device during alternative internal fault and external fault and excessively low zero-sequence voltage due to high-resistance grounding to cause that longitudinal zero-sequence protection cannot be started are solved.

Description

technical field [0001] The invention relates to a method for voltage-compensated longitudinal zero-sequence protection of transmission lines, which is suitable for the longitudinal zero-sequence protection of transmission lines, so that the longitudinal zero-sequence protection of transmission lines can operate correctly when there is a fault in the area, and the fault outside the area is reliable and correct move. Background technique [0002] Transmission lines are important equipment for power grid transmission. The safe operation of transmission lines is not only closely related to social life, but also related to the safe and stable operation of the entire power grid. As the first line of defense of the power grid, relay protection plays a vital role in the safe and stable operation of transmission lines. At present, the protection devices of transmission lines in the power grid are mainly protected by longitudinal distance, longitudinal zero sequence and longitudinal ...

AI Technical Summary

Problems solved by technology

[0003] The invention provides a voltage-compensated longitudinal zero-sequence protection method for transmission lines, which is suitable for the longitudinal zero-sequence protection of transmission lines, and solves the problem that the transmission line's longitudinal zero-sequence protection is under protection due to the existence of mutual inductance between conductors. The technical problem of misoperation when there is a phase-to-phase fault outside the protection zone solves the technical problem of low sensitivity of zero-sequence protection when a high-impedance ground fault occurs in the protection zone