Action boundary based relay protection method for interphase faults of self-adapting adjusting electric transmission line

Abstract

The invention relates to an action boundary based relay protection method for interphase faults of a self-adapting adjusting electric transmission line. The relay protection method comprises the following steps: measuring a fault interphase voltage, a fault interphase current and a fault interphase negative-sequence current at the relay location of the electric transmission line firstly; calculating an action boundary adjusting impedance, and calculating the sum of the action boundary adjusting impedance and a protection setting impedance to obtain the adjusted action boundary impedance; dividing the fault interphase voltage by the fault interphase current to obtain the measured impedance; judging whether the amplitude value of the measured impedance is less than that of the adjusted action boundary impedance or not; if yes, judging that the interphase short-circuit fault occurs within the protection setting range of the electric transmission line, and sending out an action trip signal. The relay protection method adopts a lumped parameter for modeling, is simple in algorithm principle and fast in protection action, can truly reflect the action boundary adjusting impedance affected by a transitional resistor and a load current, and adopts the action boundary adjusting impedance for real-time adjustment on the protection setting impedance, so that the protection action performance is prevented from being affected by the transitional resistor and the load current.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a relay protection method for adaptively adjusting phase-to-phase faults of transmission lines based on action boundaries. 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 phase-to-phase fault in the protection zone; if the additional impedance generated by the transition resistance is resistive and capacitive, it is easy to cause the impedance distance protection to exceed when there is a phase-to-phase fault outside the protection zone. [0003] High / super / extreme voltage AC transmission lines are often also heavy-duty transmission lines. ...

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 phase-to-phase fault in the protection zone; if the additional impedance generated by the transition resistance is resistive and capacitive, it is easy to cause the impedance distance protection to exceed when there is a phase-to-phase fault outside the protection zone

[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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