Adaptively-adjusted action boundary based single phase grounding fault relay protection method for power transmission line

Abstract

The invention discloses an adaptively-adjusted action boundary based single phase grounding fault relay protection method for power transmission line. According to the method, a fault phase voltage, a fault phase current, a fault phase negative sequence current and a zero sequence current in the protection installation position of the power transmission line are measured firstly; action boundary adjustment impedance is calculated; the summation of the action boundary adjustment impedance and protection set impedance is calculated to obtain adjusted action boundary impedance; measurement impedance is obtained by dividing the zero sequence compensation current by the fault phase voltage; then whether the measurement impedance amplitude is lower than the adjusted motion boundary impendence amplitude or not is determined; and if the measurement impedance amplitude is lower than the adjusted motion boundary impendence amplitude, a single phase grounding fault occurring in the protection set range of the power transmission line is determined, and a protection apparatus sends out an action tripping signal. The method adopts lumped parameters for modeling, so that simple algorithm principle, easy implementation of the programs, low calculated amount and high protection action speed are realized; the protection set impedance is adjusted in real time by the action boundary impedance, so that the protection action performance is not affected by the transition resistance and the load current; and therefore, the method can carry out correct and reliable action when the power transmission line is in the singe phase high resistance grounding fault.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a single-phase ground fault relay protection method for self-adaptive adjustment 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 the ground fault occurs in the protected area; if the additional impedance generated by the transition resistance is resistive and capacitive, it is easy to cause the impedance distance protection to exceed the ground fault outside the protected area. [0003] High / super / extreme voltage AC transmission lines are often also heavy-duty transmission lines. Heavy-load currents wi...

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 will easily cause the impedance distance protection to refuse to operate when the ground fault occurs in the protected area;

[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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