Voltage protection method for single-phase earth faults of electric transmission line

Abstract

The invention discloses a voltage protection method for single-phase earth faults of an electric transmission line. The voltage protection method comprises the following steps: calculating the voltage of a single-phase earth fault point by using fault phase electrical capacity at an electric transmission line protection mounting part, using the fault phase voltage to minus the voltage of the single-phase earth fault point to obtain a voltage drop from the electric transmission line protection mounting part to the single-phase earth fault point, multiplying the voltage drop of a unit length electric transmission line by the protection setting range to obtain a voltage drop from the electric transmission line protection mounting part to the protection setting range, and judging whether the argument that the amplitude of the voltage drop from the electric transmission line protection mounting part to the single-phase earth fault point is smaller than that of the voltage drop from the electric transmission line protection mounting part to the protection setting range is tenable, if yes, an action tripping signal is give out by a protection device. The method solves the problem of the influence of transition resistance and load current on the protection action performance, and when high-resistance earth faults occur to the electric transmission line, the method can act correctly and reliably, the action sensitivity is high, and the protection range is stable.

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 voltage protection method of a power transmission line. 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; Action produces transcendence. [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 ignored. Under the condition of overload transmi...

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 the ground fault occurs in the protected area; Action produces transcendence

[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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