Interphase short circuit fault relay protection method of transmission line

Abstract

The invention discloses a relay protection method for interphase short circuit faults of an electric transmission line. The relay protection method comprises the following steps: a voltage drop from an electric transmission line protection mounting part to an interphase short circuit fault point and a voltage drop from an electric transmission line protection setting range to the interphase short circuit fault point are calculated by using fault interphase electrical capacity at the electric transmission line protection mounting part, and if the angle between the voltage drop from the electric transmission line protection mounting part to the interphase short circuit fault point and the voltage drop from the electric transmission line protection setting range to the interphase short circuit fault point ranges from 90 degrees to 270 degrees, an action tripping signal is given 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 interphase high-resistance short circuit 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 power system relay protection, in particular to a relay protection method for short-circuit faults between phases of transmission lines. Background technique [0002] The additional impedance generated by the transition resistance will seriously affect the 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 phase-to-phase short-circuit fault occurs in the protection zone; if the additional impedance generated by the transition resistance is resistive-capacitive, it will easily cause the impedance when the phase-to-phase short-circuit fault occurs outside the protection zone. The distance protection action produces overreach. [0003] High / super / extra-voltage AC transmission lines are often heavy-duty transmission lines. Heavy-load curren...

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 short-circuit fault between phases in the protection zone; The distance protection action produces overtaking

[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 operates normally. The measured impedance of the traditional impedance 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 line. Normal operation has caused a huge security risk to the power grid

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