Method based on fault transient process for coordinating operating characteristics of differential relay

Abstract

A method based on fault transient process for coordinating operating characteristics of a differential relay comprises the steps that: the current sampling values of braches of each bus are obtained through AC (alternating current) sampling; the positions of switches on the branches of each bus are obtained; differential current on two buses, differential current on the bus I, and small differential current on the bus II are calculated according to bus connecting manner and the positions of the switches on every branch; and if the buses are in the dividing sate, the large-differential proportional brake coefficient is reduced to 0.3. The method can ensure that bus can act reliably at every area where fault happens.

Description

technical field [0001] The invention relates to a bus protection sampling value differential relay, a sudden change differential relay, and a phasor differential discrimination method. Background technique [0002] Compared with other primary equipment in substations, the probability of busbar failure is much smaller, but the lines connected to it often cause line failures due to various reasons. Therefore, for busbar protection, there are far more external faults than internal faults. Therefore, the reliability of the device for faults outside the busbar area must be given top priority, especially when the CT saturation of faults outside the busbar protection area, although the busbar differential protection has special anti-CT saturation criteria, these criteria are longer than those with strong discrimination. CT saturation, usually works when CT saturation is deep. The relatively shallow CT saturation is unbalanced with the general CT transmission, relying on the propo...

AI Technical Summary

Problems solved by technology

[0004] The previous approach mainly considered the two busbars connected through the tie switch. When the tie switch is disconnected, when the busbar on the weak power supply side fails or has an outflow current, the sensitivity of the large-difference ratio differential element is not enough, so the large-difference ratio The proportional braking coefficient of the differential element has two fixed values: high and low