A method to accelerate the detection of small half-wave stage of fault current

Abstract

The invention relates to the technical field of rapid detection of AC transmission line faults in power systems, in particular to a method for accelerating detection of a small half-wave phase of fault current. The invention briefly describes the problem of long detection time in the short-circuit fault rapid detection technology under certain fault voltage initial phase angles, analyzes the small half-wave shape characteristics of the short-circuit current in the early stage of the fault under such conditions, and proposes a method according to the current instantaneous The value or slope of the zero-crossing time interval is a method to quickly judge whether a short-circuit fault occurs in a transmission line. In order to ensure the reliability and effectiveness of the method, the value range of the zero-crossing time interval threshold is determined, and a zero-removing value constraint is proposed. The invention is simple and effective, and combined with the current instantaneous value and current slope fault fast detection criteria, can effectively improve the short-circuit current small half-wave stage fault rapid detection speed, and provides a new idea and method for the technical field of rapid detection of AC transmission line faults in power systems .

Description

technical field [0001] The invention relates to the technical field of rapid detection of AC transmission line faults in power systems, in particular to a method for accelerating detection of a small half-wave phase of fault current. [0002] technical background [0003] With the rise of electricity consumption in my country, the reform of power grid is deepening. The increase of power system load and the deepening of grid coupling have made the problem of grid short-circuit current exceeding the standard increasingly serious, and the short-circuit current in many places has exceeded the breaking capacity of circuit breakers. At present, among the measures to limit the short-circuit current at home and abroad, the scheme of adopting the Fault Current Limiter (FCL) is gradually welcomed with the progress of the research and development technology of power system equipment. Among them, the non-self-triggering FCL needs the fault detection and identification system to provide ...

AI Technical Summary

Problems solved by technology

For the same short-circuit current level and decay time constant, the waveforms of the short-circuit fault current are also different with different initial phase angles of the fault. When a short-circuit fault occurs at some initial phase angles of the fault voltage, the early current of the short-circuit transient process will appear A small half-wave characteristic, that is, the current change rate di / dt or the time interval between two zero-crossing points of current i is less than half a cycle, as follows figure 1 or figure 2 As shown, the basic characteristic quantities of the short-circuit current at this time, such as the instantaneous value and the size of the first-order differential di / dt, are basically equivalent to the normal operating current, so it is difficult to quickly judge whether a short-circuit fault occurs by detecting the basic characteristic quantities.

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