Line differential protection action judging method and system based on power grid fault oscillogram

Abstract

The invention provides a line differential protection action judging method based on a power grid fault oscillogram. The line differential protection action judging method comprises the following steps of: acquiring a first bus side line fault oscillogram and a second bus side line fault oscillogram on which power transmission line three-phase current waveforms and bus three-phase voltage waveforms are formed; if sudden change waveforms exist in the power transmission line three-phase current waveforms and the bus three-phase voltage waveforms of the two oscillogram, determining that a power transmission line fault exists and a differential protection action is started; after the differential protection operation is started, acquiring suddenly-changed power transmission line current waveforms of all phases and power transmission line current waveforms before corresponding sudden changes from the power transmission line three-phase current waveforms of the two oscillograms, and judgingthe correctness of the differential protection action of a power transmission line according to the phase direction change of each phase of suddenly-changed power transmission line current waveform inthe power transmission line three-phase current waveforms of the two oscillograms and the corresponding power transmission line current waveform before sudden change. By implementing the line differential protection action judging method, the defects in the prior art are overcome, mathematical calculation is not needed, and the line differential protection action judging method is simple, visual,time-saving and labor-saving.

Description

technical field [0001] The invention relates to the technical field of relay protection, in particular to a method and a system for judging line differential protection actions based on grid fault record graphs. Background technique [0002] The differential protection of high-voltage transmission lines exchanges information on changes in electrical quantities at both ends through communication channels such as optical fibers and carrier waves, which can instantaneously remove short-circuit faults within the entire length of the line and improve the safe and stable operation of the power grid. At present, Fiber Channel has become the mainstream channel type for high-voltage transmission line protection. The main reason is that Fiber Channel has outstanding advantages such as large communication capacity, no electromagnetic interference, and channel operation independent of transmission line faults. It can transmit impedance relays and direction relays. Behavioral logic signa...

AI Technical Summary

Problems solved by technology

[0007] However, at present, to judge whether the differential protection action is correct or not when the internal short circuit fault or external short circuit fault of the transmission line is correct, it is necessary to accurately judge the current magnitude and direction of the local protection device and the opposite end protection device on the optical fiber current differential protection device, and then calculate the difference It is not only easy to make mistakes, but also not intuitive, time-consuming and labor-intensive.

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