CT disconnection detection method and system based on sequence current phase comparison, and medium

Abstract

The invention discloses a CT disconnection detection method and system based on sequence current phase comparison and a medium. The method comprises the steps: acquiring the positive sequence currents, negative sequence currents and positive sequence currents of the A phase, the B phase and the C phase of a line respectively; for any one of A, B and C phases of a line, judging whether the phase difference between the positive sequence current and the negative sequence current is within a first preset angle range and the phase difference between the negative sequence current and the zero sequence current is within a second preset angle range: if so, judging that the auxiliary criterion result of the CT disconnection state of the phase is true, otherwise, judging that the auxiliary criterionresult of the CT disconnection state of the phase is false; or performing OR operation on the auxiliary criterion result of the CT disconnection state of each phase to obtain an auxiliary criterion result of line CT disconnection, and if the auxiliary criterion result is true, indicating that CT disconnection occurs in the line. According to the invention, CT disconnection can be accurately judged, the judgment is accurate, the anti-interference performance is strong, and the action criterion of the CT disconnection criterion is more strict and more reliable.

Description

technical field [0001] The invention relates to the field of substation relay protection, in particular to a CT (Current Transfer, current transformer) disconnection detection method, system and medium based on sequence current comparison and phase. Background technique [0002] In recent years, several 110kV line high-resistance grounding faults occurred in Hunan Power Grid, which led to the corresponding 220kV main transformer overstepping tripping accidents, resulting in certain power load losses and negative impacts. Under high-resistance grounding faults, the zero-sequence voltage and zero-sequence current are small, and the fault characteristics may be between the line protection CT disconnection and zero-sequence overcurrent protection action conditions, so that the CT disconnection action blocks the line zero-sequence overcurrent protection , and cause the zero-sequence overcurrent protection of the main transformer to leapfrog when the subsequent fault characteristi...

AI Technical Summary

Problems solved by technology

When the CT is disconnected, zero-sequence current will be generated, and a small zero-sequence current will also be generated under a high-resistance ground fault. Therefore, the practice of only testing the zero-sequence current for the CT disconnection criterion has certain impreciseness.

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