Standardized graphic similarity matching identification-based zero-sequence differential protection algorithm for transformer

Abstract

The invention discloses a standardized Hausdorff graphic similarity matching identification-based zero-sequence differential protection algorithm for a transformer. Waveform similarity matching identification is carried out on a self-produced zero-sequence current sequence and a neutral line TA current sequence for zero-sequence differential protection for the transformer by a standardized Hausdorff distance algorithm. The zero-sequence differential protection algorithm disclosed by the invention can effectively prevent maloperation of traditional zero-sequence differential protection caused by recovery surge after an external earth fault is eliminated under the condition of ensuring the same protection scope and transition resistance resisting ability as those of the traditional zero-sequence differential protection, and has obvious advantages in the aspect of quickness.

Description

technical field [0001] The invention relates to a transformer zero-sequence differential protection algorithm based on standardized graphic similarity matching recognition, and relates to the field of transformer zero-sequence differential protection. Background technique [0002] Generally, transformer zero-sequence differential protection has strong anti-inrush capability and high accuracy. Since the magnitude of the homodyne unbalanced current has a correlation with the magnitude of the current at both ends of the zero-sequence differential protection, in recent years, the improved zero-sequence differential protection strategy will add a proportional braking criterion to ensure accuracy. [0003] However, there are still many reports of transformer zero-sequence differential protection malfunctioning after external single-phase grounding transient faults or external single-phase grounding faults are removed for 500kV and 220kV transformers. It belongs to the fault beyon...

AI Technical Summary

Problems solved by technology

It can be clearly seen that when there is no fault in the zero-sequence differential protection and the actual zero-sequence differential current is 0, the bias accumulation of the recovery inrush current on the neutral line TA after fault removal has seriously affected the zero-sequence Accuracy of Differential Measurement Current

The peak value of zero-sequence differential current fluctuation is considerable, which will lead to zero-sequence differential protection misoperation

And, obviously, taking the traditional zero-sequence differential protection with proportional-amplitude tripping characteristics as an example, it is impossible to eliminate such zero-sequence differential protection by improving the operating current, braking coefficient or the slope of the action section of the proportional braking criterion. Occurrence of Differential Protection Misoperation

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