A Sequence Component Protection Method Based on Differential Current Increment

The transformer is a critical component in power systems, and studying fault protection methods is essential to prevent severe damage caused by short-circuit faults. Existing protection research primarily focuses on the characteristic analysis and identification of magnetizing inrush current. This involves constructing transformer models to investigate the generation mechanism of magnetizing inrush and examining the differences between inrush current and fault current, thereby reducing the likelihood of maloperation in protection schemes. However, in practical scenarios, faults often originate from minor inter-turn short circuits that progressively develop into more severe failures. Investigating protection strategies for such incipient faults can effectively prevent their escalation. Therefore, this paper proposes a sequence component protection method based on differential current increment. When the positive and negative-sequence components of the differential current increment are approximately equal and both exceed a predefined threshold, the method identifies a minor short-circuit fault. This enables the protection device to be triggered in the early stage of the fault, thereby preventing further fault escalation.