Abstract: Based on a typical single-phase grounding fault of tie-line in a centralized new energy power station, the zero sequence current characteristics of the fault are analyzed, and a differential relay protection method of zero sequence resistive current of tie-line in a small resistance grounding power station is proposed. The power stations on both sides of the tie line are grounded by small resistance, and the zero-sequence differential resistive current component is a constant when the tie line is grounded in single phase, which has nothing to do with the capacitance of the tie line and the power stations on both sides to the ground. This method improves the accuracy and sensitivity of judging the single-phase grounding fault of power station tie line.

Key words: contact line, zero-sequence resistive current differential, single-phase ground, new energy power station