Single-phase Grounding Fault Detection Method in Resonant Grounding System Based on the Ratio of Instantaneous Zero-Sequence Voltage to Current Derivative

Existing fault detection methods in resonant grounding systems mostly compare global zero-sequence electrical quantities. To address this issue, this paper proposes a single-phase grounding fault detection method in resonant grounding systems based on the ratio of instantaneous zero-sequence voltage to current derivative. Firstly, the formulas for the ratio of zero-sequence voltage to current derivative for faulty and healthy lines under single-phase grounding faults are theoretically derived, and the differences of their characteristic are compared. Based on it, single-phase grounding fault detection method based on the mean index of the ratio of instantaneous zero-sequence voltage to current derivative is constructed. Finally, the performance of the proposed method is comprehensively verified and tested by using PSCAD/EMTDC software. The results show that this method has the advantages of strong tolerance to transition resistance, requiring only the calculation of the ratio of the instantaneous voltage to current derivative locally after the fault. This method has strong real-time performance, small data processing volume, and easy implementation. Moreover, it still maintains high fault selection accuracy under interference factors such as noise and changes in sampling frequency.