Single-phase Ground Fault Detection Method Based on Phase-current of Deeply Fusion Switch

Most of my country’s power distribution networks are small-current grounding systems. With the transformation of the power system under the goal of carbon neutrality, a high proportion of new energy will gradually be integrated into the distribution network. When a single-phase ground fault occurs, the conventional transient line selection method based on zero-sequence voltage and zero-sequence current is easy to misjudge after the polarity change caused by power flow conversion. Due to the characteristics of high-precision three-phase current sensors of the primary and secondary deeply fusion switch, this paper conducts grounding detection based on the different fault characteristics of the three-phase currents of the faulty line and the non-faulty line. The period integral method is used to compare the amplitude and phasor of each phase to complete the ground fault detection. This method can be adapted to the grounding detection after the power flow is transferred. Combined with field application cases, it is proved that the proposed scheme can effectively realize ground fault location and isolation, and has universal applicability and economy.