DC-side high impedance ground fault detection for transformerless single-phase PV systems

The ground fault is one of the most common faults in the Photovoltaic (PV) power generation system. Previously, the ground fault detection interrupter (GFDI) and spread spectrum time domain reflectometry (SSTDR) methods were applied in the PV system to detect the ground fault of PV arrays. However, the limitations of GFDI constrain its ability to detect high impedance ground fault (HIGF) at PV arrays, and the implementation of SSTDR will increase the system cost. A novel approach based on the common mode (CM) model of the full-bridge inverter to detect the HIGF of PV arrays is proposed in this paper. Both the mathematical verification and PSIM simulation prove the effectiveness of CM model in detecting the HIGF for transformerless single-phase PV systems.