Ground Fault Detection for Transmission Lines Connected to Photovoltaic Systems Using Inverters DC-Link Voltage

This study proposes a ground fault detection method for transmission line systems connected to inverter-based resources (IBRs), such as electronically coupled wind turbines and solar photovoltaic (PV) systems. IBRs, typically, have an initial high-frequency transient response to power system faults with limited magnitudes of short circuit current, which is different from conventional synchronous generators. IBRs' fault contribution may impact distance protection by reducing the security or dependability of the element. Distance protection may misoperate by tripping for reverse faults or not tripping for forward faults when IBRs are the main source of fault current. The proposed ground fault detection method analyses dc voltage variation in inverters' dc-link to indicate fault location during single-line-to-ground (SLG) faults. The method is designed to aid distance protection to trip forward SLG faults faster and avoid tripping for reverse faults by communicating with the inverters through low-bandwidth communication channels. The PV system and the detection method are modeled and simulated using an electromagnetic transients program.