Ground-Fault Detection and Localization Method of PV String Based on Spread-Spectrum Time Domain Reflectometry (SSTDR)

Any healthy PV string has a specific impedance, and the impedance value will change in the event of a ground fault. At a certain frequency, the capacitance of PV modules will be difficult to ignore, and the capacitance size changes with the change of temperature and irradiance. Therefore, based on the transmitted SSTDR signal, transmission line, PV module parameters under different irradiance and temperature, this paper proposes a ground fault detection and localization method combining SSTDR and dictionary learning. This method does not need to measure the voltage and current parameters of the photovoltaic system, which can eliminate the detection blind spots in the traditional detection method, and is effective under fault conditions such as different grounding resistance.