Voltage Support and Fault Suppression Strategy for DC Photovoltaic Islanded Systems

When large-scale photovoltaic (PV) power plants transmit electricity through flexible DC transmission systems, transient DC faults caused by environmental factors frequently occur in the cables, posing challenges to stable system operation. This study proposes an adaptive fault current limiting strategy based on current comparison feedforward control, aiming to effectively reduce both the rising rate and magnitude of DC fault currents, thereby enhancing the stability of PV islanded systems during fault conditions. By precisely regulating the fault current, the proposed method avoids control disturbances commonly observed under traditional V/f control schemes, offering a reliable safeguard for the stable operation of PV systems within distribution networks. The strategy was validated using the PSCAD/EMTDC simulation platform, and the results demonstrate that the adaptive current limiting approach significantly suppresses sharp fluctuations in DC fault current while maintaining stable power output from the PV system.