A String Current Based Solar PV Array Fault Detection Technique

Line-to-line or line-to-ground faults are the most common types of PV array faults. In contrast to faults in a power grid, which typically lead to very high currents, faults in a PV system do not necessarily lead to high currents, as these depend on the solar irradiance and the location of the fault. Therefore, fault detection in PV systems becomes a challenging task. The presence of series blocking diodes in a PV system connected in series in parallel makes fault detection with conventional PV array protection devices almost impossible. During partial shading, a solar PV system may exhibit characteristics similar to a fault and vice versa. Therefore, actual fault may go undetected and potentially leads to fire hazard.In this work, a fault detection technique based on monitoring array voltage and string currents is proposed. This technique can detect faults in a series-parallel configured (SPC) PV array, even when the strings are connected with series blocking diodes. A PV array system is developed using MATLAB SIMULINK, where the proposed algorithm is implemented. Simulation results from various faults and partial shading cases justify the applicability of the proposed fault detection algorithm.