Reliability Investigation of Long Photovoltaic String Generators under Electrical Fault Scenarios

Long string photovoltaic generators are the most commonly adopted connection architecture in PV systems. But, these generators are prone to electrical faults that can cause severe power losses, system damage and failure. In this paper, the effect of various electrical faults such as short-circuit fault, line-ground fault, bypass diode faults and mismatch fault on the long string have been investigated. Also, the performance of the string with increasing strength of the electrical faults has been studied. The electrical faults have been studied for a long string of twenty series connected modules in the MATLAB environment and the performance analysis has been done based on the power, voltage and current outputs, power losses, fill factor, efficiency and power-voltage curves analysis. It has been found that the series strings are highly vulnerable to line-ground and short-circuit faults whereas mismatch faults can create temporary losses in the system. The maximum losses in the PV string have been calculated as SO%, 100%, SO% and 86.70% under short-circuit, line-ground, bypass diode and mismatch faults.