Online module-level fault detection of PV arrays using an improved two-stage Hampel identifier

This paper presents a novel fault detection method for photovoltaic (PV) array using an improved two-stage Hampel identifier, which can quickly detect the occurrence of faults and locate them at PV module level. The fault detection method is implemented in a two-level wireless sensor network based distributed on-line monitoring system which is developed to monitor the voltage of each PV module and current of all parallel PV strings in real-time. The 1^st stage Hampel identifier detects and locates the faulty PV strings by comparing the instantaneous currents of different PV strings. The 2^nd stage Hampel identifier detects and locates the faulty PV modules by comparing the instantaneous voltages of different PV modules in the faulty strings. Experimental results show that the proposed method can successfully detect and locate faulty strings and modules in several faulty cases, including the line-line faults, the degradation faults, the partial shading faults and the open-circuit faults.