A Grid Connected PV System Fault Diagnosis Method

In this paper, a fault diagnosis method for grid-connected photovoltaic (GCPV) systems is presented. The method is based on the monitoring of the ac electrical variables and especially on the measurements of the currents and voltages at the output of the inverter. After a short introduction on the topic, the necessary steps to build a GCPV system model are described; the photovoltaic (PV) array is connected to the grid through a boost converter and an inverter. Four categories of faults were studied: a) faults inside the PV array, b) faults between the dc bus and the ground, c) faults in the power electronics devices and d) faults in the grid. The response of the system to each fault case was then observed, leading to the generation of a set of symptoms and the creation of the fault signature table. Using this fault signature table, a fault diagnosis method was developed. This latter is able to detect all the studied faults and localize sixteen out of the total of twenty fault cases; two groups of faults and fourteen individual fault cases. Finally, it creates an alarm signal in less than 60 ms, assuming that only one fault is occurring at a time. The robustness of the method was validated for different irradiance levels by simulation means.