Power converters have become an indispensable component of photovoltaic (PV) systems in recent years, despite their significant role, reliability concerns have hindered their broader implementation. Power converter faults constitute approximately 12% of all electrical system failures, with transistors being the primary source of these issues, accounting for over 31% of such faults. To ensure the continued advancement of photovoltaic technology, it is imperative that these components operate reliably and effectively. The reliability and performance of photovoltaic (PV) systems can be compromised by the challenges associated with fault detection, diagnosis, and mitigation. Traditional fault detection methods may prove insufficient for complex PV systems, potentially resulting in system failures and financial losses.

This paper contributes the study of an open switch fault tolerant control of a grid-connected photovoltaic system. The novelty of this method consists in analyzing the grid currents within normal and faulty operating modes. The fault-tolerant topology (FT) was achieved by adding one redundant leg to the grid side converter (GSC) to maintain system performance even under fault condition. Some simulation results for different irradiance levels prove the validity of the proposed FTCS. The proposed diagnosis and control strategy improves the reliability of the photovoltaic system in terms of cost, reliability, low detection time, and service continuity. Compared to existing methods presented in literature, the proposed approach achieved a reduction in fault detection up to 4 ms. Finally, the experimental validation of the proposed fault diagnosis algorithm is conducted on a high-performance dSpace DS1104 controller board using Matlab/Simulink show that this method can accurately detect the fault IGBTs.

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Fault-diagnosis and tolerant control based on direct power control for a grid connected PV system