Grid integration of three phase solar powered fault-tolerant cascaded H-bridge inverter

Grid integration of solar photovoltaic (PV) systems is becoming popular recently due to the merits of stable support to conventional grid, limiting global warming and reduced emissions. However, maintaining capacitor voltage balancing, unity power factor, sinusoidal grid current, and harmonic profile improvement are challenging tasks owing to change in irradiation conditions. Multilevel inverters (MLI) in grid-connected systems will enhance the system's power quality in terms of voltage and current total harmonic distortion (THD). One of the most promising multilevel topologies for renewable energy applications is the cascaded H-bridge (CHB) inverter. Since CHB inverters include many components, they have a higher risk of failure, lowering system reliability. Due to the change in irradiation condition, the voltage across the corresponding DC link capacitor may vary. Therefore, the DC-link capacitor balancing is mandatory and done by an individual control scheme. This paper presents a highly reliable, robust, and modular solar PV-fed fault-tolerant CHB inverter with an individual voltage/current control strategy for grid integration. Higher reliability and modularity, power factor correction, and harmonic profile improvement are the main objectives of the proposed system. The proposed system has been simulated in MATLAB/Simulink and validated with experimental results on the developed prototype for different irradiation conditions.