Operation of Cascaded H-Bridge Multilevel Converters for Large-Scale Photovoltaic Power Plants Under Bridge Failures

A cascaded H-bridge (CHB) converter is one of the viable options for next-generation large-scale photovoltaic (PV) power conversion. Owing to the increased number of components involved, converter reliability and fault-tolerant control are important issues. A CHB converter must also manage unequal power generation among bridges, which is inherent in PV applications because of unequal solar irradiance and/or module temperatures. This paper proposes a fault-tolerant strategy, which maintains balanced three-phase grid currents during faults with unequal power generation in healthy H-bridges. The effectiveness of the presented fault-tolerant control is verified using the results obtained from a 430-V 10-kW laboratory prototype.