Robust Control of Cascaded H-Bridge Multilevel Inverters for Grid-Tied PV Systems Subject to Faulty Conditions

This letter deals with the design and implementation of a robust control approach for grid-tied PV systems. The main controller's objectives are to inject the maximum available power to the grid, whilst guaranteeing power quality even under faulty conditions. To this end, a multi-loop regulator is designed for the Cascaded H-Bridge Multilevel Inverters (CHBMIs) by combining a sliding mode control strategy for maximum power point tracking and a Lyapunov approach for Power Factor Correction (PFC). Validation of the proposed approach using MATLAB/SimPowerSimscape environment confirmed the ability of the proposed approach to successfully accomplish its objectives in terms of references tracking and regulation under both matching and mismatching irradiation levels as well as faulty modes stemming from the photovoltaic (PV) panels and/or the dc-dc converters. Additionally, the proposed approach was shown to outperform conventional approaches and enable the continuous operation of the PV system under various failure modes affecting multiple PV panels and/or their associated dc-dc boost converters.