Advanced control strategies for multilevel inverter in grid-connected and off-grid photovoltaic systems: A multi-objective approach using LS-PWM for THD reduction

We propose, in this paper, an advanced control strategies to enhance the efficiency and stability of grid-connected and off-grid photovoltaic (PV) systems. Utilizing a multilevel inverter and a DC/DC boost converter, we integrate a novel multi-objective control strategy that combines sliding mode control and LS-PWM techniques. The primary goals are to maximize energy production, ensure grid stability, and minimize total harmonic distortion (THD). The proposed approach leverages the nonlinear model of the PV system, which includes the photovoltaic field, boost converter, and multilevel inverter. The innovative control strategy is designed to achieve the following objectives: optimizing the performance of the PV system in terms of energy output and grid stability under varying weather conditions, controlling active and reactive power to ensure a unity power factor on the grid side, and adapting the power output to match the load demand in off-grid mode. Extensive simulations conducted in the MATLAB/Simulink environment demonstrate the robustness and stability of the proposed control methods. Results show significant improvements in energy production, power quality, and system efficiency, validating the effectiveness of our advanced control strategies in real-world scenarios.