Improving the performance of grid-connected photovoltaic systems using a novel SPO-SHE-PWM algorithm with an AHB multilevel inverter

One promising approach to limiting greenhouse gas emissions is to use renewable energy sources, such as photovoltaic (PV) systems. Grid-connected PV systems utilise grid installations. However, they must satisfy international distribution network standards. This involves minimising harmonic orders and complying with standards for voltage injection into the distribution network. The inverter is the key for grid energy injection. Multilevel inverters (MLI) are a viable option, offering advantages over two-level inverters. Several approaches are used to control the fundamental voltage and eliminate or reduce low-order harmonics. The combination of MLI, the Asymmetric H-bridge Multilevel Inverter (AHB-MLI) with the Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) technique is the main topic of this paper. The aim is to improve the efficiency of the AHB-MLI inverter in grid-connected PV systems. A novel application of the Stochastic Painter Optimisation (SPO) algorithm is proposed to determine optimal switching angles, a concept not yet reported in the literature. A new SPO-based SHE-PWM (SPO-SHE-PWM) algorithm is proposed to compute optimal switching angles that meet international grid codes while reducing low-order harmonics. The proposed SPO-SHE-PWM strategy achieves rapid convergence, reaching optimal solutions in fewer than 10 iterations. This paper presents the development of the SPO-SHE-PWM algorithm, implemented with a seven-level AHB-MLI to validate the strategy, with performance evaluated and compared with state-of-the-art metaheuristic methods. Simulations and Processor-In-the-Loop (PIL) results show that the proposed approach achieves superior harmonic elimination, lower Total Harmonic Distortion (THD), a reduced fitness value and faster convergence rate, with no additional parameters or memory requirements. Experimental validation on a single-phase, seven-level inverter confirms that the SPO-SHE-PWM algorithm is ideal for achieving efficient harmonic control and high-quality power injection into grid-connected PV systems.