Grey wolf optimization-tuned PI controller for DC bus voltage stabilization and energy management in a hybrid PV-wind-battery energy system integrated with a nine-level switched-capacitor multilevel inverter: Experimental validation

The main challenge in combining hybrid solar and wind renewable energy sources into a common DC bus bar is ensuring the stability of the DC bus and energy management under variable source and load conditions. The variable nature of the sources degrades system performance and power quality. This research presents a hybrid solar-wind-battery energy system that comprises a quadratic boost converter (QBC) for photovoltaic (PV) power extraction and a boost converter for wind power extraction and a DC bus bar. A nine-level multilevel inverter (MLI) is employed to improve the AC voltage waveform quality while reducing total harmonic distortion (THD). A metaheuristic technique called grey wolf optimization (GWO) is integrated with the proportional-integral (PI) controller to enhance voltage stability in the DC bus. To assess its efficacy, it is compared to the performance of the conventional PI controller under diverse transient settings using MATLAB/SIMULINK software. The findings suggest that the GWO-PI controller decreases the voltage overshoot and undershoot and stabilizes the system within 0.01 to 0.08 seconds across all transient conditions. The experimental setup validates the simulation outcomes, ensuring DC bus stability, enhanced dynamic response, and power quality.