PSO optimized DC Voltage regulation and H∞ Controllers for grid-connected PV system

In this paper, a PSO tuned H ∞ based cascaded control strategy is designed for a Voltage source inverter in a 10 kW grid-connected photovoltaic (PV) microgrid system and validated through simulation. Traditional approaches focus on optimizing MPPT, DC-link voltage control loops, or AC-side current loops individually, leading to reduced stability for extreme variations in weather conditions. In this work, a unified design approach is proposed for simultaneously optimizing the PI parameters of the DC-link voltage controller as well as the weighting parameters for the dual loop H ∞ cascaded controllers according to ITAE criteria. The design approach provides low-order realizations of the complicated H ∞ dynamics through filtering of high-frequency pole-zero cancellations. The simulation results achieved using MATLAB/Simulink show excellent performance compared to other standard controllers when subjected to drastic changes in irradiance and loading. Quantitative analysis has established a quick dynamic settling time in the range of 0.15s - 0.25s, operational transient overshoot constrained under 4.0%, and outstanding quality measures for power such as load voltage THD of 0.71%, and grid current THD of 3.44%, guaranteeing full adherence to requirements of IEEE 1547 standard for grid code. The performance of the proposed controller is also compared with other standard controllers available in the literature such as PI, PR and MPC controllers. It is found that the proposed controller has a steady state error of 0.15% which is comparatively less than the other controllers. Also, all physical real-time challenges are thoroughly analyzed to lay out the groundwork for further prototype design and implementation.