Optimal Tuning of Fractional Order PI for a Multi-DG Microgrid using the Starfish Optimization

Nowadays, the smart microgrid is a promising solution to overcome the issues of depleting fossil fuel, climate change, global warming and environmental pollution. A microgrid depends on the installation of renewable and distributed generation sources beside the local loads to minimize the cost of power transmission and high reliability against sudden faults. Among the various renewable energy micro-sources (REMSs) utilized in distributed generation (DG) systems, photovoltaic (PV) technology has gained significant traction due to its modularity, declining costs, and environmental benefits. This paper presents a modified architecture for an AC microgrid that includes six master units (MUs) powered by PV cells. Unlike conventional PI controllers, the proposed Fractional Order Proportional-Integral (FOPI) controllers feature an additional tunable parameter, which increases the complexity of the controller design. To address this, Star Fish optimization techniques are utilized and compared for selecting the optimal parameters of the FOPI controller. The optimization process focuses on enhancing power quality and improving both dynamic and steady-state performance by fine-tuning the HC controller parameters. Multiple objective error functions are used and evaluated to minimize the total harmonic distortion of the grid’s output current. The effectiveness of the proposed FOPI controller is verified in MATLAB/Simulink, considering permissible variations in inverter output active and reactive powers, as well as under conditions of grid voltage distortion.