Coordinated AC frequency vs DC voltage control in a photovoltaic-wind-battery-based hybrid AC/DC microgrid

The intermittent nature of renewable energy generation and the variable AC and DC loads are major factors that offer great challenges in power management for AC/DC hybrid microgrids. In this context, this paper presents a coordinated AC frequency vs DC voltage control (CFVC) scheme for managing contemporary renewable energy-based hybrid AC/DC microgrids. The proposed control strategy enables appropriate power interactions between the AC and DC subgrids while sharing power fluctuations in a coordinated way. Both the AC and DC subgrids support each other in accordance with their normalized relative changes in AC frequency and DC voltage, respectively. The proposed CFVC scheme is designed using fractional-order-proportional-integral-derivative (FOPID) controllers, and bacterial-foraging optimization (BFO) method is employed for calculating the design parameters, viz. the controller gains and set-point orders. A typical photovoltaic (PV) wind-battery-based hybrid AC/DC microgrid is modelled and investigated, and the usefulness of the proposed scheme is validated under the renewable energy variations and load perturbations.