Fractional-order virtual inertia control based on a hybrid energy storage system for frequency control in an island microgrid

High penetration of renewable sources through microgrids leads to several instabilities, including frequency instability due to a lack of inertia and variability of solar and wind sources, as well as loads. In this paper, a control strategy based on virtual inertia control, also known as synthetic inertia control, is applied in an isolated microgrid (IMG) to ensure frequency stability. By analogy with conventional systems, the proposed virtual inertia controller is based on fractional order (FOVIC) and applied to the hybrid energy storage system. The parameters of these controllers are optimised by a novel metaheuristic algorithm known as the augmented grey wolf algorithm (AGWO), which is an improvement of grey wolf optimisation. The use of these allows better performance in terms of overshoot, and undershoot for frequency deviation compared to the entire virtual inertia control, the system without inertia controller, and another optimisation algorithm.