Comprehensive performance assessment of energy storage technologies for fractional virtual inertia control in unconventional-source-dominated microgrids

Power systems encounter significant frequency control challenges as the share of dispatchable generation with inherent inertia decreases, while renewable energy sources (RESs), interfaced through power electronics, lack natural inertia response. Microgrids (MGs) with high RESs penetration are particularly vulnerable due to their low inertia and limited reserve. Recent studies have shown that fractional-order virtual inertia control (FVIC) based on energy storage systems (ESSs) provides improved frequency support compared to integer-order VIC. However, to date, no published studies have thoroughly examined the performance of FVIC with various energy storage systems (ESSs) technologies. Since each ESS technology has distinct characteristics, there is a need to understand their performance in frequency control if FVIC controls their power output. Therefore, this study investigates the performance of FVIC using five ESS technologies (i.e., battery energy storage, Redox flow battery, supercapacitor, flywheel energy storage, and superconducting magnetic energy storage systems) for frequency stability of an isolated MG with generation from a thermal power plant and intermittent RESs. Simulation results reveal that ESS characteristics significantly influence FVIC performance. Across all studied disturbances, including step load changes and RES fluctuations, the Redox Flow Battery-based FVIC achieved the lowest frequency deviation of 0.05–0.1 Hz, representing up to a 60% reduction compared to the other ESS technologies. It also exhibited the fastest damping response, rapidly restoring the frequency to its nominal value. These results emphasize the crucial role of ESS technology selection in determining the effectiveness of FVIC for MG frequency stability.