Coordinated V2G control for transient voltage–frequency support in renewable microgrids

The increasing penetration of converter-interfaced renewable energy and electric vehicles (EVs) has significantly reduced the effective inertia of modern microgrids (MGs), thereby increasing their sensitivity to abrupt voltage and frequency disturbances. While uncoordinated EV charging typically exacerbates these stability issues, aggregated EV batteries can serve as a fast-acting, flexible resource when managed through advanced control. This paper proposes a coordinated control framework that leverages vehicle-to-grid (V2G) capability to enhance the dynamic stability of renewable-rich MGs, addressing the reduced inertia and fast-support capabilities inherent in converter-dominated renewable generation. The architecture uniquely integrates grid-forming voltage-source converter (VSC) control for distributed generation with a current-source converter (CSC)-based bidirectional interface for EV stations. This dual-layer approach enables complementary regulation across distinct control timescales: dispatchable units maintain steady-state power balance, while V2G-enabled EVs provide rapid MG-level transient support by adaptively modulating power injection/absorption via converter-level current-tracking dynamics. The strategy incorporates critical real-world constraints, including heterogeneous user behavior and battery state-of-charge (SOC) limits. Validation in a complex MG environment comprising wind, PV, synchronous generation, and dynamic loads demonstrates that the proposed framework suppresses frequency and voltage deviations, accelerates post-disturbance recovery, and improves overall grid resilience, as quantified by frequency nadir, voltage deviation, settling time, and integral absolute error metrics.