Assessing the Frequency Response Potential of Heavy-Duty Electric Vehicles with Vehicle-to-Grid Integration in the California Power System

The integration of heavy-duty electric vehicles (EVs) with Vehicle-to-Grid (V2G) capability can enhance primary frequency response and improve stability in power systems with high renewable penetration. This study evaluates the technical potential of heavy-duty EV fleets to support the California power grid under three practical charging strategies: immediate charging, delayed charging, and constant-minimum-power charging. We develop a simulation framework that couples aggregated frequency dynamics with battery and charger constraints, state-of-charge management, and fleet-availability profiles. Performance is assessed using standard frequency security metrics, including nadir, rate-of-change-of-frequency, overshoot, and settling time, across credible contingency scenarios and renewable generation conditions. Results indicate that both non-V2G modes and V2G-enabled operation can contribute meaningful primary response, with V2G providing the strongest and fastest support while respecting mobility and network limits. Sensitivity analyses show that the relative benefits depend on charging strategy, control parameters, and renewable output, highlighting design trade-offs between response magnitude, duration, and battery usage. Overall, heavy-duty EV fleets-when coordinated by appropriate charging and V2G controls-offer a viable resource for strengthening primary frequency control on the California grid and mitigating stability challenges associated with increasing renewable penetration.