Dc Bus Ancillary Controller Enabling Fast Frequency Response From Fast Charging Stations

Fast charging stations (FCSs) for electric vehicles (EVs), particularly those with integrated functionalities such as vehicle-to-grid (V2G) and embedded energy storage systems, represent a rapidly growing area in both research and industry. These advanced FCSs can provide ancillary services to support grid stability during disturbances. To enable such functionalities while ensuring robust and future-proof operation, control strategies must accommodate diverse and often complex operational requirements. In this context, grid-forming control has emerged as a promising alternative to conventional gridfollowing approaches, especially under weak grid conditions. Furthermore, ancillary control schemes can enhance the contribution of distribution-level resources to overall power system stability. However, existing literature lacks unified control frameworks that deliver fast frequency response (FFR) while accounting for system-specific components. This paper proposes an FFR strategy for FCSs based on a grid-forming control architecture. The proposed method leverages the energy stored in the internal DC bus capacitors to enable rapid response during transient events and supports communication-free reserve dispatch during critical conditions. The effectiveness of the approach is validated through simulations and controller hardware-in-the-loop (C-HIL) testing.