Dynamic Interaction Stabilization Method for Multi-Parallel Hybrid Energy Storage Supplied Electric Vehicle DC Charging Station

For electric vehicle DC charging station (EVCS) supplied by energy storage units (ESUs) with virtual inertia and damping control (VIDC), the dynamic interaction oscillation (DIO) might exist due to the inconsistent inertia among VIDC-controlled ESUs. For this issue, a dynamic interaction stabilization method is proposed as the dynamic voltage stabilizer (DVSer), including a hybrid energy storage system (HESS) architecture and unified inertia and power sharing control. A super-capacitor (SC) bridge arm is reserved to improve the high-frequency inertia and a secondary voltage regulation link is design to remove the voltage error. From the views of system architecture and control design, the inertia inconsistency and DIO are eliminated by the unified-inertia-controlled HESS architecture, and the dynamic power sharing balance is guaranteed with prerequisites of no voltage deviation. Meanwhile, the multi-timescale equivalent model of the proposed DVSer is established and control parameters are designed based on phase margin. Abstract control links are mapped into visual impedances to study the working principle and external transient characteristics of DVSer from the perspectives of impedance connection and control links interaction. Afterward, the potential instability factors are identified, and relevant correction links are designed to offset their negative damping. The passivity analysis and impedance-based stability analysis assess the function of SVR loop, correction links and SC bridge arm. Finally, the experiment results validate this dynamic interaction stabilization method.