Grid-Integration of Battery-Enabled DC Fast Charging Station for Electric Vehicles

This paper presents, develops, and evaluates a system architecture and its control structure that mitigates impact of the Electric Vehicles’ (EVs) DC fast-charging station on its host weak AC-grid. The charging station incorporates a battery energy storage and (i) limits the imported power based on grid-imposed requirements and (ii) its control system decouples dynamics of the station from those of the grid. The charging station can operate in either grid-connected mode or islanded mode. The dynamic models of the charging station, in both modes, are presented and eigenvalue analyses performed to design the Local Controllers (LCs). Time domain simulation results in PLECS software are presented to verify that the station's internal dynamics, based on the proposed architecture and designed controllers, are sufficiently decoupled from the host AC-grid dynamics.