Mitigation of the mutual dynamic interactions between a direct-current fast charging station and its host distribution grid

The fast and intermittent power changes in a direct-current fast charging (DCFC) station impose adverse dynamic impacts on the station's host grid, particularly a weak AC distribution grid. This paper (i) investigates the impacts of the electric vehicle (EV) conventional DCFC station on its host distribution power system, and (ii) shows that the station can be enhanced by a battery energy storage system and an appropriate control strategy to mitigate the mutual dynamic interactions between the station and its host grid. The enhanced DCFC station is based on a variable-voltage, common DC-bus architecture which masks the station's internal dynamics, including rapid and intermittent EV charging processes, from the grid. Thus, it can be interfaced to a host grid, regardless of short-circuit level, X/R ratio, and power capacity. The focus is also on the dynamic immunity of the DCFC facility to potential disturbances in its host weak-grid. The reported studies are based on detailed time-domain simulation of two DCFC stations in the PLECS software platform.