Performance Evaluation and Enhancement of an Electric Vehicle DC Fast Charging Station in a Weak Distribution Feeder

Abstract

This work investigates and evaluates the performance and impact of a dc fast charging station (DCFCS) in a rural distribution feeder under various grid conditions. The station includes three dc fast chargers, each of which is rated at 360 kW and 900 V. The studies are conducted in time-domain using the off-line PLECS software platform. The studies show that the point of common coupling (PCC) voltage drop limits the lowest short-circuit ratio (SCR) that the DCFCS can satisfactorily operate with. An enhancement method, utilizing both a load curtailment strategy and a battery energy storage system, is consequently proposed to maintain the PCC voltage above its lower limit under low SCR conditions, thereby extending the charging station’s range of operation. RTDS-based real-time simulation results i) verify that the enhanced DCFCS is able to operate under the extended grid condition and ii) demonstrate the hardware implementation feasibility of the proposed methodology.