Design of a Medium Voltage DC Fast Charging Station with Grid Voltage Regulation and Central Modular Multilevel Converter

Fast, Superfast and Hyperfast Charging Stations (FCS) are now a reality and will become even more common in the next few years. Their integration in the medium voltage grid will impose new challenges and developments not only in the power electronics application range, but also in the grid analysis and dynamics. This paper presents a FCS structure based on a central AC-DC bidirectional converter, which for this study is the modular multilevel converter (MMC), with ancillary services provision capability. To evaluate the integration of the FCS on a standard distribution grid, a study case is described, in which an analysis on how load variations connected to it may affect the voltage regulation and how the FCS can contribute to reduce this effect. Once the requirements for the converter design are defined from the study analysis, a cost/losses optimization for the medium level MMC is provided. Finally, with experimental results presented, the current and future set-ups are discussed.