Investigation of a Decentralized Energy Management System for Undersupplied EV Charging Parks

In this paper, an energy management system (EMS) for undersupplied EV charging parks is presented. This undersupply is due to the maximum power demand for all charging stations connected to a common DC grid being larger than the maximum in feed power from AC mains. The EMS is completely decentralized and therefore allows easy addition of additional participants like chargers, AC/DC converters or storage systems into the common DC grid. This decentralization requires changes to the control structure of the connected power converters. These changes are evaluated for their effect on the stability of the whole grid. To investigate the proposed EMS, a simulation model based on real world charging park data is set up. The model is then used to evaluate the EMS for different degrees of undersupply and buffer storage. The findings are evaluated for different performance indicators to show the trade off between peak power shaving, installed storage and the charging of EVs.