Hierarchical energy storage configuration method for pure electric vehicle fast charging station

Aiming at short-term high charging power, low load rate and other problems in the fast charging station for pure electric city buses, two kinds of energy storage (ES) configuration are considered. One is to configure distributed energy storage system (ESS) for each charging pile. Second is to configure centralized ESS for the entire charging station. The optimal configuration strategy of hierarchical ESS is studied based on some influencing factors such as basic capacity cost, electricity charge, cost of ESS, costs of the transformer and converter and energy loss costs caused by efficiency factors. Combining with the different characteristics of charging load timing of multiple charging piles, the economic comparison of the ES configuration schemes are carried out and the effects of the components in the total cost are analyzed based on the topology of the charging system in the station. With the measured data of a fast charging station for electric city buses in Beijing, a multi-level linear programming optimization method is adopted. With the target of the lowest comprehensive cost of the charging station, it is concluded that it is more economical to configure centralized ESS at the DC bus.