A Novel Scheme for Grid Interconnection and Protection of EV Charging stations

Electric vehicles (EV) are becoming more popular in transportation sector in recent years. As this trend is upward, concerns are raised about fulfilling EVs’ energy demand, therefore more EV charging stations (EVCS) should be constructed in different parts of a power system. Furthermore, there is another concern about providing a safe charging condition. Thus, this paper is focused on the protection of power network in the presence of EVCSs and defining the necessary protective devices for each kind of charging stations; residential, public and parking lots. Firstly, a classification of charging stations and connection types, based on their power demand, is suggested for either of grid to vehicle (G2V) and vehicle to grid (V2G) modes. According to the classification, essential protective devices as well as the type of connection are explained for each class. Besides, a simulation is carried out on a real power system in order to find out the impacts of EVCS on the system protective equipment in both G2V and V2G modes. The results show that the G2V mode effects on the system’s protection coordination and could increase the current passing through the protective devices, whereas, in V2G mode, the protective system works properly and there is no need to change their setting.