Electrical protection in a smart dc node that feeds electric vehicles charging stations

This research provides a detailed overview of the design and functionalities specified in electrical protection requirements for the grid-interconnection systems of a smart dc node used to feed electric vehicle (EV) charging stations. The survey focuses on protection relays. The multi-terminal dc node connects a 0.4-kV ac secondary distribution network (SDN), a 25-kV ac railway traction system (RTS), a 3-kV dc RTS, and a local distributed generation (DG) system. The DG includes both a photovoltaic (PV) system as well as backup storage systems (battery and supercapacitor). For this purpose, a wide revision was made of all the codes and standards for the networks, DG of the smart node, and the EV charging stations.