Surge Protection of Charging Stations Against Impinging Overvoltages Due to Lightning Strikes to Incoming Medium Voltage Overhead Line

A typical 1 MVA charging station for electric cars connected to the overhead distribution system through underground medium voltage cables is modeled in the ATP-EMTP environment. Fast-front overvoltages impinging on the AC and DC sides of charging station equipment due to a wide range of lightning strikes to the incoming overhead medium voltage line are computed; positive and negative recorded lightning stroke currents are also considered. The risk of failure is evaluated by considering the rated impulse withstand voltage level of the charging station equipment by assessing the effects of lightning polarity, peak current, and soil resistivity. A protection scheme involving the installation of surge protective devices is investigated to diminish the risk of failure of equipment and interconnected charging cars. The energy absorption capability of surge protective devices against remote lightning strikes is assessed and the necessity of integrating surge protective devices to electric vehicles offering dedicated surge protection is discussed.