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

A typical 1 MVA charging station for electric cars connected to the 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 direct negative lightning strikes to the incoming overhead medium voltage line are computed. The risk of failure is evaluated by considering the rated impulse withstand voltage level of the charging station equipment by considering the effects of lightning current peak and waveform as well as soil resistivity. A protection scheme involving the installation of surge protective devices is investigated so as to diminish the risk of failure to equipment and cars. The energy absorption capability of surge protective devices is assessed and the necessity of dedicated surge protection for electric cars is discussed.