Balancing power supply-demand by controlled charging of numerous electric vehicles

High penetration of variable renewable energy generation such as photovoltaics and wind power generation will cause a supply-demand imbalance in the entire system. The mass deployment of electric vehicles (EVs) and plug-in hybrid vehicles (PHVs) will also cause significant changes in electricity demand. Therefore, controlling and managing the charging time of EVs/PHVs are imperative for power system operation. We assumed trip patterns of 10 million EVs in the Tokyo power system and analyzed the power system loads, including the charging load of EVs, in some scenarios. We verified quantitatively that charging-time controls are absolutely necessary because the fuel costs for generating power by thermal power plants increase without charging-time controls. Further, we found that load leveling is more effective for multi-car charging management than for single-car charging management.