Techno-environmental and economic impacts of EV charging strategies on urban power systems under fleet heterogeneity and electrification uncertainty

As cities are at the forefront of transport electrification, the rapid growth of electric vehicles (EVs) in urban areas introduces additional volatile electricity demand, posing challenges to the urban power grid. Therefore, effective interaction between EVs and the grid has become increasingly important, which is influenced by both variable renewable energy (VRE) on the supply side and charging strategies on the demand side. However, the impact of charging strategies on VRE capacity remains unclear. This study projects the charging loads of EVs under varying electrification levels and develops a city-scale power system dispatch optimization model that incorporates charging strategies to assess their technical, economic, and environmental impacts on the power system. Using Beijing as a case study, the results show that electrification levels significantly influence the effectiveness of charging strategies on power system operation and planning. Compared with uncoordinated charging, unidirectional (V1G) and bidirectional (V2G) charging reduce carbon emissions by up to 1 % and 41 % and total system costs by 7 % and 13 %, respectively, under high electrification. They also provide additional system flexibility, enabling a significant increase in the installed capacity of VRE and its share in the power mix, with V2G performing better and further outperforming V1G in grid stability and peak shaving capacity. Therefore, EV charging with V2G should be incorporated into VRE capacity planning to realize its full potential.