A comprehensive review of vehicle–to–grid (V2G) technology as an ancillary services provider

In recent years, the significance of electric vehicles (EVs) in smart grids has become crucial because of their eco–friendly attributes and capacity to curtail emissions, in contrast to vehicles with internal combustion engines. In vehicle–to–grid (V2G) technology, plug–in electric vehicles (PEVs) function as both loads and sources in charging and discharging mode, respectively. The increasing penetration of renewable energy sources (RESs) creates some challenges for stable grid operation like voltage and frequency fluctuation. V2G can enhance the efficiency, stability, and reliability of the power grid by injecting power back into the grid and offer various ancillary services, such as voltage and frequency regulation, peak load shaving, spinning reserves, and backup for intermittent RESs. This paper presents a comprehensive review of all possible ancillary services facilitated by V2G. The conventional and recent technological developments, control techniques, and novel approaches are reviewed in this article. Additionally, this research comprehensively and objectively investigates how these services can be achieved from other sources and compares them using V2G. Furthermore, the worldwide distribution of V2G demonstration projects and the services they offer are highlighted. Finally, potential recommendations are presented based on future prospects.