Deployment of Advanced Bidirectional Chargers to Lower Total Cost of Ownership of Electric-Vehicle Fleets

Vehicle-to-grid (V2G) technology utilizes the batteries of electric vehicles (EV) to provide services to the electric power grid. One use of V2G technology is demand charge management, which applies bidirectional DC fast chargers to deploy stored electricity from EV batteries to a site during periods of maximum power usage. Satisfying a portion of electricity demand of a building or system using EV batteries can incrementally reduce the need for power distribution infrastructure, and can provide value to building and facilities managers by reducing utility bills. This paper develops a protocol to evaluate the installation of advanced charging stations at various locations based upon factors such as duty cycles, fleet locations, and the potential for generating revenue from demand charge management. The revenue relies partly on the development of a predictive algorithm used to forecast electricity demand with a specified lead time that can enable the V2G operator to communicate with the vehicles and signal them to charge and discharge in order to mitigate peak demand incidents. The combined energy storage capacity and power output of EV fleet batteries placed behind the meter will be able to decrease the net energy supplied by the grid, thereby reducing load at the meter. The effort has suggested how demand charge management can be a viable energy storage service performed by batteries of electric vehicles with appropriate communications and systems integration. The paper builds on previous work which monetized the relatively small effects of frequency regulation on battery life cycles and simulated the duty cycle of a typical EV in a fleet to evaluate the additional value electric vehicles can provide to the electricity generation market. Based on the above results, several needs for future research are identified and prioritized.