An On-Demand Compensation Function for an EV as a Reactive Power Service Provider

Rapid growth in the deployment of electric vehicles (EVs) is creating opportunities for system operators to improve the reliability and sustainability of electricity delivery system, while reducing the operating cost. EVs can respond quickly, improve system stability, and provide reactive power support without battery wear. Therefore, EVs could be a promising source of reactive power when they are connected to smart charging equipment. However, under certain scenarios, reactive power support may raise the vehicle charging cost by shifting part of charging power to times of the day when the price of electricity is higher. Participation of EVs in an ancillary service market for reactive power will thus require some level of compensation for EV owners. In this paper, we present a framework for the calculation of reactive power supply function for EVs. We define an objective function representing charging/discharging cost of EVs and then minimize the cost under realistic constraints. An algorithm is then introduced that extracts the EV's supply function for providing on-demand reactive power service at minimum cost. Thus, the system operator can include EVs, as reactive power service providers (RPSPs) along with other service providers, to meet the on-demand need of the reactive power. Simulation results indicate the EV's ability to provide reactive power service during on-peak periods, when the system operator's need for reactive power is most likely high, at almost no cost to the EV owner.