The impact of EV battery cycle life on charge-discharge optimization in a V2G environment

In addition to improving the ground transport and the environment through reduced greenhouse gas emissions, Electric vehicles (EVs) can support a number of power grid services through the Vehicle to Grid (V2G) system. If properly integrated, EVs can help in integrating renewable energy sources, providing various demand response and ancillary services. There are a number of challenges that should be addressed before EVs can effectively provide these services. The main challenge is the availability of power from EVs. This challenge is related to the EV battery capacity, the available power at the time of need and the battery cycle life. Battery cycle life is inversely proportional to the number of charge-discharge cycles the battery goes through. Therefore, the battery cycle life and the cost of degradation should carefully be included when optimizing the V2G operation. In this paper, we develop a novel iterative algorithm to predict the effect of static and dynamic electricity and regulation prices on the battery cycle life. We optimize the charge-discharge process by considering frequency regulation signals, the day ahead real time pricing and the predicted cycle life. We develop a case study for the charge scheduling problem using actual frequency regulation and hourly electricity pricing.