Vehicle to grid — Reference architectures for the control markets in Sweden and Germany

Previous work has shown that it could be profitable on some control markets to use plug-in hybrid electric vehicles (PHEV) as control power resources. This concept, where battery driven vehicles such as PHEVs provide ancillary service to the grid is commonly referred to as Vehicle to Grid. The idea is to sell the capacity and energy of the parked PHEVs on the control market. Due to the fact that cars on average are parked 92% of the day, the availability of this capacity could be very high, even though it will be highly dependent on commuting patterns in peak hours. However, as each PHEV has a very small capacity from a grid perspective, it is necessary to implement an aggregating control system, managing a large number of vehicles. The present article investigates design requirements on such a system.