Multi-priority queuing for electric vehicles charging at public supply stations with price variation

As electric vehicles (EVs) become more popular, public charging stations for such vehicles will become common. Because the load introduced by such stations on the grid is high, the smart grid will need to balance the load among charging stations in an area while minimizing the charging waiting time. To achieve this goal, we propose two models where vehicles communicate beforehand with the grid to convey information about their charging need and location. In the first model, we develop a mathematical formalism for handling requests for charging vehicles at public charging station based on queuing theory. The second model extends the first one by considering priority queues with two EV classes, high and low, and a cut-off service discipline. Both models are evaluated while considering mobility of vehicles in an urban scenario and time-of-use pricing. Finally, we propose two algorithms for directing vehicles to charging stations in a way to minimize either their waiting time to plug-in or their waiting time to charge completion. Simulation results show the effectiveness of the proposed approaches when considering both real EV and charging station characteristics and constraints. Copyright (c) 2014 John Wiley & Sons, Ltd.