Distributed Power Profile Tracking for Heterogeneous Charging of Electric Vehicles

Coordinated charging of plug-in electric vehicles (PEVs) can effectively mitigate the negative effects imposed on the power distribution grid by uncoordinated charging. Simultaneously, coordinated charging algorithms can accommodate the PEV user's needs in terms of desired state-of-charge and charging time. In this paper, the problem of tracking an arbitrary power profile by coordinated charging of PEVs is formulated as a discrete scheduling process, while accounting for the heterogeneity in charging rates and restricting the charging to only the maximum rated power. Then, a novel distributed algorithm is proposed to coordinate the PEV charging and eliminate the need for a central aggregator. It is guaranteed to track, and not exceed, the power profile imposed by the utility, while maximizing the user convenience. A formal optimality analysis is provided to show that the algorithm is asymptotically optimal in case of Homogeneous charging, while it has a very small optimality gap for the heterogeneous case. Numerical simulations considering realistic charging scenarios with different penetration levels and tracking of a valley-filing profile are presented to validate the proposed charging algorithm.