Hierarchical Coordinated Control of Plug-in Electric Vehicles Charging in Multifamily Dwellings

This paper presents a hierarchical optimal control framework to coordinate the charging of plug-in electric vehicles in multifamily dwellings. A particular scenario is considered where distributed urban residential communities access electric power supplies through a common primary distribution transformer. We first formulate a centralized finite-horizon control problem. The proposed multistage mixed-integer program seeks to maximize the total utility of the charging service provider while satisfying customers´ charge demands and transformer capacity constraints. By exploiting the structure of the centralized model, we decompose the centralized problem with respect to each parking deck based on the Lagrangian relaxation method and design an effective heuristic method to find feasible solutions to speed up convergence. Case studies on operations of five parking decks following different charging strategies are carried out. Simulation results demonstrate that the proposed distributed hierarchical charging strategy outperforms the centralized charging strategy from the perspective of computational requirements. System reliability and customer privacy protection are also discussed.