Coordination of PEVs charging across multiple aggregators

In this paper, a hierarchical coordinated charging framework for PEVs across multiple aggregators is proposed. First, each aggregator computes its aggregate charging load boundaries based on customer charging requirements and local transformer capacity limits. With the load boundaries of aggregators, a linear optimization model is then solved at the distribution system operator (DSO) level to generate the preferred charging curve for each aggregator. Finally, each aggregator intelligently allocates the charging power suggested by the DSO based on a fast heuristic algorithm. Case studies on four aggregators following different charging strategies are carried out. Simulation results indicate this charging coordination framework successfully achieves electricity cost minimization and system peak load controlling. Moreover, considering that part of profits of aggregators might be compromised by participating in charging coordination, a simple but clear compensation mechanism for aggregators is designed. (C) 2014 Elsevier Ltd. All rights reserved.