Coordinated Charging Control of Electric Vehicles While Improving Power Quality in Power Grids Using a Hierarchical Decision-Making Approach

As electric vehicles (EVs) are connected to the distribution power system, EV owners desire to charge their EVs economically, reliably, confidentially and without requiring major modification to the charging systems in their EVs. At the same time, the increasing EV connections to the distribution power system can increase the electric load demand and decrease the power quality (PQ) of the power system due to the charging current of the EV chargers. It is, therefore, necessary to devise novel strategies for the coordination of the connection of EVs at the distribution level. Although different control methods have been proposed previously, most of these solutions require costly advanced infrastructures and computational resources. In this paper, a charging control system (CCS) using a hierarchical decision-making (HDM) approach is devised that can be easily applied for the economical and reliable charging of commercial EVs with minor modifications while improving the PQ in the power grids. The HDM approach includes a primitive energy management strategy and an adaptive droop control for the real-time operation. A thorough investigation of the effectiveness of the proposed CSS to meet the major needs of EV owners while improving the PQ of the distribution network has been carried out. The results from the case studies show that the CCS can satisfy the preferences of the EV owners, while improving the PQ of distribution grids. Specifically, the CCS can meet the economical and reliable EV charging for the EV owners, and at the same time maintain the voltage deviation within the acceptable PQ limits.