A hierarchical charging strategy for electric vehicles considering the users' habits and intentions
With the rapid growth of electric vehicles (EVs), charging large-scale EVs will affect the security and economy of power system operation. When developing the charging strategy, not only technical and economic issues but also the patterns of EVs' utilization should be considered. This paper presents a hierarchical charging strategy for EVs considering both system level and user level benefits, together with the travel habits and intentions of users. Firstly, a system level charging strategy is proposed as a multi-objective optimization problem, which can minimize the customers' charging fees, reduce the peak-valley difference and smooth the load fluctuation. Then a distribution charging strategy of EVs at user level based on the users' habits and intentions is presented, which aims for the minimization of each EV battery's charging times based on historical travel miles and real-time State of Charge (SOC). Finally, a case study indicates the effectiveness of proposed methodology to meet the requirements of power system and users.