Optimal Size of Electric Vehicle Charging Stations in Distribution System with Consideration of Bus Voltage and Line Capacity Limits

Currently, the deployment of electric vehicle charging stations (EVCSs) in a distribution system has rapidly increased to encourage the electric vehicle usage of a customer. However, this may inevitably cause the technical issues concerning the distribution system operation criteria, i.e., bus voltage and line capacity limits. Therefore, this paper proposes a method for determining the optimal size of each EVCS without violating the bus voltage limit and the line capacity limit. The proposed method is based on the iterative technique to solve the optimization problem where six patterns of EVCS installation are investigated during off-peak and peak time periods of residential loads. To illustrate the effectiveness of the proposed method, a typical low-voltage distribution system in Thailand is selected to be a test system. Moreover, the fairness of all customers is considered by supposing that the EVCSs are equally installed at each bus, and the loads are equally distributed in the distribution system. The simulation results show that the optimal size of the EVCS during off-peak and peak time periods is mostly limited by the line capacity limit and the bus voltage limit, respectively. This implies that the behavior of customers to charge their electric vehicle should occur during off-peak time period instead of peak time period.