Optimal placement and sizing of public charging stations for electric vehicles : taking into account both demand side and network infrastructure

Abstract

The growth of the share of electric vehicles (EVs) over the last years and its contribution to the reduction of greenhouse gases is seen as a positive trend for society. However, with a high penetration of EVs it might become necessary to redesign the distribution grid as these EVs represent significant loads that might cause potential overloads or excessive voltage drops. In this work we try to take into account these problems in the planning phase rather than in the operation phase as typically has been studied in the literature. Therefore we have developed a bi-level model to determine the optimal locations for electric charging stations. In the upper level we decide in which LV feeder vehicles will charge and at what time of the day they will be connected to charge. In the second level we determine the optimal location and size of the charging stations with respect to the minimal walking distance for the vehicle owners. The optimal locations are determined while taking into account the limits of the network and these results are compared with the optimal solution from a purely customer point of view. The results show that the minimum number of stations that needs to be installed as well as the walking distance can increase when a solution tries to respect all the limits of the network. Secondly it is shown that in some cases it is necessary to restrict the installed capacity in a low voltage feeder in order to avoid line overloads. Moreover, charging management could significantly improve the reliability of the system while some form of parking management could help to reduce the number of stations that needs to be installed.