PLANNING AND OPTIMAZATION OF A FAST-CHARGING INFRASTRUCTURE FOR ELECTRIC URBAN BUS SYSTEMS

The deployment of battery-powered electric bus systems within the public transportation sector plays an important role to increase the energy efficiency and to abate emissions. Raising attention is given to bus systems comprising fast -charging technology. This concept requires a comprehensive infrastructure to equip bus routes with charging points. The number of charging points in turn has significant influence on the financial investment needs. Therefore, an appropriate and efficient layout of the charging infrastructure is crucial to optimize the total cost of ownership of the deployed technology. The central issue of optimizing is described by a capacity set covering problem. A mixed-integer linear optimization model was developed to determine the minimum number and location of required charging stations for a bus line service while respecting operational and technology-related constraints, particularly the battery charging behavior. Within the scope of the study, different energy consumption scenarios are examined in order to reflect external factors affecting the bus energy consumption such as traffic volume and climate conditions. Furthermore, a sensitivity analysis on the battery capacity and required charging infrastructure was conducted. The findings reveal significant differences in terms of needed infrastructure based on the consumption scenarios and the daily operation time. Moreover, a trade-off between battery size and charging infrastructure has to be made. The model is an advanced tool for planning the fast charging infrastructure of a bus system and hence supports the financial assessment of respective bus systems. The paper addresses upcoming challenges for transport authorities during the electrification process of the bus fleets and sharpens the focus on infrastructural issues related to the fast-charging concept.