The effect of IMC bus charging behavior on the trolleygrid

Abstract

We are in the middle of a transition to zero-emission mobility. The European Union has set high targets for zero-emission bus sales. Many European local governments and public-transit operators are looking to replace their GHG-emitting diesel/gas bus fleets with clean alternatives. One such alternative is In Motion Charging (IMC) technology for trolleybuses. With this technology trolleybuses are able to charge an on-board traction battery whilst in motion and connected to the overhead wires. This makes it possible for these buses to extend their range outside the trolleygrid infrastructure. These IMC buses can replace diesel/gas buses. IMC is of particular interest for municipalities that currently have a functioning trolleybus fleet and infrastructure. Existing infrastructures are however not built with the increased power demand of IMC buses in mind. A good understanding of the power demand of IMC buses and the limits of a trolleygrid is necessary before implementing IMC buses. The explanatory research that is presented in this report aims to give insight in the design factors that influence the feasibility of adding in-motion charging buses to an existing trolleybus network. It does so by first explaining the difference in energy consumption between IMC buses and regular trolleybuses through simulations. Next, by performing a case study on the Arnhem trolleygrid the effect of IMC buses on the trolleygrid is discovered. The results of the energy consumption comparison indicate that there is promising potential for IMC implementation. It shows that there is a large margin in which IMC buses can make more efficient use of their regenerative energy compared to their regular trolleybus counterparts. It also shows that there are large degrees of freedom in IMC bus implementation leaving room for errors. The Arnhem case study uncovers where exactly these errors lie by looking at potential power demand, minimum voltage and maximum current limit breaches on the network. As long as these breaches can be mitigated through smart charging strategies there is a lot of promise for IMC bus implementation on existing trolleygrid infrastructures.