Application of Traction Supply System for Charging Electric Cars

The development of electromobility involves the development of electric car charging infrastructure. The increase in the number of chargers poses new demands for the AC power grid, especially regarding its capacity of delivering high peak power. As an alternative for the public AC power grid, urban electrified transportation systems (trams, trolleybuses, and metro) can be used for supplying electric cars chargers.

The analysis, prepared by the colleagues of Gdansk University of Technology, discusses four options of integrating electric cars chargers with a traction power supply system. The option of connecting the charger to the traction overhead supply line has been selected due to the spatial availability of the power source and the possibility to use regenerative braking energy for charging. A set of criteria has been developed for analysing the capability of the traction supply system to feed electric cars chargers. An exemplary feasibility analysis was carried out for the trolleybus traction supply system in Gdynia, Poland. Gdynia, with nearly 250,000 inhabitants, has the trolleybus transportation system featured by the total length of the overhead line of approximately 100 km.

In the city of Gdynia (Poland), a converter station that allows the use of a traction system to supply receivers with industrial voltage of 400 V AC was launched in 2021 as a result of the “EfficienCE” project. The converter links a trolleybus overhead line to an electric vehicle charging hub. In order to increase the reliability of the power supply (e.g., in the event of excessive drops of converter input voltage) and to increase the flexibility of accumulation of trolleybuses regenerative braking energy, the station was equipped with battery-based electric energy storage. For this purpose, a second-life traction battery from a trolleybus was used.

The whole analysis can be read here.