Power-sharing and flexibility of charging infrastructure seem to be the ultimate direction for fleets.
VDL, in partnership with Siemens, expanded its VDL Charging Test Centre in Valkenswaard, Netherlands to more closely investigate charging solutions, energy storage and bi-directional (V2G) systems.
"VDL is going to use this technology for purposes such as boosting interoperability – the mutual communication and exchange of information – of heavy electric vehicles and charging infrastructure. Through this initiative, VDL intends to gain greater insight into the entire power supply chain for electric heavy vehicles so that more sustainable mobility solutions can be developed that ultimately contribute to a successful energy transition."
The setup consists of three DC fast chargers supplied by Siemens with a power-sharing feature, which are capable of charging three buses simultaneously at 150 kW each, or one at up to 350 kW. If there is just one vehicle using a roof charging system, power can be up to 450 kW.
"Three Siemens fast charging stations, in combination with a VDL energy storage system, have been installed at the VDL Charging Test Centre. The data from these systems are managed via a ‘cloud-based’ energy management application. Using the data from these systems, the charging of the vehicles can be actively controlled. A special ‘switching matrix’ allows the available power capacity to be flexibly deployed and used."
To further improve utilization of the infrastructure, without increase installed capacity, there are two energy storage systems. Batteries for those ESS come from electric buses, which means a second-life battery project.
On top of that, there is also a bi-directional power transfer option, which might be used to send significant power back to the grid during short peak-demand periods, if buses are not in use.
"Two second life battery systems from an electric bus are used for the temporary buffering of power fed back from the heavy electric vehicles. On average, these batteries still have more than 80% of their original capacity and can function perfectly as a power storage system.
Thanks to this technology, buses can be tested more efficiently. At present, e-buses and e-trucks often have to drive longer than necessary, to completely discharge the batteries. Thanks to bi-directional charging, this is no longer necessary and the energy used to charge the vehicle batteries can be returned to the energy storage system."
Menno Kleingeld, Managing Director VDL ETS said:
“Deployment of heavier e-vehicles also involves technical issues such as the increasing energy demand and unpredictable load on the power network. It is important to use alternatives, both for smarter planning of charging times and so energy can be temporarily stored in a buffer. This temporary buffer can then supplement the available capacity of the power grid to deliver power back to the vehicles during periods of peak load. This new technology allows us to investigate how we can reduce the load that charging sessions place on the power grid and how we can properly store the available energy capacity and distribute it based on demand.”