Seminar on electric busses with special emphasis on dynamic charging trolleybusses and energy storage

Held in Prague on 27. / 28.06.2018

Venue: Elektroline’s offices
The seminar was geared to public transport companies from Germany and the Netherlands operating trolleybuses or with projects for the introduction of electric busses.

The first day’s program and discussions were concentrating on wayside storage of electrical energy by means of battery stations.
Such storage can be of interest to operators of trolleybus-systems (or tramways) for a number of reasons:

  • Electrical strength/stability of the power supply in the overhead network may be insufficient at some locations, having as a consequence a voltage drop when busses consume power, or there may be an oversupply at certain locations – also due to recuperation – having as a consequence overvoltages. Generally, the voltage of 600 V should not vary by more than +20%/-30%. Otherwise, there is a risk that the trolleybuses, respectively the control systems and electric systems of the bus, switch off.

A battery station will effectively flatten out the voltage fluctuations so that the voltage never drops below or rises above the critical limits.

  • The partial operation without overhead wiring has become increasingly popular. In fact, this type of operation has great future potential.

During on-wire operations, the trolleybuses charge the onboard batteries while driving underwire (dynamic charging / in-motion-charging) or – when recuperating – can charge the onboard batteries if not full or they can supply back into the overhead wiring surplus energy while recuperating. During off-wire operations, the trolleybuses drive with power supplied from the onboard batteries only.

When coming back to a wired section, the busses go on-wire with the poles and this may lead to sudden voltage drops, where again the way-side battery storage station will support the network.The combination of on-board batteries and way-side battery storage systems is a useful and cost-effective solution for the introduction of dynamic charging concepts. Technical presentations, a site visit at the Pilsen Transport Company, which has adopted this concept, and a workshop among the participants and specialists were on the order of the day.

The second-day‘ program concentrated on the new concept of DPP Prague Transport Company for the introduction of dynamic charging trolleybuses. Presentations of the technical and operational concepts were given, as well as an oversight on the simulation principles for simulation of the length of overhead network needed for operation of a given network. A site visit and ride on one of the dynamic charging busses along the route also were part of the program of the second day. The participants extended their thanks to Elektroline, who had agreed to host the seminar in their offices, and to the Transport Companies of Pilsen and Prague for their interesting presentations and site visits.