One promising approach is the development of intelligent control systems that efficiently link operations management and control of the rail power grids. Rail travel protects the climate. This is another reason to expand public transportation. So far, the capacity of the railways has been the main focus in the expansion scenarios that have been proposed. The concepts are therefore based primarily on the assumption that the lack of routes is the limiting factor.
Energy-efficient speed profiles
If more trains are to be put on the tracks, they will have to run more frequently. However, industry, research and transportation companies have long known that there is another factor that must be taken into account if expansion is to be possible: energy. Rail transport has always been one of the largest consumers of electricity in Germany: the industry requires around eleven billion kilowatt hours per year. Energy-saving concepts have therefore been around for many years – for better climate protection and for cost reasons. They are based primarily on the finding that energy consumption can be significantly reduced through energy-efficient speed profiles.
Electricity consumption of rail transport per year in Germany
Energy-saving concepts have therefore been around for many years - for better climate protection and for cost reasons. They are primarily based on the realization that energy consumption can be significantly reduced through energy-efficient speed profiles.
First development stage
The concepts of the first development stage consider only the energy-saving potential of a single vehicle. For example, driver assistance systems provide speed recommendations, especially for starting and braking. However, this approach, like the incentive systems introduced afterwards, did not lead to the hoped-for results. Drivers rarely and inconsistently follow the recommendations.
Next expansion stage
The next stage of development no longer considers only the individual vehicle, but several vehicles and the further route, for example, a slower train ahead or a red signal. In addition, an automatic system, such as an Automatic Train Operation System (ATO), takes over the driving control for speed control as well as for starting and braking.
For example, it regulates the acceleration of a train and thus phases of maximum speed as well as phases in which a vehicle travels at a slightly reduced speed over a longer distance. It also controls coasting phases and makes extensive use of opportunities for trains not to consume energy. This control system determines the best energy profile for the specified arrival and departure times of all trains.
Avoiding peak loads
However, the electricity required for the currently planned, higher frequencies cannot be saved using these solutions. In particular, the capacity of the existing electrical networks is insufficient during peak loads. This will not change in the medium term either. Industry, research and transport companies are therefore currently working on control systems that link the entire operational management with the control of the rail power networks. At the center is, among other things, the required departure energy.
This is particularly high and therefore particularly expensive. Peak loads have a significant influence on the electricity prices that the companies have to pay. For this reason, mathematical formulas are being developed that take into account all other influencing factors in order to reduce the number of simultaneous departures.
Synchronization of arrivals and departures
The focus is also on synchronizing arrivals and departures so that the energy released when a train braking as it enters the station can be fed directly back into the power grid and used to accelerate a departing train. To do this, the trains have to brake and start up at exactly the same time. If transport companies combine energy-optimized driving of trains, reduce simultaneous departures across the entire network, and time incoming and outgoing trains in such a way that the braking energy is used for the departure energy, they could not only expand their services but also save energy costs at the same time.
Current research projects and outlook
Current research projects also suggest that transport companies can save a considerable amount of energy and immense costs simply by adjusting timetables by seconds – and thus without passengers noticing – and by using driver assistance systems for real-time control of trains. This requires the development of algorithms that enable the control systems to react quickly and reliably to faults in day-to-day operations. The fact is that so far, the control of traction power and operational management have been two separate worlds – and thus also in their own control centers.
In the future, however, it will be necessary for these organizationally independent areas to converge within the transport company and create a holistic system by linking existing data and using artificial intelligence.
With this in mind, PSI is planning the development of an intelligent control system that optimally coordinates and manages the operational management and control of the entire electrical infrastructure. For all areas – systems for public transport, the control of railway power grids, and artificial intelligence – PSI can draw on proven solutions and will create valuable synergies for customers in the future.
Harmonizing operations and energy efficiency
The expansion of local public transport services is only possible with intelligent systems that holistically consider and control the operational and energy-related conditions. Experts agree that it will be crucial to use the remaining degrees of freedom to balance the load in the rail power network when creating timetables and to include all aspects of operations in real time, in addition to energy-saving concepts.