Optimal Control of an EMU Using Dynamic Programming and Tractive Effort as the Control Variable

The electric traction system used in trains is the most energy efficient traction system in the transportation sector. Moreover, it has the least NOx and CO2 emissions in comparison to other transportation systems (e.g. busses, passenger cars, airplanes, etc.). On the other hand, they are extremely expensive, mainly due to high installation and maintenance cost of the catenary system, including e.g. overhead lines and substations. Consequently, the share of electrified lines is only slightly higher than non-electrified lines. For instance in Europe, 60% of the railway networks are electrified, and the percentage is much lower in other continents. Battery driven trains are a new generation of electric trains that can overcome such high costs while keeping CO2 emissions and energy consumption low.At the moment, there are only two battery driven electric trains developed and both of the trains are passenger electric multiple units (EMUs). An EMU is an electric train with a traction system in more than one wagon, in contrast to loco-haul electric trains which have a traction system in one wagon only. Energy management during the operation of battery driven trains is a crucial task, as energy optimal operation of trains considering the optimal use of batteries can increase both the operating time and the lifetime of batteries. Energy efficient train operation is realized using driver advisory systems (DAS) that instructs drivers on how to drive trains for minimum energy consumption. The aim of this research is to propose an algorithm for speed profile optimization of both EMUs and battery driven EMUs. The desired algorithm should be suitable as a core component for an online DAS with short response time.Several approaches are proposed in the literature for speed profile optimization of electric trains, and a few of these have been proposed for speed profile optimization of battery driven electric trains. The trains modeled in almost all of the approaches are trains using a notch system for controlling tractive effort. The proposed solution in this research project is to use discrete dynamic programming (DP) to find the optimum speed profile. The application of DP is studied for speed profile optimization of EMUs with a notch system as well as EMUs with a smooth gliding handle for controlling tractive effort. The problem is solved for both normal EMUs and battery driven EMUs.The results of this research show that DP can provide accurate results in a reasonably short time. Moreover, the proposed algorithm can be used as a base for a DAS with fast response time (real-time).