Efficient design of Automatic Train Operation speed profiles with on board energy storage devices

Energy usage in electrical railway systems is being studied in order to find technologies and developments for increasing energy efficiency. It is not only an environmental problem, but also concerns railway infrastructures as an economical aspect. The problem is finding which system to invest in for decreasing energy consumption and costs. In this paper, two possibilities are studied. The first one is the redesign of the ATO (Automatic Train Operation) speed profiles of metro lines. The speed commands in service nowadays were selected based on time and comfort criteria. In addition, in this paper the consideration of energetic criteria is taken into account. Complementing the previous possibility, the implementation of an on board energy storage device is evaluated. The regenerated energy of electrical brakes in metropolitan railways is not used if there is no other train starting up at the same time, and it is wasted with heating resistors. With the aim of taking advantage of regenerative energy, the economical and energetic advantages of investing in an on board storage device, despite its additional mass, are studied. Both approaches are finally jointed, obtaining speed profiles that are even more efficient with the implementation of the device. Optimal Pareto curves, where the best solutions are placed, are modified taking into account on board storage devices. A simulator is needed for the proper simulation of all the possible speed commands. It has been developed and validated with measurements in line 10 of the Madrid Underground. Solutions show that about 25% of energy savings are expected with only the speed profiles redesign. In addition, it is shown how these optimal speed profiles are modified when an on board energy storage device is also taken into account.