Energy-Efficient Train Driving Considering Energy Storage Systems

Abstract

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Regenerated energy has the potential to produce great energy saving figures in railway operation. However, in DC systems, regenerated energy cannot be harnessed completely. The presence of rectifier filters does not allow returning energy from the railway system to the utility grid. Therefore, the regenerated energy that cannot be consumed by other trains instantaneously must be wasted in on-board resistors. Energy storage systems, on-board the train or in the track-side, can be implemented to avoid this situation and maximise regenerated energy usage. The main technologies that have been applied in railways, the modelling of these energy storage systems and its control are discussed in this chapter. Besides, a case study is presented where different scenarios of energy storage and receptivity to regenerated energy are analysed based on the characteristics of a real line of the Madrid Underground. These scenarios allow to evaluate the influence in the energy consumption reduction because of the installation of energy storage devices and the influence in the optimal design of ATO speed profiles. The results indicate that energy storage systems would provide energy savings in scenarios with low density traffic, but low benefits are obtained in dense traffic scenarios where the regenerated energy can be exchanged between trains easily.