Early validation of heterogeneous battery systems in the railway domain

In general, trains are referred to as environment-friendly transportation means when compared e.g. to cars, busses, or aircraft, being modern trains electrified systems. Unfortunately, the costs due to creation and maintenance of railway infrastructures, notably the overhead lines to power the trains, impose boundaries to their expansion potentials. In this respect, the advances in battery technologies are disclosing new opportunities, like serving partially electrified tracks. In particular, on board batteries can be used as backup energy where overhead lines are not available. In such scenarios, analysing battery requirements and evaluating possible solutions is of critical importance.This paper proposes a model-based systems engineering methodology for evaluating the feasibility of heterogeneous battery systems in the railway domain. The methodology leverages separation of concerns to reduce the complexity of the problem and abstracts the different railway system components by means of corresponding simulation models. The methodology is illustrated through a study performed at an industrial partner; in particular, the paper discusses how simulation models have been conceived, refined, validated, and integrated to analyse the properties of various battery configurations for several passenger trains operating on commercial lines in France. Interestingly, the results demonstrate that heterogeneous battery systems provide a suitable trade-off alternative when compared to homogeneous batteries.