Energy savings in urban mass transit systems: A probabilistic approach for sizing electric energy storage devices

In the paper an analytical probabilistic methodology is presented at the aim of improving the energy efficiency of light transportation systems. The analytical approach is essentially based upon the classical method of the calculus of variations, which is a powerful methodology for properly describing the isoperimetric problems. Thanks to the possibility of deriving closed form for interest variables, this allows also to handle in a feasible and proper way the stochastic aspects involved in the description of the system under study. The probability density functions of the interest variables can be consequently deduced. The numerical application is developed with respect to the employment of a supercapacitor based energy storage, whereas only the train mass is regarded as a stochastic variable.