Today, the term cyber-physical modelling systems refers to models which combine\ud control and controlled systems. These models are very useful, since they closely\ud reproduce the architecture of the systems to be modelled: the “cyber” part is the\ud control system; the “physical” part is the controlled system. Modelica is a standard\ud language for modelling systems in a cyber-physical way. Its usage brings the\ud additional bonus of being a standard, and therefore models can in principle be run by\ud any Modelica-capable tool. Modelica is conceived from the ground-up to allow\ud hierarchical description of systems, and hybrid continuous-time or discrete time\ud simulations. Finally, Modelica comes with a large library of validated models. This\ud paper shows how the favourable characteristics of the Modelica language can be\ud exploited to create powerful, flexible models of railroad vehicle systems. The special\ud issue of the specific running pattern of railroad vehicles is addressed using a state\ud machine. The special issue of the ever changing topology is dealt with the usage of\ud variable resistors and a “commutator” model specially created for this application.\ud The validity of the proposed techniques and the main physical effects simulated are\ud shown

Today’s city traffic is often congested, because of the large amount of vehicles in\ud comparison to the available space. Moreover road transportation contributes to the\ud urban pollution and greenhouse gas emissions. One solution in the urban\ud environment is the use of tramways. The most important bonus comes from the\ud inherent reversibility of electric drives: energy can be sent back to the electricity\ud source, while braking the vehicle. This can be done by installing some storage\ud device on-board trains, or installing them in one or more points of the supply\ud network.\ud This paper therefore draws some results about when these systems can be useful\ud and how they can be controlled. In general, storage systems with the following\ud variants can be considered:\ud  Stationary supercapacitors.\ud  Stationary high-power lithium batteries.\ud When the storage system is constituted by a supercapacitor, it is mandatory to\ud interpose between it and the line a DC/DC converter. When, on the contrary, it is\ud constituted by a lithium battery, the presence of the converter can be avoided.\ud This paper provides an evaluation of the variant based on stationary high power\ud lithium batteries, in a realistic case study. Some rather general conclusions will be\ud drawn from the proposed analysis