Cyber-Physical Modelling of Railroad Vehicle Systems using Modelica Simulation Language

Abstract

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

Energy and wear optimisation of train longitudinal dynamics and of traction and braking systems

“…In order to further verify the possibility of using the model for the simulation, a second group of tests was performed. A tramway (Sirio) produced by Breda, whose main data are kindly supplied by Ansaldo Breda (Table 2), was chosen as the benchmark case; in fact, there were available some validation data both from previous research activities with Ansaldo Breda, concerning the tramway of Besancon (France), and from the literature, in particular from [10,32,33] whose works were mainly referred to the simulation of Sirio tramway of Bergamo (Italy).…”

Cost effective storage for energy saving in feeding systems of tramways

“…Note that the contact line is also represented by a block, since it is not just a network of resistors but has a special structure that was specifically developed for train-ways [2].…”

“…The tool has been already developed and described in [1], [2], and based on a realistic case study to make some preliminary analysis of the energy flows, as cited in [1], [3], [4].…”

Use of Modelica language to simulate electrified railway lines and trains

“…The difference is small but simplifies the software significantly. After these simplifications, the train movement loop can be implemented by means of the state machine shown in Figure B, drawn with some adaptation from the work of Barsali et al Note that transition from start to acceleration is governed by a simple delay time iniWait in transition toAcc; transition to Brake is controlled by code, which verifies reaching the braking distance to the next stop, and stop is determined by reaching zero speed.…”

“…In the case of urban tramways, it might be convenient to brake vehicles by converting their kinetic energy back into electricity for reuse. This topic has been analyzed in depth in several papers . Here, it is just recalled that, depending on the system characteristics, storage systems such as batteries or supercapacitors can be installed on‐board trains or near one or more FSSs, in order to partially recover such braking energy.…”