Electro-Mechanical Modelling and Simulation of Railroad Vehicle Systems using Modelica Language

Modelling the electro-mechanical interaction of railway lines is very important nowadays, because a global energy optimisation can be attained only considering these systems as a whole, for example to exploit regenerative braking energy converting this energy into electricity, and sending it onto another point of the system where other trains or an energy storage station can absorb it. This feature is effectively exploited in particular in urban environment lines, such as underground and tram lines where regenerative braking occurs very often. Today a general purpose modelling language, the Modelica language, developed starting from the late nineties, is more and more used for “multi-engineering” systems, i.e. systems that mix different kinds of subsystems such as electro-mechanical, electro-hydraulic, thermal-mechanical, etc. This paper explains the basic opportunities and issues in using Modelica language and tools in simulating electromechanical railroad systems, i.e. systems containing electrical feeding substations, contact lines, trains, and, possibly storage stations. It shows that the Modelica language has reached a great flexibility and reliability, and is thus very good for creating these models, that are developed and give results very fast in comparison to older tools. The validity of the proposed techniques and the main physical effects simulated are shown in simple sample cases.