Modelling 2×25 kV–50 Hz traction systems for power frequency studies

The paper shows the typical architecture of a 2×25 kV–50 Hz traction system, and the details that need to be considered and approximations that can safely be done, for power frequency studies. Power frequency models are important to allow simulations of long timespans, such as those needed when evaluation of trains acceleration/braking, for instance to analyse active and reactive power flows, voltages and currents. The proposed models are implemented in two ways: as data to be inputted to the well-known ATP Program, and as specific models written in the standard Modelica language. The latter can be virtually used for simulations using any of the available Modelica-capable simulation tools; moreover, the power of Modelica allows flexibility, expandability, scalability. A comparison between the two tools is proposed.