Harmonic disturbances in electric traction system overhead lines

The paper presents the disturbance spectrum generated by electric traction units in different operating conditions. In particular, an experimental data set is used to analyze the electric systems for transportation currently in use in Italy, based on static power conversion stations and DC supply feeders are present. In these traction systems the train supply voltage has harmonic spectrum characterized by the switching pulse of the rectifier bridges, by possible disturbances that affect the AC supply network and by the interaction between the converters on board devoted to supply traction motors and auxiliary services, too. As the main goal of a public transportation service is to guarantee the safety and regularity of the train circulation, it is necessary that harmonic disturbances generated by the train units respect the compatibility margins with the signaling systems to which the traffic control is devoted.