Investigation of the propagation of harmonic distortion from traction converters into traction and transmission systems

Modern locomotives that utilize pulse-width modulated power converters produce harmonics that propagate along the traction system and ultimately into the transmission system. This paper investigates the occurrence of this in a traction system in Central Queensland, Australia. The study was carried out using time-domain simulation of a pulse-width modulated power converter, and a representative subsection of the traction and transmission systems. The series and parallel resonating frequencies of the traction system were found to be the most significant factor influencing the magnitude of the harmonics, which flow into the transmission system. The resonances of the traction system resulted in the formation of standing waves along the length of the traction system. Passive harmonic filters were effective at reducing the propagation of harmonics into the transmission system