Effect of primary high voltage supply lines on the high speed AC railways systems

The High Speed/High Capacity railway lines uses the 2x25kV-50Hz power supply system that is supplied at high-voltage by dedicated lines that can be placed in close proximity to the railway line. The power system adopted for HS railway lines includes a lot of harmonic sources. Resonance phenomena can cause harmonics amplification with consequent problems as voltages distortion, interference problems and electromagnetic interference with communication lines. This paper presents a detailed model for the railway system (including the primary line) with the aim to evaluate the resonance frequency of the impedance seen by the pantograph.