Study of resonances in 1x25kV AC traction systems

Abstract

Abstract: AC traction systems are 1x25 or 2x25 kV 50 Hz single-phase, non-linear, time-varying loads that can cause power quality problems. One of the main concerns about these systems is voltage distortion because adjustable speed drives for trains may inject harmonic currents of frequencies below 2 kHz. Since the presence of parallel resonances in the contact feeder section of the traction circuit worsens the scenario, traction system resonance phenomena should be analyzed to prevent problems. Several works address these phenomena but they only draw weak numerical conclusions based on the frequency scan method. This paper studies 1x25 kV traction system resonances at pantograph terminals and provides more effective analytical expressions to locate them and determine the impact of traction system parameters on them. These expressions are validated from several traction systems in the literature.