Analysis of resonant modes in the single-phase industrial AC electrified railway systems

Operation of thyristor-controlled locomotives in the single-phase industrial AC electrified railway systems causes overvoltages and power quality degradation on the traction substation. These factors affect substation electrical equipment significantly and premature failure may be occurred due to insulation breakdown. For example, the frequently occurring insulation breakdowns of electrical equipment as well as high partial discharge activity were registered on the 10-kV traction substation of Poltavskyi ore-dressing and processing enterprise (Ukraine). In this paper, the results of recording voltage waveforms, power quality indices and transients on the traction substation buses are presented. Possible solutions for resonant overvoltages damping are discussed. Extensive analysis of the amplitude-frequency responses of the driving-point impedance at the point of locomotive connection was executed. Behavior of the traction system at different operational modes has been extensively simulated in MATLAB environment.