Low-Frequency Oscillations Analysis in AC Railway Networks Using Eigenmode Identification

Dynamic interactions among AC railway networks and train power converters have been reported to cause low-frequency oscillations (LFO) and eventually instability phenomena, which can collapse the railway power system. Several system parameters can influence the appearance of LFO, including catenary line length, power consumption, control bandwidths, etc. This paper proposes a methodology for the analysis and understanding of the impact of all these parameters on the LFO. The proposed method combines time-domain simulations with eigenvalue analysis. Eigenvalue migration will be shown to be a powerful tool to understand the risk of instability and to analyse potential remedial actions.