Use of participation factors and parameter sensitivities in study and improvement of low-frequency stability between electrical rail vehicle and power supply

Dynamical phenomena like oscillations and instability in railway power systems have come into concern in the experts´ community the recent years. In several occasions, modern advanced electrical rail vehicles have been a source for low-frequency power oscillations leading to an unstable power system due to lack of damping, and as a consequence operational problems. Traditionally the dynamical behaviour of such a power-electronic based vehicle is studied by instantaneous-value time-domain simulations. In this paper, the entire single-phase railway power supply including the vehicle is modelled together in the time-invariant rotating reference frame. Such a reference-frame transformation is common for power-system analysis and allows utilization of linearization tools as eigenvalue analysis including participation factors and parameter sensitivity analysis. Such tools are used here for study and analysis of possible improvement of the stability of the complex railway power system. The results from the linear analysis are compared to time simulations.