Application of linear analysis in railway power system stability studies

Abstract

Dynamical phenomena, such as oscillations and instability in railway power systems, have become of growing concern in the experts' community in recent years. On several occasions, modern advanced electric rail vehicles have been the source for low-frequency power oscillations leading to an unstable power system due to the lack of damping, and as a consequence of operating problems. A method to study these phenomena is needed. Well known linear techniques based on small-signal analysis provide valuable information about the inherent characteristics of even non-linear single-phase power systems. This paper describes how a railway power system and its dynamical railway-related components are modelled in a commercially available power system analysis software and studied by linear analysis such as eigenvalues, participation factors and parameter sensitivities. This is used to gain knowledge about the interaction between the rail vehicles and the electric infrastructure. Linear analysis is found to be a powerful tool in this respect, provided that adequate models of the relevant components can be established in the RMS mode. The results reflect the experienced poor interaction.

Research on Transient Low-Frequency Oscillation of Electrified Railway Vehicle-Grid Coupling System

“…𝑑𝑑|𝑍𝑍 0 (𝜔𝜔)| 𝑑𝑑𝜔𝜔 = 0 (26) At this time, 𝜔𝜔 𝑟𝑟 = 8.21(𝑟𝑟𝑟𝑟𝑑𝑑/𝑠𝑠) , and the oscillation frequency of the system is 1.31Hz.…”

“…Any oscillation problem can be attributed to the impedance problem. At present, there are two mainstream stability analysis methods of vehicle-grid coupling system: eigenvalue analysis based on state space formula [25][26][27] and impedance analysis based on frequency domain model [28][29][30][31][32].…”

“…Reference [25] described how a traction power system and its dynamical railway-related components are modelled in a commercially available power system analysis software and studied by linear analysis such as eigenvalues, participation factors and parameter sensitivities. In reference [26], 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 allows utilization of linearization tools as eigenvalue analysis including participation factors and parameter sensitivity analysis.…”