Application of linear analysis in traction power system stability studies

Abstract

Dynamical phenomena such as oscillations and instability in railway power systems have caused concern in the experts' community the recent years. On several occasions, modern advanced electrical rail vehicles have been the source of low frequency power oscillations leading to an unstable power system due to lack of damping, and as a consequence operational 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 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. This is used to gain knowledge about the interaction between the rail vehicles and the electrical 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 RMS mode. The results clearly indicate poor interaction.

Fine Tuning of On-Board Traction Converters for High-Speed Electric Multiple Units at Depot

“…The issue of LFOs first came to light in 1996 on the Norwegian railways [10]. Subsequently, similar problems were observed in France, the USA, Germany, and Switzerland [11], [12]. To address these challenges, researchers have explored various methodologies: in [13][14], advanced synchronization methods employing Phase-Locked Loops (PLL) and closed-loop input impedance techniques for FERs were discussed.…”

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

“…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].…”

“…The first method is to describe the impedance problem with the formula of state, and transform the stability analysis of the vehicle-grid coupling system into the eigenvalue problem. 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.…”

Research on Low-Frequency Stability under Emergency Power Supply Scheme of Photovoltaic and Battery Access Railway Traction Power Supply System

“…The first reported occurrence of the LFO phenomenon dates back to 1996 in Norway when a rotating converter was Energies 2023, 16, 4814 3 of 32 adopted in a traction substation [20]. Since then, in Germany, Sweden, and Norway, rotating converters have been used to interface the traction network, transforming three-phase utility power into a single phase for the catenary network [21]. The main cause of LFO has been attributed to the electromechanical characteristics of rotating converters [22].…”