Controller Stability and Low-frequency Interaction Analysis of Railway Train-Network Systems

In electrified railways, low-frequency oscillations (LFO) are commonly observed as a result of the widespread implementation of electric trains incorporating power electronic converters. While the impedance method has been employed in current stability studies for train-network systems, there is a requirement to extend stability modeling and analysis studies for the train-network system considering multiple trains having different control strategies. Hence, this paper establishes a unified impedance model in the dq-frame for the aforementioned system. Subsequently, an improved stability criterion, namly the dominant eigenvalue frequency response criterion (DEFRC), is proposed to assess system stability and unveil the mechanism of LFO. Furthermore, the interaction between different trains is clarified by analysis and case studies. Finally, the theoretical analysis is verified for accuracy based on time domain simulations.