Eigenvalue-Based Harmonic Instability Analysis of Electrical Railway Vehicle-Network System

Dynamical movement of electrical rail vehicle will change the topology of the vehicle-network system. Small-signal state-space modeling of the vehicle-network system is proposed in this paper to study the harmonic instability of electrical railway. This state-space model takes into account the complete structure and multiconductor nature of the network, and the single-phase grid-connected converters of the vehicle. With the modular models of system and by flexibly combining the submodules, the vehicle-network state-space model is constructed, and the change of the vehicle positions can be realized. The eigenvalue-based method is used to analyze the harmonic instability. Influences of converter controller parameters, sampling frequency, and particularly, the vehicle positions on the high-frequency harmonic modes are analyzed. Participation factors of state variables are calculated and compared. Besides, catenary node voltages under high-frequency harmonic modes are analyzed according to the mode shape to find the most affected nodes. Finally, the theoretical analysis results are verified by nonlinear time-domain simulations and measured waveforms.