Harmonic State Space Modeling and Stability Analysis of Traction Power System Connected to the Three-Phase Grid

In recent years, vehicles based on power electronic converters are widely used in high-speed railways, and the interaction between vehicles and the network causes instability. The existing researches assume that the vehicle is powered by a single-phase power supply, so that a single-phase vehicle-grid system is utilized for the oscillation analysis. However, in China, the traction power systems are supplied by three-phase power grids, which leads to asymmetric systems. Considering the three-phase real structure of the power grid, the existing vehicle-grid models are no longer applicable. Therefore, in order to analyze the stability of this three-phase asymmetric system, this paper derives a harmonic state-space model of the CRH5 EMU according to the linear time period theory, which can be combined with the three-phase structure of a power grid. In addition, the stability of a traction power system connected to a three-phase grid is analyzed based on the proposed model, and the correctness of this model and theory analyzing results are verified by simulation.