Research on Low-frequency Oscillation of Multi-train-network System Based on Modal Analysis

The low-frequency oscillation (LFO) problem has occurred in electrified railway train-network system, which will threaten the safe and stable operation of the trains. In this paper, based on the phase-domain impedance model of China high speed trains, and considering the actual network topology of multi-train-network system with three-phase power grid, traction transformer, traction network, and the trains, the modal analysis is adopted to study the system oscillation modes and propagation characteristics. The participation factor, observability and controllability of each network node to the critical LFO mode under the bilateral and unilateral power supply modes are analyzed and compared. Finally, the correctness of the theoretical analysis is verified by the electromagnetic transient simulations.