Research on Low-Frequency Oscillation in Multi-Train Bilateral Power Supply Systems Based on Harmonic State-space Model

The high-density operation of the trains may cause the low-frequency oscillation (LFO) of train-network system. The existing researches mostly establish a single-phase circuit to study the LFO which has the single-phase voltage source, network impedance and multiple trains connected to the traction network at the same node. This paper focuses on the LFO of the multi-train access to the bilateral power supply system where trains are supplied by two traction substations. Firstly, the harmonic state-space (HSS) model of this system formed by multiple trains, traction network, traction transformers, and three-phase grid is derived. Secondly, considering the traction network has up and down lines which has not been accurately modeled in recent researches, the LFO of train-network system with and without up and down lines modeled are analyzed and compared. Finally, the correctness of theoretical results is verified by simulations in MATLAB/Simulink.