Stability Analysis of Low-Frequency Oscillation in Train-Network System Using RLC Circuit Model

The low-frequency oscillation (LFO) between traction network and electric locomotives is a typical phenomenon in high-speed railway and will result in traction blockade accidents. To analyze the respective contribution of traction network and electric locomotives to LFO and reflect the interaction between them clearly, an RLC circuit model is proposed in this paper. First, the negative incremental resistor and capacitance characteristic of electric locomotives is analyzed. Then, the RLC circuit model is built based on single-input single-output (SISO) supersynchronous and subsynchronous impedance. By analyzing the equivalent impedance parameters and resonance of the RLC circuit, the respective contribution of network and locomotives to LFO and system stability is studied. Furthermore, the influential factors of LFO, both grid parameters and locomotives parameters, are investigated. Finally, the analysis results are verified by simulation and experiments based on RT-LAB. Compared with multiple-input multiple-output (MIMO) impedance model, the proposed RLC circuit model can not only explain the LFO phenomena in high-speed railway intuitively and clearly but also simplify the calculation procedure.