Modelling of high-speed railway traction power supply systems based on subspace identification

In this paper, reduced mathematical models for high-speed railway traction power systems based on subspace identification method (SIM) are proposed. SIM applies reliable algebra tools to estimate state variables, and then provides an analytic representation for the identified systems, especially those of large dimension. Accuracy for identification results of different orders is discussed, under both normal operation and fault cases. With appropriate accuracy-simplicity trade-off, a uniform order decision is deduced. Reduced models derived from identification could be used for further studies of network-side impact on train-network coupling problems.