Traction Power Supply for High-Speed Railway: A Case Study in Vietnam

Maintaining a three-phase current balance at the point of common connection (PCC) and ensuring voltage quality during train operation have been the outstanding obstacles in railway power supply. To address this problem, this study investigates the feasibility of using a Roof-Delta transformer in traction substations and an autotransformer in the traction power supply network for application in Vietnam. MATLAB simulation results indicate that under balanced load conditions, the three-phase current at the PCC is perfectly balanced. Even when the load is not uniform due to the influence of power factor and when the influence of track railway, such as curve radius and uphill gradients, is considered, the asymmetries are very low, 2.94% and 2.95%, respectively. These asymmetries satisfied 3% less than the IEC 61.000-4-30 standard. Under a minimum headway of 200 seconds, the overhead contact line with an autotransformer feeding system maintains voltages useful for the catenary of 22.59 kV and 21.71 kV, ensuring compliance with operational voltage requirements larger than 19 kV with the EN50163 standard. Furthermore, the results with various cases have demonstrated that the proposed modelling for high-speed railway power system is reliable, providing a solid foundation for analysis, reasoning and criticism in the process of planning, construction and development of high-speed railway in Vietnam, in line with the global modern trend of reducing installation costs, solving problems of improving power quality and the reliability of power supply system during operation.