Study On The Optimization For The Capacity Of Traction Power Supply System In Electrified Railway

With the rapid economic development, the high-speed railway becomes the inevitable trend of Chinese railway business development. At present, China has become a superpower of the high-speed railway with the increasing of high-speed railway mileage. Therefore, the security, reliable and economic operation of the high-speed railway traction power supply system is extremely important to the high speed railway transport. The internal high-speed railway been built or building are designed in accordance with the long-term traffic. Its traction power supply system using large capacity Vx traction substation with2×27.5kV traction power supply which has high reliability and strong loading capacity. However, at the beginning of the operation, the high-speed railway capacity is generally small and far from the design grid density so that the power supply equipment capacity is excess affecting the system economy operation.On the basis of the high-speed electrified railway’s load characteristic and the related calculation with actual measurement data of the traction substations, the current operation situation and the existing problems of high-speed railway are analyzed in this paper. And the flexible operation mode of the traction power supply system is proposed. So that the traction power supply system has high efficiency in the early opening and could meet the requirements of long-term traffic volume at the same time.The simulation model of the all-parallel AT traction power supply system in Matlab/Simulink software based on the actual parameters of high-speed railway line is built in this paper. Considering the different train operation numbers and a variety of the position situations, the traction grid voltage as an important constraint condition of the electric traction is analyzed to test the power supply capacity. The negative sequence current of the traction transformer in the different wiring method is analyzed using the negative sequence current general expression of the traction transformer by system variation.The three-phase voltage imbalance degree of the traction substation in the optimization scheme is got by the calculation the traction substation actual measurement data and the contrast of the negative sequence current before and after optimization.According to the actual load data of the traction substation, the traction substation temperature rise curves of the traction transformer before and after optimization is described using the calculation method of traction transformer temperature rise and the life loss. The influence of the high-speed railway traction load level to the traction transformer temperature rise and the life lost is discussed and analyzed. And make the traction transformer winding temperature rise and the life lost as the constraint condition, the rationality of the optimal operation scheme is analyzed.