Research On Negative Sequence Impact Of Traction Power Supply System Of High-Speed Railway

China's first high-speed railway—the Beijing-Tianjin inter-city high-speed railway has been opened in August 1,2008, which shows the beginning of the rapid development of China's high-speed railway. The high-speed railway brings great changes to the railway transportation industry and promotes the country's economic development, but at the same time, negative sequence,harmonics and other power quality impact are becoming increasingly serious. Compared to the traction power supply system of general speed railway, the traction power supply system of high-speed railway has lots of its own characteristics. The top technologies of high-speed railway are controlled by some foreign companies, for example the Siemens company. The task to develop the "traction power quality assessment software of high-speed railway" , which has self-owned intellectual property, is placed in front of domestic researchers. This article attempts to make some research on negative sequence impact of traction power supply system of high-speed railway, at least, to provide a research base for the later researchers.First of all, this article discusses the basic principles and circuit models of traction power supply system of high-speed railway, including the traction substation type, the power supply mode from traction substation to traction network, the power supply mode from traction network to high-speed trains and the load modeling of high-speed trains. All above make a solid foundation for the power flow of the traction power supply system of high-speed railway.Second, the power flow of traction network is solved by a novel algorithm. The basic principle of this algorithm is described. The calculation method of volage and current distribution is improved to make it easier for the program implementation. The improved algorithm is verified to be effective by several simulation examples.Finally, the formula for calculating three-phase voltage unbalance of high-speed railway traction substation is derived by applying symmetrical component method. "The dynamic negative sequence anlysis program for traction power supply system of high-speed railway " is developed successfully based on negative sequence anlysis of traction substation, train diagram method and power flow of traction network. This program has succeeded in real-time negative sequence assessment of traction power supply system. Then, a practical example—the Beijing-Tianjin inter-city high-speed railway is carried out for simulation, the results of which verify the validity and correctness of this program.