Research On The Scheme Of Cophase Power Supply System In Newly Built High Speed Railway

Since the first high-speed railway, Tokaido Shinkansen, opened in Japan, high-speed railway has been developed rapidly in the world. Our country began to develop high-speed railway after Qinshen Passenger Railway started to construct. Our traction power supply technology exist two prominent problems when high-speed trains running on it, the electrical sectioning and the netative-sequence current. Cophase power supply technology could solve these two problems simultaneously, but the existing cophase power supply scheme was not applicable to newly-built high-speed railway. Under the background of high-speed railway develop rapidly in our country, it is meaningful to research a cophase power supply scheme which is suitable to newly-built high-speed railway.The main work of this paper is to research a kind of cophase power supply scheme which is suitable to newly-built high-speed railway.First of all, the construction situation and operating details of high-speed railway in the word was introduced, the key technical issues of our traction power supply system was analysed; After that, the system structure and implement method of the cophase power supply system was introduced. Cophase power supply technology could solve electrical sectioning problem and netative-sequence current problem at the same time, but analysis results proved that the existing cophase power supply system was not suitable to newly-built high-speed railway; Finally, single-phase combined cophase power supply scheme was researched detailedly.Single-phase combined cophase power supply technology is a scheme which is more suitable to newly-built high-speed railway. Firstly, the structure of single-phase combined cophase power supply system was introduced, the calculation method and detection method of cophase compensation current was inferred; After that, the simulation model based on Matlab/Simulink was built. Simulation results show that no matter cophase compensation device running in model one or model two, single-phase combined cophase power supply system could reach a decent compensation effect on negative sequence, and control the three-phase voltage imbalance less than the national standard; Finally, the single-phase combined cophase power supply system was designed and analyzed based on testing data. Load process analysis proved that on the premise of three-phase voltage imbalance satisfy the national standard, running model two make full use of the overload ability of the traction transformer, reduce the system loss of the cophase compensation device, and is more cost-efficient than running model one.In the last part of the paper, techno-economic analysis shows that the single-phase combined cophase power supply system obtain the optimal combination between and among the traction transformer, the cophase compensation device and the national rated value, further reduce the investment, and it will show larger and larger technical advantage as time goes on.