Nowadays railway transportation is merely important for city and country developments. Various countries, including China and America, have been putting lots of efforts to develop railway system which is safe and can achieve high speed. Among all, electrified railway is preferred since it is safer, cleaner and more efficient. Co-phase traction power supply is one of the newly proposed systems, which has advantages of elimination of neutral sections, allowing higher locomotive speed as well as enhancement of transformer utilization ratio over conventional ones. It is one important research study supported by the Chinese government.In fact, the world’s co-phase supply device has already been put into trial operation at China ChengDu KunMing MeiShan substation. The reseach in this study is an extension based on the important study of co-phase traction power. Although co-phase traction has many advantages. However, the high operation voltage and device rating of the power quality compensation device, Railway Power Quality Compensator (RPC) in a sense limit co-phase traction power development. Therefore in this project, a railway traction power supply system suitable for high speed railway is proposed and investigated based on co-phase traction power with Railway Hybrid Power Quality Conditioner (Railway HPQC). Besides the advantages of co-phase traction power supply, the proposed system is advantageous for lower compensation device operation voltage and device rating, which leads to reduction in initial cost and operation loss. In this project, the design of co-phase traction power supply system with the following Railway HPQC design techniques based on various considerations is being analyzed: iii
Railway HPQC developed based on minimum operation voltage under fixed designed rated load;
Railway HPQC with enhanced operation voltage to increase compensation capability during load variations;
Railway HPQC with impedance-mapping technique to provide satisfactory compensation within load variation range with lower operation voltage and lower coupled capacitance;
Railway HPQC with adaptive DC link voltage control algorithm to automatically adjust operation voltage to adjust the compensation capability for load variations and to reduce switching loss; PSCAD simulations of proposed system are performed based on the practical locomotive power data obtained from China WuQing substation. A laboratory scaled hardware system and prototype is also constructed to verify the performance of proposed system. Comparisons are also made between proposed system with Railway HPQC and conventional one with RPC to show the advantages of providing similar system performance with lower operation voltage. Finally, further possible investigations and research directions are discussed. This research study can help to enhance the development of co-phase traction power through reducing the compensation operation voltage and initial cost. A National patent has been granted, and the PhD candidate has published 7 SCI jourmal transaction papers, another 1 under review, and 4 Interenational Conference Papers.