Research On Cophase Traction Power Supply System

The unbalanced three phases, reactive power and harmonics are the technic characteristics of traction power supply system because of single phase AC load. Phase rotation of traction transformers are set to reduce influence of unbalanced three phases,which causes different voltages of each supply section. Neutral sections are necessary, but are the weak link of supply, and limit locomotive current got smooth and continuous, restrict improvement of railway high speed and over loading. So it is a great meaning to study on novel traction power supply systems to resolve these problems overall and essentially.Cophase power supply of substation doesn't need phase rotation and neutral sections. Combining active filter and YNvd connected balance transformer constructs novel traction cophase power supply systems, which can thorough resolve problems above. By controlling filter with real time detecting methods balances three phases, filter reactive and harmonic currents.Different structures of cophase supply are designed due to booster transformer (BT) supply (or direct supply), and auto transformer (AT) supply. One structure of using YNvd connection balance transformer and two single phase converter under direct or BT supply, one structure of using two single phase converter and YNvd connection under AT supply are both researched and simulated detailed. Balance transforms are discussed; power relations, capacity and capacity availability of system are analyzed; methods on detecting reference currents and controlling filters are researched.These two proposed systems are modeled and simulated under MATLAB/SIMULINK in this paper. The proposed configurations of cophase power supply systems, currents balance compensation methods, comprehensive detecting reference are proved to be true and feasible.