Research On Cophase At Traction Power Supply System In High-Speed Railway

Problems of harmonics, reactive power, negative, communication disturbance, and crossing neutral sections in electric railway are getting worse as the improvement of railway high-speed and overloading, which will be seriously influenced if these problems are not resolved. So it is a great meaning to study on novel traction power supply systems to resolve these problems overall and essentially.Combining active filter, AT supply and different connection transformers constructs novel AT traction power supply systems, which can thorough resolve problems above. It is showed different "V" connection transformers, "Y" connection transformers and balance transformers, and some other transformers used in AT supply system. All of these transformers are analyzed from safe power supply, economic advantages, and technology required.In order to be more economic, effect and rational in different situations, two optimal compensation models are proposed in this paper: symmetrical resistance model, which can get the best load, and minimum waveform distortion model, which can get the best waveform quality. Relations between equipment capacity and compensation location, transformer connection mode are discussed, and three satisfied compensation models, method on getting smallest equipment capacity are gave.Problems of normal methods on detecting harmonics and reactive currents, particularity of methods on real time detecting comprehensive reference currents in cophase power supply are both discussed. Novel methods of equivalent fictitious three-phase and power definition based on Fryze on detecting harmonics and reactive currents in single phase are proposed;optimal compensation current detecting based on symmetrical resistance with no PLL and being not affected by distort voltage are proposed;based on minimum waveform distortion model, extraction of active current, equivalent fictitious three-phase, considered compensation degree, method with no PLL, these four methods areproposed.Configurations of normal active filters and connection modes with systems are discussed. Configurations of balance transform sets in different cophase power supply systems are analyzed. Double current hysteresis optimal state control method in single active filter is proposed.The proposed cophase power supply systems are modeled under Matlab/Simulink. Simulation results of systems with V,v connection, three-phase-to-four-phase connection and single YN,dl 1-275 connection are showed in this paper. The proposed configurations of cophase AT power supply systems, balance compensation methods, comprehensive detecting reference currents are proved to be true and feasible.