The Research Of New Testing Method And Basic Characteristic To Negative Sequence Current And Harmonic In Electrified Railway

Electrified railway has high speed, heavy load, pollution and other advantages, which quickly became the main direction of the development of Chinese railway. However, the electrified railway traction load is the volatility of the single phase large power rectifier load, which will influenced the power supply. The influence has the following characteristics:(1) Asymmetry, it will produce a lot of negative sequence component in the power supply system.(2) Nonlinear, it will generates an enormous of high order harmonic, such as3th5th7th11th13th.(3) Volatility, it causes voltage fluctuation of the power supply system.(4) High power, wide distribution, it has serious harm in the power supply system.Therefore, to electrified railway technical subject; it has three major technical subject harmonic reactive and negative sequence.In this paper, the impedance matching balance transformer, V/v transformer, YND11transformer will be analyzed.Analysis of item characteristics of harmonic and negative sequence, and discusses main harm of the harmonics and negative sequence of in power system supply. By analying, giving a description of electrified railway harmonics and negative sequence detection necessity. And based on the existing harmonic and negative sequence detection method research and analysis, this paper proposes a new theory based on the FBD of the positive and negative sequence current detection method. It includes the following several aspects.Firstly, this paper introduced the basic mode of traction power supply system, such as, the impedance matching balance transformer, V/v transformer, YND11transformer. To this common transformer, a lot of simple analysis will give, and analysis of the actual operation of harmonic and negative sequence fundamental characteristics.Secondly, this paper discussed the negative sequence current and harmonics on power system and electric equipment and relay protection device of the influence and harm of harmonic to communication system, and strong interference, negative sequence and put forward to the necessity of harmonic detection.Thirdly, this paper analyzed the instantaneous reactive power theory and the basic theory of adaptive current detection method, and discussed of using in electrified railways about detection of positive and negative sequence current. Finally, with the above research as the basis, a detailed analysis about the existing FBD theory method and its use in electrified railways, this paper proposes a new theory based on the FBD medium wave and negative sequence current detection method, and impedance matching balance traction transformer for the main study, the use of MATLAB modeling simulation analysis, applied in the electrical railway usage and effectiveness, and the FBD theory, instantaneous reactive power theory, adaptive method in electric railway for positive and negative sequence current detection to do some comparison, from the side proved the theory of FBD in electrified railway harmonics and negative sequence detection superiority.