Based On Matlab-electric Locomotive Rectifier - Chopper Model

In recent years, there is a rapid development in electrical railway in China. It makes the ratio of trunk line electrification reach 25%. The electrical railway assume 50% of the total cargo transport. It brings huge economical benefit to the country economy. But during the function of electrical railway, which also induces a mass of higher harmonic and negative current. On this condition, it makes the power quality drop. It threatens the safety of the electrical railway function, the safety and normal work of other users' equipment. So the researchers make great efforts to study the characteristic of the harmonic.Electrified railway is a special consumer of electric power system; its load is of nonlinear, asymmetry and fluctuation. Taking power supply of Scott transformer as an example firstly, this paper analyzes the unbalanced harmonic of inputting electric power system, explains its impairment on electric power system, and presents a series of counter measures. Based on the lower load power factors of electrified railway, it expounds the necessity of reactive power compensation, existing problems, and relevant countermeasures. Detailed analysis shows that the negative effects of electrified railway on power system can be reduced greatly.At present, The measure to confront the harmonic which produced by electrical railway is install two groups of irreversible parallel capacitor compensation devices and filters. But the traction lode is intermittent lode. This kind of lode changed largely. Capacitor compensation devices can not compensate automatically. It influences the advance of the load power factors of electrified railway. All of these methods can't restrain harmonic effectively.In this paper, electric locomotive's characteristics are firstly introduced. Secondly a new project is put forward in order to restrain harmonic radically—PWM rectifier-chopper instead of SCR bridge which is used now. This project was developed by using simulation software Simulink based on MATLAB. Then the mathematical models of this paper's two projects are established by using the PSB of simulation software. On the base of the models, the simulation is done. At last the harmonic characteristics of the type of SS4 Electrical Locomotive are presented.