The Research Of Eliminating Electric Locomotive Negative Sequence Current Based On Complex Coefficient Transfer Function Filter

Railway electrification is an important development direction in China. From 1958 to now, fifty years of development, China Railway Electrification has been in the world leading level. Although developed electrified railways have brought great convenience to people’s travel, and provided a strong support for the development of the national economy, but there are advantages and disadvantages at the same time, because the electrified railway has the characteristics of frequent load fluctuation and large impact, and the electrified railway is a single phase rectifier load, this will transport a large number of harmonics, negative sequence and reactive power to the power grid, the power quality of the electric power system has caused a lot of pollution, seriously affect the safety and stability of power system operation. In order to solve this problem, scholars from all over the world have conducted or deep or shallow research in order to reduce the harmonic, negative sequence and reactive power. On the basis of previous work, this paper has carried out the corresponding work in order to remove the negative sequence component in the current.This paper firstly introduces the basic situation and characteristics of the electrified railway in our country, introduces the cause of the negative sequence current and its harm. In order to filter the negative sequence current, a complex coefficient transfer function filter is constructed, and the feasibility of the proposed filter is verified by Simulink simulation.In this paper, several common traction transformer connection modes are introduced, then the common locomotive model is introduced with the example of the SS6 B type AC/DC locomotive and the CRH2 type AC-DC-AC locomotive. After this, in Simulink, this paper choose V/v connection traction transformer, verified by complex coefficient transfer function filter to filter out the SS6 B type locomotives and CRH2 type locomotive running in the negative sequence current feasibility, and it can successfully eliminate negative sequence current of three-phase symmetrical current which will feedback to the power system.