The Analysis Of High-speed Locomotive Harmonic Characteristic And Its Impact On Power Quality

With the popularity of high-speed locomotives, the harmonic problems and the impact on power quality of Access Grid is increasing. Today, how to evaluate and manage harmonics is a major problem of power quality, while the content of harmonic is also an important indicator of the power quality. Therefore, studying harmonic characteristics of high-speed locomotives and exploring its impact on power quality have become particularly important. The thesis put the harmonic problems caused by high-speed locomotives as the main content to expand research, the main work is as follows:(1) This thesis describes the basic concepts of harmonic, the causes and measure index, then details of several harmonic analysis methods were introduced, such as fourier transform algorithm, wavelet transform algorithm, neural network algorithm, instantaneous reactive power algorithm, state space method. Then the characteristics of the above methods were analyzed in several ways, and the author compares their advantages and disadvantages and puts forward the following conclusions:fourier transform algorithm is the foundation, wavelet transform algorithm and neural network algorithm further improve the timeliness and accuracy, instantaneous reactive power algorithm mainly for real-time, and he state space method applicable to a non-integer harmonics.(2) On the basis of understanding harmonic analysis method, the thesis analyzes the high-speed locomotives four-quadrant converter according to bilateral fourier series method, and respectively analyzes the main circuit and control strategy of two kinds of topology of four-quadrant converter, at last the author derives the formulas of four-quadrant converter grid side harmonic current. The author put the traction drive system of high-speed locomotive as the harmonic source model, and particularly introduces the structure and harmonic generation mechanism of the model. By means of the combination of mathematical analysis and simulation experiment, the thesis works out the distribution of high-speed locomotives harmonic currents.(3) By setting up a simulation model of system analysis,data collection on traction system in Xinyang area, this thesis analyzes power quality characteristics of traction station from three aspects:harmonics,the three-phase voltage unbalance and voltage fluctuations, to better grasp the grid power quality status of Xinyang and to improve the safety performance of the grid, to promote the level of economic operation.