Research On Active Power Filter Based On Unity Power Factor

At present, the power factor is small and the pollution of harmonic is very serious in power system, which affects the quality of electric power energy. In view of such a situation, this dissertation puts forward a way that apply active power filter to compensate with reactive power and harmonic, which increases the power factor.This dissertation is a part of the project of Flexible Alterative Current Distribution System which is belongs to School Fifteenth Special Science and Technology Fund. This dissertation is focus on the study of parallel active power filter for distribution power system which capacity is 10kVA.This dissertation introduces the basic theory and construction of active power filter, derivates the mathematical model of three phase three wire active power filter, focus on the study of harmonic and reactive power detecting methods of active power filter and PWM control methods. By comparison with the advantage and disadvantage of different PWM control methods, the dissertation finally chooses the most suitable control method. To compensate reactive power and harmonic at the same time, the dissertation adopts Unity Power Factor detecting method and detailedly builds the mathematical model of current loop and small signal voltage loop. Particularly to analyse the stability of small signal voltage loop model. This dissertation also designs the parameters of parallel active power filter main circuit and combination with simulation to optimize the parameters.A full digital control system based on DSP is built with TMS320LF2407A and the hardware circuit of active power filter control system have been designed and tested. The control program is written by assembly language. Furthermore by using MATLAB, the dissertation builds simulation model of single phase and three phase three wire active power filter separately. By analysis of the simulation result of different harmonic source, which proves that choosing Unity Power Factor detecting method is correct and feasibility.Finally this dissertation does the experiments with the method of Unity Power Factor, shows the experiment wave and analyses the experiment result.