Research On The Control System Of Shunt Active Power Filter In Three-Phase Three-Wire System

With the extensive use of the power electronic devices in the power system, harmonic pollution becomes more and more serious in recent years.In various harmonic suppress techniques, active power filter has been widely used because of its excellent performance.This paper, first of all, has introduced the generation and the harm of harmonic, the harmonic suppression methods and the development of active power filter. In the meanwhile, the importance of the application of APF has also been explained. In this foundation, some deeper researches have been done on the control system of shunt APF in three-phase three-wire system.Real time and accurate detection of harmonic and reactive currents is the premise for compensation of APF.On the basis of introduction and comparison of several harmonic detecting methods, d-q method which is based on park transform has been emphatically studied. In addition, owing to the fact that low pass filter is used on the harmonic separation link, a kind of digital low pass filter has been designed according to the actual requirements of the system. This low pass filter is based on sliding window iteration algorithm.How to convert the harmonic component to actual current is the key for carrying out the function of APF.This paper has introduced the structure of APF in three-phase three-wire system.Besides that, the mathematics model of APF has been established. On the basis of this, the PI controller of the current loop has been designed.In the foundation of theoretical analysis, with TMS320LF2407A chip of Texas Instruments as the core, the hardware circuit has been designed. Furthermore, combining the hardware circuit, the control software has also been designed by adopting C language and assembly language.In the end, some experiments have been done on the prototype of APF in three-phase three-ware system and the experimental results have also been analyzed.