Research On Control Strategies Of Active Power Filter Based On DSP

With the development of power electronic technology, non-linear loads are widely applied, which leads to serious pollution to power network. The traditional way to restrain the harmonics is to install the passive filter, but it is easily influenced by the system impedance and can only eliminate harmonics of given order, however, the active power filter (APF) can overcome the limitations of the passive filter, and can precisely track and compensate the harmonics, and the performance doesn't depend on the system characteristics, so more and more concern is put on the APF in the last few years.The paper firstly presents the backgrounds and development of active power filters, then the categories, the control methods and the theory of APF are discussed, and after comparison of multiple harmonics detection methods, the i_p-i_q calculation method based on instantaneous reactive power theory is used. The control system determines the performance of an active power filter, and an effective compensation method can assure the active power filter well performed. The paper focused on research on control methods. On the basis of researching several mainly-used compensation ways, three most effective ways were chosen to be further analyzed, which are instantaneous comparison method, triangle wave comparison method and voltage space vector control method.The simulation models of the three methods are built using MATLAB/SIMULINK tool, and a detailed simulation analysis was realized. The result of simulation showed the effectiveness of the three control methods, as well as the advantages and disadvantages of those methods, so after a complete discussion, it revealed that voltage space vector was more accurate and easier to realize on DSP, so the control system based on space vector is determined. The hardware design of the compensation circuit is also presented in the paper, including the power element selection, the capacity design and the induction design as well as realization of voltage space vector method.A shunt active power filter controlled by TMS320F2812 was built on the basis of theory analysis and simulation research, and a basic experiment was conducted.The result of the experiment showed that the i_p-i_q calculation method based on instantaneous reactive power theory combined with voltage space vector control method can precisely eliminate the harmonics in power network in real time.