The Study On Control Method Of Paralleled Modular Active Power Filter

According to the requirements of green and low-carbon development, harmonic problems get more and more attention. As one of the effective devices of harmonic elimination, active power filter is effective in controlling harmonics, therefore the development of its technology provides a good prospect in governing harmonics. With its flexible and high reliability, multi-modular paralleled active power filter become an important direction of development and research focus.Firstly, the paper gives a brief introduction to the concept and damage of harmonics, the standard of harmonic control as well as the main method of harmonic governing, outlining the research status of active power filter, and introduced the topological classification of Active Power filter and the Shunt Active Power filter work principle. According to the constituent elements of the active power filter system, carried on a relevant comparative analysis on the harmonic detection method, current tracking control method in controlling the core portion of the Active Power filter. Introduces two commonly used to current tracking strategy, the dual-predictive control and quasi-resonant control strategy design, gibe an in-depth study on the stability and tracking performance of dual-predictive control. Simulation on the dual-predictive control and quasi-resonant control analysis showed that the designing of quasi-resonant parameters is more complex, but can achieve better performance of zero steady-state error tracking, with better harmonics elimination.For high power applications, operating in parallel through multiple small-capacity active power filter filter system can improve the overall capacity. Wherein the modular active power filter to improve the stability of the system operating in parallel, the paralleled system is good in redundant, there they are of great prospects for future development. In this paper, three current control methods of the current active power filter modular are compared, analyzed and compared the advantages and disadvantages of multi-level current compensation, dividing compensation of each current frequency, and capacity ration allocation method, and outlining the control methods on current sharing and current limiting. On this basis, brings out the problems of widespread inter-modular circulation current. To reduce switching harmonics injected circulation of parallel system injecting to the grid, in-depth analysis of the produce mechanism of circulation current, and proposed a method of carrier phase compensating to achieve the purpose of inhibiting the circulation current caused by the carrier phase difference. Finally, the simulation shows carrier phase compensation can inhibit a good circulation current between the modular units, thus verifying the feasibility and correctness of the proposed method.Based on the above analysis, the paper developed a system with two modular paralleled Active Power Filter. Gives it the hardware and software design, and finally carried on the current compensation on the experiment platform. The experimental results confirmed that the hardware and software design is reasonable, which provides a reference to the future application of modular parallel system.