Design Of Modular Three-level Active Power Filter

Many industrial and daily life of the electrical load generated a lot of harmonic currents,affecting the stability of the grid voltage,in order to ensure the stability of the grid,the need for harmonic compensation corresponding to the grid from a node in the grid.According to domestic and international development of harmonic compensation device,combined with the corresponding converter topology structure of the system development,key technology for cascaded H bridge topology structure of APF was studied,and based on the design and test of prototype.Based on the analysis of the dynamic modeling of DQ rotating coordinate system,a fast detection algorithm of harmonic current,a simplified model based on voltage source,reveal the compensation mechanism of the system,on the basis of the study on the working characteristics of different APF topology characteristics,to provide theoretical support for the cascaded H bridge topology selection.In this paper,then the cascade structure of the main circuit is designed,and based on the analysis of its switch topology model of three level H bridge is simplified,deduces the internal coupling mechanism of converter unit,and provide a theoretical basis for the control of converter unit current loop and voltage loop,on the basis of introducing LCL three order filter,reduce the output ripple converter unit,and analyzed the influence of LCL filter parameters on the compensation effect.Then,considering the particularity of the APF environment,the study of adaptive function,through the real-time monitoring of the environment temperature and the characteristics of power grid,the output ability of the dynamic control system of the power grid to prevent flicker problems caused by non breakdown.Finally,according to the engineering application,this paper adopts the technical route of theoretical exploration,model simulation verification and prototype experiment verification.The concrete implementation scheme design of cascaded APF,surrounding the design,completion of the cascade APF prototype building and debugging,and performance verification test,after testing the prototype performance meet the design requirements,reached the leading domestic level,and in some of the key performance indicators is better than the other domestic manufacturers.