The Study On The Shunt APF Used In Low Voltage Distribution Networks

With the development of the electronic technology, the widespread use of nonlinear load has made power quality problems more and more serious such as harmonic pollution in low voltage distribution networks.Some effective and reasonable measures must be adopted to solve these problem.With the three-phase and four-wire parallel active power filter as the object of the research, this article deeply studies the algorithm of harmonic detection and control strategy for current compensation.Firstly, the background and meaning of project is introduced. The paper analyzes the cause, harm and treatment methods of harmonic elimination in low voltage distribution networks and elaborates the development of the shunt APF and its experimental investigation home and abroadSecond, the paper introduces the categories of passive filter and active power filter and focuses on the analysis of the working principles of the main circuit of three-phase four wire shunt APF.Third, introduces the common methods of harmonic detection,the p-q and ip-iq method based on Instantaneous Reactive Power Theories have a comparative analysis. The simulation results show that when the voltage distortion doesn't occur, the two methods have the same accuracy in harmonic detection. However when the voltage distortion occurs, the ip-iq method is more accurate than that one. And the control technology of the shunt hybrid APF of three-phase four-wire system is analyzed. The paper analyses the control performance of the tradition controller in detail, key research on deadbeat controller, and the deadbeat control algorithm software process is described. the results show that deadbeat controller has good effect on current tracking. At the same time, the design and Simulation of DC side voltage control is also carried out.Fourth,The simulation model of three-phase four wire system shunt active power filter is built with the help of MATLAB. It is used to do harmonic elimination and unbalanced control.And the simulation analysis is carried out in the case of the phase unbalance and load sudden change.The result shows the shunt hybrid APF of three-phase four-wire system designed in this paper has good harmonic compensation and unbalanced control ability.Finally, the realization of the shunt hybrid APF of three-phase four-wire system device were researched.Then it was designed from the aspects of both main circuit parameters and the control system hardware and software.Engineering application result shows that the device has good harmonic elimination effect.