Research Of Photovoltaic Grid-connected System With Active Power Filter Function

With the problem of worldwide energy crisis and environmental issues becomingincreasingly prominent, renewable energy source development attracted wide attention.Solar energy has become one of the most prospective new energy for its characteristicsof inexhaustibility and cleanness. Photovoltaic (PV) power generation is an effectiveway to make full use of solar energy. On the other hand, a large number of nonlinearloads have appeared. The power quality of power system is deteriorating caused by theharmonic.This paper compares the topology and control strategy of the PV grid-connectedsystem with Active Power Filter (APF). A combined control strategy for PVgrid-connected system integrated with active filter. The system can not only provideactive power but also suppress the harmonic, which saves investment of the equipmentand improves the utilization of PV grid-connected system.Summarizes design methods of the LCL filter in fundamental or harmonicapplication, and a new design method for both fundamental and harmonic application isproposed on this basis. LCL filter is used in the photovoltaic grid-connected systemwith APF function, and factors such as active current injecting, slew rate ofcompensation current, switching harmonic and the bandwidth are considered.Parameters values are directly determined by MATLAB. In this way, better switchingharmonic and grid current ripple suppression effect are obtained.The detection of harmonic and the synthetic method of the grid-connected currentare analyzed in this paper. For the grid-connected current may exceed the rated range, asynthetic method based on capacity limitation control is proposed to limit the inverteroutput current, and ensure the system work within the rated range. Quasi-PR controlleris used to achieve steady-state error of the fundamental signal tracking, and the specificfrequency of the harmonic suppression.Finally, verifies the correctness and effectiveness of the system structure,parameters design method and control by MATLAB/Simulink simulation and RT-LABexperimental results.