Research On Improved Method Of Hybrid Filtering In Distributed Generation System

The participation of the distributed power supply in the grid connection leads to a large number of harmonics,which seriously affects the safety and stability of the power system.The filtering effect of passive filters is limited,and the advantages of active filtering performance are obvious,with better harmonic suppression effect,and it has gradually become an important means of controlling harmonic pollution.Although the active filter has a good harmonic suppression effect,it also has the problems that the passband range is limited by the bandwidth of the active device,additional DC power supply is required,and the reliability is not high.In order to pursue better filtering effect,this paper innovatively proposes a hybrid filter combining passive filtering technology and active filtering technology to achieve better filtering effect.This paper studies the use of Active Power Filter(Active Power Filter,APF)to deal with harmonics in distributed power generation systems,analyzes the causes of harmonics generated by distributed power sources and nonlinear loads and their impact mechanism.For new energy power generation systems such as wind power generation systems and photovoltaic power generation systems,the basic working principles and control strategies are analyzed,and a distributed power generation system simulation platform is built for verification.Systematic analysis and research were conducted on traditional detection methods and control methods,and an improved APF mathematical model of the ip-iq harmonic current detection method and the SVPWM control method with no beat was established,and the APF was established using MATLAB/SIMULINK software.Simulation model.In order to verify the filtering effect of APF in the distributed power generation system,based on the completed distributed generation system simulation model,APF was used to carry out related simulation experiments.The simulation results show that APF makes the odd harmonic content A significant reduction was achieved,and the distortion rate was also reduced by more than 2%,demonstrating that the filtering method can effectively suppress harmonics in the distributed power generation system.In addition,this paper focuses on the photovoltaic power generation system filtering,using the hybrid filter proposed in this paper to simulate the photovoltaic power generation system filtering,respectively changing the passive filter LC and LCL before and after the active filter to get four structures Of hybrid filters,it is found that when the same structural parameters are selected,the structural filtering effect of LCL placed in front of the active filter is the best.Then,the comparison of the four hybrid filters in the photovoltaic grid-connected system is conducted,and the simulation results are consistent with the simulation results in the power system.Then,this paper further studies the influence of LCL parameter selection on the filtering effect,and obtains a better parameter configuration.The optimal scheme reduces the distortion rate from13.96% to 0.61%.It can be seen that this filtering method can effectively suppress the harmonics in the photovoltaic grid-connected system.By comparing the changes of the harmonic content and distortion rate of the system before and after APF participation,it is proved that APF based on the deadbeat SVPWM control technology can play a good role in suppressing harmonics in grid-connected.The hybrid filter proposed in this paper has a better filtering effect than a single passive filter and a single active filter.The application and promotion of the new filter technology of the hybrid filter can improve the power quality of the distributed power generation system and meet the The actual engineering needs will promote the progress and development of distributed power generation technology,and have important theoretical and practical significance for improving the power quality and stability of distributed power generation systems.