Research On Active Power Filter Control Technology

With the widespread application of power electronic devices and non-linear loads in the power grid,the problem of harmonic pollution has become more serious,and power quality has attracted more and more attention.Active Power Filter(APF),as a new type of equipment to improve power quality,has also become a hot topic of research by related scholars.This paper takes the three-phase three-wire parallel APF as the research object,and mainly studies the harmonic current detection method and current tracking control strategy of the parallel APF.This paper first studies the definition of harmonics,generation,hazards and corresponding harmonic standards of harmonics.By comparing and analyzing different suppression methods of harmonics,APF with superior performance is selected for research.Subsequently,the basic principles of APF are analyzed,and its mathematical models based on switching functions are established in the abc three-phase static coordinate system and the dq two-phase roating coordinate system.At the same time,the commonly used harmonic current detection methods and current tracking control methods are broefly introduced.Secondly,in the harmonic current detection part,through the analysis and comparison of the p-q harmonic detection method and the ip-iq harmonic detection method based on the instantaneous reactive power theory,using the superior performance ip-iq harmonic detection method.And to address the problem of delay in using traditional filters in the ip-iq harmonic detection method,use adaptive filter based on variable step size instead of traditional filter,greatly improve the speed of harmonic detection.And through the use of power electronics simulation software to simulate and verify the proposed harmonic detection method,it proves the correctness of the analysis.And then,in the current tracking control part,analyzed the influence of the harmonic detection delay caused by the system on the APF compensation effect and proposed the use of repetitive predictor to solve the system delay problem.Then the PI regulators required for current and DC side voltage control are designed separately,and verify the effectiveness of the controller through power electronics simulation,it shows that using repetitive predictor to predict the commanded harmonic current signal can improve the compensation performance of APF.Aiming at the steady-state error problem of using PI regulators in current tracking control,the use of model predictive control(MPC)is proposed.Then introduced the basic principles of MPC,and carried out a detailed analysis and design of the MPC system,and verified the feasibility and superiority of using MPC method in APF system through power electronic simulation.Finally,the hardware and software of the three-phase three-wire parallel APF experimental platform are designed,and the experimental platform built is used to verify the validity and correctness of the relevant analysis and control strategy proposed in this paper.