Parallel Type Based On Repetitive PI Control Research On Active Power Filter

With the development of national science and technology productivity,more and more new electric power equipment have been put into use in the power grid,which not only brings huge economic benefits,but also produces harmonics that pollute power quality.Active Power Filter(APF)is an effective method to eliminate harmful harmonics.In this paper,three-phase three-wire shunt APF is taken as the research object,and its harmonic detection and control algorithm are studied in depth.Firstly,the working principle of APF is analyzed,the mathematical models in three-phase stationary coordinate system and two-phase rotating coordinate system are given,and the system parameters are designed.Whether the instruction current is generated correctly or not is the premise of effective compensation of APR FBD(Fryze-Buchholz-Depenbrock)harmonic detection algorithm uses reference voltage to project transformation,which can detect both the fundamental current and any harmonic current with great flexibility.It has great flexibility,so it is selected as the harmonic detection method in this paper.Secondly,the reason why repetitive control can track command signal without static error is analyzed.For the problem of poor dynamic performance,the PI algorithm commonly used in industry is proposed and used in combination,and the scheme of repeated control and PI control in series and the repeated control and PI control parallel scheme,and strive to make the two complement each other,not only play the repetitive precision but also play the rapidity of PI.The parameter design was carried out according to the control block diagrams of the above two schemes.The simulation results obtained also confirmed that the composite control has a high superiority compared with the single PI control and repeated control,but under the same conditions,the repeated PI series connection The filtering effect is better than that of the repeated PI parallel filtering,and the needle is given a brief analysis.Finally,set up a experimental platform for the shunt active power filter,using the FPGA+DSP as control chip,choose external AD to improve sampling accuracy.The design process of current and voltage conditioning circuit is introduced in detail.The experimental results further verify that the repetitive PI compound control strategy can be well applied to active power filter and ensure the superior compensation performance.