Research On The Hybrid Active Power Filter

With the increasing of various non-linear loads in Power system,the power quality has been more and more deterioration.Improving power quality has became one of the focuses of the electric power research.The methods of improving the quality of power have many, active Power filter is considered as the most effective method to harmless the serious Power pollution and improve power quality because the active power filter(APF) can compensation harmonic and reactive currents quickly and accurately.This paper discusses the causes of power quality be affected,analysis the methods of improving power quality,and introduces the development of Active Power Filter.The unified power quality conditioner(UPQC)is the most perfect hybrid active power filter. The topological structure and compensatory characteristics of UPQC are researched.The mathematical modes of series and shunt compensation part are built according to the main circuit topological structure of the unified power quality conditioner. This paper focus on the analysis of detection methods of harmonic and reactive current,and adopts current and voltage detection technique that based on Park transforms.This detection technique can detect distortion signal accurately when the voltage and vurrent of power system are asymmetry or distortion.This paper introduces advantages and disadvantages of various control methods,including compensatory current,voltage control,and DC voltage control.In this paper, series compensatory part adopts triangle wave compare control,shunt compensatory part adopts hysteresis compare control and DC voltage control adopts P1 closed loop control.The parameters are calculated according to the main circuit topological structure of the unified power quality conditioner and Low pass filter(LPF) is designed.At last the UPQC is simulated according to the parameters by Matlab simulation software.The simulation results show the detection and control method that this paper adopts arevery effective,input voltage and input current of the load in control by UPQC.