Reserch On The Control Method For Active Power Filter

Grid harmonic pollution is becoming increasingly serious and the power quality isgetting worse because of the use of a large number of non-linear loads of electricalinstallations.Active power filter is an ideal device to suppress harmonics.It is a tool toeliminate the hazards of electricity and improve the quality of power supply.Active powerfilter has the characteristics of dynamic response,real-time and high compensationaccuracy compared with the passive filter.Experimental research on active power filter is agreat meaningful thing.The main research area is the structure and working principle of the active powerfilter,the compensation object detection algorithm,control strategy, the DC-link voltagecontrol and the design of the experimental apparatus.The focus on this paper is the control method for shunt active power filter.Introducethe control principle and characteristics of the wave control, hysteresis current control,deadbeat control, predictive control and repetitive control method.By comparison andanalysis this several control methods,summed up a more optimized current tracking controlmethod.It’s deadbeat control method based on the predicted current.First, the outputreference current value of the next time is predicted using the prediction method at the timeof k. Then, the duty cycle of PWM signal is calculated based on the discrete mathematicalmodel of the APF. This method can not only eliminate the calculation delay due to thealgorithm complexity effectively but also ensure the stability of the system. At the sametime, the DC-link impact current is inhibited using the method of DC capacitorpre-charging and DC-link voltage increases linearly before the active power filter intoinverter operation. PI control method is used to make the DC-link voltage fluctuatingwithin a certain range. In order to verify the practicality and effectiveness of various detection and controlmethods,we have completed the software design of the active power filter control systemon the controller hardware platform of digital signal processor TMS320LF2407A.And current tracking control performance of active power filter is studied in theexperiment. Experimental results show that the proposed current tracking control andDC-link voltage methods can make the active power filter effectively eliminate harmoniccurrents in the power grid.