Study On Wavelet Detection Method And Compensation Control Of Active Power Filter

In this paper, the sources and hazard of power system harmonics are described. manytraditional harmonic detection methods are introduced. The active power filter can track andcompensate the varying harmonics, reactive and negative sequence currents dynamicly and fastly.Compared with the traditional current suppression methods, the active power filter has a fastresponse and high accuracy compensation. With the development of power electronicstechnology, modern digital signal processing, intelligent control technology and many otherdisciplines, the performances of the active power filter are improved, and it becomes modular,integrated and miniature with a good potential in the market.In this paper, harmonics curret detection method based on instantaneous reactive powertheory and wavelet transform are described in detail. These two approaches simulation arecompleted separatly using the simulink and wavelet toolbox. The detection platform based on thePCI1712L data sampling card is designed, the software part of the platform is completed byLabVIEW and MATLAB. Harmonic waveform display, fundamental waveform display andspectrum analysis can be seen in the platform, reflected the superiority of the wavelet detectionmethod.The control system determines the performance of an active power filter. Firstly, the basicprinciples of the triangular wave control, instantaneous comparison control and space voltagevector PWM control are introduced. The simulation models of the three methods are built usingMATLAB/SIMULINK tool, which are analyzed and compared. And based on the closed-loopcontrol, the PI controller adjusting the voltage of the direct-current side is used to improve theeffectiveness of compensation, reduce the tracking error of the compensation current and thecurrent distortion of the supply side.On the base of theoretical analysis and simulated research, in the active power filter, themain circuit layout, the parameters of the filter capacitor, filter inductance and the choice ofswitching devices are explored in detail. This test has a good effect of compensation.In this design, the uncontrollable three-phase rectifier with resistance load is selected as theharmonic source. a set of110kVA parallel APF (active power filter) prototype system based onTMS320F2812DSP is completed. In this paper, the active power filter hardware devices and software programming have been designed. The hardware parts include fiber-optic system circuit,drive and protection circuit, buffer circuit, current and voltage signal conditioning circuit,synchronous signal circuit, touch screen, power monitor, RS232-RS485conversion circuit and soon. The software components include the program of harmonic current detection and control, aswell as communication program among touch screen, power monitor and DSP.Finally, a remote control system of the harmonic current detection is designed in the paper,the system is completed by LabVIEW, serial communication and classic structure-producer/consumer design patterns (event) of LabVIEW are used in this paper. Ultimately, the remotecontrol system is achieved.