Research On Three-Phase-Four-Weir Shunt Active Power Filter Based On FPGA And DSP

At present, the power electronic devices are widely used in the production andlife, the grid are severely affected by power energy change of power electronicdevices, more serious the power system harmonic problems, more deterioration thepower quality. Harmonic suppression and reactive power compensation are paidmore and more attention. With the rapid development of power electronic devicesand control theory, active power filter has received extensive attention and study.This paper mainly studies three-phase four-wire active power filter based onTopological structure of the four bridge arms，harmonic detection method andcompensation current control strategy.This paper, firstly in harmonic detection, studied the harmonic current, zerosequence current, reactive current and other harmful components of unbalance loadcurrent in three phase four wire system with asymmetric load. According tocompensation purposes, ip-iq-i0method based on the instantaneous reactive powertheory is detailedly researched and symmetrical load harmonic current can also bedetected. In harmonic detection algorithm, in order to avoid impact of the distortionof the voltage, this paper analyzes the three-phase phase-locked loop technology. Inorder to improve detection precision and dynamic response, the low pass filter usedin detecting link is studied.Secondly, this paper studies main circuit topology of the three-phase four-wireshunt active power filter. Analyze its working principle and establish respectivelythe system mathematical model in static three-phase a-b-c coordinates, stationarythree-phase α-β-0coordinates and the d-q-0rotation coordinates.In order toaccurately compensate the harmonic current and reactive power, compensationcontrol strategy is the most crucial, control strategy contains control method of DCside voltage stability and control method of current tracking command.Andaccording to the energy flow,PI control strategy is employed in DC side voltagecontrol method and the controller parameter design method is given out.Accordingto the harmonic current periodic,this paper analyzes the repetitive controller in twokinds of control strategies in the application of active power filter, and gives thesimulation and experimental results.Three-phase four-wire active power filter used3D-SVPWM modulation to four bridge arms. Because of modulation algorithm complexity, the paper takearchitecture with the software and hardware design based on the DSP and FPGACombined controller, using FPGA’s fast parallel processing ability. The necessaryfunctions that need to be completed are distributed to DSP and FPGA Accordiongto DSP and FPGA respective advantages, to achieve better control effect.On the basis of the study on the system hardware and software design,develope a33KW three-phase four-wire shunt APF prototype. The simulation andexperimental results show that the system can effectively compensate harmonic andreactive current.