Application Research Of Repetitive Control In Harmonic Suppression And Reactive Power Compensation Device

With modernization and intelligent of the power grid continuously, Power electronics equipment accounts for a lot of applications in grid operation, transmission, Electronic devices make the control and optimization of the grid simply, however, due to its nonlinear characteristics, a lot of harmonic current is generated, reactive power is also consumed. At the same time, more and more non-linear idductive load is used in enterprise production and people’s lives, such as electric motors, electric arc furnace, and a variety of household appliances, consumes reactive power and produces harmonic current. The waveform of grid current is distortion seriously, power factor of the grid is reduced, does not meet the requirements of the national grid power quality. Active power filter (APF) is electronic device, it can suppress harmonic and compensate reactive current, the application and research of APF is very widely due to its reliable performance and flexible control mode.In this paper, the research object is three-phase three-wire APF system, structures and principle of APF are introduced, mathematical model is derived. ip-iq detection method is used to detect harmonic and reactive current, in this method, the choice of low-pass filter has a great impact to the detection results, second-order digital butterworth filter is used. To track the instruction current accurately, in the current tracking control method, composite controller composed of PI and repetitive controller is adopted, make sure the system has good dynamic and stability performance.Detection circuit, main circuit and control circuit modles are built on the platform of MATLAB/SIMULINK, PI regulator and compound controller are used in control circuit respectively. Compare the harmonic compensation effect of load stability and changed, the simulation results shows that compound control has a higher compensation accuracy and the dynamic performance is equal to PI regulator. Harmonic and reactive current compensation simulation system is also built; the simulation waveform and data both reflecte the good compensation effects of APF.To make APF system practical, detection circuit, drive circuit, main circuit and fault protection hardware circuit are built on experimental platform. The calculation of instruction current and the realization of control method are completed in DSP2812, intelligent power module IPM(PM25RSK120)is adopted in main circuit. The main program and various functional module subroutine are written, based on the hardware platform, and debugs the program in CCS2.2, experimental results demonstrate the feasibility of the method used in this paper.Finally, space vector pulse width modulation SVPWM is used in APF experimental system, write the control algorithm program and debug, experimental result illustrates the effectiveness of SVPWM in the application of APF, which laies a foundation for the further improve experiment.