Simulation Research Of Shunt Active Power Filter Base On Repetitive Control Theory

In recent years, with the development and extensive application of powerelectronic technology, it has become the most prominent harmonic source, whichcausing serious harmonic pollution to the power system, making grid voltage andcurrent distortion; seriously affecting the grid quality, therefore harmonic suppressionhas become very important and urgent. Active power filter is one of the most effectivemeans in suppressing harmonic, has a broad application prospect.For active power filter, the compensation precision depends heavily on thedesign of current loop controllers, the key is how to make the compensating currenttracking the reference current better and reduce the tracking error. The error betweencompensating current and reference current is periodic, wherefore the control effectusing traditional Proportion (P) controller is not ideal enough, it cannot control theoutput current waveform without any steady error, but the dynamic response is ideal.The internal mold of repetitive controller includes mathematic model describing theerror signal, thus theoretically can completely eliminate the steady-state error of thesystem. Therefore, the paper uses P control plus repetitive control algorithm for thedesign of current loop of active power filter.Repetitive controller and P controller connected in series or in parallel. Themultiple control strategy is a kind of output current waveform control method, Pcontroller is used to improve the dynamic performance, and repetitive controller isused to improve the system steady compensation accuracy. This paper also shows thedetailed design process of both approaches.Finally, the paper designs the model and simulation of shunt active power filterby Matlab/Simulink simulation software. The simulation results show that themultiple control strategy is entirely applicable to active power filter, and has bettercompensation precision and dynamic response, to control the total harmonic distortionin requirements range, improve efficiently the harmonic pollution.