In this paper, a grid-connected voltage source power converter with a digital vector current controller is used as a shunt active filter at a moderate switching frequency. The system is investigated analytically as well as experimentally. Four different active filtering methods are compared: two direct methods based on the instantaneous active and reactive power theory; and two selective active filtering methods. Experimental results show that the active filtering methods operate successfully at a moderate switching-frequency. Individual harmonic cancellations up to the 13th order are successful for the selective filters, and also the direct method works satisfactorily when compensating for the time delay of the current controller.
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