A New Harmonic Repetitive Controller for DG Interfacing Converters

Repetitive controller (RC) has the merits of simple structure, small computational burden, and providing zero steady-state control error for the closed-loop at the zero frequency, fundamental frequency, and its multiples. However, for a distributed generation (DG) interfacing converter with the auxiliary harmonic compensation capability, its harmonic control loop often does not need to control the direct current (DC) and fundamental frequency components, thereof RC is inapplicable. To address this issue, this paper proposes a new harmonic RC (HRC) for DG interfacing converters. To construct the HRC, a digital second-order high pass filter and a notch filter are respectively used to cancel poles of the internal model of conventional RC at zero and fundamental frequencies. When implemented in the harmonic control loop of the DG converter, the proposed HRC only deals with harmonics, avoiding the extra harmonic extraction. Both the mathematic model derivation and the controller parameters design are given in detail in the paper. Finally, experiments are performed to validate the effectiveness of the proposed scheme.