Robust repetitive control of grid-connected DG-AC converters'

This paper proposes a possible circuit topology and voltage controller design for connecting a DC-AC converter to the power grid. This converter is meant to operate in conjunction with a small power generating unit. The design of the output voltage controller is based on H-infinity and repetitive control. This leads to a very low harmonic distortion of the output voltage, even in the presence of nonlinear loads and/or a distorted grid voltage (The complete controller has also other components besides the output voltage controller, which will be discussed elsewhere). The output voltage controller contains an infinite-dimensional internal model, which enables it to reject all periodic disturbances which have the same period as the grid voltage and whose frequency components up to approximately 1.5kHz are considered.