H∞ repetitive control of DC-AC converters in microgrids

This paper proposes a voltage controller design method for dc-ac converters supplying power to a microgrid, which is also connected 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 techniques. This leads to a very low harmonic distortion of the output voltage, even in the presence of nonlinear loads and/or grid distortions. 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 highest frequency components are up to approximately 1.5 kHz.