Analysis and Design of Repetitive Controllers for Applications in Distorted Distribution Grids
P. Schülting, C. H. van der Broeck, R. W. De Doncker, IEEE Transactions on Power Electronics, 2018
This paper proposes a generalized design procedure for repetitive current controllers in distorted distribution grids to obtain good disturbance rejection properties and well behaved and robust system dynamics. Different implementation options for repetitive controllers are discussed based on an accurate discrete time model. A simple control design is derived, which allows any desirable dynamics to be adjusted by one single parameter. Even a dead beat design is possible. The impact of model inaccuracies and numerical errors on the dynamic and stability of the system is investigated. It is shown that the repetitive controller leads to low damping or even instability at high switching frequencies caused by modeling errors or numerical inaccuracies. Based on the stability analysis it is discussed how to handle these design challenges which exist especially for repetitive controllers of high order. The proposed control structure and control design concept is verified by simulations and experiments.