Design of multi-objective robust pitch control for large wind turbines

This paper proposes a design of sophisticated multi-Objective H2/H∞ collective pitch controllers using linear Matrix Inequalities' techniques. The proposed controller's design takes into account model uncertainties by designing a controller based on a polytopic model. The LMI-based approach allows additional constraints to be included in the design (e.g. H∞ problem, H2 problem, H∞/H2 trade-off criteria, and pole clustering).These constraints are exploited to include requirements for perfect regulation, efficient disturbance rejection, and permissible actuator usage. The proposed controller is compared to an optimal linear quadratic regulator pitch controller based on single model. Both controllers are tested on 5-MW Reference wind turbine model developed by NREL using FAST software code.