Optimal control for load alleviation in wind turbines

Nowadays, trailing edge flaps on wind turbine blades are considered to reduce loading stresses in wind turbine components. In this paper, an optimal control synthesis methodology for the design of gust load controllers for large wind turbine blades is proposed. We discuss a control synthesis approach that minimises the power expenditure of the actuated trailing edge flap, while at the same time guaranteeing that certain blade load measures remain bounded in a probabilistic sense. To illustrate our proposed control design methodology, a standard NREL 5-MW reference turbine was considered. The obtained numerical results indicate that through the use of optimal feedback considerable reductions in loading stresses could be achieved for moderate actuation power.