Wind turbine mechanical stresses reduction and contribution to frequency regulation

•A MIMO LQG controller is designed to control an island 400 kW wind turbine (WT).•The objectives are to alleviate fatigue loads and to involve the WT in the frequency regulation.•Numerical simulations are carried out to compare the controller with a base-line controller.•Results show that the LQG reduces much more mechanical stresses.

The aim of the present research work has been to design an optimal MIMO LQG controller to reduce the drive-train, blades and tower mechanical stresses of a wind turbine (WT), and at the same time, to involve the WT in the grid primary frequency regulation when it is operating in full load (FL) zone. To verify the effectiveness of the proposed controller, the achieved results are compared to those obtained by a base-line controller based on a PI regulator.Simulation results show that thanks to these controllers, WT can effectively contribute to the grid frequency regulation, tracking tightly the generator power reference which depends on that frequency. Compared with the base-line controller, the LQG controller significantly reduces the mechanical stresses of the WT׳s most costly components.