Fatigue load estimation and reduction for wind turbine

Fatigue is the structural damage that leads the components of a wind turbine to sudden brittle failure when it suffers cyclic loading [15]. As the size of wind turbines is growing, fatigue loads become more and more significant for the design of major structural components. Concerning fatigue in a wind turbine tower, the fore-aft tower foot bending moment is considered as the most critical load. The benefits of fatigue load reductions, which can be achieved by appropriate design of a wind turbine control system, are increasing [12].The purpose of this study is to estimate fatigue loads in frequency domain [18] for control design, then to regulate the pitch angle in response to the measurement of acceleration of tower top oscillation, thus to reduce the fatigue damage from the tower bending moment.