Extreme and Fatigue Load Reduction of Wind Turbines Towers: Optimal Design of a Hinge-Spring-Friction Device

Wind turbines experience dynamic wind loads that can exert substantial forces and fatigue stress on their structural components. These challenges adversely impact their productivity, performance, and overall lifespan. One promising solution involves the implementation of a Hinge-Spring-Friction Device (HSFD) to mitigate wind-induced structural loads on both the tower and the foundation. To address this issue effectively, a comprehensive optimization process is employed to design the HSFD. This process utilizes a multicriteria approach, considering three key response parameters: peak bending moment, cumulative damage (fatigue) at the base of the wind tur-bine generator (WTG), and displacement demands at the top of the tower. Preliminary results from a case-study turbine in the operational phase ex-posed to various wind loads indicate that the optimized HSFD design for passive energy dissipation can lead to significant reductions in both bending moment (up to 25%) and fatigue load demand (up to 50%) on the tower when compared to the conventional fixed base structural design. Further-more, structural assessments of both controlled and uncontrolled WTGs were conducted using operational modal analysis (OMA) to simulate real-world scenarios and evaluate their structural behavior.