Fatigue Life Evaluation of a Wind Turbine Tower with a Hydraulic-Pneumatic Flywheel System in the Rotor

This study investigates the effectiveness of a hydraulic-pneumatic flywheel system integrated into the rotor of a wind turbine for structural load reduction. The analysis uses the state-of-the-art aeroelastic simulation tools OpenFAST and HAWC2, coupled with a novel Simulink based flywheel and control model, to evaluate fatigue loads mitigation abilities of the flywheel. Fatigue load simulations are performed for cases with and without the flywheel system, with a specific focus on the fatigue life of the tower. The findings indicate that different flywheel control functionalities exhibit varying levels of influence on tower fatigue loading in both simulation environments. A fatigue-life extension of up to 20% is achieved, demonstrating the potential of flywheel control strategies for structural load mitigation.