Presentations

Abstract

Rotor imbalance is a common source of tower and monopile fatigue in offshore wind turbines, yet its real operational impact on foundation lifetime is rarely quantified. This study presents a real-life case from an offshore wind farm, integrating 10-minute SCADA (supervisory control and data-acquisition) data, fore-aft tower acceleration measurements, and strain-gauge-derived Damage Equivalent Moments (DEM). By analyzing 1P accelerations, a turbine with pronounced rotor mass imbalance was identified. The magnitude of the imbalance was quantified from the spectral amplitudes. DEM analysis revealed approximately 20% higher fore-aft fatigue in the affected turbine compared to other turbines in the fleet. Foundation lifetime impact was estimated using DEM increase and the principles of structural steel S–N (or Wöhler) curves. This analysis demonstrates a substantial reduction in expected monopile lifetime due to rotor imbalance. The study provides operational evidence linking rotor imbalance to monopile fatigue and lifetime reduction in offshore conditions. The approach demonstrates a practical framework for operators to detect, monitor, and mitigate rotor imbalance, thereby optimizing turbine reliability and structural longevity.