Validation of Uncertainty in IEC Damage Calculations Based on Measurements from Alpha Ventus

The aim of this paper is to validate environmental assumptions used in the design of offshore wind turbines. This is done by comparing the load uncertainty (load variation) resulting from assumptions to full scale measurement data from a Senvion 5 M turbine on a jacket substructure positioned in the offshore test field Alpha Ventus in the North Sea. The focus is put on fatigue loads occurring during power production. Sensors at the tower base and tower top of the turbine are evaluated. Simulations are performed by using the coupled simulation tool Flex5-Poseidon. Measurements over a period of 10 months are selected so that a high quality of reference data is ensured. Uncertainty from both measurements and simulations are determined by Monte Carlo experiments and evaluated by Bootstrap methods. Results show that a variation of damage from simulations is significant and that the presented method could be used for evaluation of assumptions used in the design process.