SCADA-based thrust load estimation of an offshore wind turbine

In order to use the offshore wind farms as optimal as possible, the optimal usage of the actual fatigue lifetime of a wind turbine and predominantly its foundation and substructure is crucial. For offshore wind turbines fatigue is driven both by the quasi-static wind/thrust loads and the dynamic loads, as induced by turbulence, waves and the interaction with the turbine’s structural modes. This contribution mainly focuses on the estimation of the quasi-static thrust load. Actual strain measurements show a correlation between thrust load and several SCADA parameters. Therefore a model is created to estimate the thrust load using 10 min SCADA data and 10 min averages of strain measurements. Afterwards the thrust load acting on the wind turbine is estimated using the created model and 1s SCADA data only. The proposed approach is tested using SCADA and load measurements of an operational wind farm and promising results are shown and discussed in this contribution. Moreover the combination of this approach with a modal decomposition and expansion based virtual sensing technique to estimate the actual stresses acting on an offshore wind turbine and its foundation, as induced by both the quasi-static thrust loads and the dynamic loads, is introduced.