A wind turbine digital shadow with tower and blade degrees of freedom - Preliminary results and comparison with a simple tower fore-aft model

This paper analyzes the formulation of a wind turbine digital shadow using a Kalman filter to estimate tower loads. At first, a simple model is considered, which is limited to the sole fore-aft dynamics of the tower. Next, to quantify the potential benefits of a more refined approach, the tower side-side motion and the blade flapwise and edgewise degrees of freedom are added to the filter-internal model. For both the simple and refined formulations, the model coefficients are optionally scheduled as functions of the inflow conditions. Preliminary results, limited to non-waked and non-misaligned conditions, indicate that the refined formulation has some positive - but limited - effects on the quality of the tower fore-aft loading. Additionally, it is found that the scheduling of the coefficients does not further improve the results.