Uncertainty analysis of offshore wind turbines including effects of soil

Offshore wind turbines (OWTs) supported on fixed platforms are usually analysed by considering the foot print of the platform rigidly fixed with the soil; and then a suitable foundation is designed depending on the soil properties and loading. Such a procedure may have adverse implications when the structure is located in marine soils. In the present study, dynamic analysis of an offshore wind turbine supported on a monopile in a water depth of 25m is performed considering the effects of the soil. The soil properties are a representative scenario for the western coast of India. The analysis is performed in a finite element framework which accounts for hydrodynamic and soil effects simultaneously. The wind load applied as a point load on top of the turbine tower and the dynamic wave loads are applied on the monopile. The study shows that considering soil structure interaction in OWT may have an important bearing on the power production. A parametric study has been carried out to identify the influence of variation in pile and soil characteristics on the turbine response. The results clearly highlight the importance of consideration of soil parameters in the overall dynamic analysis of the fixed-platform OWT.