Optimum Design of Extra-Large Wind Turbine Monopile Covering Multiple Conditions

Offshore wind energy is developing rapidly in the United States, particularly off the East coast, which has an extensive continental shelf and where the water depths are such that monopile wind turbines founded directly on the seabed are the most attractive. In a previous paper, the authors demonstrated how the design of a monopole for a 15-MW turbine can be optimized to survive hurricane conditions using several commercially available design tools. This paper extends the study to address multiple loading conditions, including operational working conditions. To do that, different optimizations were run in parallel to find a global solution for multidisciplinary optimization. In the previous study, three independent design tools were used: Wind-plant Integrated System Design and Engineering Model (WISDEM) which was developed by the National Renewable Energy Laboratory (NREL), ANSYS Workbench, a finite element analysis program commonly used in the industry, and the ModeFRONTIER integration platform. To simulate the additional loading conditions, the OpenFAST software from NREL is now included in the workflow to estimate the loads in the different conditions examined.