Three Legged Articulated Support for 5 MW Offshore Wind Turbine

This numerical study discusses the preliminary design of a three-legged articulated supporting structure for 5 MW Offshore Wind Turbine.Although articulated tower has many advantages as deep water platform, studies on wind turbine installed over articulated supports are scarce.First stable configuration of a Multi-legged articulated support, the three legged articulated structure is selected for detailed study.Wind dynamics coupled with that of wave is veryimportant while analyzing an offshore wind turbine support.An effective coupling of finite element software NAOS (Nonlinear Analysis of Offshore Structures developed at Dept. of Ocean Engineering, IIT Madras) with aerodynamic code FAST (Fatigue, Aerodynamics, Structures and Turbulence, developed by NREL, USA) was done to simulate wind-wave coupling.A candidate supporting structure is designed based on basic stability considerations as well as natural frequency ranges. The dynamic response of the structure to various wave and turbine orientations was investigated to get the optimum orientation of structure. Response Amplitude Operators (RAOs) corresponding to six degrees of freedom were examined for different wind speed to study the dynamic effect of wind turbine on the system. Some extreme load cases were also simulated to study the response of structure to harsh environment. The results revealed that the proposed structure suits well for the selected site.