Research On Technologies Of Simulation Based On Hydrodynamic For Monopiles Offshore Wind Turbines

Offshore wind turbines has enormous potential economic value.In order to accurately simulate offshore wind turbine load, it is necessary to set up a simulation model including offshore wind turbines coupling with hydrodynamic. But this part of the work does not carried out at present in domestic. This paper used FORTRAN language to complete the SIMPACK/Hydro Dyn hydrodynamic interface development, introduced a hydrodynamic calculation morrison force element, connecting with the mature drivetrain module and aerodynamic module. Established a air-elastic-control-hydro full coupling simulation model including fixed platform and offshore wind turbines in SIMPACK,. Finally, according to IEC 61400-3 offshore wind turbine design guideline design typical load cases, based on single pile fixed offshore wind turbines performed hydrodynamic calculation and whole machine load research.The main research contents and results in the paper were summarized as follows:①Overview of monopiles offshore wind turbine domestic and overseas modeling and simulation,hydrodynamics interface development research current situation. Finally, clarify this research’s significance and major research content.②Clarify related modeling theory and introduced the SIMPACK user-difined subroutine, then analyzed calculation source program of Hydrodyn and write the interface program between SIMPACK and Hydrodyn. Then, completed dynamics modeling of wind turbine balde, tower, gearbox. Finally, introduced Chapter three defined hydrodynamics force element to achieve coupling multibody dynamics and hydrodynamics.③Performed modal analysis and verified the accuracy of the model by base frequency verification. Then perform simulation analysis and verified the hydrodynamic interface’s accuracy by compared with FAST simulation result. Then analyzed the effect of wave, wind, tide, extreme sea condition to hydrodynamics and structure load. Finally analyzed the influence of hydrodynamics to mode.④Simulation results show that: a. For fixed single pile offshore wind turbine the hydrodynamic load is mainly viscous water load and inertia load, and a few additional mass load, it shows that for fixed single pile offshore wind turbine inertial load and viscous load are dominated, radiation and scattering strength almost can be ignored; b.Waves has a certain influence for the natural frequency of the whole machine, it can make the natural frequency decrease slightly; c.Hydrodynamic load, structural load is mainly influenced by the type of wind and wave, the influence of tide is little; d.Extreme sea condition can make the hydrodynamic load and structure load increases sharply, far greater than the load of the linear regular wave conditions. So the wind turbines through feathering and downtime to protect themselves under limit conditions.