Research On The Influence Of Mooring Line's Pre-tension Of 6MW Floating Wind Turbine

Wind energy is inexhaustible as a sustainable clean energy and has become one of the themes of new energy research.The development of onshore wind power is limited by factors such as land resources and working noise.The development and utilization of offshore wind power has become the mainstream direction of new energy development and utilization.In this paper,the mooring system of the new 6MW offshore single-column floating wind turbine is optimized from the perspective of mooring chain pre-tension,and the time-domain coupling analysis method is used to study the working condition of the floating wind turbine under rated working conditions and extreme working conditions.This paper first reviews the research status of coupling analysis of mooring system and floating wind turbine,introduces the calculation principle of various loads received by floating wind turbine in marine environment,and establishes the equation of motion of wind turbine in time domain.Then use the Genie module in Sesam software to build the wet surface model and free surface model of the 6MW floating wind turbine,and use the Hydrod module to calculate the hydrodynamic coefficient,the amplitude response operator,etc.Using software FAST simulates the full-coupling time-domain dynamic response of the floating wind turbine to explore its working stability and survivability.When the length of the mooring chain is constant,the extreme value of the surge motion response and the natural period of surge motion of the floating wind turbine will decrease;With the increase of the pre-tension,the standard deviation of the mooring chain tension response decreases first and then increases.By adjusting the pretension of the mooring chain,a mooring chain arrangement with optimal fatigue performance can be obtained.The numerical simulation results show that the coupling effect between surge and pitch is evident,and the coupling effect between t yaw,pitch and heave is also obvious.Yaw motion is mainly affected by the natural period of yaw motion and the wave load.The tension of the chain is affected by the low-frequency wind load and the wave load.,but the low frequency wind load has a stronger effect on the tension of the anchor chain than the wave load.The sway,pitch and heave motions under extreme conditions are mainly affected by wind loads.The mooring system with delta-line design can effectively avoid excessive yaw response The optimized mooring system ensures that the floating wind turbine has a good overall motion response and can guarantee the survivability of the floating wind turbine under extreme sea conditions.