Preliminary Design And Performance Study Of Floating Offshore Wind Turbine With Truss Structure

With the rapid development of offshore wind power industry,wind energy has gradually become a popular,economical and clean energy.In the field of deep-sea offshore wind energy development,offshore floating wind turbines are a frontier scientific issue that scholars in various countries have paid attention to.The research in this paper is of great significance for the development of new floating infrastructure and improving the efficiency of wind energy utilization.This paper first analyzes the development of floating fans,and gives the design of floating fans in this paper,and then introduces the calculation theory of the environmental load of offshore floating fans.In the hydrodynamic analysis,the hydrodynamic coefficient of the floating foundation is first analyzed,and then the hydrodynamic characteristics of the floating foundation in the frequency and time domains are studied,and then the floating wind turbine under the coupling of aerodynamic and hydrodynamic forces is studied.The motion response was analyzed,and the heave motion of the floating wind turbine foundation under different wind and wave conditions under viscous flow was analyzed.Finally,the appropriate wave load was selected according to the CCS specifications,and the overall strength of the floating wind turbine foundation was analyzed,and The stress concentration factors of key nodes are calculated.The main conclusions of this article are as follows:1.Through hydrodynamic analysis,it was found that the additional mass curves of the floating foundation,sway,yaw,and yaw first increased and then decreased,and the radiated damping of the yawing was the largest.Different incident angles have no effect on the heave of the floating foundation.The motion response value of the floating foundation at different water depths does not change much,and it has good water depth adaptability near the design water depth.2.Through the short-term forecast spectrum analysis method in the frequency domain of hydrodynamic analysis,it is found that the natural periods of movement in the six degrees of freedom directions are far away from the incident wave's own period,which can effectively avoid the frequency range of wave energy concentration,indicating the floating foundation has good hydrodynamic performance.3.By comparing the time-domain motion response analysis of the floating wind turbine with the time-domain motion response analysis of the floating foundation,the sag value calculated by FAST is less than the time domain value calculated by AQWA.At the same time,in terms of pitch angle,the FAST pitch response value is correspondingly smaller than the AQWA pitch response value.4.In the viscous flow hydrodynamic analysis,it is found that the VOF model can better reflect the influence of the nonlinear wave interaction including the viscous effect on the motion of the floating platform,and can effectively simulate the motion of the offshore floating fan under the waves.5.The overall strength of the floating foundation was checked according to CCS's “Guidelines for Dynamic Evaluation and Emergency Response Service of Structure Status of Offshore Mobile Platforms”,and it was concluded that the connection between the heave plate and the truss is a high-stress area,but the overall structure conforms to the yield strength.