考虑系缆拉伸-弯曲-扭转变形的浮式风力机动力响应研究

考虑系泊系统拉伸-弯曲-扭转变形产生的非线性系泊力，研究海上浮式风力机系统的动力响应。考虑系缆非线性几何变形，建立系泊系统拉伸-弯曲-扭转变形的动力学分析模型。建模过程中，采用了四元数方法进行局部坐标系与全局坐标系之间的旋转，避免了旋转过程中奇点的产生。综合考虑系缆非线性系泊力、水动力、空气动力及风力机结构系统，建立了系统动力学分析模型，开发了考虑系泊系统非线性系泊力的系统动力响应计算程序。针对OC3 Hywind Spar型5 MW浮式风力机，分析额定作业海况与极限海况下风力机系统的动力响应，并将结果与系泊系统采用准静态悬链线方法的模拟结果进行了对比。结果表明，考虑拉伸-弯曲-扭转变形效应后，系泊缆张力的波频响应被放大，同时还出现了多个高频峰值，将对系泊缆的疲劳寿命计算产生影响。

STUDY ON DYNAMIC RESPONSE OF FLOATING OFFSHORE WIND TURBINE BASED ON STRETCHING-BENDING-TORSION COUPLED NONLINEAR MOORING LOADS

Based on the nonlinear mooring loads induced by the deformations of mooring lines, including sketching, bending and torsion effects, the dynamic responses of floating offshore wind turbines (FOWTs) were analyzed. By considering the nonlinear geometric deformations, a stretching-bending-torsion coupled dynamic analysis model for a mooring system was proposed. Euler parameters were used for the transformation between the global and local coordinate systems to avoid the occurrence of singularity. The dynamic analysis model of the FOWT was established by considering the nonlinear mooring loads, hydrodynamics, aerodynamics as well as the mechanical system of a wind turbine. Based on this nonlinear formulation, a numerical program of the dynamic response of FOWT was developed. The OC3 Hywind Spar with a 5 MW baseline wind turbine was selected as a sample platform. The dynamic responses under both the operating and extreme sea states were simulated. The results were compared with those calculated based on the catenary theory. By considering the dynamic effect of mooring lines, the wave frequency response of tension is amplified, and several peaks in the range of high frequencies occur. Those responses will affect the fatigue life of mooring lines.