【作者】 柴子元；

【导师】 朱才朝；

【作者基本信息】 重庆大学 ， 工程（机械工程）（专业学位）， 2021， 硕士

【摘要】 发展可再生能源是实现“双碳”目标和解决生态环境问题的根本途径,是加快我国能源转型的重大发展战略。风能作为最重要的可再生能源之一,是实现低碳发展的重要途径,我国风能储量约10亿k W,居世界首位,其中海上风能资源储量达7.58亿k W,开发潜力巨大。深远海风能资源丰富,风速稳定且对沿海环境影响较小,是当前海上风电发展的主流趋势之一。海上浮式风电机组是目前最有效地开发深远海风能资源的海洋工程装备。然而,在25年全寿命周期内,浮式风电机组的漂浮式结构设计会使其在风浪联合作用下产生复杂的动态响应,容易加剧塔筒和系泊锚链等关键结构的疲劳损伤,影响整机寿命。本文以某型5 MW海上浮式风电机组为研究对象,根据国内某海域的风浪实测数据,考虑了风浪环境变量的相依性结构,推导了随机风浪的Copula联合概率分布函数,建立了浮式风电机组系统动力学模型,基于最长相异性距离算法和径向基函数插值法开展了浮式风电机组长期动态响应重构方法研究,基于环境等值线法研究了浮式风电机组极限载荷,分析了风浪联合作用下浮式风电机组短期和长期疲劳损伤。研究结果对评估浮式风电机组动态服役性能和提高浮式风电机组设计优化能力具有重要意义。论文的主要研究内容如下:(1)基于国内某海域的数值后报风浪联合分布统计,采用威布尔分布、伽马分布和对数正态分布三种常用的参数分布构造了风浪的边缘分布函数,以Copula理论为载体建立了风浪联合概率密度分布模型,探究了平均风速、有义波高和谱峰周期的相关性,分析了风浪的随机分布特征。(2)考虑了气动力学模型、水动力学模型、系泊系统和控制系统等子系统间的非线性耦合因素,建立了浮式风电机组系统动力学模型,研究了基于最长相异性距离算法的代表性海况选取方法,并结合浮式风电机组系统动力学模型,利用径向基函数插值法重构了浮式风电机组的动态响应统计特征。(3)结合风浪联合概率分布特征,并考虑超越概率因素,基于逆一次可靠度法和逆二次可靠度法的环境等值线法研究了基于Gumbel极值分布的浮式风电机组长期极限载荷计算方法,分析了不同关键环境工况下浮式风电机组极限载荷变化规律,实现了对浮式风电机组50年重现周期的极限载荷预测。(4)在风浪联合作用下,研究了浮式风电机组塔顶、塔基和系泊锚链等结构的疲劳损伤计算方法,分析了风浪联合作用下浮式风电机组结构的短期和长期疲劳损伤,探究了风浪载荷和风浪夹角等因素对浮式风电机组结构疲劳损伤的影响规律。更多还原

【Abstract】 The development of renewable energy is not only a fundamental way to achieve the ‘dual carbon’ goal and solve ecological environment problems,but also a major development strategy for accelerating our country’s energy transition.As one of the most important renewable energy,wind energy is a significant way to achieve low-carbon development.China’s wind energy resources reserves are about 1 billion k W,ranking first in the world,among which offshore wind energy reserves reach 758 million k W,showing huge development potential.Deep sea wind power is one of the mainstream trends in the development of offshore wind power,which is rich in deep sea wind energy resources,stable wind speed and little impact on coastal environment.Floating wind turbine is currently the most effective offshore engineering equipment for developing deep sea wind energy resources.However,in the whole life cycle of 25 years,the floating structure design of floating wind turbine will make it produce complex dynamic response under the combined action of wind and wave,which will easily aggravate the fatigue damage of key structures such as tower and mooring lines,and affect the life of the whole floating wind turbine.In this paper,a 5 MW floating wind turbine is taken as the research object.Based on the measured data of wind and waves in a domestic sea area,considering the dependence structure of wind and wave,the Copula joint probability distribution function of random wind and wave is deduced,and the dynamic model of the floating wind turbine system is established.Based on the maximum dissimilarity algorithm and the radial basis function interpolation method,the long-term dynamic response reconstruction method of the floating wind turbine is carried out.The extreme loads of the floating wind turbine based on the environmental contour method are studied.The short-term fatigue damage and long-term fatigue damage of the floating wind turbine under the combined action of wind and wave are analyzed.The research results are of great significance for evaluating the dynamic service performance of floating wind turbine and improving the design optimization capabilities of floating wind turbine.The main research contents of the thesis are as follows:(1)Based on the joint distribution statistics of wind and wave in a domestic sea area,the marginal distribution functions of wind and wave are constructed by using the three commonly used parameter distributions of Weibull distribution,Gamma distribution and Lognormal distribution.The joint probability density distribution model of wind and wave is established using Copula theory as the carrier,and the correlation between the mean wind speed,the significant wave height and the spectral peak period is explored.Finally,random distribution characteristics of wind and wave are analyzed.(2)Considering the nonlinear coupling factors among subsystems such as aerodynamic model,hydrodynamic model,mooring system and control system,the dynamic model of the floating wind turbine system is established.The selection method of representative sea states based on the maximum dissimilarity algorithm is studied.Combined with the dynamic model of the floating wind turbine system,the radial basis function interpolation method is used to reconstruct the statistical characteristics of dynamic response of floating wind turbine.(3)Combined with the characteristics of the joint probability distribution of wind and wave,as well as considering the exceedance probability,the environmental contour methods based on the inverse first reliability method and the inverse second reliability method are proposed,and the calculation method of long-term extreme load of floating wind turbine based on Gumbel extreme value distribution is studied.The variation law of extreme load of floating wind turbine under different key environmental conditions is analyzed,and the extreme load prediction of 50-year return period of floating wind turbine is realized.(4)Under the combined wind-wave action,the fatigue damage calculation methods of floating wind turbine tower top,tower base and mooring lines are studied.The short-term fatigue damage and long-term fatigue damage of floating wind turbine under the combined wind-wave action are analyzed,and the influences of wind-wave loads and wind-wave misalignment on the fatigue damage of floating wind turbine are discussed.更多还原