随着半潜式风机大型化，其下部支撑平台尺寸也随之增大，刚度降低，不能再将其视为刚体，需考虑平台刚度变化对风机动态响应的影响。选取OC4-DeepCwind半潜式风机为研究对象，将平台按中心柱与侧柱划分为4个刚体，采用梁单元建立平台结构有限元模型。基于势流理论计算平台结构有限元模型中每个刚体的水动力载荷传递函数，将其导入OpenFAST中进行风机整体时域耦合分析。通过改变梁单元的刚度研究平台刚度变化对风机动态响应的影响。研究结果表明：平台固有周期随刚度增大略微增大；平台纵摇运动及塔架底部弯矩随刚度降低出现高频响应；平台沿纵荡和垂荡方向的内力受刚度影响明显，降低平台刚度将出现高频载荷响应。

英文摘要:

As semi-submersible wind turbines increase in size, the dimensions of their lower support platforms also expand, leading to a reduction in stiffness. Consequently, the platform can no longer be regarded as a rigid body, and the impact of platform stiffness variations on the dynamic response of the wind turbine must be considered. This study examines the OC4-DeepCwind semi-submersible wind turbine, dividing the platform into four rigid bodies according to the central column and side columns. A finite element model of the platform structure is established using beam elements. Based on potential flow theory, the hydrodynamic load transfer functions of each rigid body in the finite element model are computed and incorporated into OpenFAST for full-system time-domain coupled analysis. The influence of platform stiffness variations on the dynamic response of the wind turbine is investigated by adjusting the stiffness of the beam elements. The results indicate that the natural period of the platform slightly increases with increasing stiffness. As stiffness decreases, high-frequency responses appear in the pitch motion of the platform and the bending moment at the tower base. Internal forces in the surge and heave directions are significantly affected by platform stiffness, with lower platform stiffness leading to high-frequency load responses.

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