浮式风机动力系统的线性耦合动力学分析

Linear Coupled Dynamic Analysis of Floating Wind Turbines

浮式风机的前期开发需通过大量的方案比选确定结构基本形式和主尺寸参数,对动力学数值模拟效率提出了较高的要求。与时域非线性耦合模拟法相比,频域线性模拟法更适用于概念设计阶段。对此,文章提出了一种高效的线性耦合数值分析方法。采用了九自由度动力学模型描述浮体、塔筒以及叶轮的运动,对结构动力、气动力以及水动力问题进行线性化处理后,将动力学控制方程写成状态空间表达形式,进而推导出环境扰动-结构响应的传递函数,实现结构-控制系统在频域内的联动求解。为了验证模型的有效性,以时域非线性耦合软件Open FAST作为参考,对比了某半潜式风机在风浪联合工况下的运动响应。结果表明,线性模型的响应标准差相对误差大多在20%以内,而计算效率有大幅度提升,为概念设计阶段的结构选型及主尺寸优化设计提供了高效的分析工具。

In the early design stage of floating wind turbines(FWT),the substructure and main dimension parameters are determined based on a large number of design comparisons,which require high efficiency of dynamic numerical simulation.Compared with nonlinear coupling simulation in time domain,linear simulation in frequency domain is more suitable for conceptual design stage.An efficient linear coupled numerical analysis method is proposed.A nine-degree-of-freedom dynamic model is employed to describe the platform motion,tower top deflection and rotor rotation.The structural dynamics,aerodynamics and hydrodynamics are properly linear zed,based on which the equations of motion are written in the state space representation.Then the transfer function between dynamic response and environmental disturbance is derived.The responses of the FWT system are solved in frequency domain.To verify the linear model,the time-domain nonlinear coupling software Open FAST is used as a reference to compare the FWT response predicted by the linear model.The results show that the relative error of the response standard deviation of the linear model is mostly less than 20%,and the computational efficiency is greatly improved.This work provides an efficient simulation tool for substructure selection and optimization in the FWT conceptual design stage.