转子-机舱组合体模型对海上风机结构特征频率和地震响应的影响

转子-机舱组合体(Rotor-Nacelle Assembly, RNA)又称风机机头，常用的简化模型包括点质量(RNA＿M)、偏心点质量(RNA＿ME)、偏心点质量-转动惯量(RNA＿MEJ)和刚性机舱-刚性叶片(RNA＿RB)。该文基于NREL5MW单桩式海上风机原型，使用Abaqus软件分别建立包含这四种RNA简化模型的风机模型，以刚性机舱-可变形叶片(RNA＿FB)风机模型为基准，分析不同的RNA简化模型对风机结构特征频率和地震响应的影响。研究结果表明：对于只涉及支撑结构1阶模态的问题，四种简化RNA模型计算的频率均是准确可靠的；当涉及支撑结构的2阶模态或/和扭转模态时，应采用RNA＿MEJ、RNA＿RB或RNA＿FB模型；当涉及支撑结构的更高阶模态时，应采用RNA＿FB模型。对于风机结构地震响应分析，RNA＿MEJ与RNA＿RB模型计算的结构响应更准确，但它们的大多数结构响应峰值的最大相对偏差均超过了10%，在实际工程应用时应慎重使用这些RNA简化模型。

EFFECTS OF ROTOR-NACELLE ASSEMBLY MODELS ON THE STRUCTURAL NATURAL FREQUENCIES AND SEISMIC RESPONSE OF OFFSHORE WIND TURBINE

For the Rotor-nacelle assembly (RNA), which is also known as the head of wind turbine (WT), the frequently used simplified models mainly include point mass (RNA_M), point mass with eccentricity (RNA_ME), point mass with eccentricity and rotational inertia (RNA_MEJ) and rigid nacelle with rigid blades (RNA_RB). Based on the prototype of the NREL 5MW offshore wind turbine (OWT) with monopile foundation, Abaqus is adopted to establish WT models with these four simplified RNA models. Taking the elaborated RNA_FB WT model as the baseline, this paper analyzes the influences of these different simplified RNA models on the natural frequency and seismic response of the WT structure. The results show that for the problems involving only the 1st order mode of the supporting structure, the calculated frequency values of the four simplified RNA models are all accurate and reliable; The RNA_MEJ, RNA_RB or RNA_FB model should be used when the 2nd order mode or/and torsion mode of the supporting structure is involved; The RNA_FB model should be used when higher-order modes of the supporting structure are involved. For the seismic response analysis of WT structure, the structural responses calculated by the RNA_MEJ and RNA_RB models are more accurate, but the maximum relative deviation (RD) of the majority of their structural response peaks still exceeds 10%. Therefore, the simplified RNA models should be used cautiously in engineering application.