考虑冲刷的单桩式海上风力机动力响应研究

Research on Dynamic Response of Monopile Offshore Wind Turbines considering Scour

为了研究复杂海洋环境下桩周冲刷对海上风力机动力响应的影响,以美国可再生能源实验室5 MW海上风力机为研究对象,建立风力机塔架-单桩-土体有限元模型,计入风浪和地震荷载对冲刷情况下的单桩式海上风力机进行动力响应研究。对比分析不同冲刷深度以及冲刷坡角对风力机系统固有频率和动力响应的影响。研究表明:当冲刷深度增加到二倍桩径时,风力机一阶固有频率降低至转子1P频率附近,容易引起共振;在风浪荷载以及风浪、地震联合荷载作用下,冲刷坡角不变,风力机最大位移与弯矩随着冲刷深度增加而增大,疏松土质条件下的增量大于紧密土;保持冲刷深度不变,冲刷坡角的变化对风力机动力响应影响较小。

In order to study the impact of pile scour on the dynamic response of offshore wind turbines in complex marine environment,taking the 5 MW offshore wind turbine of the National Renewable Energy Laboratory(NREL)as an example,the finite element model of wind turbine tower⁃monopile⁃soil was established.Considering the wind wave and seismic load,the dynamic response of the monopile offshore wind turbine was investigated under scour conditions.The effects of different scour depth and scour slope angle on natural frequency and dynamic response of wind turbine system were analyzed comparatively.Research shows that as the scour depth increases to twice the pile diameter,the first⁃order natural frequency of the wind turbine decreases to the vicinity of the one⁃phase(1P)frequency of rotor,which is easy to cause resonance;under the action of wind wave load and combined wind wave and seismic load,the scour slope angle is unchanged,and the maximum displacement and bending moment of the wind turbine increase with the increase of scour depth,and the increment in loose soil is greater than that in dense soil;the change of scour slope angle has little effect on the dynamic response of wind turbine while the scour depth remains unchanged.