畸形波作用下张力腿浮式风力机动力响应特性

针对张力腿系泊浮式风力机的基础运动,忽略柔性构件的影响,建立气动—水动—系泊非线性耦合运动方程。在运动控制方程中包含张力腿系泊系统的非线性回复刚度,桨距角控制以及浮式基础运动对空气动力载荷的影响。在波浪载荷的计算中考虑二阶波浪载荷的作用。采用随机频率相位角调制法生成畸形波波面时历,计算在畸形波作用下张力腿型浮式风力机的动力响应特性。数值模拟结果表明,在畸形波作用下,浮式基础的运动及空气动力性能均受到了显著的影响。其中浮式基础的纵荡和纵摇运动分别受二阶差频与和频波浪力的影响,而垂荡运动的增加则主要是受下沉运动的影响。在畸形波经过的时刻,风力机的功率系数迅速下降,水平方向的风载荷波动先减小,随后其数值急剧下降,而垂直方向的风载荷波动增大。

Dynamic response characteristics of TLP type offshore floating wind turbine in freak wave

In this research, the offshore floating wind turbine moored by tension leg was studied. The motion of the floating structure in six degrees of freedom was solved considering the effect of the nonlinear restoring stiffness provided by the tension leg. The second-order wave force, pitch control system and the effect of floating structure motion on the aerodynamic force were all included to establish the aero-hydro-mooring coupled nonlinear control equations. The time series of freak wave was generated by the Random Frequency Components Selection Phase Modulation Method. The dynamic response characteristics of TLP type floating offshore wind turbine (FOWT) were obtained under the freak wave. The results show that the motions of floating structure and the aerodynamic force are obviously affected by the freak wave. The surge and pitch motion of the floating structure are mainly affected by second order difference-frequency and sum-frequency wave forces, respectively. And the heave motion is increased by the effect of set-down motion. At the moment when freak wave passes through the floating structure, the power coefficient of wind turbine decreases rapidly. The vibration amplitude of the horizontal wind load is reduced at first, and then it decreases sharply. However, the vibration amplitude of vertical wind load is increased.