Offshore wind energy is one of the fastest growing powers in the field of renewable energy.An offshore wind farm situated sufficiently far away from the coast can generate more wind power and will have a longer operation life since the winds are stronger and more consistent than those on or near the coast.It can also avoid some major problems of the traditional wind farms like the visual and noise impacts and potential damage to wildlife.From the technical point of view,it is difficult to anchor the wind turbines directly on the seabed in deep water.Thus,new constructive solutions based on floating support structures are proposed.One of the main challenges is to reduce the fatigue of a floating offshore wind turbine so as to guarantee its proper functioning under the constraints imposed by the floating support structures subject to a greater range of motion than that of the fixed-bottom support structures.This paper analyzes the loads and dynamic response of floating support structures and addresses the problem of designing semiactive controllers to mitigate the dynamic wind and wave loads on floating wind turbines.The output feedback control strategy is proposed to avoid the dependence on the knowledge of the system states.The H∞ output feedback control technique is used for formulating the semiactive control law,which is implemented using a tuned liquid column damper (TLCD).Numerical simulation is done to verify the obtained results.%海上风能是可再生能源领域中增长最快的一种能源.与海岸边与近海处相比,远离海岸处的风更强、且更稳定,因此坐落在离海岸足够远处的海上风电场可以产生更多的风电、具有更长的运行寿命.它可以避免传统风电场的一些重大问题,比如视觉和嗓音影响、对野生动物的潜在伤害等；但从技术角度看,直接在海底固定风力涡轮机是比较困难的,为此,提出了一些基于浮动支撑结构的建设性解决方案.这些方案面临着一个重要挑战,即减少浮动海上风力发电机组的磨损、确保其在浮动支撑机构引起的各种状况下都能正常工作.与底端固定的支撑机构相比,浮动支撑机构的运动范围被扩大了很多.首先分析了浮动支撑结构的负荷和动态响应,并设计了半主动控制器来减弱浮动风力涡轮机上的动态风力和波浪负载;然后提出采用输出反馈控制策略,避免了对系统状态的依赖.用H∞输出反馈控制技术来设计半主动控制算法,并运用一个调谐液柱阴尼器(TLCD)实现了该算法.通过数值模拟,对所获得的结果进行了验证.
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