Study on Dynamic Characteristics of Substructures for Development of Offshore Wind Turbine

由于日本没有太多适合海上风力涡轮机（OWT）的浅水区域，以及诸如海况变化幅度的经济缺点，因此有必要开发安全、经济且具有高抗疲劳性的子结构，即塔和海底基座。为此，我们进行了1）提出相应的土壤条件，水深，风和波浪条件下的适当的海底基础，2）明确的动态特性的OWT组成的叶片和机舱，一个支撑塔和海底基础受到波浪和风，和3）建立疲劳分析方法来评估OWT的耐久性。实际上，在2001年，我们进行了以下工作：1）对可能用于海上的水平和垂直轴风力涡轮机进行了调查; 2）对OWT进行了关于固定海底基础结构（如单桩、沉箱和导管架沿着浮动基础）应用的研究; 3）对于水平风力涡轮机，将其安装到B ...更多信息 对大功率的海洋平台进行了基于模态分析的时域动力结构分析程序的可行性研究，并结合脉动风、浪荷载的生成程序，说明了海底基础特性对海洋平台振动特性的影响。4）雨流等计算方法的调查2002年，我们还进行了如下工作：1）计算循环次数和应力范围的计算程序的开发; 2）应用于模拟应力历史与每年的波浪和风的组合发生，3）将分析得到的应力幅值与应力个数的关系拟合为一个双参数威布尔分布，并利用Miner准则对疲劳损伤进行评估。计数程序采用雨流计数法、极差对计数法和通常过零计数法。关于2），假设一台500 kW海上涡轮机设置在15 m水深处，进行了20年的脉动风浪载荷下的模态分析，然后进行应力时程分析，得到应力幅的累积数。最后，比较了各种计算方法的差异，并对威布尔分布方法在疲劳寿命估算中的适用性进行了评价。少

As there is not so many shallow water areas appropriate for offshore wind turbine (OWT) in Japan, as well as economical disadvantage such as the magnitude of variability of sea conditions, it is necessary to develop substructures i.e. tower and sub-sea base, which should be safe, economic and having high fatigue resistance. To do this, we conducted to 1) propose appropriate sub-sea base corresponding to the soil condition, water depth, and wind and wave conditions, 2) to make clear the dynamic characteristics of OWT consisted of blades and a nacelle, a supporting tower and sub-sea base subjected to wave and winds, and 3) to establish fatigue analysis methodology to evaluate the endurance of OWT. Actually in 2001, we carried out as follows,1) Survey of horizontal and vertical axis wind turbine possible to use in offshore,2) Study for OWT on application of fixed sub-sea base structures such as a mono-pile, a caisson and a jacket along with floating base3) For horizontal wind turbine to b … More e feasible for OWT with large Mega Watt capacity, time domain dynamic structural analysis program based of modal analysis together with the fluctuating wind and wave loadings generator routines, indicating the effect of the sub-sea base property to the vibration characteristics of OWT.4) Survey of counting method such as the rain flowIn 2002, we also conducted as follows,1) Development of counting program that calculates numbers of cycle and stress ranges,2) Application for simulated stress histories with annual combined occurrence of waves and winds,3) Fitting the analyzed relation of stress ranges and numbers to a two- parameter-Weibull distribution and evaluation fatigue damage by Miner rule.In detail, the counting program is based on three kinds of counting methods i.e. rain flow, range pair and ordinarily zero up cross. About 2), assuming that a 500kW offshore turbine set a water of 15m, we conducted the modal analyses against fluctuating wind and wave loadings during twenty years, then stress time histories were analyzed to get cumulative numbers of stress ranges. Finally, we compared the difference of counting methods, including evaluation of applicability of Weibull distribution method for fatigue life estimations. Less