考虑连接段厚度影响的风力机组合塔架优化设计*

钢-混组合塔架是低风速地区风力机支撑结构的主要型式之一,连接段对结构的性能有重要影响,组合塔架结构设计直接影响风力机的安全与建设成本。为改善塔架的结构性能以及降低塔架造价,构建了以各塔段外径、壁厚、连接段厚度和混凝土段高度等关键几何尺寸为设计变量,以塔架的固有频率、应力、位移和稳定性等关键性态指标为约束条件,以塔架成本为目标函数的优化设计数学模型。利用模型对某3 MW风力机组合塔架进行优化设计。结果表明：优化方案的塔架总成本减少了15.7%,塔架的整体结构性能得到一定改善;混凝土段高度为塔架总高度的62%时总成本最低;考虑连接段厚度的优化模型能有效调整连接段的受力性能,有利于提高塔架整体优化的效果。考虑组合塔架连接段厚度的优化设计可为同类塔架的设计提供参考。     

预应力砼-钢组合风电塔架穿筋连接段弹塑性分析

预应力砼-钢组合结构形式是发展大功率风机以及解决山区风场建设运输难题的必然选择,其预应力砼段与钢结构连接段的分析与设计是关键。文章提出一种新型的嵌入式开孔板和穿孔钢筋连接段结构方案,并以某高度为77.5 m的风电塔架为例,建立有限元模型,在预应力和最不利荷载组合设计值作用下进行了弹性及弹塑性结构分析,得到钢制连接件、砼、穿孔钢筋的应力分布和变形特点。结果表明:在法兰盘下部设置嵌入式钢筒和穿孔钢筋可以有效提高过渡段刚度,改善应力分布;当连接过渡段中砼榫发生塑性变形后,穿孔钢筋有效地发挥了传递剪力作用,并将上部荷载分散传递到下部砼塔筒中;从而验证所提方案的合理性。     

组合式风力发电塔架静力学有限元分析

为解决常规的锥型风力发电塔筒在大型风电机组中的制作、加工和施工运输成本大幅上升的问题,提出了新型组合式风力发电塔架结构以及在组合式塔架连接处采用过渡段连接的改进方案。分析了组合式塔架的静力学特点和最佳过渡段设计方案,并与常规锥台型塔筒的力学性能进行了对比。结果表明,组合式塔架在额定工况和暴风工况下均满足强度和刚度要求;过渡段最佳厚度为255mm、高度为25m,改进后的塔架提高了组合式塔架的力学性能;暴风工况下,改进后的组合式塔架塔顶位移比锥台型塔筒约小17%,且总体上组合式塔架的用钢量明显小于锥台型塔筒,具有良好的经济适用性能。     

海上风力机高桩承台基础反应特性研究

采用ANSYS建立由实体单元、壳单元、杆单元和管单元组成的海上风力机高桩承台混合模型。对极端工况下高桩混凝土承台进行有限元分析,得到承台混凝土和钢结构应力分布模型。通过对不同荷载组合下混凝土拉应力超限区域分布对比得到海上高桩承台基础结构在风力机荷载作用下的反应特性。结果表明:桩基础结构应力主要受波流荷载影响,塔筒过渡段结构应力主要受风力机荷载影响。高桩承台基础最易发生破坏结构为混凝土承台,在风力机荷载和波流荷载联合作用下,混凝土承台拉应力超限区主要分布在法兰盘受压区混凝土和钢管桩管壁处填芯混凝土。风力机上部结构产生的风力机荷载使高桩承台迎水面填芯混凝土处和与中心法兰盘接触处的混凝土拉应力超限;在波流荷载作用下,该超限区中高桩承台与风力机塔筒连接处和迎水面填芯混凝土处的拉应力超限区域减小。     

额定风速下装配式UHPC风电塔筒静力与疲劳性能

随着风电装备对超高高度风电塔筒需求的增长,装配式混凝土-钢混合塔筒正逐渐成为主要形式。超高性能混凝土（UHPC）因其优异的力学性能,是进一步改善高塔受力性能的有效途径。文章以轮毂高度为120m的UHPC装配式风电塔筒为对象,基于ABAQUS开展了额定风速下的H120型塔筒静力性能研究,分析获得了3种UHPC抗拉强度等级下沿该塔筒迎风面和背风面主要控制截面的应力水平。采用有限元软件FE.SAFE研究了塔筒的整体疲劳性能,分析了疲劳载荷下的塔架寿命、安全系数及疲劳失效概率,获得了考虑疲劳载荷后的塔架寿命和安全系数值,给出损伤局部分布特征,为H120型高性能塔筒结构方案分析与设计提供了依据。     

基于均匀设计的风力机塔架结构参数优化研究

针对大型水平轴风力机塔架结构优化过程中主要影响要素不显著问题,以塔架塔顶与机舱底座连接处为研究对象,采用均匀设计法对连接处2要素(厚度、高度)进行U*9(92)静强度试验设计并进行数值仿真模拟。研究结果表明:塔架最大变形值与最大应力值与连接处2要素(厚度、高度)呈线性与双曲抛物面函数关系,其中高度变化较厚度变化对塔架的应力值变化影响更大,优化塔顶结构参数后比原塔架最大应力值减小0.89%,最大位移值减少0.22%,质量降低0.24%,该研究为风力机塔架多目标结构优化设计提供理论依据。     

风电机组混合塔架结构阻尼比的研究

混合塔架作为风电机组广泛应用的一种高塔架形式,其结构模态阻尼比精度对塔架载荷和成本有着重要影响。基于以材料阻尼比作为输入求解风电机组混合塔架结构阻尼比的有限元分析方法,计算出140 m混合塔架第1阶模态阻尼比为0.96%。为验证该方法的正确性,通过测量阻尼性能差异较大的有机玻璃单件、钢板单件的材料阻尼比,以及有机玻璃与钢板组件的模态阻尼比,以测量的材料阻尼比作为输入开展了有机玻璃与钢板组件模态阻尼比的有限元分析。有限元求解与试验测试的1阶模态阻尼比结果分别为0.570%和0.589%,两者相差3.33%。结果表明,以材料阻尼比作为输入计算混合塔架模态阻尼比的有限元分析方法是正确的。     

海上风机塔架和单桩一体化试验设计方法

  目的  国内海上风电项目的业主在招主机标时,对风机厂商提供的基础顶载荷和塔架质量提出要求,在招设计标时很少对设计院提供的基础质量提出要求;详细设计阶段时风机厂商和设计院分别对塔架和基础进行设计,因此通常难以得到塔架和基础总质量最小的全局最优设计。  方法  提出了海上风机塔架和单桩一体化试验设计方法,通过对某海上风电项目进行试验设计得到多个不同塔架构型、塔底和单桩直径的设计方案,并通过载荷计算、塔架和单桩设计迭代优化得到相应的基础顶载荷、塔架质量和单桩质量等结果。  结果  研究表明:基础顶载荷或塔架质量最小的方案不是塔架和单桩总质量最小的方案。通过试验设计方法可以给出单桩和塔架总质量最小的最优设计。  结论  研究成果表明,在设计中采用一体化试验设计方法寻找塔架和单桩总质量最小的全局最优设计是降低海上风电度电成本的有效方法。业主将制定塔架和基础总造价最小的招标规则,要求采用一体化试验设计方案找到全局最优设计。     

海上风电机组塔架基础一体化设计

  [目的]  随着国家对于海上风电竞价上网指导意见的出台,降低开发成本的需求越来越迫切,急需通过技术创新降低成本。而海上塔架和基础的成本,显著影响着海上风电的平准化度电成本LCoE(Levelized Cost of Energy),直接决定着海上风电项目的竞争力。  [方法]  为了有效降低塔架基础的成本,文章提出了基于数字化云平台iDO(integrated Design Offshore)的一体化设计方法,对极端极限状态ULS工况下结构的静强度、疲劳极限状态FLS工况下结构的疲劳损伤进行了数值计算分析。为验证一体化设计方法在降低海上风电塔架基础成本的效果,文章针对两个实际工程项目,基于iDO云平台和传统分步迭代法SIA(Sequentially Iterated Approach)进行设计分析,对比ULS工况和FLS工况下的结构安全衡准指标。  [结果]  计算结果表明:ULS和FLS工况下,基于iDO云平台的一体化设计方法比SIA在结构强度、变形、疲劳损伤等指标有较大幅度下降,可显著优化塔架基础结构,降低结构重量,减小整个支撑结构成本,降低海上风电的LCoE。  [结论]  在实际海上风电工程项目应用中,基于iDO云平台的一体化设计方法可有效降低塔架基础结构成本,从而提高海上风电项目的竞争力,同时可对未来海上风电支撑结构优化设计提供借鉴。     

大型风电机组气动响应特性分析

针对大型风电机组柔性多体塔架-叶片耦合结构气动响应问题,文章提出了在不同偏航角度下的分析方法。根据该方法的流程图,建立了大型风电机组柔性多体塔架-叶片耦合结构动力学模型。采用谐波叠加法计算气动载荷分布,考虑塔影效应与风剪切的影响,得出诱导因子时程曲线与气动响应均值。计算结果表明:轴向与切向诱导因子变化较小,尾流稳定;偏航角逐渐增大导致塔顶顺风向位移均值减小,根方差值增大。该结果为大型风电机组运行过程中监测状态参数的变化与流体动力学分析提供了参考。     

钢-混凝土组合式风力发电塔架地震响应分析

钢-混凝土组合式风力发电塔架上部为钢塔筒,下部为混凝土塔筒,高度方向具有较大的质量和刚度突变,其在地震作用下的响应和传统单管式钢塔架显著不同.利用ABAQUS对同一风电场的2.0 MW单管式钢塔架和组合式塔架建立精细化模型,选取3种场地条件,采用振型分解反应谱法计算2种塔架的地震响应并进行对比.针对3种场地条件,选取相...     

Optimization of turbine design in wind farms with multiple hub heights,using exact analytic gradients and structural constraints

Wind farms are generally designed with turbines of all the same hub height. If wind farms were designed with turbines of different hub heights, wake interference between turbines could be reduced, lowering the cost of energy (COE). This paper demonstrates a method to optimize onshore wind farms with two different hub heights using exact, analytic gradients. Gradient‐based optimization with exact gradients scales well with large problems and is preferable in this application over gradient‐free methods. Our model consisted of the following: a version of the FLOw Redirection and Induction in Steady‐State wake model that accommodated three‐dimensional wakes and calculated annual energy production, a wind farm cost model, and a tower structural model, which provided constraints during optimization. Structural constraints were important to keep tower heights realistic and account for additional mass required from taller towers and higher wind speeds. We optimized several wind farms with tower height, diameter, and shell thickness as coupled design variables. Our results indicate that wind farms with small rotors, low wind shear, and closely spaced turbines can benefit from having two different hub heights. A nine‐by‐nine grid wind farm with 70‐meter rotor diameters and a wind shear exponent of 0.08 realized a 4.9% reduction in COE by using two different tower sizes. If the turbine spacing was reduced to 3 diameters, the reduction in COE decreased further to 11.2%. Allowing for more than two different turbine heights is only slightly more beneficial than two heights and is likely not worth the added complexity.     

Multidisciplinary design optimization of offshore wind turbines for minimum levelized cost of energy

This paper presents a method for multidisciplinary design optimization of offshore wind turbines at system level. The formulation and implementation that enable the integrated aerodynamic and structural design of the rotor and tower simultaneously are detailed. The objective function to be minimized is the levelized cost of energy. The model includes various design constraints: stresses, deflections, modal frequencies and fatigue limits along different stations of the blade and tower. The rotor design variables are: chord and twist distribution, blade length, rated rotational speed and structural thicknesses along the span. The tower design variables are: tower thickness and diameter distribution, as well as the tower height. For the other wind turbine components, a representative mass model is used to include their dynamic interactions in the system. To calculate the system costs, representative cost models of a wind turbine located in an offshore wind farm are used. To show the potential of the method and to verify its usefulness, the 5 MW NREL wind turbine is used as a case study. The result of the design optimization process shows 2.3% decrease in the levelized cost of energy for a representative Dutch site, while satisfying all the design constraints.     

Development of a modified stochastic subspace identification method for rapid structural assessment of in‐service utility‐scale wind turbine towers

The strong drive to harness wind energy has recently led to rapid growth of wind farm construction. Wind turbine towers with increased sizes and flexibility experience large vibrations. Structural health monitoring of wind turbines is proposed in the wind energy industry to ensure their proper performance and save maintenance costs. This study proposes a system identification method for vibration‐based structural assessment of wind turbine towers. This method developed based on the stochastic subspace identification method can identify modal parameters of structures in operating conditions with harmonic components in excitations. It benefits wind turbine tower structural health assessment because classical operational modal analysis methods can fail as periodic rotation excitation from a turbine introduces harmonic disturbance to tower structure response data. The effectiveness, accuracy and robustness of the proposed method were numerically investigated and verified through a lumped‐mass system model. The method was then applied to an in‐service utility‐scale wind turbine tower. The field testing campaign and modal parameter identification as well as structural assessment results were presented. Copyright © 2017 John Wiley & Sons, Ltd.     

Aeroservoelastic design definition of a 20 MW common research wind turbine model

Wind turbine upscaling is motivated by the fact that larger machines can achieve lower levelized cost of energy. However, there are several fundamental issues with the design of such turbines, and there is little public data available for large wind turbine studies. To address this need, we develop a 20 MW common research wind turbine design that is available to the public. Multidisciplinary design optimization is used to define the aeroservoelastic design of the rotor and tower subject to the following constraints: blade‐tower clearance, structural stresses, modal frequencies, tip‐speed and fatigue damage at several sections of the tower and blade. For the blade, the design variables include blade length, twist and chord distribution, structural thicknesses distribution and rotor speed at the rated. The tower design variables are the height, and the diameter distribution in the vertical direction. For the other components, mass models are employed to capture their dynamic interactions. The associated cost of these components is obtained by using cost models. The design objective is to minimize the levelized cost of energy. The results of this research show the feasibility of a 20 MW wind turbine and provide a model with the corresponding data for wind energy researchers to use in the investigation of different aspects of wind turbine design and upscaling. Copyright © 2016 John Wiley & Sons, Ltd.     

基于粒子群优化算法的风力机塔架结构优化设计

为了降低风力机塔架成本以及提高塔架的结构性能,编制粒子群优化算法程序,在算法程序中嵌入有限元方法,选取塔架壁厚、塔底直径及塔顶直径为设计变量,以强度、刚度、振动性能及稳定性为约束条件,建立了以质量最轻为目标函数的塔架优化数学模型,对某1.5 MW风力机塔架结构进行了优化设计。结果表明,优化后塔架的结构性能得到了改善,塔架变形对壁厚变化较为敏感,塔架质量减少了16.3%,说明了计算模型的有效性,可为同类塔架的设计提供参考。     

A new method for improved hub height mean wind speed estimates using short-term hub height data

The estimation of the wind resource at the hub height of a wind turbine is one of the primary goals of site assessment. Because the measurement heights of meteorological towers (met towers) are typically significantly lower than turbine hub heights, a shear model is generally needed to extrapolate the measured wind resource at the lower measurement height to the hub height of the turbine. This paper presents methods for improving the estimate of the hub height wind resource from met tower data through the use of ground-based remote sensing devices. The methods leverage the two major advantages of these devices: their portability and their ability to measure at the wind turbine hub height. Specifically, the methods rely on augmenting the one year of met tower measurements with short-term measurements from a ground-based remote sensing device. The results indicate that the methods presented are capable of producing substantial improvements in the accuracy and uncertainty of shear extrapolation predictions. The results suggest that the typical site assessment process can be reevaluated, and alternative strategies that utilize ground-based remote sensing devices can be incorporated to significantly improve the process.     

输电铁塔主材加固方法试验

设计时间较早的塔型没有考虑风压高度变化系数,最大设计风速偏低。对原有铁塔进行加固补强,提高其抵抗大风的能力,保证铁塔的安全运行迫不及待。通过试验对背靠背主材加固措施进行探讨,考虑连接板形式以及连接螺栓个数对加固后承载力的影响,在试验的基础上提出加固优化方案,为同类塔型的加固补强提供参考。     

风电机组高柔塔二阶涡激振动特性研究

针对现有风电机组涡激振动研究侧重于无顶部质量刚塔的一阶涡激振动,忽视有顶部质量高柔塔的二阶涡激振动的不足,开展高柔塔二阶涡激振动特性研究.首先,基于GH Bladed软件建立高柔塔风电机组模型,并通过模态分析得到高柔塔二阶固有频率及模态振型;然后,基于涡激振动相关标准,计算二阶涡激振动作用时各高度处的惯性力;最后,以某...