Damage Identification of A TLP Floating Wind Turbine by Meta-Heuristic Algorithms

Damage identification of the offshore floating wind turbine by vibration/dynamic signals is one of the important and new research fields in the Structural Health Monitoring (SHM). In this paper a new damage identification method is proposed based on meta-heuristic algorithms using the dynamic response of the TLP (Tension-Leg Platform) floating wind turbine structure. The Genetic Algorithms (GA), Artificial Immune System (AIS), Particle Swarm Optimization (PSO), and Artificial Bee Colony (ABC) are chosen for minimizing the object function, defined properly for damage identification purpose. In addition to studying the capability of mentioned algorithms in correctly identifying the damage, the effect of the response type on the results of identification is studied. Also, the results of proposed damage identification are investigated with considering possible uncertainties of the structure. Finally, for evaluating the proposed method in real condition, a 1/100 scaled experimental setup of TLP Floating Wind Turbine (TLPFWT) is provided in a laboratory scale and the proposed damage identification method is applied to the scaled turbine.     

基于实密度的卧式浪流轮机水槽实验研究分析

实密度是影响轮机获能特性的关键因素之一。文中以卧式轮机实密度为基变量,以其获能系数为主要考察点,对3种实密度卧式轮机进行水槽实验方案设计和水动力性能研究。实验分别对水流流速、轮机旋转角速度、主轴转矩以及功率进行测量,并对其对主轴的扭矩、轮机的获能系数以及叶片的旋转特性进行定量分析,最终证实了该卧式轮机的单一运行特性。通过绘制基于实密度的轮机转矩—转角曲线、获能系数—尖速比曲线和轮机功率—尖速比曲线,阐明了实密度影响卧式轮机获能水动力性能的规律,即其获能系数和发电功率都随着工况速比呈先增后降趋势。实密度较低轮机因浪流流失而获得能量小,但实密度过高轮机会导致叶片间湍流涌动,加速叶片失速特性而影响轮机获能。这为卧式浪流轮机结构优化提供了可靠依据和借鉴。     

Undrained Bearing Capacity of Suction Caissons for Offshore Wind Turbine Foundations by Numerical Limit Analysis

Determining the ultimate capacity of suction caissons in response to combined vertical, horizontal, and moment loading is essential for their design as foundations for offshore wind turbines. However, the method implemented for stability analysis is quite limited. Numerical limit analysis has an advantage over traditional limit equilibrium methods and nonlinear finite element methods in this case because upper and lower bounds can be achieved to ensure that the exact ultimate capacity of the caisson falls within the appropriate range. This article presents theories related to numerical limit analysis. Simulations are conducted for centrifuge model tests, the findings of which reveal the ability of numerical limit analysis to deal with the inclined pullout capacity of suction caissons. Finally, this article proposes an estimation of the ultimate capacity of a 3.5 MW offshore wind turbine foundation on normally consolidated clay based on the typical environmental parameters of Bothkennar, Scotland. Undrained failure envelopes and safety factors are obtained for suction caissons with different embedment ratios. Failure mechanisms, plastic zones, clay stress distributions, and the influence of the skin friction coefficients of caissons are discussed in detail.     

风力发电机对黄河三角洲水体蒸发的影响研究

蒸发是湿地水循环的重要组成部分和水分损失的重要途径,风力发电对水体蒸发的影响干扰湿地生态系统的水热平衡。利用SEBAL模型,采用风力发电机建设前2004年、2005年、2009年的Landsat 5数据,风力发电机建成后2013年、2015年的Landsat 8数据,以及MODIS数据和气象数据,通过对比风力发电机建设前后以风机点为中心200m缓冲区范围内水体蒸发的变化,研究风力发电机对黄河三角洲湿地水体蒸发的影响。结果表明:①与建成前相比,风力发电机建成后风机周围各风向水体的蒸发在空间特征上趋于均匀;②与其他风向相比,风力发电机对下风向的影响更大,使下风向水体的蒸发值的均匀程度远大于上风向和旁风向。     

Numerical Simulation and Experimental Investigation on Performance of the Wells Turbine in Irregular Oscillating Flow

The Wells turbine is an axial-flow air-turbine designed to extract energy from ocean waves. An important consideration is the self-starting capability of the Wells turbine, a phenomenon encountered where the turbine accelerate by itself up to a certain speed for the best turbine performance. In order to clarify the self-starting characteristic and running performance of the Wells turbine in an irregular oscillating flow, a numerical simulation process is established in this paper on the rational assumption of quasi-steady flow conditions. Both self-starting characteristics and running performance are obtained through the numerical simulation and subsequently compared with the experimental data achieved on a computer-controlled oscillating flow test rig which could realize some irregular oscillating flow according to the specified spectrum. Results show that the self-starting time decreases with the increase of the significant wave height and the mean frequency of the irregular oscillating flow. Therefor     

长江口北支潮汐能源的综合利用

长江口北支有着丰富的潮汐能源及淡水，航运、水产等资源，因长期未加规划、治理，以致远未开发利用，反使河道淤浅，迳流减少，通航能力降低，且有大量泥沙，盐倒灌南支，恶化航道、水质，亟待整治、开发。研究提出，北支潮汐能可有效地用以发电和疏浚河道。可利用北支有利的河势，建造大、小双库开发方式的潮汐电站，并利用该河上、下游端间具有潮时差的有利因素，使电站可以连续不断发电、供电。同时可利用建造的上、中、下游三座水闸，逐级集水攻沙，冲刷航道淤沙，提高通航能力，实现江、海直接联运。另可兼收淡水供应，水产养殖、旅游，以及沟通崇明岛与苏北的陆上交通等效益，潮汐电站工程可采用现实可行的新技术、新材料、新的结构形式，以降低造价，使我国潮汐能得到充分开发利用。     

基于实测数据的海上风电结构动力响应分析

地震是危害海上风电结构作业安全的重要环境因素,目前,国内尚未公开发表真实地震响应下,海上风电结构的实测动力响应数据。分析了某地震活动区海上风电结构的实测地震响应,采用随机子空间识别方法进行风机的模态识别,阐述了风机机舱偏航将引起前后、左右两个正交方向振动的耦合,并从理论上证明了利用耦合、解耦数据识别模态参数的差异。结果表明：1）耦合与解耦信号识别的频率、阻尼比完全相同,而耦合信号识别的模态振型与偏航角有关;2）地震作用会对结构产生巨大冲击;3）非地震作用下,风机塔筒前后、左右第一阶弯曲模态为主要模态,地震作用可以激发风机的高阶模态,使得塔筒中上部而不是顶部的振动响应最大。此分析对地震活动区海上风电结构的抗震设计具有一定的参考价值。     

Experiment Study of Dynamics Response for Wind Turbine System of Floating Foundation

The floating foundation is designed to support a 1.5 MW wind turbine in 30 m water depth. With consideration of the viscous damping of foundation and heave plates, the amplitude-frequency response characteristics of the foundation are studied. By taking into account the elastic effect of blades and tower, the classic quasi-steady blade-element/momentum (BEM) theory is used to calculate the aerodynamic elastic loads. A coupled dynamic model of the turbine-foundation- mooring lines is established to calculate the motion response of floating foundation under Kaimal wind spectrum and regular wave by using the FAST codes. The model experiment is carried out to test damping characteristics and natural motion behaviors of the wind turbine system. The dynamics response is tested by considering only waves and the joint action of wind and waves. It is shown that the wind turbine system can avoid resonances under the action of wind and waves. In addition, the heave motion of the floating foundation is induced by waves and the surge motion is induced by wind. The action of wind and waves is of significance for pitch.     

小型风力发电机扇叶朝向控制系统

设计了一种基于单片机的小型风力发电机扇叶朝向控制系统,该系统由风向传感器模块、液晶显示模块、驱动模块和扇叶朝向控制装置组成.系统以MSP430F149单片机作为控制核心,利用风向传感器测量风向信息传输给单片机,单片机根据风向信息控制步进电机调节扇叶朝向来风方向,并且风向信息由LCD显示.该系统可以提高风力发电机的工作效率,具有一定的实用意义.     

浮式风机一体化模拟的计算参数设置影响研究

随着海上浮式风机的大型化发展,针对漂浮式风机的一体化耦合分析越来越重要。本文利用Simo-Riflex-Aerodyn 仿真工具建立OC4-Deepcwind 漂浮式风机一体化耦合模型,分析计算时间步长、初始截断时间、弹性结构单元离散数等计算参数对模拟结果的影响,包括浮式基础运动、系缆张力、叶片受力等。结果表明：当计算时间步长为0.005 s、0.01 s、0.02 s 时,浮式风机的响应结果差别较小,而计算消耗时间相差较大,0.01 s、0.02 s 的计算时间分别是0.005 s的70%、37%。相同工况下,不同参量响应达到稳定所需时间不同,纵荡需要的时间较长,最长达200 s;不同工况下,同一参量达到稳定所需时间也不相同,切出工况需要的时间最短,较额定工况快约60 s。结构单元离散数对塔柱受力影响较小,对叶片变形影响相对明显,当叶片离散数目减小时,响应值增大12%。实际中应根据具体工况选择合理的计算时间步长、初始截断时间和弹性结构单元离散数量。