Active tuned mass damper for damping of offshore wind turbine vibrations

An active tuned mass damper (ATMD) is employed for damping of tower vibrations of fixed offshore wind turbines, where the additional actuator force is controlled using feedback from the tower displacement and the relative velocity of the damper mass. An optimum tuning procedure equivalent to the tuning procedure of the passive tuned mass damper combined with a simple procedure for minimizing the control force is employed for determination of optimum damper parameters and feedback gain values. By time domain simulations conducted in an aeroelastic code, it is demonstrated that the ATMD can be used to further reduce the structural response of the wind turbine compared with the passive tuned mass damper and this without an increase in damper mass. A limiting factor of the design of the ATMD is the displacement of the damper mass, which for the ATMD, increases to compensate for the reduction in mass. Copyright © 2016 John Wiley & Sons, Ltd.     

基于粘滞阻尼器的单桩式海上风力机结构振动控制

为探究湍流风与地震联合作用下单桩式海上风力机的结构动力学响应与振动控制,以单桩式NREL5 MW海上风力机为研究对象,采用有限元法建立三维壳模型并基于二次开发将体等效线性模型集成于ABAQUS中,通过附加粘滞阻尼器对地震诱导风力机振动进行控制.结果表明:粘滞阻尼器能够大幅降低地震导致的风力机塔顶振动,但对湍流风引起的塔...     

Damping of edgewise vibration in wind turbine blades by means of circular liquid dampers

This paper proposes a new type of passive vibration control damper for controlling edgewise vibrations of wind turbine blades. The damper is a variant of the liquid column damper and is termed as a circular liquid column damper (CLCD). Rotating wind turbine blades generally experience a large centrifugal acceleration. This centrifugal acceleration makes the use of this kind of oscillatory liquid damper feasible with a small mass ratio to effectively suppress edgewise vibrations. A reduced 2‐DOF non‐linear model is used for tuning the CLCD attached to a rotating wind turbine blade, ignoring the coupling between the blade and the tower. The performance of the damper is evaluated under various rotational speeds of the rotor. A special case in which the rotational speed is so small that the gravity dominates the motion of the liquid is also investigated. Further, the legitimacy of the decoupled optimization is verified by incorporating the optimized damper into a more sophisticated 13‐DOF aeroelastic wind turbine model with due consideration to the coupled blade‐tower‐drivetrain vibrations of the wind turbine as well as a pitch controller. The numerical results from the illustrations on a 5 and a 10MW wind turbine machine indicate that the CLCD at an optimal tuning can effectively suppress the dynamic response of wind turbine blades. Copyright © 2015 John Wiley & Sons, Ltd.     

基于SMA阻尼器控制的鼓型塔风振响应分析

以某220kV输电线路的风致振动为例,研究了基于SMA阻尼器的鼓型塔振动控制方案和控制效果。先应用有限元软件ANSYS建立鼓型塔的有限元模型,采用线性自回归滤波器法模拟随机脉动风荷载的时程样本,再应用能量法计算所需阻尼器数量,根据SMA阻尼器的工作原理和鼓型塔的结构特点,设计了3种阻尼器布置方案进行结构风致振动瞬态响应仿真,提取各方案控制点位移、加速度时间历程进行比较分析。结果表明,安装SMA阻尼器后,对塔顶位移、加速度的最大减振率分别为37.8%、75.4%,方案3为最优布置方案,可见将SMA阻尼器应用于输电塔振动控制效果较好,合理设计阻尼器布置方案能使阻尼器发挥最大耗能功能,获得最好控制效果。     

Comparison of the performance and stability of two torsional vibration dampers for variable‐speed wind turbines

Alleviation of excess fatigue loads due to vibrations in the drive‐train of wind turbines can be achieved through the use of torsional vibration dampers. Two torsional dampers based on different design approaches were designed and assessed: the first employs a conventional band‐pass filter technique, whereas the second involves an alternative model‐based approach. Frequency domain analyses were carried out on the system with the two dampers for the cases with and without model uncertainty. The system using the band‐pass filter‐based damper showed deterioration in stability and performance when subjected to uncertainty in the model and had to be re‐tuned to recover a good damping performance. Conversely, the system employing the model‐based damper maintained good stability and superior damping performance in the presence of model uncertainties. These attributes can ensure that the damper exhibits a good performance even if the wind turbine parameters vary during operation, such as when ice forms on the blades. Time domain simulations were carried out to verify the frequency domain analyses. © 2014 The Authors. Wind Energy published by John Wiley & Sons, Ltd.     

A new multibody modelling methodology for wind turbine structures using a cardanic joint beam element

This paper presents a new multibody modelling methodology for wind turbine structures. The methodology is based on the hybrid multibody system being composed of rigid, flexible bodies, force elements and joints. With a cardanic joint beam element based on the Timoshenko beam theory, the flexible bodies, e.g. rotor blades and tower, shafts, are modelled by a set of rigid bodies connected by cardanic joints geometrically and constrained by spring forces elastically, thus a whole wind turbine structure can be represented by a discrete system of rigid bodies, springs, and dampers. Using some concepts of the differential geometry, the Lagrange's motion equations of the multibody system are represented in explicit form. With this model, the global natural vibrations of a wind turbine structure of 600 kW are analysed.     

基于TMD的风力机塔筒振动控制研究

针对风力机塔筒在风振效应下振动过大的问题,该文基于调谐质量阻尼器(TMD)开展对风力机塔筒的减振控制研究。以某大型2 MW风力机塔筒为研究对象,基于ANSYS建立柔性的风力机塔筒有限元模型,并基于Kaimal谱和模态脉动曳力功率谱模拟得到脉动风速时程和风载时程曲线。为取得较好的TMD减振控制效果,根据Den Hartog法得到TMD的最优频率比和阻尼比。为分析TMD对塔筒结构强度的影响及其TMD的振动控制效果,对风力机塔筒进行静力学和风载作用下的动力响应仿真分析。研究结果表明:TMD对塔筒的静强度影响较小,相比于将TMD放置于塔筒内部,将TMD放置于塔顶机舱内能更有效地减小塔筒在风振效应下的位移峰值、标准偏差以及瞬态应力峰值,其抑制率分别达到63.51%、63.38%和59.74%。     

Passive control of wind turbine vibrations including blade/tower interaction and rotationally sampled turbulence

This paper investigates the use of a passive control device, namely, a tuned mass damper (TMD), for the mitigation of vibrations due to the along‐wind forced vibration response of a simplified wind turbine. The wind turbine assembly consists of three rotating uniform rotor blades connected to the top of a flexible uniform annular tower, constituting a multi‐body dynamic system. First, the free vibration properties of the tower and rotating blades are each obtained separately using a discrete parameter approach, with those of the tower including the presence of a rigid mass at the top, representing the nacelle, and those of the blade including the effects of centrifugal stiffening due to blade rotation and self‐weight. Drag‐based loading is assumed to act on the rotating blades, in which the phenomenon of rotationally sampled wind turbulence is included. Blade response time histories are obtained using the mode acceleration method, allowing base shear forces due to flapping motion for the three blades to be calculated. The resultant base shear is imparted into the top of the tower. Wind drag loading on the tower is also considered, and includes Davenport‐type spatial coherence information. The tower/nacelle is then coupled with the rotating blades by combining their equations of motion. A TMD is placed at the top of the tower, and when added to the formulation, a Fourier transform approach allows for the solution of the displacement at the top of the tower under compatibility of response conditions. An inverse Fourier transform of this frequency domain response yields the response time history of the coupled blades/tower/damper system. A numerical example is included to qualitatively investigate the influence of the damper. Copyright © 2007 John Wiley & Sons, Ltd.     

Modeling aspects of a floating wind turbine for coupled wave–wind-induced dynamic analyses

This paper deals with the numerical modeling of a catenary moored spar-type wind turbine in the integrated coupled analyses. The current spar-type wind turbine is inspired by the Hywind concept. In this paper, different hydrodynamic models based on the Morison formula, Pressure integration method and Panel method considering the mean drift, first and second order forces are studied. A floating wind turbine in deep water depth supporting a 5-MW turbine system is considered. Simo-Riflex (DeepC), HAWC2 and FAST codes are used to carry out the coupled wave–wind-induced analyses. The results show that the damping and inertia forces of the mooring lines are important for the tension responses; especially, the damping of the mooring lines can help to damp-out the high-frequency elastic-deformations of the mooring system. However, the motion responses are not significantly affected by the mooring line damping-effects. The drift and second order forces do not significantly affect the motion and tension responses. However, the heave motion is more affected by the drift and second order forces. The results indicate that either the Morison formula considering the instantaneous position of the structure or first order hydrodynamic forces based on the Panel method and considering the quadratic viscous forces can provide accurate results for the slender spar-type wind turbines. Considering the second order forces is found to be 10–15 times more time consuming while the responses are not significantly affected for the present floating wind turbine. The coupled aero-hydro-servo-elastic code-to-code comparison of HAWC2 and FAST codes shows that the dynamic motion responses, structural responses at the tower–spar interface and at the blade root as well as the power production are in good agreement.     

Real‐time hybrid aeroelastic simulation of wind turbines with various types of full‐scale tuned liquid dampers

The present paper presents the real‐time hybrid simulation (RTHS) technique for multimegawatt wind turbine (WT) with various types of full‐scale tuned liquid dampers (TLDs). As an evolvement of the pseudodynamic testing technique, the RTHS is executed in real time, thus allowing accurate investigation of the interaction between the aeroelastic WT system and the rate‐dependent nonlinear TLD device. As the numerical substructure, the WT is simulated in the computer using a 13‐degree‐of‐freedom (13‐DOF) aeroelastic model. As the physical substructure, the full‐scale TLDs are manufactured and physically tested. They are synchronized with each other by real‐time controllers. Taking advantage of RTHS technique, 2‐ and 3‐MW WTs have both been simulated under various turbulent wind conditions. TLDs with different configurations have been extensively investigated, eg, various tuning ratios by varying the water level, TLD without and with damping screens (various mesh sizes of the screen considered), and TLD with flat and sloped bottoms. It is shown that a well‐designed TLD is very effective in damping lateral tower vibrations of WTs. Furthermore, RTHS results and results from a proposed theoretical model are compared. This study gives comprehensive guidelines for employing various types of TLDs in large WTs and indicates huge potentials of applying RTHS technique in the area of wind energy.     

考虑黏性效应的半潜浮式风力机动力特性研究

对半潜浮式风力机动力特性进行研究，推导考虑黏性阻尼的动力学方程及传递函数。对黏性效应的影响及其计算方法进行探讨，对比附加阻尼矩阵法、Morison单元法的优缺点，并提出考虑黏性阻尼效应水动力计算的混合法，在此基础上对半潜浮式风力机气动-水动-锚泊全耦合动力响应进行分析。结果表明：黏性效应主要影响共振周期附近的响应值，在数值分析时不可忽略；附加阻尼矩阵法在考虑水平面内运动黏性阻尼时有所不足，且无法考虑黏性效应对共振周期的影响，Morison单元法在考虑垂荡、转动黏性阻尼时有所不足，混合法是考虑黏性阻尼水动力计算的更有效方法；该半潜浮式风力机垂荡和纵摇响应主要受波浪控制，而水平面内运动受风、浪、流联合作用的影响；浮式风力机运动和加速度的最危险工况可发生在发电工况时，最大锚链张力发生在极端环境条件时。     

Adaptive tower damping control for offshore wind turbines

This paper deals with the problem of wind turbine tower damping control design and implementation in situations where the support structure parameters vary from their nominal design values. Such situations can, in practice, occur for onshore and especially offshore wind turbines and are attributed to aging, turbine installation, scour or marine sand dunes phenomena and biofouling. Practical experience of wind turbine manufacturing industry has shown that such effects are most easily quantified in terms of the first natural frequency of the turbine support structure. The paper brings forward a study regarding the amount to which nominal tower damping controller performance is affected by changes in the turbine natural frequency. Subsequently, an adaptive tower damping control loop is designed using linear parameter‐varying control synthesis; the proposed tower damping controller depends on this varying parameter which is assumed throughout the study to be readily available. An investigation of the fatigue load reduction performance in comparison with the original tower damping control approach is given for a generic three‐bladed horizontal‐axis wind turbine. Copyright © 2016 John Wiley & Sons, Ltd.     

An investigation on the impacts of passive and semiactive structural control on a fixed bottom and a floating offshore wind turbine

The application of structural control to offshore wind turbines (OWTs) using tuned mass dampers (TMDs) has shown to be effective in reducing the system loads. The parameters of a magnetorheological (MR) damper modeled by the Bouc‐Wen model are modified to utilize it as a damping device of the TMD. Rather than showcasing the intricate design policy, this research focuses on the availability of the MR damper model on TMDs and its significance on structural control. The impact of passive and semiactive (S‐A) TMDs applied to both fixed bottom and floating OWTs is evaluated under the fatigue limit state (FLS) and the ultimate limit state (ULS). Different S‐A control logics based on the ground hook (GH) control policy are implemented, and the frequency response of each algorithm is investigated. It is shown that the performance of each algorithm varies according to the load conditions such as a normal operation and an extreme case. Fully coupled time domain simulations are conducted through a newly developed simulation tool, integrated into FASTv8. Compared with the passive TMD, it is shown that the S‐A TMD results in higher load reductions with smaller strokes under both the FLS and the ULS conditions. The S‐A TMD using displacement‐based GH control is capable of reducing the fore‐aft and side‐to‐side damage equivalent loads for the monopile by approximately 12% and 64%, respectively. The ultimate loadings at the tower base for the floating substructure are reduced by 9% with the S‐A TMD followed by inverse velocity‐based GH control (IVB‐GH).     

单桩海上风力机风致振动变阻尼控制研究

风致振动是大型风力机发生破坏性事故的主要原因.为探究半主动控制在近海单桩风力机风致振动控制中的应用效果,基于ABAQUS有限元软件二次开发了风力机半主动控制模块,以单桩式NREL5 MW海上风力机为研究对象,通过磁流变阻尼器对Bang-Bang控制、改进Bang-Bang控制及Lyapunov控制3种半主动控制算法在单...     

考虑时变气动阻尼的风电机组塔筒地震响应分析

为了分析时变气动阻尼对风电机组塔筒地震响应的影响,首先分析了塔筒所承受的地震载荷和气动载荷,然后基于气动载荷和相对风速之间的导数关系推导了塔筒前后和左右方向上的时变气动阻尼计算方法,将地震加速度和时变气动阻尼引入到塔筒动力学运动方程中并进行时域求解,以某2.0MW风电机组塔筒为例进行地震响应计算,分析了影响气动阻尼大小的翼型气动特性,并着重研究了地震作用下时变气动阻尼对塔顶振动位移的影响程度,为风电机组塔筒抗震设计提供一定参考。     

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...     

An investigation on wind turbine resonant vibrations

Wind turbine resonant vibrations are investigated based on aeroelastic simulations both in frequency and time domain. The investigation focuses on three different aspects: the need of a precise modeling when a wind turbine is operating close to resonant conditions; the importance of estimating wind turbine loads also at low turbulence intensity wind conditions to identify the presence of resonances; and the wind turbine response because of external excitations. In the first analysis, three different wind turbine models are analysed with respect to the frequency and damping of the aeroelastic modes. Fatigue loads on the same models are then investigated with two different turbulence intensities to analyse the wind turbine response. In the second analysis, a wind turbine model is excited with an external force. This analysis helps in identifying the modes that might be excited, and therefore, the frequencies at which minimal excitation should be present during operations. The study shows that significant edgewise blade vibrations can occur on modern wind turbines even if the aeroelastic damping of the edgewise modes is positive. When operating close to resonant conditions, small differences in the modeling can have a large influence on the vibration level. The edgewise vibrations are less visible in high turbulent conditions. Using simulations with low‐level turbulence intensity will ease this identification and could avoid a redesign. Furthermore, depending on the external excitation, different aeroelastic modes can be excited. The investigation is performed using aeroelastic models corresponding to a 1.5 MW class wind turbine with slight variations in blade properties. Copyright © 2015 John Wiley & Sons, Ltd.     

Passive structural control of offshore wind turbines

The application of control techniques to offshore wind turbines has the potential to significantly improve the structural response of these systems. A new simulation tool is developed that can be utilized to model passive, semi‐active and active structural control systems in wind turbines. Two independent, single degree of freedom (DOF) tuned mass‐ damper (TMD) devices are incorporated into a modified version of the aero‐elastic code FAST (Fatigue, Aerodynamics, Structures and Turbulence). The TMDs are located in the nacelle of the turbine model, with one TMD translating in the fore‐aft direction, and the other in the side‐side direction. The equations of motion of the TMDs are incorporated into the source code of FAST, yielding a more realistic system for modeling structural control in wind turbines than has previously been modeled. The stiffness, damping and commanded force of each TMD are controllable through the FAST‐Simulink interface, and so idealizations of semi‐active and active control approaches can be implemented. A parametric study is performed to determine the optimal parameters of a passive single DOF, fore‐aft, TMD system in both a barge‐type and monopile support structure. The wind turbine models equipped with TMDs are then simulated and the performance of these new systems is evaluated. The results indicate that passive control approaches can be used to improve the structural response of offshore wind turbines. The results also demonstrate the potential for active control approaches. Copyright © 2010 John Wiley & Sons, Ltd.     

风电机组变速与变桨距控制过程中的动力学问题研究

讨论了额定风速以下的变速运行控制和额定风速以上的变桨距控制以及变速与变桨距两种控制策略的相互耦合关系;分析了风电机组主要部件包括叶轮、传动系统、塔架的各阶振动模态以及它们之间的相互影响力;提出了转矩控制对传动系统扭转振动和变桨距控制对塔架前后振动的影响力及控制方案;应用BLADED和MAT- LAB软件对主要控制环节进行设计及参数调整,并对机组的控制效果进行仿真。结果表明,所采用的控制策略和控制算法能够满足控制要求,并能有效地解决动力学问题。     

基于TMD的海上漂浮式风力机稳定性研究

海上漂浮式风力机的稳定性研究已逐渐成为风电研究的重点与热点。以NREL(国家可再生能源实验室)5 MW风力机及ITI Barge平台为研究对象,建立海上漂浮式风力机整机模型,通过配置TMD(调谐质量阻尼器),研究其对环境载荷作用下的海上漂浮式风力机稳定性的控制效果。结果表明:TMD对漂浮式风力机塔架和平台的运动响应有明显的抑制效果,在TMD控制下,漂浮式风力机塔顶左右位移最大值降低近50%,稳定性提高38%;对漂浮式风力机平台的横摇及横荡运动控制效果较明显,平台横荡稳定性提高18%,横摇稳定性提高41%。