Design Of Wind Turbine Towers Research Articles

Considerations for the structural design of wind turbine towers: A practical application

Considerations for the structural design of wind turbine towers: A practical application

Nonlinear Finite Element Analysis of Tubular Steel Wind Turbine Towers near Man Door and Ventilation Openings to Optimize Design against Buckling

The safe and cost-effective design of wind turbine towers is a critical and challenging aspect of the future development of the wind energy sector. This process should consider the continuous growth of towers in height and blades in length. Among potential failure modes of tubular steel towers, shell local buckling due to static axial compressive stresses from the rotor, blades, and tower weight, as well as dynamic flexural compressive stresses from wind actions on the rotating blades and the tower itself, are dominant as thickness is optimized to reduce weight. As man door and ventilation openings are necessary for the towers’ operation, the local weakening of the tower shell in those areas leads to increased buckling danger. This is compensated for by tower manufacturers by the provision of stiffening frames around the openings. However, the cold-forming and welding of these frames are among the most time-consuming aspects of tower fabrication. Working towards the optimization of this design aspect, the buckling response of tubular steel towers near such openings is investigated by means of nonlinear finite element analysis, accounting for geometrical and material nonlinearity and imperfections (GMNIA), and also considering several wind directions with respect to the openings. The alternatives of stiffened and unstiffened openings are investigated, revealing that a thicker shell section around the opening may be sufficient to restore lost stiffness and strength, while the stiffener frame may also be eliminated, offering substantial benefits in terms of manufacturing effort, time and cost.

Semi-Analytical Formula for Estimating Variance Response of Megawatt Wind Turbine Tower Under Parked Condition

As the supporting structure of the wind turbine, the tower is important for the safety of the wind turbine. The accurate estimation of tower response is critical for the wind turbine tower design. In the preliminary design, lots of calculations are necessary to determine design parameters. The traditional time domain calculation suffers its low efficiency and hinders the design progress. To overcome this difficulty, the frequency domain analysis should be developed, especially for the large wind turbine which may be significantly affected by the aerodynamic damping. In this study, a semi-analytical formula for the variance of the tower base bending moment is developed from the frequency domain analysis at parked condition. First, based on the quasi-steady theory and the three-component (mean, background and resonant components) method commonly used in the wind-resistant design of structure, the analytical formula of the variance for the tower base bending moment is presented considering the three components of the wind velocity. Second, the analytical formula is corrected based on the comparison with the calculation result by FAST. In the correction, the empirical aerodynamic damping is adopted. Finally, the applicability of the developed semi-analytical formula is verified by 5[Formula: see text]MW, 10[Formula: see text]MW and 15[Formula: see text]MW wind turbines.

Towards optimal reliability-based design of wind turbines towers using artificial intelligence

Metaheuristic Optimization Techniques and Artificial Neural Networks (ANNs) have proven to be useful tools to find the best design solutions for different structural systems. However, the application of both techniques oriented toward the optimal design of wind turbine towers still requires further research. A methodology is presented to obtain the best design solutions for onshore wind turbine steel towers using the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm and ANNs. The proposed methodology is applied to steel towers with heights of 70, 75, 80, and 85 m. Case studies are assumed to be located in La Ventosa, Oaxaca. Three design objectives are defined: minimize the mass of the structure, maximize the structural reliability, and maximize the wind power. In order to avoid high computational costs, ANNs are trained and used to obtain the structural reliability index β. First, the design variables and constraints are defined; subsequently, a metaheuristic swarm intelligence-based optimization (MOPSO) technique is implemented. As a result of the optimization process using the MOPSO algorithm, a Pareto Front that includes the best design solutions is efficiently obtained. Finally, graphs are generated in order to recommend initial parameters for pre-design of steel towers, satisfying three design objectives.

Design optimisation of wind turbine towers with reliability-based calibration of partial safety factors

Having an optimal design of the wind turbine tower, with a minimum mass (cost) while fulfilling multiple design constraints, plays an important role in ensuring an economic and safe design of the wind turbine. During the design of wind turbine towers, partial safety factors (PSFs) are currently commonly used to account for the uncertainties in the loads and material properties due to its easy implementation. The values of PSFs given in design standard are generic and are not derived for a specific design. For a site-specific design of wind turbine towers, the details of the load parameters, such as the type of distributions and the coefficient of variation, can be obtained through the condition monitoring system. With these information, the PSFs can be calibrated based on the reliability method, meeting the target reliability index and avoiding over or under engineering of wind turbine tower structures. In this work, a parametric finite element analysis model is integrated with a genetic algorithm to develop a structural optimisation model of wind turbine towers. The optimisation framework minimises the tower mass under multiple design constraints. The optimisation model has been applied to a representative 2.0 MW onshore wind turbine tower. PSFs are calibrated on the basis of reliability. The optimal tower design with calibrated PSFs is compared against the design with un-calibrated PSFs. Results indicate that the tower design with calibrated PSFs achieves a mass reduction of 2.9% in comparison to the design with un-calibrated PSFs.

Wind Turbine Tower Design, Wind Turbine Site Selection with GIS and Analysis by Finite Element Method

Wind Turbine Tower Design, Wind Turbine Site Selection with GIS and Analysis by Finite Element Method

Analysis of sea ice parameters for the design of an offshore wind farm in the Bohai Sea

Offshore wind power has gained much attention as a clean and renewable source of energy. In cold regions, offshore wind farms (OWFs) face many challenges due to sea ice cover. In response to these challenges, this paper establishes a scheme to evaluate sea ice parameters for the design of wind power projects. We have successfully applied this scheme to the OWF in the Bohai Sea. The scheme is based on data from sea ice satellite images, operational forecasting systems and field tests. The ice period, joint probability distribution function of ice velocity and thickness, and return period (RP) of thickness are investigated. Moreover, we determine the air temperature relationship between the OWF and Laizhou city. Then, the effective ice temperature is calculated for the OWF based on the air temperature. Combining the RPs of ice temperature and thickness, we compute the RPs of bending and compression strengths, which are two key parameters for the ice load design of wind turbine towers. Our scheme is feasible to implement and can provide complete sea ice information for OWFs from the stages of design and construction to operation.

Computing Marginal Cost of Durability of Energy Systems Components by Structural Optimization With Fatigue Constraints

Abstract There is a relationship between product durability and the effect the product has on the environment and economy. One approach that impacts this dynamic involves a circular economy. The idea of a circular economy is gaining more traction as some businesses have begun to shift toward a product as a service model in which they, the businesses, maintain ownership of the product. One example of this business model is emerging in the energy sector. Given this shift, the life of the product becomes more important as it directly impacts the bottom line of the business. This gives rise to the marginal cost of durability (MCD) metric. The MCD determines the cost of the product in relation to the life of the system. For longer life, the design generally necessitates more cost-intensive measures to ensure durability. In the context of sustainable design, system life is particularly important for renewable energy systems that promote sustainable living. These large structures often require a high volume of materials and the end-of-life disposal for those materials. The design requirements for material also increase as the design life increases. The additional materials provide a safeguard against failure phenomena, such as fatigue. The MCD metric has been used in previous studies. However, there is no formal method for determining the MCD. This article examines a method for measuring the MCD for the commercial class of wind energy production systems. A metamodel of the damage response is built in lieu of expensive computational models. Design optimization is used to search for the design parameters having fatigue damage as a constraint. This process is repeated for a set of system life values, yielding a set of designs. Curve fitting is used to find a mathematical relationship between life and cost. An example of this method is applied to the study of a wind turbine tower life. The study indicates that the wind turbine tower design for 80 years has 34% more mass and cost than a 20-year design. The results from the proposed method provide information that can be used to determine the design life of a system.

Seismic performance analysis of a wind turbine tower subjected to earthquake and ice actions.

Sea ice is one of the main loads acting on a wind turbine tower in areas prone to icing, and this threatens safe working life of the wind turbine tower. In our study, a simplified calculated model of ice, wind turbine tower, and water dynamic interaction under earthquake action was proposed, which could avoid to solve a large number of nonlinear equations. Then, the seismic behaviour of the wind turbine tower with and without the influence of sea ice was investigated, and we found that the influence of the greater mass of the sea ice on the seismic response of a wind turbine tower should be considered when the wind turbine tower is designed in an area with thick ice. With the influence of the most unfavourable ice mass, the deformation and energy dissipation capacity of the wind turbine tower are decreased, and the wall thickness or stiffening rib thickness should be increased to improve the seismic performance and ductility of the wind turbine tower; the shear force and bending moment increased significantly on the wind turbine tower, and the shear force changes at the bottom of the wind turbine tower and position of action of the sea ice: attention should be paid to the wind turbine tower design at these positions. Finally, we conducted the shaking table test, and verified the rationality of our proposed simplified model.

Structural design of wind turbine tower climbing robot

This paper combines the actual needs of the structure design of the climbing robot, uses the three-dimensional software to virtual design the mechanical structure, and performs finite element simulation on the key components to verify the reliability. On this basis, the components with higher quality are Topology optimization reduces weight without reducing stiffness, enabling lightweight design and improved overall performance. Through the structural design of the robot, the overall layout of the robot is functional. Important parts such as the body, power system, and mobile system are designed in detail, and the physical parts of the prototype are processed. Converting the roll cage design in the racing field into the body design of the robot to increase the rigidity of the body.

Wind Turbine Tower Climbing System Design

Currently there is a certain degree of difficulty for China wind turbine blades and tower inspection and maintenance. In this paper, the design of wind turbine tower climbing system is mainly used in wind turbine blades and tower inspection and maintenance, which can replace altitude operations, reduce labor intensity of workers, improve the accuracy of inspection, and get experimental verification.

Lightweight structure design for wind energy by integrating nanostructured materials

Wind power develops very fast nowadays with high expectation. Although at the mean time, the use of taller towers, however, smacks head-on into the issue of transportability. The engineering base and computational tools have to be developed to match machine size and volume. Consequently the research on the light weight structures of tower is carrying out in the main countries which are actively developing wind energy. This paper reports a new design scheme of light weight structure for wind turbine tower. This design scheme is based on the integration of the nanostructured materials produced by the Surface Mechanical Attrition Treatment (SMAT) process. The objective of this study is to accomplish the weight reduction by optimizing the wall thickness of the tapered tubular structure. The basic methods include the identification of the critical zones and the distribution of the high strength materials according to different necessities. The equivalent strength or stiffness design method and the high strength material properties after SMAT process are combined together. Bending and buckling are two main kinds of static loads concerned in consideration. The study results reveal that there is still enough margin for weight reduction in the traditional wind turbine tower design.

The Finite Element Analysis and Comparison of Wind Turbine Tower under Static Wind Load and Fluctuating Wind Load

In this paper, a 1.5 MW wind turbine tower in Dali, Yunnan Province is used as the research object, using large-scale finite element software Ansys to carry on the dynamic analysis. These natural frequencies and natural vibration type of the first five of tower are obtained by modal analysis and are compared with natural frequency to determine whether the resonance occurs. Based on the modal analysis, the results of the transient dynamic analysis are obtained from the tower, which is loaded by the static wind load and fluctuating wind load in two different forms. By comparing the different results, it provides the basis for the dynamic design of wind turbine tower.

Field Testing of a Wind Turbine Tubular Tower and Structural Design of a Space Frame Steel Tower

Wind energy industry has been growing tremendously in recent years. Tubular steel towers are currently dominant supporting structures for wind turbines. With the increase of the converter capacity, there is a great demand for higher supporting towers. However, structural vibrations in extreme wind events tend to become a major concern during tower design. To study wind turbine tower dynamics, an existing tubular steel tower was tested. Vibrational frequencies and damping ratios were identified. To avoid unexpected dynamic problems, a space frame steel tower has been proposed for supporting larger wind turbines. It is a structural system that can be assembled on-site by using prefabricated beams, columns, and brace members. A typical space frame steel tower was designed in this paper. Static loading, modal and buckling analyses of the tower were presented. It is expected to introduce engineers and designers more options for wind turbine tower design.

Influence of Simplified Models on Seismic Response Analysis of Wind Turbine Towers

Abstract. The dynamic response of wind turbine tower under earthquake is analyzed by aid of the ANSYS program in this paper. To investigate the effects of simplification calculation models of blades and engines on calculation results, a blades-tower integrated finite element (FE) model and a mass-tower finite element (FE) model are established respectively. Then model analysis is discussed and the time history analysis of the system under the input of mean value earthquake record is carried out. The results show that seismic responses of a wind turbine tower are remarkable and seismic action may be the dominant factor in the design of wind turbine towers that located at a seismically active zone. Torsion effect of a tower is evident as a result of the impact of mass eccentricity. Bottom stress at the direction perpendicular to seismic waves is much bigger than that along it. It is also found that the blades-tower integrated finite element model can reflect more accurately the dynamic responses of the tower in the whole process of the earthquake and the “time-lag” effect by comparison, and these provide reliable reference to design and further research of towers.

Influence of Earthquake Directions on Wind Turbine Tower under Seismic Action

Influence of earthquake directions on wind turbine tower under seismic action are numerically investigated in this paper. First, equations of motion and an integrated finite element model of a wind turbine system consisting of a rotor, a nacelle and a tower shaft are established. Second, the finite element modal analysis is discussed. Third, relationships between upper displacements in x, y directions and bottom bending stress when the angle is 0, 30, 45, 60, 90 degree respectively between earthquake directions and concentrated eccentric mass direction (x direction) are analyzed by adjusted Taft seismic wave .The results show that: seismic responses of a wind turbine tower are remarkable and seismic action may be the dominant factor in the design of wind turbine towers that located at a seismically active zone. Under different earthquake directions structure’s dynamic responses are different, 90 degree with regard to x direction is the most unfavorable direction. Both maximum upper displacements in x, y directions and bottom bending stress appear at 90 degree direction with regard to x direction.

Methodology for seismic risk assessment for tubular steel wind turbine towers: application to Canadian seismic environment

The seismic response of tubular steel wind turbine towers is of significant concern as they are increasingly being installed in seismic areas and design codes do not clearly address this aspect of design. The seismic hazard is hence assessed for the Canadian seismic environment using implicit finite element analysis and incremental dynamic analysis of a 1.65 MW wind turbine tower. Its behaviour under seismic excitation is evaluated, damage states are defined, and a framework is developed for determining the probability of damage of the tower at varying seismic hazard levels. Results of the implementation of this framework in two Canadian locations are presented herein, where the risk was found to be low for the seismic hazard level prescribed for buildings. However, the design of wind turbine towers is subject to change, and the design spectrum is highly uncertain. Thus, a methodology is outlined to thoroughly investigate the probability of reaching predetermined damage states under any seismic loading conditions for future considerations.

Automatic Design Method of Wind Turbine Tower and it’s Application

In order to solve the engineering application problems of parametric rapidly in design of wind turbine tower, an automatic design method of wind turbine tower is put forward first, and the automatic design model was built through analyzing the key parameters and parameters’ calculation relation in different cases: same taper tower design and variable taper tower design. The key parameters, height, diameter and wall thickness of the tower, are mainly considered. Then, an automatic design system of the wind turbine tower is developed and realized according to the model. Finally, the system effectiveness is verified through taking a wind turbine for example. The results show that the system can enhance the design efficiency and shorten the cycle times at the same time.

Wind-induced response analysis of a wind turbine tower including the blade-tower coupling effect

To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects, and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method (FEM) was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases (one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower), and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.

New methods in Wind Turbine Tower Design

The main consideration in this wind turbine tower analysis was the use of Finite Element Modelling (FEM) and Computational Fluid Dynamics modelling (CFD). For application, the first wind turbine installation was planned in the hilly region on the banks of the Danube, near Dunaujvaros, where wind speed measurements were recorded from the beginning of 1999. The topographical and wind speed measurement data were used as input for the pre-feasibility study. Flow around the tower was modelled with CFD, with the on-site wind measurement data used as inlet boundary condition for a dynamic system analysis. The aim was to find the most suitable height and cross section for tower design, considering the possible vibrations and torque. The results were verified with wind tunnel and vibration measurements on physical models.