scholarly journals Repowering Steel Tubular Wind Turbine Towers Enhancing them by Internal Stiffening Rings

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1538 ◽  
Author(s):  
Yu Hu ◽  
Jian Yang ◽  
Charalampos Baniotopoulos
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Structural Response ◽  
Critical Design ◽  
Element Size ◽  
Wind Turbine System ◽  
Design Variables ◽  
Wind Turbine Tower ◽  
Mesh Density ◽  
Wind Turbine Towers

This paper presents a robust repowering approach to the structural response of tubular steel wind turbine towers enhanced by internal stiffening rings. First, a structural response simulation model was validated by comparison with the existing experimental data. This was then followed with a mesh density sensitivity analysis to obtain the optimum element size. When the outdated wind turbine system needs to be upgraded, the wall thickness, the mid-section width-to-thickness ratio and the spacing of the stiffening rings of wind turbine tower were considered as the critical design variables for repowering. The efficiency repowering range of these design variables of wind turbine towers of various heights between 50 and 250 m can be provided through the numerical analysis. Finally, the results of efficiency repowering range of design variables can be used to propose a new optimum design of the wind turbine system when repowering a wind farm.

Load Measurement Method of the MW Class Wind Turbine

2013 ◽  
Vol 333-335 ◽  
pp. 146-151 ◽  
Author(s):  
De Yi Fu ◽  
Bo Jiao ◽  
Yang Xue ◽  
Shi Yao Qin
Keyword(s):  
Fatigue Strength ◽  
Life Span ◽  
Wind Turbine ◽  
Measurement Method ◽  
Wind Farm ◽  
Structural Response ◽  
Load Measurement ◽  
Wind Turbine Tower ◽  
Measurement Results ◽  
Large Wind

In recent years, wind turbine tower buckling and blade broken often happened. Large wind turbine load and insufficient fatigue strength should be the main reasons. To prevent this case, load measurement of the wind turbine is necessary. The wind turbine load measurement is one of the type tests of wind turbine. The load of the wind turbine structure components will strongly affect the safety and life span of the wind turbine. The wind turbine load measurement can help the wind turbine manufacturer and wind farm operator to know the structural response of the wind turbine components with different load cases. According to the IEC 61400-13 standard, a method of the wind turbine load measurement is introduced in this article. Meanwhile, the measurement results are given in this article. The results indicate that the accuracy of this measurement method can fulfill the requirements of the related standards.

Study on the Dynamic Response for Floating Foundation of Offshore Wind Turbine

2011 ◽  
Author(s):  
Yougang Tang ◽  
Jun Hu ◽  
Liqin Liu
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Load ◽  
Mooring Lines ◽  
Floating Foundation ◽  
Wind Turbine System ◽  
Sea Area

The wind resources for ocean power generation are mostly distributed in sea areas with the distance of 5–50km from coastline, whose water depth are generally over 20m. To improve ocean power output and economic benefit of offshore wind farm, it is necessary to choose floating foundation for offshore wind turbine. According to the basic data of a 600kW wind turbine with a horizontal shaft, the tower, semi-submersible foundation and mooring system are designed in the 60-meter-deep sea area. Precise finite element models of the floating wind turbine system are established, including mooring lines, floating foundation, tower and wind turbine. Dynamic responses for the floating foundation of offshore wind turbine are investigated under wave load in frequency domain.

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

2011 ◽  
Vol 38 (3) ◽  
pp. 293-304 ◽  
Author(s):  
Elena Nuta ◽  
Constantin Christopoulos ◽  
Jeffrey A. Packer
Keyword(s):  
Seismic Hazard ◽  
Wind Turbine ◽  
Seismic Loading ◽  
Element Analysis ◽  
Design Spectrum ◽  
Wind Turbine Tower ◽  
Damage States ◽  
Wind Turbine Towers ◽  
Hazard Level ◽  
Hazard Levels

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.

scholarly journals Study of the Bearing Capacity of Stiffened Tall Offshore Wind Turbine Towers during the Erection Phase

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5102
Author(s):  
Yu Hu ◽  
Jian Yang ◽  
Charalampos Baniotopoulos
Keyword(s):  
Wind Energy ◽  
Bearing Capacity ◽  
Wind Turbine ◽  
Structural Response ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Nonlinear Buckling ◽  
Wind Turbine Towers ◽  
Nonlinear Buckling Analysis

Offshore wind energy is a rapidly maturing renewable energy technology that is poised to play an important role in future energy systems. The respective advances refer among others to the monopile foundation that is frequently used to support wind turbines in the marine environment. In the present research paper, the structural response of tall wind energy converters with various stiffening schemes is studied during the erection phase as the latter are manufactured in modules that are assembled in situ. Rings, vertical stiffeners, T-shaped stiffeners and orthogonal stiffeners are considered efficient stiffening schemes to strengthen the tower structures. The loading bearing capacity of offshore monopile wind turbine towers with the four types of stiffeners were modeled numerically by means of finite elements. Applying a nonlinear buckling analysis, the ultimate bearing capacity of wind turbine towers with four standard stiffening schemes were compared in order to obtain the optimum stiffening option.

Resonance Avoidance of Offshore Wind Turbines

2010 ◽  
Author(s):  
Martin L. Pollack ◽  
Brian J. Petersen ◽  
Benjamin S. H. Connell ◽  
David S. Greeley ◽  
Dwight E. Davis
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Response ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Support Structure ◽  
Offshore Wind Turbines ◽  
Wind Turbine System ◽  
Dynamic Forces ◽  
Technical Basis

Coincidence of structural resonances with wind turbine dynamic forces can lead to large amplitude stresses and subsequent accelerated fatigue. For this reason, the wind turbine system is designed to avoid resonance coincidence. In particular, the current practice is to design the wind turbine support structure such that its fundamental resonance does not coincide with the fundamental rotational and blade passing frequencies of the rotor. For offshore wind turbines, resonance avoidance is achieved by ensuring that the support structure fundamental resonant frequency lies in the frequency band between the rotor and blade passing frequencies over the operating range of the turbine. This strategy is referred to as “soft-stiff” and has major implications for the structural design of the wind turbine. This paper details the technical basis for the “soft-stiff” resonance avoidance design methodology, investigates potential vulnerabilities in this approach, and explores the sensitivity of the wind turbine structural response to different aspects of the system’s design. The assessment addresses the wind turbine forcing functions, the coupled dynamic responses and resonance characteristics of the wind turbine’s structural components, and the system’s susceptibility to fatigue failure. It is demonstrated that the design practices for offshore wind turbines should reflect the importance of aerodynamic damping for the suppression of deleterious vibrations, consider the possibility of foundation degradation and its influence on the support structure’s fatigue life, and include proper treatment of important ambient sources such as wave and gust loading. These insights inform potential vibration mitigation and resonance avoidance strategies, which are briefly discussed.

scholarly journals Frequency Support of Smart Grid Using Fuzzy Logic-Based Controller for Wind Energy Systems

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1550 ◽  
Author(s):  
Marcelo Godoy Simões ◽  
Abdullah Bubshait
Keyword(s):  
Fuzzy Logic ◽  
Smart Grid ◽  
Wind Turbine ◽  
Wind Farm ◽  
Fuzzy Controller ◽  
Rate Of Change ◽  
Wind Turbine System ◽  
Point Of Common Coupling ◽  
Local Measurements ◽  
Wind Energy Systems

This paper proposes a fuzzy logic-based controller for a wind turbine system to provide frequency support for a smart grid. The designed controller is aimed to provide an appropriate dynamic droop rate depending on the local measurements of each wind turbine of a wind farm such as the maximum power available and the amount of power reserve. The designed fuzzy controller depends on the rate of change of frequency (ROCOF) at the point of common coupling (PCC). The main advantage of the proposed fuzzy controller is to provide frequency support by the wind turbine system connected to a smart grid. The dynamic rate of the controller is defined by the fuzzy sets considering the change in the grid’s frequency and the available reserve power. First, the response of static droop curves is investigated for different scenarios of wind turbines connected to a smart grid. Then, the proposed fuzzy logic-based droop controller is integrated into the system, and its performance and response are evaluated, and the results are compared with static-droop based controller. The proposed controller is tested using Matlab\Simulink.

scholarly journals Nonlinear Structural Control Analysis of an Offshore Wind Turbine Tower System

Processes ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 22 ◽  
Author(s):  
Y. Hamed ◽  
Ayman A. Aly ◽  
B. Saleh ◽  
Ageel F. Alogla ◽  
Awad M. Aljuaid ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Nonlinear Oscillations ◽  
Oscillation Amplitude ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Control Analysis ◽  
Control Force ◽  
Wind Turbine System ◽  
Wind Turbine Tower ◽  
Tower System

This paper investigates the vibration control, stability, and energy transfer of the offshore wind turbine tower system with control force and nonlinearity terms. A nonlinear proportional derivative (NPD) controller was connected to the system to reduce a high oscillation amplitude and to transfer the energy in the wind turbine system. Furthermore, the averaging method and Poincaré maps were used with respect to the controlled system to study the stability and bifurcation analysis in the worst resonance cases. The curves of force response and frequency response were plotted before and after the control unit was added to the wind turbine system. In addition, we discuss the performances of the control parameters on the vibration magnitudes. Numerical simulations were carried out with Maple and Matlab algorithms to confirm the analytical results. The results show the effectiveness of the NPD controller in suppressing the nonlinear oscillations of the wind turbine system.

Vibration Characteristics Analysis of Wind Turbine Towers under Foundation Conditions

2013 ◽  
Vol 446-447 ◽  
pp. 721-727
Author(s):  
Xi Song ◽  
Yin Guang Wu ◽  
Jie Yu Li ◽  
Rong Zhen Zhao
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Natural Frequency ◽  
Large Scale ◽  
Horizontal Axis Wind Turbine ◽  
Static And Dynamic Analysis ◽  
Wind Turbine Tower ◽  
Characteristics Analysis ◽  
Wind Turbine Towers ◽  
Tower Foundation

Based on a kind of 1.5MW large-scale horizontal axis wind turbine tower, the mechanical modeling of a wind turbine tower-foundation is established, the static and dynamic analysis of the model is carried out by ANSYS software. The top displacement of the system is calculated by the static analysis to meet the design requirements in engineering. In dynamic analysis, each pile foundation is equivalent to a group of springs for the simulation of horizontal and vertical rigidity of the pile. The influence of top mass and foundation elasticity on wind turbine tower modes is analyzed, and calculated the natural frequency of the tower within a certain scope of rigidity in different directions about the piles foundation. The results show that the natural frequency of the wind turbine tower is influenced significantly by the mass on the tower top and foundation rigidity. The study provides a theoretical basis for optimal design of the wind turbine.

scholarly journals A Novel Tripod Concept for Onshore Wind Turbine Towers

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5772
Author(s):  
Charis J. Gantes ◽  
Maria Villi Billi ◽  
Mahmut Güldogan ◽  
Semih Gül
Keyword(s):  
Wind Turbine ◽  
Cross Sections ◽  
Structural Features ◽  
Performance Criteria ◽  
Wind Turbine Tower ◽  
Wind Potential ◽  
Pile Cap ◽  
Tripod Concept ◽  
Wind Turbine Towers ◽  
Maintenance Requirements

A wind turbine tower assembly is presented, consisting of a lower “tripod section” and an upper tubular steel section, aiming at enabling very tall hub heights for optimum exploitation of the wind potential. The foundation consists of sets of piles connected at their top by a common pile cap below each tripod leg. The concept can be applied for the realization of new or the upgrade of existing wind turbine towers. It is adjustable to both onshore and offshore towers, but emphasis is directed towards overcoming the stricter onshore transportability constraints. For that purpose, pre-welded individual tripod parts are transported and are then bolted together during erection, contrary to fully pre-welded tripods that have been used in offshore towers. Alternative constructional details of the tripod joints are therefore proposed that address the fabrication, transportability, on-site erection and maintenance requirements and can meet structural performance criteria. The main structural features are demonstrated by means of a typical case study comprising a 180-m-tall tower, consisting of a 120-m-tall tubular superstructure on top of a 60-m-tall tripod substructure. Realistic cross-sections are calculated, leading to weight and cost estimations, thus demonstrating the feasibility and competitiveness of the concept.

scholarly journals Influence of external loads to wind turbine tower

2021 ◽  
Vol 3 (2) ◽  
pp. 112-120
Author(s):  
Marin Petrovic ◽  
Nejra Isic
Keyword(s):  
Wind Turbine ◽  
Wind Velocity ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Steel Pipes ◽  
Wind Turbine Tower ◽  
Wind Turbine Towers ◽  
Lattice Towers ◽  
The Moment ◽  
External Loads

One of the most important parts of a wind turbine is a tower. There are various designs of the wind turbine towers, and they are most often made of steel pipes, lattice towers or concrete towers. In order to increase energy density to meet the growing electricity needs, larger wind turbine projects have been developed. Larger wind turbine towers can generate more electricity, but such large sizes also create higher costs in terms of development and maintenance. This research sets up a model of a wind turbine tower, where the load to the tower is calculated by its relation to the wind velocity. Analytical approach coupled with a finite element method (FEM) is used to analyse the distribution of tower stresses under these loads. The fatigue analysis of the column is performed using the load from its own weight, the weight of the housing and the distribution of the wind velocity. The effects of different loads are also compared. The results show that the main loads of the tower are the wind force acting on the area of ??rotation of the wind turbine blades and the moment caused by the uneven wind velocity. Construction is modelled using SolidWorks modelling package, where the analysis was performed using FEM in ANSYS software. As a result of the analysis, the stress distribution in the support was determined and compared with analytical calculations.

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