A Conceptual Design Method for Parametric Study of Blades for Offshore Wind Turbines

2011 ◽  
Author(s):  
Lars Fro̸yd ◽  
Ole G. Dahlhaug
Keyword(s):  
Wind Turbines ◽  
Design Method ◽  
Design Procedure ◽  
Rotor Blades ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Integrated Method ◽  
Horizontal Axis Wind Turbines ◽  
Parametric Studies ◽  
The Time Domain

This article presents a simplified, integrated method for design studies of blades for offshore wind turbines. The method applies to variable speed horizontal axis wind turbines with pitch control, and allows designing the rotor blades based on a very limited set of input parameters. The purpose of the method is to allow parametric studies of different design configurations of the rotor at a reasonable effort. The resulting wind turbine models are at a level of detail suitable for preliminary design considerations using e.g. aero-elastic simulations in the time domain. The aerodynamic design is based on blade element momentum (BEM) considerations using a distribution of 2D airfoil characteristics. The structural design of the blades is based on aerodynamic forces calculated from a small number of load cases. The design procedure is facilitated by using simplified cross-section definitions and iterative approaches. The resulting blade designs are shown to compare well with data from available turbine models.

scholarly journals Effective Method for Determining Environmental Loads on Supporting Structures for Offshore Wind Turbines

2016 ◽  
Vol 23 (1) ◽  
pp. 52-60
Author(s):  
Paweł Dymarski ◽  
Ewelina Ciba ◽  
Tomasz Marcinkowski
Keyword(s):  
Wind Turbines ◽  
Computational Method ◽  
Offshore Wind ◽  
Cfd Simulations ◽  
Drag Coefficients ◽  
Offshore Wind Turbines ◽  
Drag Forces ◽  
The Time Domain ◽  
Range Of Variation ◽  
Supporting Structures

Abstract This paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates) pyramids of polygon with a large number of sides (8 or more). The presented computational method is based on the Morison equation, which was originally developed only for cylindrically shaped structures. The new algorithm shown here uses the coefficients of inertia and drag forces that were calculated for non-cylindrical shapes. The analysed structure consists of segments which are truncated pyramids on the basis of a hex decagon. The inertia coefficients, CM, and drag coefficients, CD, were determined using RANSE-CFD calculations. The CFD simulations were performed for a specific range of variation of the period, and for a certain range of amplitudes of the velocity. In addition, the analysis of influence of the surface roughness on the inertia and drag coefficients was performed. In the next step, the computations of sea wave, current and wind load on supporting structure for the fifty-year storm were carried out. The simulations were performed in the time domain and as a result the function of forces distribution along the construction elements was obtained. The most unfavourable distribution of forces will be used, to analyse the strength of the structure, as the design load.

scholarly journals Nonlinear Wave Loads on Offshore Wind Turbines: Extreme Statistics and Fatigue

2019 ◽  
Author(s):  
Yu Zhang ◽  
Paul D. Sclavounos
Keyword(s):  
Nonlinear Wave ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Wave Loads ◽  
Extreme Statistics ◽  
Support Structure ◽  
Nonlinear Load ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
The Time Domain

Abstract The development is presented of an analytical model for the prediction of the stochastic nonlinear wave loads on the support structure of bottom mounted and floating offshore wind turbines. Explicit expressions are derived for the time-domain and frequency-domain nonlinear exciting forces in a seastate with significant wave height comparable to the diameter of the support structure based on the fluid impulse theory. The higher order moments of the nonlinear load are evaluated from simulated force records and the derivation of analytical expressions for the nonlinear load statistics for their efficient use in design is addressed.

Support Structure Optimization for Offshore Wind Turbines With a Genetic Algorithm

2014 ◽  
Author(s):  
Lucía Bárcena Pasamontes ◽  
Fernando Gómez Torres ◽  
Daniel Zwick ◽  
Sebastian Schafhirt ◽  
Michael Muskulus
Keyword(s):  
Genetic Algorithm ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Hot Spot ◽  
Offshore Wind ◽  
Support Structures ◽  
Hot Spot Stress ◽  
Offshore Wind Turbines ◽  
Structural Design Optimization ◽  
The Time Domain

This study considers the use of a genetic algorithm for the structural design optimization of support structures for offshore wind turbines. Member diameters, thicknesses and locations of nodes are jointly optimized. Analysis of each design is performed with a complete wind turbine simulation, for a load case in the time domain. Structural assessment is in terms of fatigue damage, evaluated for each joint using the hot-spot stress approach. This defines performance constraints. Designs are optimized with respect to their weight. The approach has been tested with the modified 4-legged UpWind jacket from the OC4 project. The weight is quickly reduced, convergence slows after about 100 iterations, and few changes occur after 250 iterations. Interestingly, the fatigue constraint is not active for any member, and it is the validity of stress concentration factors that determines the best design, which utilizes less than 90 percent of the available fatigue lifetime. These results of the preliminary study using the genetic algorithm demonstrate that automatic optimization of wind turbine support structures is feasible under consideration of the simplified load approach. Even for complex, multi-member structures such as the considered jacket a weight reduction was achieved.

New Design Proposal for the TLP Type Offshore Wind Turbines

2013 ◽  
Author(s):  
Yasunori Nihei ◽  
Midori Matsuura ◽  
Motohiko Murai ◽  
Kazuhiro Iijima ◽  
Tomoki Ikoma
Keyword(s):  
Wind Turbines ◽  
Oil And Gas ◽  
Design Method ◽  
Offshore Wind ◽  
Wave Forces ◽  
Oil And Gas Development ◽  
Offshore Wind Turbines ◽  
Motion Characteristics ◽  
Set Up ◽  
High Set

In this paper, we will show a new proposal to design a Tension Leg Platform (TLP) type offshore wind turbines. Generally, TLPs are used in deepwater oil and gas development fields due to their favorable motion characteristics. In this field, they have high set up costs. An upper structure of 5MW wind turbine, however, is only 450tons at its total weight, which is much lighter than that of oil and gas platforms. Therefore the displacement and water plane area of the platform might be smaller. As a result, wave forces could decrease and it could lead initial tensions to be lower. This idea that leads to low set up costs was discussed in our previous paper. Principal particulars of TLP prototypes was proposed and a tank test with both waves and wind that used 1/100 scale models was examined in the previous paper. Capsizing could be observed based on the conventional design method. So we reason why and how this capsizing occured in this paper. Also we propose new design process and new TLP prototypes based on this process.

scholarly journals Nonlinear Wave Loads on Offshore Wind Turbines: Extreme Statistics and Fatigue

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Yu Zhang ◽  
Paul D. Sclavounos
Keyword(s):  
Nonlinear Wave ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Wave Loads ◽  
Extreme Statistics ◽  
Support Structure ◽  
Nonlinear Load ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
The Time Domain

Abstract The development is presented of an analytical model for the prediction of the stochastic nonlinear wave loads on the support structure of bottom-mounted and floating offshore wind turbines. Explicit expressions are derived for the time-domain and frequency-domain nonlinear exciting forces in a seastate with a significant wave height comparable to the diameter of the support structure based on the fluid impulse theory. The higher-order moments of the nonlinear load are evaluated from simulated force records, and the derivation of analytical expressions for the nonlinear load statistics for their efficient use in design is addressed.

Fault diagnosis in yaw drive induction motor for wind turbine

2018 ◽  
Vol 42 (6) ◽  
pp. 576-595 ◽  
Author(s):  
Ali Ouanas ◽  
Ammar Medoued ◽  
Mourad Mordjaoui ◽  
Abdesselam Lebaroud ◽  
Djamel Sayad
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Low Frequency ◽  
Offshore Wind ◽  
Discrete Wavelet ◽  
Phase System ◽  
Offshore Wind Turbines ◽  
Three Phase ◽  
The Time Domain ◽  
The Hilbert Transform

Wind turbines are widely exploited throughout the world. The availability and reliability of offshore wind turbines are asking to impose a constant maintenance strategy. In this work, we propose a method that allows filtering the signal of the frequency inverter that feeds the yaw drive used in wind turbine. The redundant information is eliminated via discrete wavelet transform and empirical modal decomposition. The two types of faults are detected from the envelope of the Hilbert transform. The magnitude imbalance detection is carried out in the time domain. The root mean square values of the envelopes of the three-phase system have a good indicator for the fuzzy system to evaluate the severity of the defect. In the frequency domain, the signature of the broken bar fault is located in the low-frequency bandwidth. The harmonics appeared in the spectrum sensitive in amplitude and frequency to the variation of load. Experimental results have demonstrated the accuracy of the proposed method.

Pitch Angle Control of Floating Offshore Wind Turbines by H∞ Control

2014 ◽  
Vol 134 (8) ◽  
pp. 1096-1103 ◽  
Author(s):  
Sho Tsujimoto ◽  
Ségolène Dessort ◽  
Naoyuki Hara ◽  
Keiji Konishi
Keyword(s):  
Wind Turbines ◽  
Pitch Angle ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines
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