Stochastic Analysis of Short-Term Structural Responses and Fatigue Damages of A Submerged Tension Leg Platform Wind Turbine in Wind and Waves

2021 ◽  
Vol 35 (4) ◽  
pp. 566-577
Author(s):  
Yan-qing Han ◽  
Cong-huan Le ◽  
Pu-yang Zhang ◽  
Li Dang ◽  
Qing-lai Fan
Author(s):  
Carlos Eduardo Silva de Souza ◽  
Erin E. Bachynski

Abstract Dynamic analysis of floating wind turbines often considers the hull as a rigid body. This paper explores the consequences of modeling the pontoons of a tension leg platform (TLP) wind turbine as flexible beams. The analysis is based on numerical simulations of free decays, structural response to wave excitation, and short-term fatigue damage accumulation at tower base and tendons. In addition, the importance of hydroelastic effects due to the pontoons’ vertical deformations is evaluated. Pontoon flexibility changed the platform natural periods and motion amplitude significantly, and the adoption of flexible pontoons reduced the predicted fatigue damage in the tower base and tendons. On the other hand, hydroelasticity had negligible consequences for motion and load responses considered here.


2020 ◽  
Vol 53 (2) ◽  
pp. 12115-12120
Author(s):  
Zhengyang Zhang ◽  
Zaiyu Chen ◽  
Guoqiang Yu ◽  
Tianhai Zhang ◽  
Minghui Yin ◽  
...  

2014 ◽  
Vol 6 (5) ◽  
pp. 053108 ◽  
Author(s):  
Anders Mandrup Hansen ◽  
Robert Laugesen ◽  
Henrik Bredmose ◽  
Robert Mikkelsen ◽  
Nikolaos Psichogios

Author(s):  
Hasan Bagbanci ◽  
D. Karmakar ◽  
C. Guedes Soares

The long-term probability distributions of a spar-type and a semisubmersible-type offshore floating wind turbine response are calculated for surge, heave, and pitch motions along with the side-to-side, fore–aft, and yaw tower base bending moments. The transfer functions for surge, heave, and pitch motions for both spar-type and semisubmersible-type floaters are obtained using the fast code and the results are also compared with the results obtained in an experimental study. The long-term predictions of the most probable maximum values of motion amplitudes are used for design purposes, so as to guarantee the safety of the floating wind turbines against overturning in high waves and wind speed. The long-term distribution is carried out using North Atlantic wave data and the short-term floating wind turbine responses are represented using Rayleigh distributions. The transfer functions are used in the procedure to calculate the variances of the short-term responses. The results obtained for both spar-type and semisubmersible-type offshore floating wind turbine are compared, and the study will be helpful in the assessments of the long-term availability and economic performance of the spar-type and semisubmersible-type offshore floating wind turbine.


Author(s):  
Carlo Ruzzo ◽  
Nilanjan Saha ◽  
Felice Arena

The present paper deals with the estimation of the short-term extreme motions of a spar floating wind turbine in parked rotor conditions, through a 1:30 at-sea experiment, carried out at the Natural Ocean Engineering Laboratory (NOEL) of Reggio Calabria (Italy). Thanks to some favorable local environmental conditions of the site, several wind-generated sea states with relatively low significant wave height (Hs < 0.50 m) have been collected during the experiment. These sea states are scale models of ocean storms, which are relevant hydrodynamic design conditions for the spar platform. The 30-minutes extreme values of the model structure motions have been estimated for all the six degrees of freedom, using the Weibull Tail Method (WTM), and the results obtained are presented in the paper. Such estimations are 1:30 scale models of the 3-hours extreme values of the spar motions in parked rotor conditions and may be directly used for design purposes.


2019 ◽  
Vol 7 (3) ◽  
pp. 56 ◽  
Author(s):  
Timothy Murfet ◽  
Nagi Abdussamie

This paper describes model testing of a Tension Leg Platform Wind Turbine (TLPWT) with non-rotating blades to better understand its motion and tendon responses when subjected to combined wind and unidirectional regular wave conditions. The TLPWT structure is closely based on the National Renewable Energy Laboratory (NREL) 5 MW concept. Multiple free decay tests were performed to evaluate the natural periods of the model in the key degrees of freedom, whilst Response Amplitude Operators (RAOs) were derived to show the motion and tendon characteristics. The natural periods in surge and pitch motions evaluated from the decay tests had a relatively close agreement to the theoretical values. Overall, the tested TLPWT model exhibited typical motion responses to that of a generalised TLP with significant surge offsets along with stiff heave and pitch motions. The maximum magnitudes for the RAOs of surge motion and all tendons occurred at the longest wave period of 1.23 s (~13.0 s at full-scale) tested in this study. From the attained results, there was evidence that static wind loading on the turbine structure had some impact on the motions and tendon response, particularly in the heave direction, with an average increase of 13.1% in motion amplitude for the tested wind conditions. The wind had a negligible effect on the surge motion and slightly decreased the tendon tensions in all tendons. The results also showed the set-down magnitudes amounting to approximately 2–5% of the offset. Furthermore, the waves are the dominant factor contributing to the set-down of the TLPWT, with a minimal contribution from the static wind loading. The results of this study could be used for calibrating numerical tools such as CFD codes.


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