Long term response analysis of TLP-type offshore wind turbine

2018 ◽  
pp. 1-13
Author(s):  
K. G. Vijay ◽  
D. Karmakar ◽  
C. Guedes Soares
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Term Response

scholarly journals Effects of Simulation Length and Flexible Foundation on Long-Term Response Extrapolation of a Bottom-Fixed Offshore Wind Turbine

2021 ◽  
pp. 1-36
Author(s):  
David Barreto ◽  
Madjid Karimirad ◽  
Arturo Ortega
Keyword(s):  
Wind Turbine ◽  
Bending Moment ◽  
Offshore Wind ◽  
Contour Method ◽  
Offshore Wind Turbine ◽  
Modeling Uncertainty ◽  
Flexible Foundation ◽  
Extreme Responses ◽  
Term Response

Abstract This paper deals with statistical and modeling uncertainty on the estimation of long-term extrapolated extreme responses in a monopile offshore wind turbine. The statistical uncertainty is addressed by studying the effect of simulation length. Modeling uncertainty is explored by evaluating the effects of considering a rigid and flexible foundation. The soil's flexibility is taking into account by considering the improved apparent fixity method. To identify the most relevant environmental conditions, the modified environmental contour method is used. The analysis focuses on the fore-aft shear force (FASF) and the fore-aft bending moment (FABM) at the mudline. The results show that using a simulation length of 10-min, does not provide sufficient accuracy. It was found that for the FASF, simulation lengths of at least 30-min are required to achieve an accuracy of about +/-5%. For the FABM, it was found that both the extrapolations made with 20-min and 30-min simulations achieved similar levels of accuracy of about 20%. Meanwhile, the results obtained from 10-min simulations reached deviations of about 40%. Finally, from the comparison made between a rigid and flexible foundation, it was found that the extrapolated responses exhibit maximum deviations up to around 5% and 10% for the FASF and the FABM, respectively. Also, for the FABM, it was observed that the consideration of a flexible foundation causes the critical wind speed to shift from 16.5 m/s (rigid) to 18 m/s (flexible).

Long-Term Dynamic Monitoring of an Offshore Wind Turbine

2013 ◽  
pp. 253-267 ◽  
Author(s):  
Christof Devriendt ◽  
Filipe Magalhães ◽  
Mahmoud El Kafafy ◽  
Gert De Sitter ◽  
Álvaro Cunha ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Dynamic Monitoring ◽  
Offshore Wind Turbine

On the Modeling of Nonlinear Waves for Prediction of Long-Term Offshore Wind Turbine Loads

2008 ◽  
Author(s):  
P. Agarwal ◽  
L. Manuel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Return Period ◽  
Wave Model ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Irregular Wave ◽  
Inflow Turbulence

In the design of wind turbines—onshore or offshore—the prediction of extreme loads associated with a target return period requires statistical extrapolation from available loads data. The data required for such extrapolation are obtained by stochastic time-domain simulation of the inflow turbulence, the incident waves, and the turbine response. Prediction of accurate loads depends on assumptions made in the simulation models employed. While for the wind, inflow turbulence models are relatively well established, for wave input, the current practice is to model irregular (random) waves using a linear wave theory. Such a wave model does not adequately represent waves in shallow waters where most offshore wind turbines are being sited. As an alternative to this less realistic wave model, the present study investigates the use of irregular nonlinear (second-order) waves for estimating loads on an offshore wind turbine, with a focus on the fore-aft tower bending moment at the mudline. We use a 5MW utility-scale wind turbine model for the simulations. Using, first, simpler linear irregular wave modeling assumptions, we establish long-term loads and identify governing environmental conditions (i.e., the wind speed and wave height) that are associated with the 20-year return period load derived using the inverse first-order reliability method. We present the nonlinear irregular wave model next and incorporate it into an integrated wind-wave-response simulation analysis program for offshore wind turbines. We compute turbine loads for the governing environmental conditions identified with the linear model and also for an extreme environmental state. We show that computed loads are generally larger with the nonlinear wave modeling assumptions; this establishes the importance of using such refined nonlinear wave models in stochastic simulation of the response of offshore wind turbines.

scholarly journals Reliability analysis of offshore wind turbine foundations under lateral cyclic loading

2020 ◽  
Vol 5 (4) ◽  
pp. 1521-1535
Author(s):  
Gianluca Zorzi ◽  
Amol Mankar ◽  
Joey Velarde ◽  
John D. Sørensen ◽  
Patrick Arnold ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Wind Turbine ◽  
Limit State ◽  
Large Diameter ◽  
Probabilistic Approach ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Fe Model ◽  
Foundation Design

Abstract. The design of foundations for offshore wind turbines (OWTs) requires the assessment of long-term performance of the soil–structure interaction (SSI), which is subjected to many cyclic loadings. In terms of serviceability limit state (SLS), it has to be ensured that the load on the foundation does not exceed the operational tolerance prescribed by the wind turbine manufacturer throughout its lifetime. This work aims at developing a probabilistic approach along with a reliability framework with emphasis on verifying the SLS criterion in terms of maximum allowable rotation during an extreme cyclic loading event. This reliability framework allows the quantification of uncertainties in soil properties and the constitutive soil model for cyclic loadings and extreme environmental conditions and verifies that the foundation design meets a specific target reliability level. A 3D finite-element (FE) model is used to predict the long-term response of the SSI, accounting for the accumulation of permanent cyclic strain experienced by the soil. The proposed framework was employed for the design of a large-diameter monopile supporting a 10 MW offshore wind turbine.

At-Sea Experiment on Durability and Residual Strength of Polyester Rope for Mooring of Floating Wind Turbine

2019 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Iku Sato ◽  
Koji Tanaka
Keyword(s):  
Wind Turbine ◽  
Residual Strength ◽  
Offshore Wind ◽  
Synthetic Fiber ◽  
Floating Body ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Response Analysis ◽  
Initial State ◽  
Characteristic Values

Abstract When using synthetic fiber rope as a mooring line of a floating body such as floating offshore wind turbine (FOWT), it is necessary to carry out characteristic test and to grasp well about strength, stiffness, durability against monotonic and cyclic loadings. In this research, we have made characteristics test of polyester rope based on ISO. Next, based on the obtained characteristic values (mass, stiffness, strength, etc.), the dynamic response analysis of the floating body-mooring system was carried out and the mooring design was carried out. It was actually operated as a floating body mooring line for about 1 year. During the operation period, no abnormality was found, nor appearance damage occurred. After completion of operation for 1 year, the polyester rope was collected and residual strength test was carried out. As a result, no serious deterioration situation such as infiltration of marine organisms or fracture of the strands due to wear between fibers was observed at all. On the other hand, with respect to durability, it was found that the strength reduction was 2.9% from the initial state with respect to the breaking strength.

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