Lifetime extension for large offshore wind farms: Is it enough to reassess fatigue for selected design positions?

Bouty, Corantin; Schafhirt, Sebastian; Ziegler, Lisa; Muskulus, Michael

doi:10.1016/j.egypro.2017.10.381

Cited by 23 publications

(14 citation statements)

References 7 publications

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“…where, in this paper, = 2.49 and = 10.4 / are the values assumed for the shape parameter and scale parameter [31] in order to fit the available SS data. Wind turbines are typically designed for 20-25 years [32]. Under average wind conditions, an onshore wind turbine can produce electricity for 4000-7000 h a year, corresponding to 70%-80% of the total hours in the year [33].…”

Section: Environmental Conditions and Considered Sssmentioning

confidence: 99%

Fatigue Life Assessment for Power Cables in Floating Offshore Wind Turbines

et al. 2020

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In this paper, a procedure is proposed to determine the fatigue life of the electrical cable connected to a 5 MW floating offshore wind turbine, supported by a spar-buoy at a water depth of 320 m, by using a numerical approach that takes into account site-specific wave and wind characteristics. The effect of the intensity and the simultaneous actions of waves and wind are investigated and the outcomes for specific cable configurations are shown. Finally, the fatigue life of the cable is evaluated. All analyses have been carried out using the Ansys AQWA computational code, which is a commercial code for the numerical investigation of the dynamic response of floating and fixed marine structures under the combined action of wind, waves and current. Furthermore, this paper applies the FAST NREL numerical code for comparison with the ANSYS AQWA results.

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Section: Environmental Conditions and Considered Sssmentioning

confidence: 99%

Fatigue Life Assessment for Power Cables in Floating Offshore Wind Turbines

et al. 2020

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“…Dimitrov and Natarajan 14 used SCADA data for lifetime assessment and performance optimization and used machine learning to handle data limitations. Bouty et al 15 argue that it might not be economical to assess fatigue life for each turbine in a wind farm and propose an extrapolation method, when the conditions for several wind turbines are similar. Ziegler and Muskulus 16 compared a fracture mechanics model to the SN curve approach for jacket‐supported offshore wind turbines and outlined the challenges and opportunities in the fracture mechanics approach.…”

Section: Introductionmentioning

confidence: 99%

Risk‐based derivation of target reliability levels for life extension of wind turbine structural components

Nielsen

Sørensen

2021

Wind Energy

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The main wind turbine design standard IEC61400‐1 ed. 4 includes an annual target reliability index for structural components of 3.3. Presently, no standards specify specific reliability requirements for existing wind turbines, to be used in relation to verification of structural integrity for life extension or continued operation. For existing structures in general, both economic and sustainability considerations support differentiation in reliability targets, as it is generally more expensive and requires more resources to improve the reliability. ISO2394 “General Principles on Reliability for Structures” includes tables with differentiated reliability targets depending on the consequences of failure and costs of improving reliability, which are derived using risk‐based economic optimization. However, the assumptions behind these tables do not match the specific problem of life extension of wind turbines. In this paper, the risk‐based approach is applied to derive specific target reliability levels for life extension of wind turbines, and a target annual reliability index around 3.1 is proposed.

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“…Various parameters, such as turbulence intensity, mean wind speed, availability, and corrosion, affect the fatigue life, and for offshore wind turbines, additional parameters regarding the wave climate; the interaction of these are case-specific, thus site-specific assessment is generally necessary [5]. However, for a wind farm where conditions are similar for the turbines within the wind farm, it is possible to assess the fatigue life for some turbines and extrapolate for the remaining turbines [6].…”

Section: Introductionmentioning

confidence: 99%

“…The deterministic and probabilistic models are based on the models used in [29] for calibration of partial safety factors for IEC 61400-1 ed. 4 [6], and the riskinformed assessment model was first presented in [36] for the derivation of a target reliability index for life extension. The models are briefly outlined for the sake of completeness, and the reader is directed to the references above for further details.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic and Risk-Informed Life Extension Assessment of Wind Turbine Structural Components

2021

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Reassessment of the fatigue life for wind turbine structural components is typically performed using deterministic methods with the same partial safety factors as used for the original design. However, in relation to life extension, the conditions are generally different from the assumptions used for calibration of partial safety factors; and using a deterministic assessment method with these partial safety factors might not lead to optimal decisions. In this paper, the deterministic assessment method is compared to probabilistic and risk-based approaches, and the economic feasibility is assessed for a case wind farm. Using the models also used for calibration of partial safety factors in IEC61400-1 ed. 4, it is found that the probabilistic assessment generally leads to longer additional fatigue life than the deterministic assessment method. The longer duration of the extended life can make life extension feasible in more situations. The risk-based model is applied to include the risk of failure directly in the economic feasibility assessment and it is found that the reliability can be much lower than the target for new turbines, without compromising the economic feasibility.

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Lifetime extension for large offshore wind farms: Is it enough to reassess fatigue for selected design positions?

Cited by 23 publications

References 7 publications

Fatigue Life Assessment for Power Cables in Floating Offshore Wind Turbines

Fatigue Life Assessment for Power Cables in Floating Offshore Wind Turbines

Risk‐based derivation of target reliability levels for life extension of wind turbine structural components

Probabilistic and Risk-Informed Life Extension Assessment of Wind Turbine Structural Components

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