Wind-wave directional effects on fatigue of bottom-fixed offshore wind turbine

Sørum, Stian Høegh; Krokstad, Jørgen R; Amdahl, Jørgen

doi:10.1088/1742-6596/1356/1/012011

Cited by 6 publications

(7 citation statements)

References 10 publications

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“…A slightly modified version of the DTU 10-MW reference turbine is used in the present study. 30 The modifications on the turbine itself are performed by Bachynski and Ormberg, 31 while Sørum et al 32 designed the monopile foundation. The wind turbine, foundation and soil characteristics used in the current study are equal to the base model of Sørum et al, 32 with the exception of a slightly larger monopile diameter.…”

Section: Responsementioning

confidence: 99%

“…30 The modifications on the turbine itself are performed by Bachynski and Ormberg, 31 while Sørum et al 32 designed the monopile foundation. The wind turbine, foundation and soil characteristics used in the current study are equal to the base model of Sørum et al, 32 with the exception of a slightly larger monopile diameter. The water depth is 30 m and the monopile extends 43 m below the mud line.…”

Section: Responsementioning

confidence: 99%

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Quasi‐static response of a bottom‐fixed wind turbine subject to various incident wind fields

2021

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In the design of offshore wind farms the simulated dynamic response of the wind turbine structure includes loading from turbulent wind. The International Electrotechnical Commission (IEC) standard for wind turbine design recommends both the Mann spectral tensor model and the Kaimal spectral model combined with an exponential coherence formulation. These models give deviating wind loads. This study compares these two models to a large eddy simulations model and a model based on offshore wind measurements. The comparisons are performed for three situations, covering unstable, neutral and stable atmospheric conditions. The impact of the differences in the wind fields on the quasi-static response of a large bottom-fixed wind turbine is investigated. The findings are supported by an assessment of the impact of individual wind characteristics on the turbine responses. The wind model based on measurements causes high tower bottom and blade root flapwise bending moments due to a high wind load at very low frequencies. Low and negative horizontal coherence is obtained using the Mann spectral tensor model. This causes relatively large yaw moments as compared to the results using the other wind models. The largest differences in response are seen in the stable situation. We furthermore show that the quasi-static wind load has great impact on the total damage equivalent moments of the structure. From the results, we conclude that in the design of large offshore wind turbines one should carefully consider the structure of the turbulent wind.Further, longer simulations than recommended by the standards should be used to reduce uncertainty in estimated response.

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Section: Responsementioning

confidence: 99%

Section: Responsementioning

confidence: 99%

Quasi‐static response of a bottom‐fixed wind turbine subject to various incident wind fields

2021

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“…Despite this, wave spreading has received little attention in the research community, with the authors knowing only three studies. 21,22,75 The effect of the soil model is also significant, demonstrating the need for accurate modelling of soil damping and stiffness. In terms of the coherence model, most models used today are developed for small diameter rotors with onshore wind conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Including short‐crested waves was found to reduce the fatigue damage. Sørum et al 22 showed that short‐crested waves may result in both a higher and lower fatigue damage than long‐crested waves, depending on the monopile design. Bachynski and Ormberg 23 showed that wave diffraction becomes more important as monopile diameters increase.…”

Section: Introductionmentioning

confidence: 99%

Fatigue design sensitivities of large monopile offshore wind turbines

et al. 2022

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The input for fatigue analyses of offshore wind turbines is typically chosen based on design values provided by design standards. While this provides a straightforward design methodology, the contribution of different input parameters to the uncertainty in the fatigue damage estimates is usually unknown. This knowledge is important to have when improving current designs and methodologies, and the parameters governing the uncertainty is typically found through a sensitivity analysis. Several sensitivity studies have been performed for monopile‐based offshore wind turbines, typically focusing on specific turbines and engineering disciplines. This paper performs a sensitivity study for three monopile‐based offshore wind turbines (5 MW, 10 MW, 15 MW) using parameters from several engineering disciplines. The results show that the fatigue utilization is primarily governed by the uncertainty in the SN curves and fatigue capacity. Following this, the uncertainty in the environmental conditions is the dominating uncertainty, with wind loads becoming increasingly important as turbine size increases. Additionally, the effect of modelling uncertainties is investigated. The wind‐related model uncertainties dominate in the tower top, while uncertainties in the wave and soil models dominate in the tower base and monopile. Designers wanting to reduce the uncertainty in a design are recommended to focus on the environmental conditions, and using as accurate models as possible. All modelling uncertainties are significant, but research should particularly be focused on wave directionality and soil models.

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“…Current standards adopted the conservative assumption of the unidirectionality of environmental forces which represents a worst-case scenario. Such an assumption can adversely affect the accuracy of fatigue analysis, reliability analysis and also the dynamic analysis of MPOPs with complex geometries, e.g., the direct attachment of an aquaculture cage to the foundation of an OWT) ( Sørum et al, 2019 ).…”

Section: Reliability Analysis Of the Integrated Systemmentioning

confidence: 99%

Reliability of multi-purpose offshore-facilities: Present status and future direction in Australia

Aryai

Abdussamie

Salehi

et al. 2021

Process Safety and Environmental Protection

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Sustainable use of the ocean for food and energy production is an emerging area of research in different countries around the world. This goal is pursued by the Australian aquaculture, offshore engineering and renewable energy industries, research organisations and the government through the “Blue Economy Cooperative Research Centre”. To address the challenges of offshore food and energy production, leveraging the benefits of co-location, vertical integration, infrastructure and shared services, will be enabled through the development of novel Multi-Purpose Offshore-Platforms (MPOP). The structural integrity of the designed systems when being deployed in the harsh offshore environment is one of the main challenges in developing the MPOPs. Employing structural reliability analysis methods for assessing the structural safety of the novel aquaculture-MPOPs comes with different limitations. This review aims at shedding light on these limitations and discusses the current status and future directions for structural reliability analysis of a novel aquaculture-MPOP considering Australia’s unique environment. To achieve this aim, challenges which exist at different stages of reliability assessment, from data collection and uncertainty quantification to load and structural modelling and reliability analysis implementation, are discussed. Furthermore, several solutions to these challenges are proposed based on the existing knowledge in other sectors, and particularly from the offshore oil and gas industry. Based on the identified gaps in the review process, potential areas for future research are introduced to enable a safer and more reliable operation of the MPOPs.

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Wind-wave directional effects on fatigue of bottom-fixed offshore wind turbine

Cited by 6 publications

References 10 publications

Quasi‐static response of a bottom‐fixed wind turbine subject to various incident wind fields

Quasi‐static response of a bottom‐fixed wind turbine subject to various incident wind fields

Fatigue design sensitivities of large monopile offshore wind turbines

Reliability of multi-purpose offshore-facilities: Present status and future direction in Australia

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