Analysis of Offshore Wind Turbine Operation and Maintenance Using a Novel Time Domain Meteo-Ocean Modeling Approach

2012 ◽  
Author(s):  
I. Dinwoodie ◽  
F. Quail ◽  
D. McMillan
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Wave Height ◽  
Time Domain ◽  
Significant Wave Height ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Significant Wave ◽  
Modeling Approach ◽  
Operation And Maintenance

This paper presents a novel approach to repair modeling using a time domain Auto-Regressive model to represent meteo-ocean site conditions. The short term hourly correlations, medium term access windows of periods up to days and the annual distribution of site data are captured. In addition, seasonality is included. Correlation observed between wind and wave site can be incorporated if simultaneous data exists. Using this approach a time series for both significant wave height and mean wind speed is described. This allows MTTR to be implemented within the reliability simulation as a variable process, dependent on significant wave height. This approach automatically captures site characteristics including seasonality and allows for complex analysis using time dependent constraints such as working patterns to be implemented. A simple cost model for lost revenue determined by the concurrent simulated wind speed is also presented. A preliminary investigation of the influence of component reliability and access thresholds at various existing sites on availability is presented demonstrating the ability of the modeling approach to offer new insights into offshore wind turbine operation and maintenance.

scholarly journals Towing Performance of the Submerged Floating Offshore Wind Turbine under Different Wave Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 633
Author(s):  
Conghuan Le ◽  
Jianyu Ren ◽  
Kai Wang ◽  
Puyang Zhang ◽  
Hongyan Ding
Keyword(s):  
Wind Turbine ◽  
Wave Height ◽  
Significant Wave Height ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Roll Motion ◽  
Floating Offshore Wind Turbine ◽  
Pitch Motion ◽  
Significant Wave ◽  
Heave Motion

One of the advantages of floating offshore wind turbines (FOWTs) is that they can be designed to be easily wet towed and installed to reduce the cost of offshore construction. In this paper, a fully coupled towing system numerical model is established for a novel 10 MW FOWT concept, namely, a submerged floating offshore wind turbine (SFOWT) to investigate the towing performance. Firstly, the numerical simulation is validated by comparison with model experiment results. Then, a series of numerical simulations are conducted to predict and compare the towing performance for a three-column SFOWT (TC-SFOWT) and a four-column SFOWT (FC-SFOWT) under different wave conditions. The results show that the two forms of SFOWT have good towing performance when the significant wave height is less than 5 m, which is the maximum wave height for the allowable towing condition. The FC-SFOWT shows relatively better performance in heave motion and roll motion, but the towing force is relatively larger compared with the TC-SFOWT under the same condition. When the significant wave height is 5 m, the maximum values of heave motion, pitch motion, and roll motion of the TC-SFOWT are 2.51 m, 2.14°, and 1.38°, respectively, while they are 2.25 m, 2.70°, and 1.21°, respectively, for the FC-SFOWT. Both the roll motion and the pitch motion are satisfied with the requirement that the roll and pitch are less than 5° during the towing process. The mean towing force of FC-SFOWT is 159.1 t at the significant wave height of 5 m, which is 52.8% larger than that of TC-SFOWT. The peak period mainly influences the frequency where the response peak appears in power spectra. The findings in this paper could provide some guidelines for wet towed operations.

Relative Motion During Single Blade Installation: Measurements From the North Sea

2020 ◽  
Author(s):  
Aljoscha Sander ◽  
Andreas F. Haselsteiner ◽  
Kader Barat ◽  
Michael Janssen ◽  
Stephan Oelker ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Sea ◽  
Relative Motion ◽  
Significant Wave Height ◽  
Offshore Wind ◽  
Wave Excitation ◽  
Significant Wave ◽  
The North ◽  
The North Sea

Abstract During single blade installation in offshore wind farms, relative motion between nacelle and blade root due to wind and wave excitation pose a significant challenge. Wave excitation can be modelled considerably well by employing state-of-the-art simulation tools and can, therefore, be included in installation planning. Other phenomena, such as flow-induced vibrations are hard to capture and hence challenging to account for when defining installation procedures and limitations. Here, we present measurements conducted during the installation of an offshore wind farm consisting of multi-megawatt turbines installed on monopile foundations in the North Sea. A custom-built sensor capturing linear & angular acceleration and GPS-data was deployed atop the nacelle. Both partially and fully assembled turbines displayed complex oscillation orbits, swiftly changing amplitude and direction. Mean nacelle deflection correlated strongly with significant wave height as well as mean wind speed. As wind speed and significant wave height showed a strong correlation as well, it is difficult to discern which load drives the observed relative motions. While wind loads are significantly smaller than wave loads on partially assembled turbines under installation conditions, additional momentum induced by vortex shedding may prove sufficient to cause the observed effects.

scholarly journals SARAL-AltiKa Wind and Significant Wave Height for Offshore Wind Energy Applications in the New England Region

2020 ◽  
Vol 13 (1) ◽  
pp. 57
Author(s):  
Xinba Li ◽  
Panagiotis Mitsopoulos ◽  
Yue Yin ◽  
Malaquias Peña
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
New England ◽  
Wave Height ◽  
Significant Wave Height ◽  
Surface Wind ◽  
Offshore Wind ◽  
Significant Wave ◽  
In Situ Observations

The SARAL-AltiKa dataset was evaluated for refined offshore wind energy resources assessment and potential metocean monitoring capability in the Southern New England region. Surface wind speed and Significant Wave Height (Hs) products were assessed with corresponding variables from buoy observations for 2014–2019. To increase the sample size, this study analyzed and applied an approach to collect data around the reference buoys beyond the satellite footprint at the expense of a bias increment. The study corroborated the accuracy of the SARAL-AltiKa measurements for the offshore area of interest and added details for stations closer to the coast compared with past studies. A proportional bias with underestimation of high values of Hs was found in coastal sites. Wind speed estimates on the other hand appear to be less sensitive to the closeness to the coast. The empirical relationship between wind strength and Hs in the buoy observations is reproduced to a large extent by the AltiKa measurements in locations where land contamination is minimal. The histograms of surface wind and Hs are well described by the Weibull distribution and the shape and scale parameters closely resemble those of the histograms of the collocated in situ observations. We use these results to extrapolate the winds to a target domain with no in situ observations for wind energy resource estimation.

Coupled Dynamic Analysis for Multi-Unit Floating Offshore Wind Turbine in Maximum Operational and Survival Conditions

2015 ◽  
Author(s):  
H. K. Jang ◽  
H. C. Kim ◽  
M. H. Kim ◽  
K. H. Kim
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Time Domain ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Random Waves ◽  
Mooring Lines ◽  
Floating Offshore Wind Turbine ◽  
Coupled Dynamic Analysis ◽  
Floating Offshore Wind Turbines

Numerical tools for a single floating offshore wind turbine (FOWT) have been developed by a number of researchers, while the investigation of multi-unit floating offshore wind turbines (MUFOWT) has rarely been performed. Recently, a numerical simulator was developed by TAMU to analyze the coupled dynamics of MUFOWT including multi-rotor-floater-mooring coupled effects. In the present study, the behavior of MUFOWT in time domain is described through the comparison of two load cases in maximum operational and survival conditions. A semi-submersible floater with four 2MW wind turbines, moored by eight mooring lines is selected as an example. The combination of irregular random waves, steady currents and dynamic turbulent winds are applied as environmental loads. As a result, the global motion and kinetic responses of the system are assessed in time domain. Kane’s dynamic theory is employed to formulate the global coupled dynamic equation of the whole system. The coupling terms are carefully considered to address the interactions among multiple turbines. This newly developed tool will be helpful in the future to evaluate the performance of MUFOWT under diverse environmental scenarios. In the present study, the aerodynamic interactions among multiple turbines including wake/array effect are not considered due to the complexity and uncertainty.

A Comparison of Time Domain Seismic Analysis Methods for Offshore Wind Turbine Structures: Using a Superelement Approach

2019 ◽  
Author(s):  
Laurens Alblas ◽  
Corine de Winter
Keyword(s):  
Rigid Body ◽  
Wind Turbine ◽  
Time Domain ◽  
Wind Farm ◽  
Assessment Tool ◽  
Seismic Analysis ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Rigid Body Motions ◽  
Seismic Accelerations

Abstract Recently, wind farm development has gained more traction in Asian countries such as Taiwan, which are seismically active. Compared to Europe, the offshore wind structures need to be designed for these additional extreme environmental conditions. For monopiles, these calculations can typically be performed in an integrated way in the wind turbine load calculation, but for jackets the superelement (SE) approach remains preferred. At the time of writing different approaches are being applied in the industry to apply the SE approach for seismic time domain analysis. This work explains and compares three different methods, based on calculations performed in offshore strength assessment tool Sesam and aeroelastic tool BHawC. When including additional interface nodes at the foundation model bottom into the SE to which the seismic accelerations can be applied in BHawC similarly as in the re-tracking run in Sesam, the results between BHawC and Sesam are nearidentical. Using a normal SE, which only includes an interface node for the connection to the wind turbine tower bottom, and including the response due to seismic displacements into the SE load file gives a match between BHawC and Sesam, and closely matches the results of the case with additional interface nodes. Doing the same but only including the dynamic response of the interface point relative to a frame of reference moving with the rigid body motions as caused by the seismic accelerations into the SE load file, significant differences occur. This is due to the lack of the loading effect of rigid body motions. The same conclusions on how these methods compare can be drawn when using different wind and wave cases. The presented results give insights into the differences between the methods and how the choice of method may influence the results.

scholarly journals Design Optimization and Coupled Dynamics Analysis of an Offshore Wind Turbine with a Single Swivel Connected Tether

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3526 ◽  
Author(s):  
Jieyan Chen ◽  
Chengxi Li
Keyword(s):  
Wind Turbine ◽  
Design Optimization ◽  
Time Domain ◽  
Dynamic Performance ◽  
Coupled Systems ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Elastic Model ◽  
Dynamics Analysis ◽  
Coupled Dynamics

The increased interest in renewable wind energy has stimulated many offshore wind turbine concepts. This paper presents a design optimization and a coupled dynamics analysis of a platform with a single tether anchored to the seabed supported for a 5 MW baseline wind turbine. The design is based on a concept named SWAY. We conduct a parametric optimization process that accounts for important design considerations in the static and dynamic view, such as the stability, natural frequency, performance requirements, and cost feasibility. Through these optimization processes, we obtain and present the optimized model. We then establish the fully coupled aero-hydro-servo-elastic model by the time-domain simulation tool FAST (Fatigue, Aerodynamics, Structures, and Turbulence) with the hydrodynamic coefficients from an indoor program HydroGen. We conduct extensive time-domain simulations with various wind and wave conditions to explore the effects of wind speed and wave significant height on the dynamic performance of the optimized SWAY model in various water depths. The swivel connection between the platform and tether is the most special design for the SWAY model. Thus, we compare the performance of models with different tether connection designs, based on the platform motions, nacelle velocity, nacelle accelerations, resonant behaviors, and the damping of the coupled systems. The results of these comparisons demonstrate the advantage of the optimized SWAY model with the swivel connection. From these analyses, we prove that the optimized SWAY model is a good candidate for deep water deployment.

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