Limiting Wave Conditions for the Safe Maintenance of Floating Wind Turbines

Abstract

This paper investigates the limiting wave conditions at which a wind turbine technician can complete maintenance activities safely and effectively on a 15MW floating offshore wind turbine. Through linear, frequency-domain statistical analysis of floating turbine motion and applying acceptable motion limits for technician working, significant wave height and peak wave period limits are investigated. It was found that over the range of wave conditions considered, the turbine nacelle motion did not exceed the motion limits for technician working considered in this analysis. Further analysis found that the turbine nacelle motion increased with increasing significant wave height and was also significantly influenced by peak wave period. The impact of differing wave characteristics is also investigated through the use of different wave energy spectra and also found to have an impact on turbine nacelle motion.

Assessing the Welfare of Technicians during Transits to Offshore Wind Farms

“…These proxies used were selected due to their relationships with whole-body accelerations, which are supported by findings in the literature, including the relationship between the magnitude of RMS accelerations and levels of discomfort [6] and MSI as an indicator of the incidence of seasickness [5]. Significant contributions to the literature were made in describing the non-homogeneous random variables of sea-state and vessel operational parameters, as typically, studies on human exposure to acceleration calculate the RMS of vessel acceleration using a response amplitude operator (RAO) along with wave energy to produce response spectra [42] or combine numerical ocean models to seat models, providing a range of sea state and vessel parameters for analysis [22]. This is because experimental in situ measurements of sea-state and vessel characteristics have limited spatial coverage and are time-consuming and expensive [22,44].…”

“…We show the results of the model generated using the MATLAB 'ftrgp' function with 'KernelFunction = rationalquadratic', 'BasisFunction = constant', 'Standardize = true', 'PredictMethod = Exact', as the model specification. The accuracy of the models was measured using their R 2 , MSE, and RMSE values, which are best used in measuring regression model performance [42]. These measures were chosen to identify how well the models predicted the proxy variables and present measures through which improved models can be tested against.…”

A dynamic-simulation based workability and accessibility combined method for systematic analysis of floating wind operations

“…A 5 % decrease of the workable window duration was found with time domain simulations, where H s , T p and platform design had a significant impact on the results [6]. Conversely, no workability breach was estimated for waves up to H s = 3 m in a rigid frequency domain model [7], showing the need for more methodological consistency and floating industry applicable workability indicators.…”

Adaptations of Offshore Wind Operation and Maintenance Models for Floating Wind

“…In [8,9] where the dynamic responses of FOW turbines are investigated, the authors suggest that weather criteria's which are normally used to assess weather windows and accessibility for maintenance operations of FBW are no longer adequate for FOW, and may require adjustments that consider the dynamic motion response of the floating structure.…”