Browsing by Author "Scheu, Matti Niclas"
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Item Open Access Influence of statistical uncertainty of component reliability estimations on offshore wind farm availability(Elsevier, 2017-05-05) Scheu, Matti Niclas; Kolios, Athanasios; Fischer, Tim; Brennan, Feargal P.Offshore wind turbine reliability, one of the industry's biggest sources of uncertainty, is the focus of the present paper. Specifically the impact of uncertain component failure distributions at constant failure rates has been investigated with respect to its implications for wind farm availability. A fully probabilistic offshore wind simulation model has been applied to quantify results; effects shown in this paper underline the significant impact that failure probability distributions have on asset performance evaluation. It was found that wind farm availability numbers may vary in the range up to 20 % just by changing the distributions of failure to a different pattern; in particular those scenarios in which extensive failure accumulation occurred led to significant losses in production. Results are interpreted and discussed mainly from the viewpoint of an offshore wind farm developer, owner and operator, with implications underlined for application in state-of-the-art offshore wind O&M (Operations and Maintenance) models and simulation tools.Item Open Access Whole body vibration on offshore structures: an evaluation of existing guidelines for assessing low-frequency motions(International Society of Offshore and Polar Engineers, 2018-06-30) Schwarzkopf, Marie-Antoinette; Scheu, Matti Niclas; Altay, Okyay; Kolios, AthanasiosAn extensive literature research has been conducted to create an insight into the existing norms and standards regulating the assessment of human exposure to motions in offshore environments. A summary of current threshold values and their specific fields of application is included. The presented literature is analysed with respect to their applicability for assessing low frequency oscillatory motions of floating offshore wind turbines to which technicians are exposed during maintenance tasks. The review identifies the need for a consistent assessment method in combination with threshold values for floating structures.