Risk assessment of floating offshore wind turbines based on fuzzy fault tree analysis

Risk assessment of Floating Offshore Wind Turbines (FOWTs) relies on failure statistics, which are usually collected from various source. In order to quantify the information uncertainties, this paper introduces the Fuzzy Fault Tree Analysis (FFTA) to assess the risk of semi-submersible FOWTs. A Fault Tree (FT) model is adopted to analyze the risk evolution mechanism of the FOWT and the fuzzy set theory is employed to process the failure statistics. As the results of quantitative analysis, the failure intervals of the FOWT and critical assemblies are calculated. The risk measure named Fuzzy Critical Importance (FCI) is utilized to compute the sequence of the basic fault events and identify critical components. A comparison analysis is performed and the results indicate that the present FFTA method is more in line with practical and has the merit in error reduction of failure rate figured out.