Investigation on the limit state of a triple-column spar floating wind turbine concept

The limit state of a newly proposed floating wind turbine concept, in terms of ultimate structural load and fatigue damage load, is studied in the present work. This novel floating structure utilizes a triple-column spar platform to support the wind turbine. An aero-hydro-servo-elastic numerical model is developed to simulate its coupled dynamics. The probability distribution of the ultimate structural load is estimated based on the Monte-Carlo method. In order to reduce computation endeavor, a statistic model is used to extrapolate the sampled-based distribution function. The S-N curve method, a state-of-art fatigue analysis approach, is used to assess the fatigue damage load. The limit states of tower base and fairlead are investigated. It is shown that the newly proposed triple-column spar concept suffers less fatigue damage and the ultimate structural loads are also reduced, resulting in the enhancement of safety level of the floating wind turbine system