Integrated dynamic modeling and global reliability analysis of floating offshore wind turbines

Structural design methods based on global reliability are crucial to the safety and economy of floating offshore wind turbines that are designed for harvesting wind energy in the deep sea. The dynamic modeling and reliability assessment of floating offshore wind turbines are first briefly reviewed. Then the main attention of the present study is paid to the global reliability assessment of floating offshore wind turbines. To this end, an integrated dynamic model of floating offshore wind turbines is introduced by synthesizing the multibody dynamics and the finite element method so that the responses of floating offshore wind turbines can be analyzed. To reasonably consider the joint effects of wind and wave loads on the structure, a joint probability distribution model of multiple nonlinearly dependent environmental variables is adopted using the Copula method based on long-term wind and wave data from the South China Sea. On this basis, the probability density evolution method is employed to evaluate the global reliability of a spar-type floating offshore wind turbine under rated wind conditions with extreme wind shear. The present study provides a framework for global reliability analysis of floating offshore wind turbines, laying the foundation for performing reliability-based optimization designs of floating offshore wind turbines.