Floating offshore wind turbine reliability analysis based on system grading and dynamic FTA

•The scientific reliability analysis on floating offshore wind turbines and relative maintenance suggestions is first presented, which can supply the guidance for its future design and operation.•The dynamic FTA for floating offshore wind turbine is conducted on the basis of system grading, taking relations between modules and dynamic failure mechanism into consideration.•A special approach is employed in this paper to obtain failure rates of relevant events in all the fault trees, which is suitable to new product specially. To ensure the data’s reasonability, the failure rates are estimated based on different failure cases reviewed from various references, for respective characteristics of different modules.•A series of high-risk factors that results in modules and the whole system are derived, and corresponding measures are proposed for references.

Currently, floating offshore wind power acts as a new form of marine renewable energy, attracting much attention all over the world. Due to constraints of technology and cost, floating wind turbines are still at the stage of preliminary trials. Reliability analysis on floating wind turbines is essential and urgent for solving the issues caused by high cost and challenges in searching failure causes. Primarily, this research proposes the scientific, systematic grading of floating wind power equipment system based upon its structure and function, providing with explicit internal relation of system and the precondition of failure modes analysis. Dynamic fault tree analysis on floating wind turbines is conducted to discuss sequentially dependent failures and redundancy failures. Furthermore, failure rates of relevant offshore structures are searched according to previous studies, databases and reports. Different modules of floating wind turbines take respective proper failure cases for references. The overall reliability results of floating wind turbines has been achieved. The research contributes to designing, construction and maintenance of floating wind turbines to control investment and enlarge economic benefits.