Dynamic response analysis of a semi-submersible floating wind turbine based on different coupling methods

Abstract

This article compares and analyzes the overall performance of offshore floating wind turbines using fully coupled and semi-coupled methods considering aerodynamic loads, as well as decoupled methods without considering aerodynamic loads. The aim is to study the impact of different coupling methods on the dynamic response of floating wind turbines and provide a reference for selecting more convenient calculation methods for the preliminary design of floating wind turbines. Based on the open-source software OpenFAST and the commercial hydrodynamic software AQWA, the OC4-DeepCwind semi-submersible offshore floating wind turbine foundation and the NREL 5 MW reference wind turbine model are selected as the research objects. The natural period of the floating structure is validated, and then the power generation and shutdown conditions of the floating wind turbine are selected as the calculation conditions. The motion responses of the floating structure and mooring tension of the floating wind turbine are calculated in the time domain, and the calculation results are statistically analyzed. The research results show that the decoupled analysis method without considering aerodynamic loads significantly underestimates the dynamic response of the floating wind turbine, and the semi-coupled method is more conservative than the fully coupled method. Therefore, in the absence of conditions for fully coupled analysis, the semi-coupled method can be used as a substitute analysis method in the preliminary design stage.