Dynamic response of floating offshore wind turbine under different stages of typhoon passage

Offshore floating wind turbine (FOWT) represents one of the most promising frontiers for the development of wind energy. However, its safety and the dynamic response characteristics are compromised by the occurrence of typhoons, which, unlike monsoons, exhibit characteristics like extreme wind speeds, anomalous turbulence, and wind direction shifts during their moving. In this paper, the severe typhoon Hagupit is taken as the impacting storm, with modeling characteristics, including the typhoon profile, turbulent wind spectra, and wave factors, based on the actual measured data. The typhoon wind field model is further developed within the integrated analysis software OpenFAST, allowing the derivation of the response and load characteristics of a FOWT during various stages of a typhoon passage, also analyzing the impact of yaw error. The results indicate that the Front Eye-wall Stage (FEWS) exerts the greatest influence on platform motion and load response, with heightened risk of damage to turbine blades and mooring lines. The resulting response spectrum reflects a coupling characteristic of wave frequency, the first or second structural natural frequency, and typhoon frequency. The effect of yaw error on the safety of the wind turbine system is significant. Within a certain range of yaw error angles, not only does such misalignment increase the platform's response, but also amplifies the load borne by the upper structure and lower mooring system of the platform, while this effect weakens once the yaw error surpasses a certain threshold.