Sensitivity analysis and optimization of passive gyrostabilizers to mitigate pitch motion of a semi-submersible floating offshore wind turbine

Floating offshore wind turbines (FOWTs) subjected to combined wind and wave loads experience significant pitch motion, resulting in reduced energy production and increased structural damage. This study proposes the utilization of passive gyrostabilizers as an effective solution to mitigate these issues. Initially, a coupled dynamic model for a semi-submersible FOWT incorporating passive gyrostabilizers was developed using an in-house simulation tool. Building on this framework, the study investigated the effects of gyrostabilizer quantity and arrangement strategies, gyro-rotor speeds, and precession damping coefficients on its pitch reduction. Additionally, the performance of the gyrostabilizers under varying wind and wave conditions was analyzed to identify key influencing factors. Finally, genetic algorithm (GA)-based parameters optimization of the passive gyrostabilizers was conducted, achieving a maximum pitch-reduction rate of 93.8 %. However, when accounting for the power consumption of the gyrostabilizers, an optimized pitch-reduction rate of 80.7 % was identified. These findings contribute valuable insights into the potential of gyrostabilizers for FOWT applications and signify a significant advancement in the state of the art in this field. • Developing a nonlinear coupled dynamic model integrating gyrostabilizers to suppress the pitch motion of FOWTs. • Analyzing the effects of gyrostabilizers' quantity, arrangement and parameters on performance. • Investigating pitch-reduction performance variations across environmental conditions. • Optimizing the passive gyrostabilizer parameters using a genetic algorithm, significantly enhancing performance.