A Comparative Analysis of the Characteristics of Platform Motion of a Floating Offshore Wind Turbine Based on Pitch Controllers

Abstract

The installation of fixed offshore wind power systems at greater water depths requires a floating body at the foundation of the system. However, this presents various issues. This study analyzes the characteristics of the platform motion of a floating offshore wind turbine system based on the performance of the pitch controller. The motion characteristics of the platform in a floating offshore wind power generation system, change according to the response speed of the blade pitch controller since the wind turbine is installed on a floating platform unlike the existing onshore wind power generation system. Therefore, this study analyzes the platform motion characteristics of a floating offshore wind turbine system using various pitch controllers that have been applied in previous studies. Consequently, an appropriate pitch controller is proposed for the floating offshore wind turbine system. The floating offshore wind turbine system developed in this study consists of an NREL 5-MW class wind turbine and an OC4 semi-submersible floating platform; the pitch controller is evaluated using FAST-v8 developed by NREL. The results of this study demonstrate that the pitch controller reduces the platform motion of the floating offshore wind power generation system, considering both the individual pitch control and the negative damping phenomenon. Additionally, it is confirmed that the output increases by approximately 0.42%, while the output variability decreases by 19.3% through the reduction of the platform movement.