Abstract
Applied pitch control usually used in onshore wind turbine to Floating Offshore Wind Turbine, some property such as Tower vibration, produced power were negative damped. We call it negative damping. When using Floating Wind Turbine, rated power is to be reduced to avoid negative damping. In this paper, we reproduce negative damping of Floating Offshore Wind Turbine by tank test, based on it, devise and evaluate a pitch control system to suppress negative damping. According to tank test, tower pitch motion was amplified by pitch control. We propose a new pitch control system to control turbine rotation and tower movement, and evaluate this control by tank test of scale model wind turbine and numerical simulation of NREL 5MW Wind Turbine using FAST that made by NREL. This research shows that we should not use pitch control only but combine other control such as torque control to suppress negative damping.
