Pitch Motion Studies of Barge Supporting 5-MW-NREL Offshore Floating Wind Turbine with Gyrostabilizer

Abstract

The cyclic motion of a floating structure induces fatigue load on the floating wind turbine cause damage and trim the performance of the wind turbine. One has to minimize the pitch and roll angular motions to eradicate fatigue load and thereby mitigating the structural damage and increase the life time of the wind turbine. The ITI barge type floating wind turbine have highest fatigue load due to cyclic pitch motion in contrast with other basic types of floaters. For ITI barge the pitch motion is dominated over the roll for following and head sea, were roll is dominated for beam sea condition. A novel damping technique called gyroscopic motion counterpoise is used to reduce the pitch motion. Gyrostabilizer is used in various industries for motion stabilization, in ocean engineering it is used in ships and yachts for roll stabilization and in ocean energy converters for harvesting energy. For the first time the gyro-stabilizer is used in the floating wind turbine to damp the rotational motion. The numerical analysis is carried for ITI energy barge with gyrostabilizer supported 5-MW (National Renewable Energy Laboratory) NREL floating wind turbine. The results imply that the cyclic pitch rate is abated substantially by the gyrostabilizer.