Load control of floating wind turbine on a Tension-Leg-Platform subject to extreme wind condition

This paper mainly focuses on the control of a typical extreme load, i.e. Extreme Coherent Gust with Direction Change (ECD) and Normal Sea State (NSS), on a floating wind turbine (FWT) with a Tension-Leg-Platform (UP), following the International Electro-technical Commission (IEC) standard. Using an integrated aero-hydro-servo-elastic code, the control action was implemented through the local perturbations of the Deformable Trailing Edge Flaps (DTEFs) on the blade surfaces and thus to the whole FWT. Investigations were separately conducted in four phases, depending on the complex yaw or/and pitching functions of the turbine. It was found that although the uncontrolled extreme loads on the FWT, which mainly originated from the combined influences of ECD and NSS, were rather strong, the smart rotor control very effectively reduced the standard deviations in the primary fluctuating loads on the blades, driving-chain components, tower and Tip by up to 10-35%. The good control performance lay in the altered flow-blade interactions from in-phased to anti-phased situations at dominant mode frequencies, thus significantly impairing their coherences, and subsequently the loads on the blades and other interrelated elements of the turbine system. (C) 2019 Elsevier Ltd. All rights reserved.