Response of the International Energy Agency (IEA) Wind 15 MW WindCrete and Activefloat floating wind turbines to wind and second-order waves

Abstract

Abstract. The EU Horizon 2020 project COREWIND (COst REduction and increase performance of floating WIND technology) has developed two floating platforms for the new International Energy Agency (IEA) Wind 15 MW reference wind turbine. One design – “WindCrete” – is a spar floater, and the other – “Activefloat” – is a semi-submersible floater; both designs are made of concrete. In this work the design of the floaters is introduced with their aero–hydro–servo-elastic numerical models, and the responses of both floaters in both static and dynamic simulations are investigated. The static displacements and natural frequencies are simulated and discussed. Additionally, the effects of the mean wave drift forces and second-order difference-frequency wave forces on the systems' responses are presented. The increase in the turbine's power capacity to 15 MW in IEA Wind model leads to an increase in inertial forces and aerodynamic thrust force when compared to similar floating platforms coupled to the Technical University of Denmark (DTU) 10 MW reference model. The goal of this work is to investigate the floaters' responses for different load cases. The results in this paper suggest that at mild wave loads the motion responses of the 15 MW floating offshore wind turbines (FOWTs) are dominated by low-frequency forces. Therefore, motions are dominated by the wind forces and second-order wave forces rather than the first-order wave forces. After assessing and understanding the models' responses, the two 15 MW FOWT numerical reference models are publicly available to be used in the research and development of floating wind energy.

A parametric study of the mooring system design parameters to reduce wake losses in a floating wind farm

“…In our full factorial experiment, the IEA Wind 15 MW reference wind turbine coupled to the Activefloat platform [8,9] was used as a FOWT. Therefore, before deciding on our design space we looked at the baseline mooring model of the 15MW reference model.…”

Wind field reconstruction using nacelle based lidar measurements for floating wind turbines

“…In this work the WindCrete floater design concept [14] in combination with the International Energy Agency (IEA) 15 MW reference wind turbine [15] is employed for the simulation of FOWT dynamics. WindCrete is a monolithic spar design with a draft of 155 m and a tower height of 129.5 m. The spar and the tower are designed as one single concrete member with an overall mass of 3.665 x 10 7 kg including the ballast.…”

“…Station keeping of the WindCrete concept is realized with three delta-shaped catenary mooring lines with an overall length 615 m and a mass of 561.25 kgm -1 . Details on the WindCrete design parameters and the dynamic behaviour can be found in [14].…”

Wind tunnel investigation of the aerodynamic response of two 15 MW floating wind turbines

“…The research in this work investigates the aerodynamic response of two 15 MW floating turbines developed in the COREWIND project (Mahfouz et al, 2021). An experimental testing campaign has been conducted at the Politecnico di Milano wind tunnel with a 1 : 100 model of the IEA 15 MW turbine which was subjected to imposed platform motion so as to simulate the rigid-body movement of a floating turbine.…”

“…The imposed motion is sinusoidal and in one direction at a time, so it is still idealized, but the test matrix is defined to be representative of the motion of a 15 MW floating turbine in a realistic deployment site. To this end we considered the Activefloat and WindCrete floating turbines developed in the COREWIND project with reference to the Gran Canaria site (Mahfouz et al, 2021). The sinusoidal motion was preferred over a more realistic one, with the platform moving simultaneously in all directions and in a broad frequency range, to ease future comparisons with numerical codes.…”