Project

Floating offshore wind turbines (FOWT) is a new technology, which is still in its developing stage. FOWT could be the solution in order to increase the possible construction areas, as they are more suitable for deeper waters. But the downside is that a floating foundation introduces additional dynamics to the system, which could lead to complex constructions and thereby decrease their cost/effectiveness. If the FOWT control systems take these dynamics into account it could minimize the impact of these and thereby increase the advancement

of FOWTs. Therefore in this project it is sought to develop a physically scaled model of a real wind turbine, which is able to be controlled similar to real wind turbine systems, this includes generator torque control and blade pitching control. The physical model must be constructed in order to test and verify these controlling methods. In this project the scaled nacelle of a wind turbine is designed and constructed, together with the power electronics. It is a 1:35 scaled model of the NREL 5 MW reference wind turbine. Furthermore, blades are designed and constructed in order to match the scaled thrust force of the reference wind turbine. The dynamic models of the subsystems of the wind turbine are developed and controllers for them are designed. The controller's impact is simulated in simulink models of the subsystems.

This project aims to suppress the oscillation motion of floating offshore wind turbines and to improve the structural safety margin of the turbines. The tension leg platform has good vertical stiffness, but insufficient horizontal stiffness and are prone to yawing motion. By establishing a vibration isolation system to resist and dissipate wave impact and wind load impact. The excitation and damage caused by external loads to the wind turbine can be effectively mitigated. The response of the wind turbine is analyzed based on the wave load spectrum and the response curve of the floating platform is calculated using numerical simulation as a basis for designing the hybrid vibration isolation system. A suitable control strategy is selected to first dissipate the waves by controlling the actuators and then dissipate the energy using hybrid vibration isolation. Simulations and experimental studies are used to select the appropriate dynamic parameters for the vibration isolation system to achieve the desired response of the wind turbine. The life state analysis of key components such as tension legs is carried out. The performance degradation characteristics and laws of wind turbines under low-frequency cyclic waves are studied to ensure their safe operation.

This project aims at designing mooring system for floating wave energy converters (WECs) using a design approach based on numerical uncertainty quantification to estimate loads to a given tolerance level. This approach is to be compared to traditional deterministic approach with safety factors in terms of cost of the designed system. This is to be achieved by: (i) using an uncertainty quantification (UQ) toolbox based on general polynomial chaos (gPC) into a state-of-the-art mooring dynamics solver; (ii) to perform detailed numerical investigation on the influence on snap-loads on the mooring design. All parts aim at providing a base for lowering the economic cost of the mooring system.