Abstract
In this work, we demonstrate to what extent it is possible to use load optimisation to aerodynamically damp the floater motion of vertical-axis wind turbines. The loadform of a VAWT can be altered to the desired objective using an individual blade-pitch schedule. A coupled hydro- and aerodynamic simulation tool is built solving the equation of motion of the floating system in which the hydrodynamic loads and (frequency-dependent) matrices are modelled using the potential flow theory and the aerodynamic loads are computed using the Actuator Cylinder model. A blade-pitch optimisation schedule is included to redistribute the loads over the actuator with the objective to counter-act the hydrodynamic loads as much as possible without significant power loss. Using the simulation tool, it is shown that an intelligently determined blade-pitch schedule can decrease the floater motion, however, the potential of reducing the floater motion is limited by the fact that the aerodynamic loads are significantly smaller than the hydrodynamic loads especially for rough sea states.
Highlights
Over the 10 years, the wind energy industry anticipates that offshore installations will grow with 17% each year[1]
For vertical-axis wind turbines (VAWTs) it has been shown feasible to redistribute the loads over the actuator using blade pitching to achieve various objectives
The same floater is considered in this work, the HAWT is replaced by an equivalent VAWT with similar frontal area and power output inspired by Tescione[9]
Summary
Over the 10 years, the wind energy industry anticipates that offshore installations will grow with 17% each year[1]. In this evolution, floating wind farms might open new perspectives. It is of interest to study the feasibility of other concepts such as vertical-axis wind turbines.[2] In particular the insensitivity to wind direction and the low center of gravity have caused a renewed surge of interest in VAWTs for floating, deep-offshore applications.[3]. For vertical-axis wind turbines (VAWTs) it has been shown feasible to redistribute the loads over the actuator using blade pitching to achieve various objectives. Houf[4] has shown numerically that blade-pitch can be used to minimise/maximise the thrust without losing power
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