An assessment of using variable blade pitch for moored ocean current turbine flight control

Abstract

This paper investigates the possibility of using active individual blade pitch control for positioning moored ocean current turbines within an array. Using a numerical simulation of a representative ocean current turbine it is shown that harmonic blade oscillations with amplitudes of 1.5° can be used to displace an ocean current turbine laterally by a distance equal to one rotor diameter, when the mooring cable length is approximately 30 times the diameter of the rotor blade. For current flow directions that would result in a downstream turbine operating in the wake of an upstream system at a distance of 10 diameters, this technique could be used to reduce the power loss of the downstream system from about 50% (caused by the reduced flow speed available in the turbine wake) to the 1.2% power loss associated with the suggested control approach.