Abstract: In a disclosed system, yaw rotation is generated by motors, the output torque of which is maintained substantially constant when the motor speed is within a predetermined range, to reduce the variation in the output torque. In another system, yaw rotation is generated by pinion gears each controlled by a motor mounted on the tower of the generator and arranged to rotate a main gear wheel attached to the nacelle. To prevent wear on the motors arising from differences in backlash between the pinion gears and the main gear wheel, each motor is controlled to generate a low output torque until all pinion gears have engaged the main gear wheel, after which the full output torque is applied to all motors. In a further system, braking is arranged to be provided either by mechanical brakes or by generating a counter-torque in the motors, in dependence on the sensed external load.

Abstract: A blade includes an aerodynamic portion (21) and an assembly of the aerodynamic portion to a blade shank retaining the aerodynamic portion in a radial direction (23). The blade shank includes at least one passage restriction in at least one retention direction orthogonal to the radial direction, having a restricted width allowing the aerodynamic portion (21) to pass through. The base of the aerodynamic portion (21) has an overall dimension which is strictly greater than the restricted width so that, in the event of rupture of the assembly, the base is able to come into abutment against the passage restriction so as to retain the aerodynamic portion (21) in the blade shank (20).

Abstract: A wind turbine blade vortex generator unit and a method for installing it, where a wind turbine blade has at least one series of vortex generator units formed of fins extending substantially perpendicular to the surface of the airfoil and substantially in a direction from the leading edge towards the trailing edge of the wind turbine blade. The vortex generator units each comprises a fin connected to an outer side of the fin base, and where the fin is delta shaped tapering from a trailing edge towards a leading edge and where each of the vortex generator units has a layer of adhesive on an inner side of the base that extends to an outermost periphery of the base. The vortex generator unit has exactly one fin, and the base has an airfoil shaped periphery with a rounded leading edge and a trailing edge.