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Rotating an unbalanced rotor of a wind turbine Disclosure Number: IPCOM000250244D
Publication Date: 2017-Jun-16
Document File: 7 page(s) / 109K

Publishing Venue

The Prior Art Database

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Rotating an unbalanced rotor of a wind turbine

A need can arise to turn the hub of a horizontal wind turbine, while not all blades of its rotor are

installed. This can arise for example during wind turbine construction or servicing, in a construction

process in which rotor blades are individually attached to the hub. i.e. in a construction process in

which the blades are attached successively, one by one to the hub. In many instances of individual

blade attachment, a crane adopts a more or less fixed position in relation to the wind turbine tower,

nacelle and hub. Blades are then successively attached to a respective hub flange of the rotor hub,

from a same side of the tower and nacelle. This is achieved by rotating the hub in between each

blade attachment step, to thereby bring a respective hub flange into position for blade attachment

by the crane.

In the case of e.g. a three-bladed rotor, this method can require the hub to be rotated under an

unbalanced load, as the rotor, when comprising a first blade only, or only the first two blades, will be

asymmetrically loaded. As a consequence, the level of torque required to rotate the unbalanced

rotor will be significantly higher than the torque needed to rotate a balanced rotor, i.e. a rotor with

all blades in position at its hub. A single blade attachment method is known from e.g. EP1597477.

It is proposed to rotate the unbalanced rotor using a crane, using the crane to applying a lifting force

to an installed blade on the rotor. The crane may be the blade installation crane. The blade may be

suspended from the crane prior to and during attachment of the blade to the hub. A turning motion

may be imparted to the rotor by means of the crane pulling upwards on the installed blade. The

rotating action of the crane on the rotor may be imparted using the same lifting arrangement

between the crane and the blade as during blade installation. In particular, a lifting sling or blade

gripper, used as a blade support during blade lifting and installation, may be used to interface the

crane bearing line to the blade during a rotor rotation action imparted by the crane. The lifting sling

or gripper, or other, may be left in place from the lifting and attachment operation and used for the

rotation step using the crane. The sling or gripper may then be released from the blade after the

rotation of the lifting rotor.

Rotating an unbalanced rotor of a wind turbine

Alternatively, the unbalanced rotor may be rotated using a crane other than the crane which was

used for blade attachment. For example another crane on the ground may be used for rotating an

unbalanced rotor after blade attachmen...