Method, assembly and system for mounting wind turbine blades to a wind turbine hub

1. An assembly for mounting wind turbine blades to a wind turbine hub, the assembly comprising:

a frame; and

a blade retaining arrangement comprising a plurality of cage shaped blade retaining elements each pivotally connected to the frame by a hinge,

each blade retaining element further comprises a clamp,

wherein at least two blade retaining elements cooperate to repositionably hold a turbine blade during the mounting process.

2. The assembly according to claim 1 ,

wherein each of the blade retaining elements is detachably attached to the turbine blade.

3. The assembly according to claim 2 ,

wherein the clamps are repositioned by at least one actuation selected from the group consisting of mechanical actuation, electrical actuation and hydraulic actuation.

4. The assembly according to claim 2 ,

wherein at least one of the plurality of blade retaining elements further comprises a guiding means for guiding at least one of the plurality of blades towards the hub,

wherein the guide means comprises slide bearings for repositioning at least one of the plurality of blades by repositioning the clamp.

5. The assembly according to claim 2 ,

wherein at least one of the blade retaining elements is pivotable between a first position and a second position relative to the assembly.

6. The assembly according to claim 5 ,

wherein the first position of at least one of the blade retaining elements corresponds to a horizontal position of a blade held in the blade retaining element.

7. The assembly according to claim 5 ,

wherein the second position of at least one of the blade retaining elements corresponds to a vertical position of a blade held in the blade retaining element.

8. A system for mounting wind turbine blades to a wind turbine hub, comprising:

an assembly according to claim 1 ; and

a lifting device for lifting the assembly to the wind turbine hub.

9. A method for mounting wind turbine blades to a wind turbine hub positioned in a designated operating height of a wind turbine, the method comprising:

attaching at least two blades to a blade retaining arrangement of an assembly, each blade retaining arrangement comprising a plurality of cage shaped blade retaining elements which cooperate to hold the turbine blade,

wherein each cage shaped blade retaining element is pivotally connected to a frame of the blade retaining arrangement;

lifting the assembly with the blades to the wind turbine hub using a lifting device; and

mounting the blades on the lifted assembly to the wind turbine hub by repositioning the cage shaped blade retaining elements.

10. The method according to claim 9 , wherein each blade is detachably attached to a blade retaining element of the blade retaining arrangement.

11. The method according to claim 9 , wherein a plurality of blade retaining elements are connected to each other via a hinge, the method further comprising:

attaching each blade to a blade retaining element;

lifting the assembly to the wind turbine hub using a lifting device;

pivoting the blade retaining element from a first position to a second position;

guiding the blades towards the hub;

mounting the blades to the hub.

12. The method according to claim 11 , wherein pivoting the blade retaining element from the first position to the second position precedes the lifting the assembly to the wind turbine hub.

13. The method according to claim 11 ,

wherein the first position of the blade retaining element corresponds to a horizontal position of a blade held in the blade retaining element.

14. The method according to claim 13 ,

wherein the second position of the blade retaining element corresponds to a vertical position of a blade held in the blade retaining element.