Hoisting systems and methods

1. A hoisting system for mounting a hub on top of a tower in construction of a wind turbine, wherein the hub carries a first blade and a second blade in a bunny ears configuration, and a third blade extending outward and forward from the hub transverse to a longitudinal axis of the first or second blades, the system comprising:

a first crane configured to pull up the hub from a ground level to the top of the tower;

a blade support device that engages the third blade at a supported blade portion spaced from a root portion of the third blade;

a hub-blade coupling device configured between the root portion of the third blade and the hub, the hub-blade coupling device further comprising

a hub mount structure fixable to the hub;

a blade mount structure fixable to the third blade at the root portion of the third blade; and

a hinge mechanism rotatably coupling the hub mount structure and the blade mount structure.

2. The hoisting system according to claim 1 , further comprising a second crane configured with a first cable attachable to the blade support device to hold up the third blade at the supported blade portion.

3. The hoisting system according to claim 1 , wherein the blade support device further comprises a tensor system, the tensor system comprising a second cable connectable between the hub mount structure and the supported blade portion, and a regulator that controls a length of the second cable.

4. The hoisting system according to claim 1 , wherein the blade support device comprises a support base on the ground level at the supported blade portion, the third blade pivotal on the support base upon pulling up of the hub with the first crane.

5. The hoisting system according to claim 4 , wherein the blade support further comprises a support platform pivotally configured on the support base to support the third blade at the supported blade portion, the support platform pivotal on the support base upon pulling up of the hub with the first crane.

6. The hoisting system according to claim 4 , wherein the support base has a height such that the supported blade portion is above the root portion of the blade in an initial configuration of the hoisting system prior to pulling up the root portion with the first crane.

7. The hoisting system according to claim 1 , wherein the blade support device comprises a blade protector, a platform member, and a rolling member, wherein:

the blade protector is configured to cover a portion of the third blade at the supported blade portion;

the platform member attachable to the blade protector so as to extend parallel to a longitudinal axis of the third blade; and

the rolling member disposable between the platform member and the ground level such that pulling up of the hub with the first crane causes the rolling member to roll along the platform member as the root portion of the third blade is raised.

8. The hoisting system according to claim 1 , further comprising a drive system configured with a third cable between the hub mount structure and the blade mount structure, the drive system further comprising cable regulator that controls a length of the third cable.

9. The hoisting system according to claim 1 , wherein the supported blade portion is at a distance from the root portion corresponding to two-thirds of a length of the third blade.

10. The hoisting system according to claim 1 , wherein the hub is attached to a nacelle, the first crane configured to pull up the nacelle and hub as a single structure.

11. The hoisting system according to claim 1 , wherein the hub-blade coupling device further comprises a lift system that pulls up the third blade to the hub upon the third blade reaching a vertical position.

12. A method for mounting a hub on top of a tower in construction of a wind turbine with a hoisting system, wherein the carries a first blade and a second blade in a bunny ears configuration, and a third blade extending outward and forward from the hub transverse to a longitudinal axis of the first or second blades, the method comprising:

fixing a hub mount structure to the hub;

fixing a blade mount structure to a root portion of the third blade;

operating a first crane having a first cable attached to the hub mount structure to pull up the hub from ground level to the top of the tower while supporting a supported blade portion of the third blade with a blade support of the hoisting system such that:

the first crane and the blade support cooperate to cause a pivoting movement of the third blade relative to the hub during pulling up of the hub such that a height difference is generated between the root portion and the supported blade portion;

the pivoting movement of the third blade enabled by a pivotal connection between the hub mount structure and the blade mount structure; and

rotation of the third blade is continued until the third blade reaches a vertical position relative to the hub and the root portion of the third blade is facing the hub.

13. The method according to claim 12 , further comprising operating the blade support to lower the third blade at the supported blade portion so as to increase movement of the third blade to the vertical position.

14. The method as in claim 13 , wherein the blade support is lowered after operation of the first crane is completed.

15. The method as in claim 12 , further comprising operating a lift system of the hoisting system to pull up the root portion of the third blade to the hub after the third blade has reached the vertical position, and coupling the root portion of the third blade to the hub.