The present invention relates to a method for establishing a self-hoisting crane system, particularly configured for use for offshore mounting and service work on wind turbines placed in territorial waters, said wind turbine comprising a transition piece as well as a transition platform between the turbine foundation and the wind turbine tower, and said self-hoisting crane system comprises a unit com prising at least a main hoist/winch with a wire, a first hoist block connected to the hoist/winch for attachment to a first beam structure connected to the wind turbine nacelle, as well as a self-hoisting crane which is hoisted to the nacelle by means of the wire of the hoist/winch and attached in the nacelle on consoles belonging to the self-hoisting crane system, mounted on stabile structural parts in of the na celle A self-hoisting crane system for use at servicing of land based wind turbines is known from WO 2011 050812 (Liftra ApS), where the unit comprising a hoist/winch and a hoisting block and the seif-hoisting crane are placed on the ground and wherefrom the hoist block is hoisted by a crane/hoist located in the land based wind turbine nacelle for attachment on a beam structure mounted in the nacelle, and where the self-hoisting crane is subsequently hoisted controllably by the wire of the hoist/winch to the mounting position on consoles belonging to the crane system, said consoles are mounted on stabile structural parts in the na celle The self-hoisting crane can hereafter be used for servicing and replacement of the heaviest parts located in the wind turbine nacelle. The advantage of the type of crane is that it eliminates the need for use of large mobile cranes at servicing of wind turbines, which leads to substantial savings when performing these tasks.

On sea based wind turbines, the situation is different, since it is not possible to place the unit with the seif-hoisting crane on the seabed. So far jack-up plat- forms/ships have been used in these situations, with cranes for handling heavy goods, which is very costly, and which is contributing to reducing the advantages of placing wind turbines in territorial waters. Alternatively, the unit could, during performance of the service work, be placed on the deck of a ship anchored to the transition piece of the sea based wind turbine, but this will result in the ship being is tied to the assignment from start to finish, which is also costly, but cheaper than using actual jack-up units with cranes. The optimal solution would be to use the self-hoisting crane system men tioned in WO 2011 050812 for servicing wind turbines on territorial waters, without having to tie an actual ship with a deck, on which the unit comprising the self- hoisting crane, hoist/winch and hoist block is placed during performance of service work and repair of a sea based wind turbine, and it is the objective of the invention to provide a method here for as well as a device for performing the method.

By the invention it is realized that this is possible by means of a method for establishing a self-hoisting crane specially configured for use at off-shore installa tion and service work on wind turbines placed in territorial waters, said wind tur bine comprising a transition piece and a transition platform between the turbines base and the wind turbines tower, and comprising a unit containing at least one main hoist/winch with a main wire, a first hoist block connected to the hoist/winch for attachment on a first beam structure attached in the wind turbine nacelle as well as a seif-hoisting crane which is hoisted to the nacelle by means of the wire of the hoist/winch and is attached in the nacelle on consoles belonging to the self hoisting crane system, said consoles being mounted on stabile structural parts in the nacelle, wherein the crane system is configured such that its unit is displacea ble from a position on the deck of a ship to a position hanging on a stabile struc ture of the wind turbine, wherefrom the self-hoisting crane is hoisted from the unit to the installation position and is mounted on stabile structural parts, in the nacelle.

The advantage of the method according to the invention is that the known crane system, by use of the method according to the invention, can be used on territorial waters, without the ship which transports the crane system to an actual wind turbine being held in position over longer periods of time, than it takes to raise the crane system up to the hanging position in a stabile structure on the wind turbine. it is further preferred that the method comprises that the same main wire is used for raising the crane system from the deck of the ship to the position, hanging in a stabile structure on the wind turbine, hoisting of the self-hoisting crane to the installation position in the nacelle, as well as for operations with the self-hoisting crane. in another embodiment of the inventive concept, the unit is a shipping con tainer, which could either be a standard shipping container or could be a modified shipping container. This is advantageous, since most ships will be adapted to car ry shipping container.

in a further embodiment of the invention concept, the unit is a modified ship ping container, which will have the same outer dimensions as a standard shipping container, wherein said modified shipping container will have at least one side which is retractable or removable.

in a preferred embodiment, the roof of the modified container, the roof being the side which faces upwards, when placed on a ship, is retractable or removable. in an embodiment of the method according to the invention, the method comprises a step of retracting and/or removing the roof of the unit, prior to hoisting the self-hoisting crane from the unit to the nacelle. in another embodiment of the invention, the self-hoisting crane is hoisted from the unit through one end of the unit. In a further embodiment, the end which the self-hoisting crane is hoisted through is an end, which in the initial state of the unit, when placed on a ship, faces a substantially horizontal direction, and when attached to the second beam structure faces a substantially vertical direction.

In another embodiment of the method according to the invention for estab lishing a self-hoisting crane system, specially adapted for use in offshore installa tion- and service work on wind turbines placed in territorial wafers, said turbine comprising a transition piece as well as a transition platform between the wind tur bine base and wind turbine tower, and comprising a unit which in its initial state contains at least a main hoist/winch with a main wire, a first hoist block connected to the hoist/winch, for attachment to a first beam structure attached in the wind turbine nacelle, as well as a self-hoisting crane which is hoisted to the nacelle by means of the wire of the hoist/winch and attached in the nacelle on consoles be longing to the self-hoisting crane system, said consoles being mounted on stabile structural parts in the nacelle characterized by the following operations:

-providing the unit to the transition piece by ship

- hoisting of the second beam structure to the transition piece by means of a crane placed on the transition platform and/or a crane located in the nacelle and attaching one end of at least one holding means to the second beam structure,

- hoisting of another end of said at least one holding means by means of the crane located in the nacelle, ~ attaching the other end of said at least holding means at the nacelle and/or to the first beam structure, and placing the second beam structure protruding from the wind turbine tower near the transition platform,

-hoisting the first hoist block, connected to the wire of the hoist/winch, from the unit to the second beam structure with the crane on the transition platform,

- detachably attaching the first hoist block on the second beam structure,

- hoisting the unit from the ship to the second beam structure by means of the hoist/winch of the self-hoisting crane system,

- attaching the unit to the second beam structure by detachable fastening means,

- detaching the first hoist block from the second beam structure,

- hoisting the, belonging to the self-hoisting crane system, first hoist block to the first beam structure in the nacelle, by means of the crane in the nacelle,

- attaching the first hoist block to the first beam structure by detachable fas tening means,

- hoisting the self-hoisting crane from the unit to the nacelle, wherein the crane is both controlled and hoisted by the wire of the hoist/winch,

- attaching the self-hoisting crane in the nacelle with detachable fastening means to consoles mounted on stabile structural parts. in another embodiment of the method according to the invention for estab lishing a self-hoisting crane system, specially adapted for use in offshore installa tion- and service work on wind turbines placed in territorial waters, said turbine comprising a transition piece as well as a transition platform between the wind tur bine base and wind turbine tower, and comprising a unit which in its initial state contains at least a main hoist/winch with a main wire, a first hoist block connected to the hoist/winch, for attachment to a first beam structure attached in the wind turbine nacelle, as well as a self-hoisting crane which is hoisted to the nacelle by means of the wire of the hoist/winch and attached in the nacelle on consoles be longing to the self-hoisting crane system, said consoles being mounted on stabile structural parts in the nacelle characterized by the following operations:

-providing the unit at the transition piece by ship

- hoisting of the second beam structure to the transition piece by means of a crane placed on the transition platform and attaching one end of at least one stay to the second beam structure,

- hoisting of said at least one stay by means of a crane located in the nacelle, ~ attaching the other end of said at least one stay at the nacelle, and placing the second beam structure protruding from the wind turbine tower near the transi tion platform,

-hoisting a second hoist block, connected to the wire of the hoist/winch, from the unit to the second beam structure with the crane on the transition platform,

- attaching the second hoist block on the second beam structure,

- hoisting the unit from the ship to the second beam structure by means of the hoist/winch of the self-hoisting crane system,

- attaching the unit to the second beam structure by detachable fastening means,

- hoisting the, belonging to the self-hoisting crane system, first hoist block to the first beam structure in the nacelle, by means of the crane in the nacelle,

~ attaching the first hoist block to the first beam structure by detachable fas tening means,

- hoisting the self-hoisting crane from the unit to the nacelle, wherein the crane is both controlled and hoisted by the wire of the hoist/winch,

- attaching the seif-hoisting crane in the nacelle with detachable fastening means to consoles mounted on stabile structural parts.

In a further embodiment of the method, the ship departs for the wind turbine, after the step, where the unit is hoisted from the ship to the second beam struc ture.

in a further embodiment of the method, in the step, where the unit is hoisted from the ship to the second beam structure the hoist/winch of the self-hoisting crane system is located in the unit.

The advantages of the method according to the invention, is that the know crane system, by using the method according to the invention can be used on ter ritorial waters, by that the unit comprising a hoist/winch, hoist blocks, a self hoisting crane, at installation of the second beam structure and stays on the wind turbine, can be hoisted and attached to the second beam structure, carried by the stays, where after the ship, providing the unit, can sail away and perform other tasks, while the self-hoisting crane is established in the nacelle of the wind turbine and the service work is performed. The unit comprising the hoist/winch hangs in the second beam structure, during performance of the service work with the self hoisting crane, which is suspended by the stays. The second beam structure only serves as to secure that a suitable distance is maintained between the wind tur bine tower and the unit.

When the service work/repair work is finished, the disassembly of the self hoisting crane is performed, and said crane is hoisted down into the unit, and the first hoist block at the nacelle can be detached and hoisted down into the unit by means of the davit crane in the nacelle. Hereafter the ship is requested, where after the unit is detached from the second beam structure at the transition plat form, and by means of the hoist/winch hoisted onto the deck of the ship, where after the second hoist block is detached from the second beam structure and hoisted down into the unit by means of the davit crane on the transition deck. Hereafter the at least one stay is hoisted down onto the transition deck by means of the davit crane in the nacelle, and the second beam structure is detached from the turbines tower, where after the at least one stay and the second beam struc ture is hoisted down into the unit. The unit can hereafter, by means of the ship, be sailed to a new task.

The transportation ship is in this way not bound by the task, but can be used for other tasks, for example for transportation of similar self-hoisting crane systems between other turbines, or to retrieve and bring new components to the wind tur bine that the self-hoisting crane can be used to replace.

Another aspect of the inventive concept relates to a self-hoisting crane sys tem, specially adapted for use at offshore installation and service work on wind turbines placed in territorial waters, for performing of the method according to the invention, and comprising a transition piece and a transition platform between the foundation of the turbine and the tower of the wind turbine, and comprising a unit containing at least a main hoist/winch with a wire, a first hoist block connected to the hoist/winch for attachment on a first beam structure attached at the nacelle of the wind turbine, as well as a self-hoisting crane, which is hoisted to and attached in the nacelle by means of the wire of the hoist/winch, wherein the crane system comprises a second hoist block, which is connected to the hoist/winch, intended for hoisting and attachment to a second beam structure, near the transition plat form and protruding from the turbine tower, which is carried by at least one stay, said at least one stay being attached at the nacelle, where the unit is hoisted to said second beam structure by means of the hoist/winch, and the unit is attached to said second beam structure.

The second beam structure and at least one stay can in this embodiment be permanently established installations on the sea based wind turbine.

However, said installations will hardly be permanently established installa tions on existing wind turbines in territorial waters. Thus, the seif-hoisting crane system according to the invention in a further embodiment is characterized in that the self-hoisting crane system comprises the second beam structure and at least one stay.

In a further embodiment, the second beam structure and the at least one stay are comprised in the unit.

in another embodiment, the crane system comprises at least two stays. in another embodiment of the inventive concept, the unit is a shipping con tainer, which could either be a standard shipping container or could be a modified shipping container. This is advantageous, since most ships will be adapted to car ry shipping container.

in another embodiment, the unit is a standard container, which is reinforced. in another embodiment of the invention concept, the unit is a modified ship ping container, which will have the same outer dimensions as a standard shipping container, wherein said modified shipping container will have at least one side which is retractable or removable.

in a preferred embodiment, the roof of the modified container, the roof being the side which faces upwards, when placed on a ship, is retractable or removable. in an embodiment of the method according to the invention, the method comprises a step of retracting and/or removing the roof of the unit, prior to hoisting the self-hoisting crane from the unit to the nacelle.

However, there can be certain advantages of, in advance, having placed the second beam structure as well as the at least one stay, prior to the self-hoisting crane, comprised in the unit, arriving to the installation site/the sea based wind turbine. The invention is explained in further detail in the following with reference to the drawings, wherein;

Fig. 1 is a side view of a sea based wind turbine, provided with a second beam system, suspended in stays by the nacelle,

Fig. 2 is a section view of Fig. 1 , where a ship with the crane system as deck cargo is landed at the transition piece, during hoisting of a second hoist block to the second beam system at the transition platform,

Fig. 3 shows the same as Fig. 2, but where the second hoist block is at tached to the second beam system,

Fig. 4 shows the crane system according to the invention during hoisting to the second beam structure,

Fig. 5 is a section view of the transition platform, showing the crane system’s unit attached to the second beam structure, during hoisting of a first hoist block to a console belonging to the self-hoisting crane system, installed on stabile structur al parts in the nacelle,

Fig. 6 shows a section view of the sea based wind turbine, during hoisting of the self-hoisting crane to the nacelle,

Fig. 7 shows the self-hoisting crane installed on the corresponding console, installed on stabile structural parts in the nacelle, wherein the crane is ready for use, and

Fig. 8 shows an example of hoisting down of a larger component from the nacelle to a ship.

Fig. 1 shows a side view of a sea based wind turbine 2, with a transition piece 4, a transition platform 6, a turbine tower 8 and a nacelle 10. As it is shown a second beam structure 12 protruding from the side of the turbine tower 8, near the transition platform 6. The beam structure 12 is supported on the side of the turbine tower 8, and the freely cantilevered part 11 of the beam structure 12 is suspended by stays 14 attached to said beam structure, wherein the second end of said stays is attached to the nacelle 10.

Fig. 2 which is a section view of Fig.1 , shows a ship 1 with the self-hoisting crane system’s unit 16 according to the invention as deck cargo, said ship being landed at the transition piece 4.

The unit 16 of the self-hoisting crane system, in the shown embodiment comprises a container 16, which contains a hoist/winch 18 with a main wire 20, a first hoist block 24, a self-hoisting crane 26 (see Figs 3, 5 6 & 7), as well as an en ergy station 28 with a control unit 30 for the self-hoisting crane 26.

Shown in Fig. 2 is a first hoist block 24 during hoisting to the second beam structure 12, by means of a first davit crane 32, which is placed on the transition platform 6. The davit crane 32 is in the shown embodiment a part of the wind tur bine’s standard equipment.

In an alternative embodiment, the first hoist block 24 can be hoisted by a crane provided in the nacelle. This is advantageous when the second beam struc ture 12 is located above the reach of the davit crane 32.

In Fig. 3 it is seen that the first hoist block 24 is hoisted to the second beam structure 12, and is detachably attached to the second beam structure 12. Further Fig. 3 shows the unit 16 of the self-hoisting crane system with its roof in a retract ed/removed configuration.

In Fig. 4 it is seen that the unit 16 belonging to the self-hoisting crane system according to the invention during hoisting to the second beam structure 12. The hoisting occurs by means of the hoist/winch 18, with the main wire 20, which is located in the unit 16. The ship 1 is now free to perform other tasks, but has not yet sailed away. Fig. 4 further shows an embodiment wherein a second hoist block 22 is attached to the second beam structure 12, while the first hoist block 24 is still in the unit. This embodiment is advantageous as the first hoist block 24 is no long er required to be attached to the second beam structure 12, in order to hoist the unit 16 to the second beam structure 12.

Fig. 5 which is a section view of the transition platform 6, shows the unit 16 of the crane system, which is now attached to the second beam structure 12, during hoisting of a first hoist block 24 to a first beam structure 34, belonging to the self hoisting crane system, mounted to stabile structural parts 36 in the nacelle 10. Hoisting of the first hoist block 24 occurs by means of a davit crane 38 placed in the nacelle (cf. Fig. 7). The first hoist block 24 is fastened to the cantilevered part 40 of the second beam structure 12 (cf. Fig. 7).

In Fig. 6, which is a section view of the sea based wind turbine 2, the self hoisting crane 26 is seen during hoisting to its mounting location on consoles 35, mounted on stabile structural parts 36 in the nacelle 10. Hoisting of the self- hoisting crane 26 occurs with the main wire 20, by means of the hoist/winch 18, which is located in the unit 16.

In Fig. 7 which is a section view of the wind turbine 2, showing the nacelle 10, the self-hoisting crane 26 is seen mounted on the associated console 35, mounted on stabile structural parts 36 in the nacelle 10, wherein the self-hoisting crane 26 is ready for operation.

Fig. 8 shows an example of lowering of a larger component 42 from the wind turbine’s nacelle 10 to a ship 1 , which is located anchored/moored to the transition piece 4. This ship 1 can be the same ship 1 which provided the self-hoisting crane system 3 to the wind turbine 2, or it can be a different ship 1.

Establishment of the self-hoisting crane system according to the invention is described in the introductory part of the description, and is not repeated here, just as the disassembly of the self-hoisting crane system 16, according to the invention is performed in reverse order with respect to the method specified and described in the claims.

It shall be specified that the inventor has realized that the self-hoisting crane system 16 according to the invention can assume other embodiments than the previously described and as shown in the drawings, but this does not change the inventive concept, which consists in equipping a known earth based self-hoisting crane system for servicing of land based wind turbines, such that it can also be used for servicing wind turbines placed in territorial waters, by hoisting and sus pending said crane system in a second beam structure 12, suspended by stays 14, fastened to a current wind turbine near or in the nacelle 10 of said wind tur bine, which is made possible by hoisting and fastening a second hoist block 22 to the second beam structure 12, placed near the transition platform 6 of the wind turbine.