A MULTIROTOR WIND TURBINE

Abstract

A multirotor wind turbine (1) comprising a tower (2), a yaw arrangement (6) and at least two energy generating units (4) is disclosed. The yaw arrangement (6) is carried by the tower (2) and comprises an outer wall (7) being rotationally suspended about the tower (2). Each energy generating unit (4) is carried by an arm (3) extending from the outer wall (7). The multirotor wind turbine (1) further comprises a load management system (14, 30, 31, 32, 33, 34, 36) for hoisting articles (15, 26) from the tower bottom to each energy generating unit (4) via the yaw arrangement (6).

Claims

1. A multirotor wind turbine comprising: a tower formed by a tower wall extending between a tower bottom and a tower top, a yaw arrangement carried by the tower and comprising an outer wall being rotationally suspended about the tower, at least two energy generating units, each carried by an arm extending from the outer wall, and a load management system for hoisting articles from the tower bottom to each energy generating unit via the yaw arrangement.

2. The multirotor wind turbine according to claim 1, wherein a yaw space is formed between the tower wall and the outer wall, the yaw space being accessible for the load management system for hoisting the articles from the tower bottom to each energy generating unit through the yaw space.

3. The multirotor wind turbine according to claim 2, wherein: the arms form an internal arm space extending from the outer wall to the energy generating units, the the tower forms an internal tower space from the tower bottom to the tower top, and the internal arm space and the internal tower space are connected by a passage extending across the yaw space through the tower wall and through the outer wall, and wherein the load management system is configured to hoist articles from the tower bottom to each energy generating unit through the internal tower space, the passage and the internal arm space.

4. The multirotor wind turbine according to claim 3, wherein the load management system forms a first transport section extending in a vertical direction in the internal tower space between the tower bottom and an intersection platform, a second transport section extending in a transverse direction along the intersection platform through the yaw space, and a third transport section extending in the internal arm space.

5. The multirotor wind turbine according to claim 4, wherein the first, the second and the third transport sections are separate sections each forming an entrance point and an exit point such that the entry point of the first transport section can be accessed at the tower bottom, the exit point of the first transport section can be accessed at the entry of the second transport section, the exit point of the second transport section can be accessed at the entry of the third transport section and the exit of the third transport section can be accessed from one of the energy generating units.

6. The multirotor wind turbine according to claim 4, wherein each transport section comprises individual control.

7. The multirotor wind turbine according to claim 6, wherein the individual control allows operation of each transport section independent on the other transport sections relative to at least one of: the speed of the transport section, and a direction of movement of the transport section.

8. The multirotor wind turbine according to claim 4, wherein at least one of the first, the second and the third transport section comprises a rail structure with a motorised trolley.

9. The multirotor wind turbine according to claim 1, further comprising a sensor system configured to determine a position of articles being hoisted from the tower bottom to the energy generating units.

10. The multirotor wind turbine according to claim 9, wherein the sensor system comprises at least one sensor arranged at the tower, at the yaw arrangement and/or at the arms carrying the energy generating units.

11. The multirotor wind turbine according to claim 1, further comprising a warning system configured to provide an alert in the energy generating units when articles are being hoisted towards the energy generating units, or to provide an alert at the tower bottom when articles are being lowered towards the tower bottom.

12. The multirotor wind turbine according to claim 1, wherein the outer wall forms a closed ring structure.

13. The multirotor wind turbine according to claim 1, wherein the yaw space is a closed space which can only be entered from the tower or from the arms.

14. A method for hoisting articles from a tower bottom to an energy generating unit of a multirotor wind turbine which comprises: a tower formed by a tower wall extending between a tower bottom and a tower top, a yaw arrangement carried by the tower and comprising an outer wall being rotationally suspended about the tower, at least two energy generating units, each carried by an arm extending from the outer wall, and the method comprising moving hoisting the articles via the yaw arrangement.

15. The method according to claim 14, wherein the articles are transported through a yaw space formed between the tower wall and the outer wall.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention will now be described in further detail with reference to the accompanying drawings in which

[0051] FIG. 1 is a schematic view of a multirotor wind turbine according to an embodiment of the invention,

[0052] FIGS. 2-5 illustrate a yaw arrangement for a multirotor wind turbine according to an embodiment of the invention,

[0053] FIG. 6 shows an outer wall part for the yaw arrangement of FIGS. 2-5,

[0054] FIGS. 7 and 8 are perspective views of two transport containers for use in a multirotor wind turbine according to an embodiment of the invention, and

[0055] FIGS. 9-31 illustrate method steps of a method for transporting articles in a multirotor wind turbine according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 is a schematic view of a multirotor wind turbine 1 according to an embodiment of the invention. The wind turbine 1 comprises a tower 2 and two load carrying structures, each comprising two arms 3 extending away from the tower 2 along substantially opposite directions. Each arm 3 carries an energy generating unit 4 with three wind turbine blades 5.

[0057] The load carrying structures 3 are connected to the tower 2 via two separate yaw arrangements 6, thereby allowing the lower set of arms 3a to perform yawing movements relative to the tower 2 independently of yawing movements of the upper set of arms 3b relative to the tower.

[0058] In traditional single rotor wind turbines, a nacelle carrying the single rotor of the wind turbine is normally connected directly to the top of the tower. Thereby the nacelle and the rotor can readily be accessed via the interior of the tower.

[0059] However, in the multirotor wind turbine 1 of FIG. 1 the energy generating units 4 are mounted on the arms 3 at a distance from the tower 2. Thereby the energy generating units 4 are not directly accessible from the interior of the tower 2. Instead, they may be accessed from the outside, e.g. via hoisting from a position immediately below a relevant energy generating unit 4, or from above via a helicopter. In the multirotor wind turbine 1 according to the invention, the energy generating units 4 can be accessed from the interior of the tower 2 by means of a passage extending through a relevant yaw arrangement 6 and an interior part of a relevant arm 3. This will be described in further detail below.

[0060] FIG. 2 is a cross sectional view of a yaw arrangement 6 for a multirotor wind turbine according to an embodiment of the invention. The yaw arrangement 6 comprises an outer wall part 7 arranged circumferentially about an outer surface of the tower 2. Thereby a yaw space 8 is formed between the tower 2 and the outer wall part 7. The space 8 can be accessed from the interior part of the tower 2 via a passage 9.

[0061] Two arms 3, one of which is shown, are attached to the outer wall part 7 and extend in a direction away from the yaw arrangement 6 and the tower 2. The arms 3 are hollow, and the interior of each arm 3 can be accessed from the space 8 formed between the tower 2 and the outer wall part 7 via a passage 10. Thus, an energy generating unit mounted on an arm 3, essentially as illustrated in FIG. 1, can be accessed from the interior of the tower 2 via an access path extending through passage 9, space 8, passage 10 and the interior of the arm 3. This allows access between the interior of the tower 2 and the interior of the arm 3, regardless of the yaw position of the yaw arrangement 6.

[0062] The outer wall part 7 is connected to the tower 2 by means of a first bearing 11 and a second bearing 12. Thereby the outer wall part 7 can rotate relative to the tower 2 in order to orientate rotors of the energy generating units mounted on the arms 3 in accordance with the incoming wind. Accordingly, the access path described above extends across parts which are capable of performing rotational movements relative to each other.

[0063] The first bearing 11 interconnects a lower part of the outer wall part 7 and the tower 2, and the second bearing 12 interconnects an upper part of the outer wall part 7 and the tower 2. Thereby the extremities of the outer wall part 7 are each supported against the tower 2 by means of a bearing 11, 12, thereby stabilising the structure. The first bearing 11 is configured to handle axial loads as well as radial loads, whereas the second bearing 12 is configured to handle radial loads, but not axial loads. Thereby the axial loads are handled by the bearing 11 on which the outer wall part 7 rests, and the position where the highest axial loads are expected.

[0064] A platform 13 is arranged in the interior of the tower 2 at a vertical level corresponding to the position of the yaw arrangement 6. At the platform 13, equipment as well as personnel can be received and intermediately stored. For instance, equipment may be hoisted to the platform 13 from a lower interior part of the tower 2, using a hoisting arrangement 14. Once received at the platform 13, the equipment can be moved into the space 8 defined between the tower 2 and the outer wall 7, via opening 9. From there, the equipment can be moved into the interior of a relevant arm 3, via opening 10, and be moved inside the arm 3 to a relevant energy generating unit. Equipment may also be moved in the opposite direction from an energy generating unit to the lower interior part of the tower 2, via the platform 13.

[0065] FIG. 3 is a detail of the yaw arrangement 6 of FIG. 2. In FIG. 3 the passage 9 between the interior part of the tower 2 and the space 8 defined between the tower 2 and the outer wall 7 can be seen more clearly than in FIG. 2.

[0066] FIG. 4 is a cross sectional view of a part of a yaw arrangement 6 for a multirotor wind turbine according to an embodiment of the invention. Similarly to the embodiment shown in FIGS. 2 and 3, the yaw arrangement 6 comprises an outer wall part 7 arranged circumferentially about the tower 2, thereby forming a space 8 there between.

[0067] In the embodiment of FIG. 4 the outer wall part 7 comprises a casted section onto which the arms 3 are attached, and one or more further sections arranged above the casted section and being attached to the casted section. In FIG. 4 only the casted section is shown. Thereby the part of the outer wall part 7 where the arms 3 are attached is stronger than the remaining part of the outer wall part 7. Accordingly, the manufacturing costs of the outer wall part 7 are minimised without compromising the strength of the outer wall part 7.

[0068] FIG. 4 further illustrates equipment being transported inside the wind turbine in transport containers 15. The transport containers 15 have a size and a shape which ensures that the transport containers 15 can be moved from a position at the lower interior part of the tower 2 to an energy generating unit mounted on one of the arms 3. Thereby it is ensured that equipment packed in one of the transport containers 15 will actually be able to reach a destination at an energy generating unit, without risking that the equipment gets stuck.

[0069] In FIG. 4 it can further be seen that the yaw arrangement 6 is provided with a plurality of yaw drives 16 configured for driving the yawing movements of the outer wall part 7 relative to the tower 2.

[0070] FIG. 5 is a perspective view of the yaw arrangement 6 of FIG. 4. FIG. 5 illustrates that the transport system used for transporting equipment between the lower interior part of the tower 2 and the energy generating unit may also be used for transporting personnel. This could, e.g., be relevant in the case that personnel needs to be evacuated from the wind turbine.

[0071] In FIG. 5 it can further be seen that the casted section of the outer wall part 7 is provided with a reinforcement flange 17. The reinforcement flange 17 does not extend the entire circumference of the casted section. Instead, it is positioned in the part of the casted section where the arms 3 are attached, i.e. in the part where the highest loads are expected, and where additional strength is therefore needed. Accordingly, improved strength is obtained with minimal material use.

[0072] FIG. 6 is a perspective view of a casted section of the outer wall part 7 shown in FIGS. 5 and 6. The casted section is formed by three segments 18, each spanning an angle of approximately 120°, the segments 18 being joined to each other by means of bolt connections 19. One of the segments 18 includes the reinforcement flange 17 and interface portions 20 for attaching the arms to the outer wall part 7.

[0073] FIGS. 7 and 8 are perspective views of two different transport containers 15 for a load management system for use in a multirotor wind turbine according to an embodiment of the invention. The transport container 15 of FIG. 7 has a size and shape which differs from the size and shape of the transport container 15 of FIG. 8. Thereby equipment which may be accommodated in the transport container 15 of FIG. 7 may not be accommodated in the transport container 15 of FIG. 8, and vice versa. However, both of the transport containers 15 have outer dimensions which ensure that they can pass from a lower interior part of a tower of a multirotor wind turbine to each of the energy generating units of the multirotor wind turbine, in the manner described above. Furthermore, the transport containers 15 provide a standardized manner of transporting equipment in a multirotor wind turbine.

[0074] The transport containers 15 are in the form of closed containers with a hard outer surface. Thereby the equipment being transported by means of the transport containers 15 is protected during transport.

[0075] The transport containers 15 are provided with eyelets 21 for connecting the transport containers 15 to a transport system, e.g. via hooks, pulleys, etc. Accordingly, the eyelets 21 provide a standardized interface between equipment being transported and the transport system.

[0076] The transport containers 15 may be made from a material which allows them to float, even if equipment is accommodated therein. This will allow the transport containers 15 to be dragged behind a seagoing vessel in a self-floating manner, thereby reducing the requirements with regard to storage space on the seagoing vessel.

[0077] FIGS. 9-31 illustrate method steps of a method for transporting articles in a multirotor wind turbine according to an embodiment of the invention.

[0078] In FIG. 9 a seagoing vessel 22 is arriving at a multirotor wind turbine positioned at an offshore site. The lowermost part of the tower 2 of the multirotor wind turbine can be seen, and a transition platform 23 carrying a crane 24 is arranged on the tower 2.

[0079] In FIG. 10 the seagoing vessel 22 is moored at the multirotor wind turbine, and personnel is in the process of being transferred from the seagoing vessel 22 to the transition platform 23.

[0080] FIG. 11 illustrates a hoisting wire 25 being lowered from the transition platform 23 towards the seagoing vessel 22 by means of the crane 24, and the hoisting wire 25 being attached to a transport container 15 arranged on the seagoing vessel 22, the transport container 15 accommodating equipment 26 which has previously been packed into the transport container 15.

[0081] In FIG. 12 the transport container 15 is being hoisted from the seagoing vessel 22 towards the transition platform 23 by means of the crane 24.

[0082] In FIG. 13 the transport container 15 has arrived at the transition platform 23, and the crane 24 is in the process of lowering the transport container 15 onto the transition platform 23, adjacent to an opening 27 formed in the wall of the tower 2.

[0083] In FIG. 14 the transport container 15 has been connected to a transport system arranged inside the multirotor wind turbine via a wire 28, and the transport container 15 is in the process of being pulled through the opening 27 formed in the wall of the tower 2 by means of the transport system pulling the wire 28.

[0084] Accordingly, the transport container 15 is entering a lower interior part of the tower 2. It can be seen that the transport container 15 has been connected to the wire 28 via the eyelet 21.

[0085] A protective surface 29 is arranged on the floor, allowing the transport container 15 to slide along the floor without causing damage thereto.

[0086] FIG. 15 illustrates that personnel is being hoisted from the lower interior part of the tower 2 to a platform arranged at a level corresponding to the position of a lowermost yaw arrangement 6.

[0087] In FIG. 16 a hoisting wire 30 is being lowered from the platform 13 towards the lower interior part of the tower 2 by means of a winch 31.

[0088] In FIG. 17 the hoisting wire 30 has reached the lower interior part of the tower 2 and is in the process of being attached to the transport container 15, which was previously moved into the lower interior part of the tower 2.

[0089] In FIG. 18 the transport container 15 is being hoisted from the lower interior part of the tower 2 towards the platform (not shown) by means of the hoisting wire 30 and the winch (not shown).

[0090] In FIG. 19 the transport container 15 has reached the platform 13 and is about to be lowered onto the platform 13.

[0091] In FIG. 20 the transport container 15 has been lowered onto the platform 13 and is about to be released from the hoisting wire 30.

[0092] In FIG. 21 the transport container 15 has been connected to a rail system 32 arranged in the space 8 formed between the tower 2 and the outer wall part 7, by means of a chain hoist 33. The transport container 15 can thereby be pulled through the passage 9 and into the space 8 using the chain hoist 33.

[0093] In FIG. 22 the transport container 15 is in the process of being pulled through the passage 9 in the manner described above.

[0094] In FIG. 23 the transport container 15 has been pulled completely through the passage 9 and is now arranged in the space 8 and is suspended from the rail system 32. The transport container 15 is in the process of being transported inside the space 8 from the passage 9 towards a passage 10 interconnecting the space 8 and the interior of one of the arms 3.

[0095] In FIG. 24 the transport container 15 has reached the passage 10 and is in the process of being lowered from the rail system 32.

[0096] In FIG. 25 the transport container 15 has been connected to another rail system 34 arranged in the interior part of the arm 3.

[0097] In FIG. 26 the transport container 15 is in the process of being moved from the passage 10 towards an energy generating unit (not shown) being carried by the arm 3, by means of the rail system 34. Thus, the transport container 15 is being moved inside the arm 3.

[0098] In FIG. 27 the transport container 15 has reached a position immediately before a fire door 35 which is arranged near an entrance to the energy generating unit 4 being carried by the arm 3. The transport container 15 is about to be lowered from the rail system 34.

[0099] In FIG. 28 the transport container 15 has been connected to a hoisting wire 36 forming part of a hoisting system arranged in the energy generating unit 4. The transport container 15 is in the process of being pulled through an opening 37 in the fire door 35 by means of the hoisting wire 36.

[0100] In FIG. 29 the transport container 15 is in the process of being pulled further into the energy generating unit 4.

[0101] FIG. 30 shows the transport container 15 entering the interior of the energy generating unit 4.

[0102] In FIG. 31 the transport container 15 is arranged on a floor 38 inside the energy generating unit 4 and has been released from the hoisting wire. The transport container 15 has been opened, thereby allowing access to equipment 26 which has been transported inside the transport container 15. Accordingly, the equipment 26 can now be used for performing a schedule service task at the energy generating unit 4.