Wind turbine having a hoisting system

Abstract

A wind turbine comprising a nacelle assembly mounted on top of a tower, wherein the nacelle assembly includes a hoisting system. The hoisting system comprises a pedestal to which a lifting boom is attached, the lifting boom configured to deploy a lifting cable, and a counterbalance mast that is connected by a ballast line to a ground-based ballast. A benefit of the arrangement is that load capacity of the nacelle-base hoisting system can be increased significantly with the addition of the ground-based ballast, without the need for a ballast to be positioned permanently at the level of the hoisting system. A method of configuring a wind turbine structure is also provided.

Description

[0001] WIND TURBINE HAVING A HOISTING SYSTEM

[0002] Technical Field

[0003] This disclosure relates to systems, apparatus and methods for configuring or constructing a wind turbine with a hoist system.

[0004] Background

[0005] A known challenge in the field of wind turbines is how to construct the wind turbines most effectively. Typically, a very large crane is used to hoist the various components into position so they can be connected together. For example, a high-capacity ground-based boom crane may erect the tower, section by section, in a vertical position. The crane may then also hoist the nacelle to the top of the tower for connection to it, and then hoist the hub and blades into position. However, the use of such large cranes is generally preferred to be kept to a minimum because they are expensive to construct and to transport to site.

[0006] It is also known to use hoisting systems which are supported on the nacelle or tower and which can be used to lift other components up to the nacelle. An associated challenge with this approach is that large components such as hubs and blades have a very large mass and typically need to be hoisted along trajectories that keep a minimum safe distance from the tower. This challenges the capacity of many nacelle-based hoisting system.

[0007] It is against this background that the invention has been devised.

[0008] Summary of the Invention

[0009] According to a first aspect of the invention, there is provided a wind turbine comprising a nacelle assembly mounted on top of a tower, wherein the nacelle assembly includes a hoisting system. The hoisting system comprises a pedestal to which a lifting boom is attached, the lifting boom configured to deploy a lifting cable, and a counterbalance mast that is connected by a ballast line to a ground-based ballast.

[0010] A benefit of the arrangement is that load capacity of the nacelle-base hoisting system can be increased significantly with the addition of the ground-based ballast, without the need for a ballast to be positioned permanently at the level of the hoisting system. This avoids the needs to lift a large ballast mass, which may be in the region of 20 to 50 tonnes, up to the nacelle level. Instead, the ground-based ballast can be parked on the ground, e.g. in a specific landing zone, and only used as a ballast when required, for example when the hoisting system is using the main lifting boom to lift a large mass and / or a mass which is at a certain distance from the tower such that counterbalancing is required. This may be the case with lifting of rotor hubs and wind turbine blades. A specific landing zone may be helpful to provide operating personnel with knowledge about where the ballast should be located in an optimum position for the hoisting system. The landing zone may also be occupied with other features such as tether lines, loading racks for the ground-based ballast, and so on.

[0011] In some examples of the invention, the nacelle assembly may be of the form that there is a primary nacelle module and a secondary nacelle module. The primary nacelle module may be the primary load bearing component of the nacelle assembly such that it is the interface between the tower and the rotor. As such it may include components like a bedplate or base frame, main bearing housing, gearbox, rotor brake and so on. The secondary or ‘auxiliary’ nacelle module may include other component that may not be associated with the main drivetrain of the wind turbine (such as the main bearing housing, main shaft, gearbox etc) and so may include power converter electronics, hydraulic systems, cooling systems, maintenance equipment, spare parts and consumables, and so on. The power converter electronics may also be housed in the primary nacelle module.

[0012] The pedestal may be located in one of the primary nacelle module and the secondary nacelle module. However, locating the pedestal in the secondary nacelle module may provide improved access for the hoisting system to reach areas around the primary nacelle module. Moreover, it may be a more space-efficient arrangement.

[0013] The counterballast mast may be connected directly to the pedestal, or optionally connected to the lifting boom. Another option is for there to be a connection from the counterballast mast to both the pedestal and the lifting boom.

[0014] In examples where there are primary and secondary nacelle modules, the secondary nacelle module be significant in size, for example having at least 50% of the volume of the primary nacelle module. In some examples, the secondary nacelle module may be almost the same size (e.g. 80-90% by volume, or LBH dimensions) as the primary nacelle module. The arrangement may be configured so that the hoisting system lifts the ground-based ballast during a load-lifting phase of operation. In this way, a counterbalance force is only applied to the pedestal when the hoisting system is operating the main lifting boom in a lifting operation. This may avoid subjecting the pedestal to significant unbalanced loads when the hoisting system is not lifting a load.

[0015] The lifting force applied to the ground-based ballast may be achieved in various ways. For example, the hoisting system may include a linear (e.g. hydraulic or electric or a winch) actuator coupled to the ballast line and which is configured to lift the ground-based ballast by applying a lifting force thereto, namely a force in the upwards direction. The ground-based ballast need not be lifted from the ground in order to provide a suitable counterbalance for the hoisting system. Thus, the lifting force applied to the ground-based ballast should be sufficient to generate the required counterbalance force for the hoisting system, whether or not the ballast leaves contact with the ground. In other examples, the counterbalance mast may be configured to pivot and therefore apply a lifting force to the ground-based ballast.

[0016] The examples of the invention may also extend to a method of configuring a wind turbine structure, comprising providing a nacelle assembly on a tower, providing a hoisting system on the nacelle assembly, the hoisting system comprising a lifting boom and a counterbalance mast, wherein a lifting line is deployable from the lifting boom, and connecting the counterbalance mast to a ground-based ballast by a ballast line.

[0017] The hoisting system may be supported by the secondary nacelle module or a primary nacelle module. In other examples, it is envisaged that the hoisting system may be supported by the primary nacelle module and housed within or on the secondary nacelle module. The system may therefore be configured such that the primary nacelle module provides the primary load bearing structure for the hoisting system, and particularly the pedestal thereof.

[0018] Where the hoisting system is supported by a secondary nacelle module, the counterbalance mast may be connected to the ground-based ballast whilst the secondary nacelle module is coupled to the primary nacelle module. In other examples, the counterbalance mast may be connected to the ground-based ballast before the secondary nacelle module is coupled to the primary nacelle module and, in such a situation, the ballast line may be played out when the secondary nacelle module is lifted towards and attached to the primary nacelle module. Such an approach can simplify the tethering of the hoisting system to the ground-based ballast. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all examples and / or features of any example can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.

[0019] Brief Description of the Drawings

[0020] Figure 1 is a perspective view of a wind turbine in which examples of the invention may be incorporated;

[0021] Figure 2 shows a closer view of a nacelle assembly of the wind turbine in Figure 1 ;

[0022] Figure 3 shows a simplified view of the wind turbine including a hoisting system, wherein the wind turbine is shown as under construction;

[0023] Figure 4 shows another simplified view of the wind turbine, again under construction.

[0024] Detailed Description

[0025] Specific examples of the invention will now be described in which numerous features will be discussed in detail to provide a thorough understanding of the invention as defined in the claims. However, it will be apparent to the skilled person that the invention may be put into effect without the specific details and that in some instances, well known methods, techniques and structures have not been described in detail in order not to obscure the invention unnecessarily.

[0026] In order to place the embodiments of the invention in a suitable context, reference will firstly be made to Figure 1 , which illustrates a typical Horizontal Axis Wind Turbine 1 (HAWT) comprising a tower 2, a nacelle assembly 4 rotatably coupled to the top of the tower 2, a rotating hub or ‘rotor’ 6 mounted to the nacelle 4 and a plurality of wind turbine rotor blades 8 coupled to the rotor 6.

[0027] The nacelle assembly 4 is shown in more detail in Figure 2. The nacelle assembly 4 includes a primary nacelle module 10 and at least one auxiliary or secondary nacelle module 12. In the example in Figure 2, the nacelle assembly 2 includes two secondary nacelle modules 12 which are mounted one on either side of the primary nacelle module 10. The primary nacelle module 10 is therefore sandwiched in between the secondary nacelle modules 12. It should be noted that the secondary nacelle modules 12 may be permanent or temporary fixtures to the primary nacelle module 10.

[0028] The primary nacelle module 10 is the main structural load bearing component of the nacelle assembly 4. By this, it is meant that it is the primary nacelle module 10 that houses a main bearing housing and bedplate (both components not shown) that act as the load interface between the top of the tower, the nacelle assembly 4 and the rotor 16. Such an arrangement is conventional. Fore-aft thrust forces, side-side forces and torsional forces are therefore directed through the main structural load bearing components of the primary nacelle module 10.

[0029] The one or more secondary nacelle modules 12 may serve to house various operative components. Examples of such operative components are power electronics components, such as power converters, transformers and switchgear, hydraulic equipment such as hydraulic pumps, accumulators and heat exchangers, and maintenance equipment such as tools, replacement parts, and hoisting gear. The type of components that are housed within the secondary nacelle modules 12 may determine whether the module is a permanent, semipermanent or temporary fixture. Hoisting equipment and other maintenance gear for example may be stowed in a temporarily fixed secondary nacelle module 12.

[0030] The various pieces of equipment may be arranged in the secondary nacelle modules 12 so that the mass is balanced across the primary nacelle module 10. However, this is not essential.

[0031] The secondary nacelle modules 12 may in principle be any shape or configuration, but for convenience it is envisaged that they are based wholly or partly on the structure of a standard ISO shipping container such as a 40-foot container with structural specifications provided by ISO 668:2013. The secondary nacelle modules 12 may be detachably coupled to the primary nacelle module 10. This may be achieved through the use of suitable mechanical fixings. Such fixings are disclosed for example in WO2023 / 093956. Other attachment arrangements are acceptable.

[0032] The nacelle assembly 4 in this example includes a heat exchanger arrangement 14 mounted to the top side of the primary nacelle module 10. The heat exchanger arrangement 14 configured in this way is known in the art as a ‘cooler top’ and further discussion will be omitted as it does not form part of the invention specifically.

[0033] Having described the general configuration of a wind turbine to which examples of the invention apply, the focus will now turn to Figure 3 which shows a HAWT like that in Figures 1 and 2 but in a state where it is under construction.

[0034] As can be seen in Figure 3, the tower 2 of the wind turbine 1 has been constructed and the nacelle assembly 4 has been secured to the top of the tower 2. The nacelle assembly 4 in this example comprises a single secondary nacelle module 12 which is shown as being attached to the primary nacelle module 10. The precise means of attachment between the primary nacelle module 10 and the secondary nacelle module 12 is not central to the invention and so further discussion on this point will not be provided.

[0035] The wind turbine 1 includes a hoisting system 20. The hoisting system 20 is supported by the nacelle assembly 4 in a position that it can hoist objects from the ground. The ground is shown as an area surrounding the base of the tower 4 in Figure 3 and labelled as ‘G’.

[0036] The hoisting system 20 is in the form of a boom crane 21 and, as such, includes a main lifting boom 22 that is supported on a main mounting pedestal 24. The lifting boom 22 may be a fixed boom or may be a pivotable boom which is able to pivot with respect to the pedestal by a suitable hinged connection (not shown) in order to raise and lower the distal and of the lifting boom 22 in the vertical direction. In this example, the lifting boom 22 is cantilevered from the pedestal 24.

[0037] In the illustrated example, the boom crane 21 is shown supported on the secondary nacelle module 12. It could instead be supported on the primary nacelle module 10, in other examples. Although the pedestal 24 of the boom crane 21 is shown on the top of the secondary nacelle module 12, it is possible to equip the secondary nacelle module 12 with an openable upper surface, for example by way of a set of doors or a roll-back shutter so that the boom crane 21 can be stored within the confines of the outer walls of the secondary nacelle module 12. In this way, the boom crane 21 can be configured into a deployed condition ready for use, when required, but otherwise housed within the protective interior of the secondary nacelle module 12. For convenience of illustration, however, the pedestal 24 is shown here as mounted to the top of the secondary nacelle module 12 although this should not be taken as constituting any limitation on its required position. It is also envisaged that the boom crane 21 , for example by way of the pedestal 24, may be structural supported by the primary nacelle module 10 so that the load path of the boom crane 21 is transferred directly into the primary nacelle module 10. From the primary nacelle module 10, the load would therefore be transferred into the tower 2. The secondary nacelle module 12 may therefore be equipped with a suitable structure (not shown) that provides a direct connection between the pedestal 24 of the crane and, more generally, the loaded structure of the boom crane 21 , and the loadbearing structure of the primary nacelle module 10. The outer walls of the secondary nacelle module 12 can therefore be considered to act as environmental protection for the boom crane 21 when stowed.

[0038] The boom crane 21 includes a winch 26 that provides a lifting cable 28. The lifting cable 28 extends from the winch 26, through a distal end 30 of the lifting boom 22, and then hangs vertically downwards where it connects to a load 32. The load 32 in the illustrated example is a rotor hub of the wind turbine. As can be appreciated from the vertical viewing perspective in Figure 3, the position of the boom crane 21 and the configuration of the lifting boom 22 provides that the distal end 30 can be positioned far enough out from the tower 2 and the front of the nacelle assembly 4 to enable large and heavy components such as a rotor hub to be lifted from the ground into a position relative to the nacelle assembly 4 so they can be mounted to it.

[0039] In order to provide a counterbalance to the mass of the load 32, the hoisting system 20 includes a counterbalance boom or mast 34. In the illustrated example, the counterbalance mast 34 extends from the pedestal 24 in a cantilevered manner. However, in other configurations it is envisaged that the counterbalance mast may extend from the lifting boom 22. As can be seen in the vertical viewing perspective in Figure 3, the counterbalance mast 34 and the lifting boom 22 are aligned in a vertical plane to provide optimum counterbalance of loads, although precise alignment in this respect is not essential. The counterbalance mast 34 provides for the provision of a counterbalance mass or ‘ballast’ to be attached to balance the loading on the lifting boom 22. As can be seen in Figure 3, however, the counterbalance mast 34 is connected to a ground-based ballast 36 by a ballast line 38. The ballast line 38 may be any suitable structure to connect the counterbalance mast 34 to the ballast 36, for example a wire cable or a chain.

[0040] By the term ‘ground-based’, it is meant that the ballast 36 is normally supported on the ground near to the base of the wind turbine tower 2. This is as opposed to conventional ballast arrangements that are permanent fixtures to cranes at the point where they are working. Expressed another way, it is common for ballasts in conventional crane arrangements to be located in the same plane, or close to the plane, in which the yaw ring of the crane is positioned. Conventionally, it will be understood, ballasts are attached to the back end of a crane opposite the main boom, so that they are able to counter the load that is lifted. Being ground-based, the ballast 36 in the illustrated example is not required to be hoisted to the top of the tower in order for the hoisting system 20 to lift heavy loads such as rotor hubs. Instead, the ballast 36 can be located on the ground in the vicinity of the tower so that it is ready for use. Moreover, this means that the ballast 36 is located a significant vertical distance from the yaw ring of the hoisting system 20, namely the pedestal 24. In the illustrated example, the ballast 36 is located a vertical distance from the pedestal 24 which is at least 50 % of, or is comparable to, or is greater than, the vertical height of the tower 2. The exact position of the ballast 36 on the ground may be demarked by a landing zone LZ. This may be helpful from a safety perspective so that operators are aware of where the ballast 36 needs to be positioned for it to be lifted safely by the hoisting system 20. The landing zone LZ may be marked appropriately, e.g. via ground markings in paint, or virtually using geofencing for example. The landing zone LZ may therefore act as a ‘parking space’ for the ballast 36 during a non-load-lifting phase of operation, before the ballast 36 has been lifted off the ground. The landing zone LZ may also contain other features such as tether cables, a loading rack for the ballast 36 and other optional items. The ground-based ballast 36 therefore may ordinarily be positioned on the ground, e.g. in the landing zone LZ, when it is not needed for use.

[0041] In circumstances where the hoisting system 20 is required to lift a heavy load, or a load which is at a distance from the tower 2 such that a counterbalance is required, the hoisting system 20 may be operated to load the counterbalance mast 34 using the ground-based ballast 36. Therefore, the hoisting system 20 may be operated during a load-lifting phase of operation to lift the ground-based ballast 36 off the ground, or at least apply an upward force to the counterbalance mast 34 sufficient to counterbalance the main load, even if the ballast 36 is not lifted clear of the ground. A load-lifting phase of operation is considered to be covered a time before the load is lifted by or even attached to the lifting boom 22.

[0042] Notably, the counterbalance mast 34 may remain connected to the ground-based ballast 36 whether or not it is being used to load up the counterbalance mast 34. In other examples, the counterbalance mast 34 may only be connected to the ground-based ballast 36 by the ballast line 38 when required for a lifting operation. In this way, there is the potential to release load on various component parts of the boom crane 21 .

[0043] The loading of the counterbalance mast 34 may be achieved in various ways.

[0044] In order to provide a suitable counterbalance mass, the hoisting system 20 must apply a sufficient load to the counterbalance mast 34 in the downwards direction. This does not mean that the ground-based ballast 36 must be lifted clear of the ground, although that is indeed possible. Instead, the ground-based ballast 36 can be considered an anchor through which a downwardly directed load / force can be applied to the counterbalance mast 34 in order to provide a balancing force to the main load 32 that is being lifted by the lifting boom 22.

[0045] Such a load may be applied by applying an upwardly directed force on the ballast line 38 when the ballast line 38 is connected to the ground-based ballast 36. For example, the hoisting system 20 may include a hydraulic actuator 39 (shown schematically) that is configured to draw in the ballast line 38 and thereby apply an upwards force on the ground- based ballast 36. It will be appreciated that a downward force equal to the weight of the ground-based ballast 36 will be applied to the ballast line 38 in this way without causing the ground-based ballast 36 to leave contact with the ground. It is also envisaged that the ballast line 38 may be attached to the ground-based ballast 36 in a position such that a lifting force applied to the ground-based ballast 36 causes it to pivot with respect to the ground such that one part of it is lifted whilst another part of it remains in contact with the ground. This may be achieved by connecting the ballast line 38 to an off-centre position on the ballast 36. In both these scenarios, it is possible that the downwards force applied to the ballast line 38 is sufficient to act as a counterweight for the hoisting system 20.

[0046] The same or at least comparable functionality would be achieved by providing the ballast line 38 on a winch e.g. the winch 26. The winch 26 could therefore operate to draw in the ballast line 38 when counterbalancing is required to lift the ground-based ballast 36. It will be appreciated that the hoisting system 20 provides a convenient way to lift heavy loads such as rotor hubs without the need to use conventional high-capacity cranes. A significant benefit of this arrangement is that the capacity of the nacelle-based hoisting system 20 can be increased significantly with the addition of the ground-based ballast 36. What is more, the hoisting system 20 can be installed at the nacelle assembly 4 more easily because it does not have the addition of a large counterbalance mass. Typically, such counterbalance masses may be in the region of 20 to 50 tonnes.

[0047] The hoisting system 20 may be installed at the nacelle assembly 4 after the nacelle assembly 4 has been installed at the top of the tower 2. For this purpose, the nacelle assembly 4 may include a relatively low-capacity lifting jib crane (not shown) or similar device that is capable of lifting relatively small loads. The jib crane may therefore be employed to lift the hoisting system 20 to the nacelle assembly 4 prior to the hoisting system 20 being used to lift the heavier loads, such as the rotor hub.

[0048] Another option is shown in Figure 4. Here, the secondary nacelle module 12 is being lifted up to the level of the primary nacelle module 10 by a low-capacity lifting device 40. Once the secondary nacelle module 12 has reached the required position, it can be secured to the primary nacelle module 10 by suitable attachment means, in which case it will be in the position shown in Figure 3.

[0049] In Figure 4, it will be appreciated that the hoisting system 20 has already been installed at the secondary nacelle module 20 before it has been attached to the primary nacelle module 10. In this example, therefore, the ballast line 38 is attached to the ground-based ballast 36 whilst the secondary nacelle module 12 is being lifted upwardly to the primary nacelle module 10. To allow this, the ballast line 38 is associated with a winch 42. The winch 42 may be part of the same system as winch 26, although the two winches 26,42 may be separate.

[0050] The hoisting system 20 may therefore be operated so that the second winch 42 feeds out the ballast line 38 at the same time as the secondary nacelle module 12 is lifted by the lifting device 40 so that the ground-based ballast 36 stays in place on the ground.

[0051] The ground-based ballast 38 may be embodied in various forms. As one example, it may be in the form of one or more concrete plates. The plates may be stackable to achieve a desired mass. The plates may lock together so that may be lifted as one unit. The ground-based ballast may also take the form of a tray with a suitable connection system to connect to the ballast line 38. Suitable weights may be placed on the tray to increase its mass. The weights may be rocks, concrete blocks and so on. In principle it is also acceptable that the ballast is embodied as an anchoring point on the ground, for example a large mass embedded in the ground such as a foundation of a wind turbine, or other similar anchor point, or indeed a combination of the approaches mentioned above.

[0052] Various modifications may be made to the specific embodiments that have been discussed above with reference to the accompanying figures. Some variants have already been discussed but others would be apparent to the skilled person. Therefore, the scope of the invention should be determined from the appended claims rather than with reference to the specific examples discussed in this text.

Claims

CLAIMS1. A wind turbine (1) comprising: a nacelle assembly (4) mounted on top of a tower (2), wherein the nacelle assembly includes a hoisting system (20), the hoisting system comprising: a pedestal (24) to which a lifting boom (22) is attached, the lifting boom configured to deploy a lifting cable (28), a counterbalance mast (34) that is connected by a ballast line (38) to a ground-based ballast (36).

2. The wind turbine of Claim 1 , wherein the nacelle assembly comprises a primary nacelle module (10) and a secondary nacelle module (12) that is mounted to the primary nacelle module.

3. The wind turbine of Claim 2, wherein the pedestal (24) is located in one of the primary nacelle module (10) and the secondary nacelle module (12).

4. The wind turbine of Claims 2 or 3, wherein the secondary nacelle module (12) has at least 50% of the volume of the primary nacelle module (10).

5. The wind turbine of any one of the preceding claims, wherein the hoisting system (20) is configured to lift the ground-based ballast (36) during a load-lifting phase of operation.

6. The wind turbine of Claim 5, wherein the hoisting system includes a linear actuator (39) coupled to the ballast line (38) and which is configured to lift the ground-based ballast (36).

7. The wind turbine of Claim 5, and wherein the counterbalance mast (34) is configured to be pivoted to lift the ground-based ballast.

8. The wind turbine of any one of the preceding claims, wherein the hoisting system (20) is configured to park the ground-based ballast on a ground landing zone (LZ) during a non- load-lifting phase of operation.

9. A method of configuring a wind turbine structure (1), comprising: providing a nacelle assembly (4) on a tower (2), providing the nacelle assembly (4) with a hoisting system (20), the hoisting system comprising a lifting boom (22) and a counterbalance mast (34), wherein a lifting line (28) is deployable from the lifting boom, and connecting the counterbalance mast (34) to a ground-based ballast (36) by a ballast line (38).

10. The method of Claim 9, wherein providing a nacelle assembly (4) on the tower (2) includes providing a primary nacelle module (10) coupled directly to a tower top of the tower, and providing a secondary nacelle module (12) that is coupled to the primary nacelle module (10).

11. The method of Claim 10, wherein the hoisting system (20) is supported by the secondary nacelle module (12).

12. The method of Claim 10, wherein the hoisting system (20) is supported by the primary nacelle module (10) and housed within or on the secondary nacelle module (12).

13. The method of Claim 11 or 12, wherein the counterbalance mast (34) is connected to the ground-based ballast (36) whilst the secondary nacelle module (12) is coupled to the primary nacelle module (10).

14. The method of Claims 11 to 13, wherein the counterbalance mast (34) is connected to the ground-based ballast (36) before the secondary nacelle module (12) is coupled to the primary nacelle module (10).

15. The method of Claim 14, wherein the counterbalance mast (34) is connected to the ground-based ballast (36), and then the secondary nacelle module (12) is lifted towards and attached to the primary nacelle module (10).

16. The method of any one of Claims 9 to 15, wherein the hoisting system (20) is controlled to lift the ground-based ballast (36) during a load-lifting phase of operation of the lifting boom.

17. The method of Claim 16, wherein, during lifting of the ground-based ballast (36), the ballast line (38) is lifted by a hydraulic actuator (39).

18. The method of any one of Claims 9 to 17, wherein the hoisting system (20) is further configured to park the ground-based ballast (36) on a ground landing zone (LZ) during a non- load-lifting phase of operation of the lifting boom.

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