WIND TURBINE WITH A NACELLE HAVING OFFSET CENTER OF GRAVITY - Patent application

Abstract

The wind turbine comprises a tower, a nacelle mounted to the tower, and a rotor defining a rotor axis extending in a vertical central plane and adapted to extract wind energy by rotation of blades about the rotor axis in a rotor rotation direction. The nacelle comprises a rotor support assembly comprising a main frame, defines a load path from the rotor to the tower, and is adapted to receive rotor torque caused by rotor rotation. To reduce tower loads and provide a potentially cheaper construction, the nacelle has a center of gravity offset from the central plane in a direction relative to the rotor rotation direction to counteract rotor torque.

Description

[Technical field]

[0001] The present disclosure relates to a wind turbine comprising a tower, a nacelle mounted to the tower, and a rotor for harvesting wind energy by rotation of the rotor about a rotor axis. The nacelle comprises a rotor support assembly forming a load path from the rotor to the tower, and main bearings mounted to the rotor support assembly and supporting rotation of the rotor relative to the rotor support assembly. [Background technology]

[0002] Wind turbines are becoming larger, both in terms of nominal power output and in terms of the physical dimensions of the individual parts of the wind turbine. Accordingly, the size of the nacelle must also increase to accommodate the necessary wind turbine components. Wind turbines are typically transported by road, rail, ship, or a combination thereof from the manufacturing site for the individual parts to the operating site where the wind turbine is installed.

[0003] The increase in size leads to an increase in loads that must be accommodated at multiple locations in the wind turbine. Within the nacelle, the issue of torque-based loads, i.e. reactive loads that arise from the rotor when exerting forces in the powertrain, must be addressed. Significant reactive torques are exerted from the powertrain, especially the gearbox. In many designs, the torque from the driveline is captured via torque arms into the frame that mounts the gearbox. Typically, such forces are directed towards the main frame and are experienced as asymmetric loads. Thus, the rotor support components must be configured and dimensioned to accommodate the torque. Summary of the Invention [Problem to be solved by the invention]

[0004] An objective of the disclosed embodiments is to reduce loads, particularly reactive loads arising from the rotor when exerting energy in the drive train. In particular, to reduce such asymmetric loads on the tower of the wind turbine, and thus potentially reduce the weight, size and cost of the wind turbine, particularly the tower section. This can potentially reduce transportation and handling costs, without limiting the possible size of the wind turbine. A further objective is to provide a good balance between weight distribution and modularity. [Means for solving the problem]

[0005] In accordance with these and other objects, the present disclosure provides in a first aspect a wind turbine comprising a tower, a nacelle mounted to the tower, and a rotor defining a rotor axis extending in a vertical central plane and configured to harvest wind energy by rotation of blades in a rotor rotation direction about the rotor axis.

[0006] The nacelle includes a rotor support assembly with a main frame, provides a load path from the rotor to the tower, and receives torques induced by rotation of the rotor.

[0007] The nacelle has a center of gravity (COG) that is offset from the center plane in a direction opposite to the direction of rotation of the rotor to counteract torque induced by rotor rotation.

[0008] Because the COG is offset to counter the rotor torque, the load on the tower from this asymmetric torque is reduced, and the tower and tower interface between the tower and the nacelle, including the yaw assembly for yawing the nacelle, can be selectively made smaller and less expensive.

[0009] Clockwise rotation of the rotor may be considered when looking at the rotor from the windward side, in which case the COG should be displaced to the left of the centre plane.

[0010] If the rotor rotates counterclockwise, which is unusual for wind turbines, the COG should be displaced to the right of the center plane.

[0011] The nacelle may be carried directly by the tower or indirectly by the tower via an intermediate tower structure. If the wind turbine is of the traditional horizontal axis type, the nacelle is usually carried by a yaw arrangement between the tower top and the nacelle. However, the present disclosure may also relate to multi-rotor wind turbines of the type in which one or more nacelles are carried by a cross beam structure that is again carried by the tower, for example via a yaw arrangement between the tower and a cross beam structure.

[0012] The present disclosure may relate to upwind or downwind wind turbines.

[0013] The wind turbine may be a direct drive wind turbine, typically with the generator located outside the nacelle, or the wind turbine may have the generator located in the main unit, which supports the rotor via a rotor shaft.

[0014] The nacelle comprises a rotor support assembly that forms a load path from the rotor to the tower, e.g., via said mid-tower structure and, e.g., via said yaw arrangement. The rotor support assembly comprises a main frame, e.g., in the form of a cast part, such as a one-piece cast part.

[0015] The nacelle may further include various components for power generation, hydraulic control, computers, and the like.

[0016] In addition to the main frame, the rotor support assembly may include bearing structures and other components that support the rotor in the wind turbine.

[0017] In a development that facilitates modularization of the turbine, the nacelle may include a main unit with a rotor support assembly and a first auxiliary unit attached to the main unit, the first auxiliary unit housing the working components for power conversion. In such a configuration, the units are produced in a manufacturing facility away from the site where the wind turbine will be erected, and have advantages for assembly in that the units are a subset of the entire nacelle and are more efficiently transported due to their smaller size and weight. At the site where the wind turbine will be erected, the units can be assembled either on the ground beside the tower or on top of the tower.

[0018] The actuating component may comprise a first transformer and a first converter, and a distance from the first converter to the central plane may be greater than a distance from the first transformer to the central plane.

[0019] The wind turbine may comprise a second auxiliary unit arranged such that the first auxiliary unit and the second auxiliary unit are located on opposite sides of a centre plane.

[0020] Providing the main actuating components with significant weight within the auxiliary unit provides the opportunity for a large resulting displacement of the center of gravity to counteract reaction torques as compared to conventional designs. The second auxiliary unit comprises the actuating components for power conversion, and the actuating components of the first and second auxiliary units may be positioned asymmetrically relative to the central plane to provide an offset of the COG away from the central plane.

[0021] The second auxiliary unit may include a second transformer and a second converter, the distance from the first converter to the central plane being greater than the distance from the second converter to the central plane, such that the converter contributes to a shift of the COG away from the central plane.

[0022] The nacelle may be rotationally coupled to the wind turbine tower for rotation about a yaw axis extending in a vertical transverse plane perpendicular to the vertical center plane, in this embodiment, the transverse plane may be between the COG and the rotor, i.e., the COG is aft of the vertical yaw axis as viewed from the wind direction.

[0023] A first working component for power conversion, in particular a transformer, may be mounted on the rotor support assembly such that a first center of gravity (herein referred to as the first COG) of the first working component is upwind relative to the COG, where upwind means the direction of the wind when the rotor is placed in its working position upwind relative to the wind.

[0024] A second component for power conversion, in particular the converter, may be mounted on the rotor support assembly such that when the rotor is placed in its working position up against the wind, a second center of gravity (herein referred to as the second COG) of the second component is downwind relative to the COG. Downwind means away from the wind. A first working component for power conversion, in particular the transformer, may be mounted on the rotor support assembly such that a first center of gravity (herein referred to as the first COG) of the first working component is upwind relative to the COG. Upwind means the direction of the wind when the rotor is placed in its working position up against the wind.

[0025] The rotor support assembly may include a main frame and a main bearing housing mounted to the main frame, the main bearing housing including main bearings for rotational suspension of the rotor shaft relative to the main frame.

[0026] The main bearing housing may form part of the load path from the nacelle to the tower, particularly from the first working component.

[0027] Displacement of the COG away from the center plane may result from a load component, for example a first working component for power conversion, being mounted directly to the rotor support assembly, for example directly to the main frame.

[0028] Displacement of the COG away from the center plane may be caused by a load component, e.g., a second working component for power conversion, being attached directly to the rotor support assembly, e.g., via an auxiliary unit and a main unit to the main frame.

[0029] Examples of the main unit and / or auxiliary unit include units of any size and shape and configured to be assembled.

[0030] The auxiliary units and / or the main unit may be formed with a size and / or outline that is the same or similar to that of a shipping cargo container, so that each unit inherits the advantages of the shipping cargo container with respect to handling, transportation and storage. For example, the transportation of cargo containers can be done anywhere in the world by ship, train, truck, etc., at a low cost compared to bulk transportation.

[0031] The cost savings are even more pronounced when the primary and / or auxiliary units are shipping cargo containers.Maritime freight containers, also known as intermodal containers, standard cargo containers, box containers, ocean freight containers, or ISO containers, generally refer to containers used to store and move materials and products in the global containerized intermodal freight transportation system for intercontinental traffic.Shipping freight containers may follow the dimensional and construction specifications of the ISO standard ISO668:2013 for Series 1 freight containers.

[0032] The main and auxiliary units may be arranged side-by-side so that, rather than being spaced apart from one another axially, they are spaced apart in a centre plane in a direction away from the axis of rotation defined by the rotor support assembly.

[0033] Each of the two auxiliary units may have the size of half a single shipping freight container, in accordance with the dimensional and construction specifications of ISO standard ISO668:2013 for series 1 freight containers, and may be arranged such that the two container halves are assembled to form one container during transport, split into two auxiliary units, for example, on opposite sides of the main unit.The container may in particular be split at an interface extending in the longitudinal direction of the container, i.e. in the longest dimension of the container.

[0034] In the following, embodiments will be described with reference to the following drawings: [Brief description of the drawings]

[0035] [Figure 1a] FIG. 1 shows a wind turbine having a nacelle mounted to a tower. [Figure 1b] FIG. 1 shows a wind turbine having a nacelle mounted to a tower. [Figure 1c] FIG. 1 shows a wind turbine having a nacelle mounted to a tower. [Diagram 2] FIG. 1 shows a nacelle with a main unit and two auxiliary units. [Diagram 3] FIG. [Figure 4] FIG. 2 illustrates part of the rotor support assembly, i.e. the main frame formed as a single piece, cast part. [Diagram 5] FIG. 2 shows the rotor support assembly as viewed from the end of the rotor shaft. [Figure 6] 1A-1D show different embodiments of the nacelle seen from above. [Figure 7] 1A-1D show different embodiments of the nacelle seen from above. [Figure 8] FIG. 2 shows details regarding the centers of gravity of different components. [Figure 9a]FIG. 1 illustrates different interfaces between the operating components and the main frame. [Figure 9b] FIG. 1 illustrates different interfaces between the operating components and the main frame. [Figure 10] FIG. 1 illustrates different interfaces between the operating components and the main frame. [Figure 11] FIG. 13 is a diagram showing the main unit and the auxiliary unit as separate devices. [Figure 12] 1A and 1B are diagrams showing different interfaces between the main unit and the auxiliary unit. [Figure 13] 1A and 1B are diagrams showing different interfaces between the main unit and the auxiliary unit. [Figure 14] 1A and 1B are diagrams showing different interfaces between the main unit and the auxiliary unit. [Figure 15] 1A and 1B are diagrams showing different interfaces between the main unit and the auxiliary unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The detailed description and specific examples, while illustrating embodiments, are given by way of illustration only; various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description.

[0037] Figures 1a and 1b show a wind turbine 1 having a nacelle 2 mounted on a tower 3. A hub 4 carrying three rotor blades 5 forms the rotor and is carried by a rotor support assembly within the nacelle 2. Typically the rotor support assembly comprises a gear arrangement and a rotor shaft connecting a generator to the hub. However, gears are not necessarily required as the generator can be driven directly by the shaft. Figure 1b shows a direct drive wind turbine in which the generator 6 is located outside the nacelle. The rotor support assembly further comprises a main frame and main bearings in main bearing housings connected to the main frame.

[0038] As the rotor rotates, energy is dissipated in the drive train, particularly as bearing losses, optional gearbox losses, and as energy transferred to the generator for conversion to electrical energy. In response to the dissipated energy, the rotor support assembly must counteract the torque resulting from the rotor exerting a force on the drive train. This reactive torque is perceived as a load directed from the rotor support assembly to the tower.

[0039] As defined here, the rotor rotates about a rotor axis 7. A vertical central plane 8 can be defined that bisects the wind nacelle 2 longitudinally with the rotor axis extending in this plane. To orient the rotor upwind relative to the wind, the nacelle 2 can be rotated about a vertical yaw axis 9. A transversely extending transverse plane 10 can be defined, with the yaw axis extending in this transverse plane 10. The transverse plane 10 is perpendicular to the central plane. The yaw axis 9 extends in both the transverse plane 10 and the central plane 8.

[0040] Figure 1c shows the centre and cross sections of the nacelle as viewed from above. The tower is indicated by a circle 11 and has a radial dimension indicated by an arrow 12.

[0041] Figure 2 shows a nacelle with a modular structure where certain working components are provided in separate modules. More specifically, the nacelle comprises a main unit 20 and two auxiliary units 21, 22. The auxiliary units are assembled separately, transported and attached to the main unit. A cooling area 23 is arranged at the top of the nacelle. The cooling area is formed by a heat exchanger which may form part of the main unit and / or the auxiliary units. The main unit 20 is attached to the tower 3 via a rotor support assembly and a yaw arrangement (not shown). The yaw assembly allows the nacelle 2 to rotate about the yaw axis to point the rotor into the wind.

[0042] Figure 3 shows a perspective view of the nacelle 2 of Figure 2. In Figure 3, the outer wall of the nacelle 2 is transparent (for purposes of illustration), thereby revealing the internal portion of the nacelle 2 and the wind turbine components housed therein. The main unit 20 houses a rotor support assembly that supports the rotor. The rotor support assembly comprises, among other things, a main frame and main bearings 31 mounted to the main frame to facilitate rotation of the rotor.

[0043] Figure 3 shows a perspective view of the nacelle 2 of Figure 2. In Figure 3, the outer wall of the nacelle 2 is transparent (for purposes of illustration), thereby revealing the internal parts of the nacelle 2 and the wind turbine components housed therein. The main unit 20 houses a rotor support assembly that supports the rotor. The rotor support assembly comprises, among other things, a main frame and main bearings 31 mounted to the main frame to facilitate rotation of the rotor.

[0044] The disclosed wind turbine further comprises a gear arrangement 32 and a generator 33 arranged sequentially behind the hub 4 along a direction defined by the axis of rotation of the rotor. The components within the main unit mainly form part of the drive train. In an alternative embodiment, the generator is arranged outside the nacelle as shown in FIG. 1b.

[0045] The auxiliary unit 22 houses the main components that form part of the power conversion system, more specifically the converter unit 34 and the transformer unit 35. In another embodiment, the auxiliary unit 22 houses, for example, an electrolytic cell stack or a battery. Other auxiliary units 21 are mounted to the main unit on the opposite side of the central plane and may comprise similar operating components or other parts, for example a crane, etc. In the following, such parts are referred to as operating components.

[0046] The actuating components are selected and positioned such that the center of gravity (COG) of the complete nacelle is offset from the center plane in a direction opposite to the direction of rotor rotation to counteract and, if necessary, eliminate the received torque.

[0047] Figure 4 shows the main frame 40 formed as a single piece, cast part. The main frame further comprises an assembly structure 41 bolted directly to the cast part. The rotor support assembly forms part of the nacelle and defines the load path from the rotor to the tower 3. In the embodiment of Figures 1 and 2, the rotor support assembly is typically located within the main unit 20.

[0048] Figure 5 shows the rotor support assembly looking upwind from the rear of the nacelle towards the rotor. The main bearing housing 50 is mounted on the main frame 40. The main bearings allow the rotor to rotate relative to the main frame. Arrows 51 indicate the torque experienced by the rotor support assembly.

[0049] FIG. 5 shows, diagrammatically, that the load components 52 are located on the assembly structure 41, which serve to shift the center of gravity of the nacelle (COG) away from the center plane 8, as indicated by arrow 53. The COG not being in the center plane counteracts the experienced torque 51 caused by the rotation of the rotor. The counteracting torque provided by the shifted COG is indicated by arrow 54. As will be described later, the load components are the main operating components with a large weight, for example the transformers. In the current latest generation designs, rated at 10 to 15 MW, the transformers weigh several tons, up to 20 tons, and therefore their placement has a large impact on the position of the COG.

[0050] When mounted to the main frame, the main bearing housing forms part of the load path from the load component 52 to the nacelle and tower.

[0051] 6 is a top view of the nacelle 2. The main unit 20 includes a rotor support assembly 40, and the auxiliary units 21 and 22 include a converter 34 and a transformer 35, respectively.

[0052] The main frame 40 comprises a pair of assembly structures 41, 42 on either side of the main frame 40. The working component, in this example in the form of a transformer 35, is mounted directly to the main frame. The main frame is secured to the tower via a yaw assembly that allows rotation about a yaw axis. The main frame thereby defines a load path from the working component 35 that extends directly through the main frame to the tower.

[0053] The other operating components 34 are indirectly attached to the rotor support assembly via the auxiliary units. The second operating component is attached, for example, to a floor or wall of the auxiliary unit, which is attached to the main unit. The auxiliary unit and the main unit thereby define a load path from the second operating component through the auxiliary unit to the rotor support assembly and tower.

[0054] 6 shows that the actuating component 35, in this case a transformer 35, is positioned at the same distance relative to the central plane 8, and a second operating part, exemplified by a transducer 34, is positioned at a different distance relative to the central plane. This causes the COG to move away from the central plane 8, thereby cancelling the experienced torque.

[0055] The optimum counter action is obtained by different combinations of positions. The transformer is typically heavier than the converter (however, the converter weighs several tons, 15 tons at most), so a small displacement of the transformer 35 has a larger effect than a relatively large displacement of the converter 34.

[0056] FIG. 7 shows another example where only one auxiliary unit is placed on one side of the centre plane 8 and therefore the full mass of the auxiliary unit shifts the nacelle COG very significantly away from the centre plane, counteracting the experienced torques.

[0057] FIG. 8 shows a nacelle with the single piece, cast main frame of FIG. 4. A first working component 35 is mounted directly to the rotor support assembly with the center of gravity of the first working component marked as first COG. This first COG is located near the transverse plane 10. By moving one of the first working components or by selecting first working components of different weight, a displacement of the COG away from the center plane can be induced by a load component in the form of the first working component mounted directly to the rotor support assembly.

[0058] The second working component 34 is located on the floor of the auxiliary unit and is therefore only indirectly attached to the rotor support assembly via a connection between the auxiliary unit and the main unit. The center of gravity of the second working component is marked as the second COG. This second COG is located further away from the transverse plane 10. Due to the different position of the second working component, the displacement of the COG away from the central plane is caused by a load component indirectly attached to the rotor support assembly.

[0059] The auxiliary unit has a center of gravity marked in the drawing as AU-COG. The distance from the rotor plane 80 to the AU-COG is greater than the distance from the rotor plane to the 1st COG.

[0060] The first COG of the first component is upwind relative to the COG, and the second COG of the second component is downwind relative to the COG.

[0061] FIG. 9a shows another assembly structure connecting the main frame to the working components. In the illustrated embodiment, the assembly structure 90 connects a transformer 91 to the main frame. At the upper end of the assembly structure a cross pin 92 can be suspended from the main frame, and at the lower end of the assembly structure the assembly structure can be bolted to the main frame via holes 93. The assembly structure further comprises a lower support structure 94 that can carry the transformer, for example to the floor of the nacelle, until final assembly and attachment to the main frame. In particular, the transformer can be placed on the floor of the auxiliary unit and is bolted to the main frame once the auxiliary unit is attached to the main unit.

[0062] Figure 9b shows an alternative assembly structure with pins 92, 95 that are suspended at both the upper and lower ends from the main frame.

[0063] FIG. 10 shows an alternative assembly structure in which both the upper and lower ends on one side include a bolt structure 100 that engages the main frame, and both the upper and lower ends on the other side of the assembly structure form hook structures 101 for suspending a working component.

[0064] Figure 11 shows diagrammatically that the main and auxiliary units are separate units that are assembled before the nacelle is mounted on the tower or after the nacelle is mounted on the tower. Reference numbers also refer to the wind turbine of Figure 3.

[0065] Figures 12 to 15 show four different embodiments of a unit fixing structure forming an interface between a main unit and an auxiliary unit. In each of these four figures, a main unit 121 and an auxiliary unit 122 are connected by a cooperating structure forming a unit fixing structure, which will be described in more detail below.

[0066] In FIG. 12, the cooperating structure is formed by a bracket 123 to which the main unit and the auxiliary unit are joined by bolts.

[0067] In Figure 13 the cooperating structure is constituted by a bottom bracket 123 similar to that used in Figure 12. At the top the main and auxiliary units are assembled by a hook 131 which is pivotally attached to the unit at hinge point 132. The hook can be rotated as shown by arrow 133 and when in the position shown engages an edge bracket 134 on the auxiliary unit. Once the bottom bracket 123 is removed and the hook 131 rotated onto the main unit the auxiliary unit can be lowered to the ground.

[0068] The embodiment of FIG. 14 is similar to that of FIG. 13, but the lower bracket is replaced by an upper bracket 141, and the hook is located at the lower edge.

[0069] In Figure 15, a bottom bracket and an upper bracket are used to bolt the auxiliary unit to the main unit, with a slidable support 151 supporting the underside of the auxiliary unit with the bolts attached. If it is desired to lower the auxiliary unit to the ground, for example for replacement or maintenance of working components, the slidable support can be slid to the left and the auxiliary unit can be lowered, for example using a crane built into the body.

[0070] In any of the embodiments shown in Figures 12-15, the brackets or hooks direct the load from the auxiliary units to a rigid portion of the main unit, for example, a load-carrying column such as a corner column of the main unit. Various structural features can connect the brackets or hooks carrying the auxiliary units directly to the main frame in the main unit to establish a load path to the tower. Thus, the auxiliary units are indirectly connected to the tower through the main unit.

[0071] In addition to the hook and bracket unit fixing structures shown in Figures 12 to 15, assembly structures (e.g., as shown in Figures 4, 8, 9 and 10) connect working components, such as transformers, directly to the main frame within the main unit.

[0072] The main unit and auxiliary unit may be joined after the operating components are placed on the auxiliary unit, for example, after a transformer is placed on the auxiliary unit. The operating components may be placed, for example, on the floor of the auxiliary unit, and when the auxiliary unit is fixed to the main unit, it may be desirable for the weight of the operating components to be carried primarily or entirely by the main frame within the main unit.

[0073] During the assembly procedure, loads from the operating components are transferred from the auxiliary unit, for example from the floor of the auxiliary unit, to the main frame. This load transfer can occur while or after the auxiliary unit is attached to the main unit.

[0074] In one procedure, the working components are gripped by the assembly structure while the auxiliary unit is lowered into a position where it is secured to the main unit. Once the auxiliary unit reaches its assembly position, the load is transferred from the auxiliary unit to the main unit, and in particular to the main frame within the main unit.

[0075] In an alternative procedure, the auxiliary unit is lowered into a position where it is secured to the main unit. Thereafter, i.e., when the auxiliary unit reaches its assembled position, the load is transferred from the auxiliary unit to the main unit. This may include, for example, securing the working components to the assembly structure and, optionally, removing or lowering the support between the working components and the floor of the auxiliary unit, thereby allowing the entire load to be transferred to the main frame.

[0076] In another alternative procedure, the auxiliary unit is held at an inclined angle to the horizontal while being lowered into position. Once the first end of the auxiliary unit reaches the correct level, it is fixed to the main unit. The working component is placed on the opposite side of the auxiliary unit, the second end, and at the time the first end is joined to the main unit, the working component is still carried by the auxiliary unit, for example on the floor of the auxiliary unit. Once the first end is fixed, the second end is lowered and the working component is gripped by the assembly structure. During the continued lowering of the second end, the weight of the working component is transferred from the auxiliary unit to the main frame, and finally the second end of the auxiliary unit is attached to the main unit.

[0077] In another alternative procedure, the auxiliary unit is lowered to a position where it is secured to the main unit. During the lowering of the auxiliary unit, the working components are gripped by the assembly structure and the lifting force from the crane is simultaneously adjusted to accommodate the changed balance when the working components are gripped. Once the assembly position of the auxiliary unit is reached, the load is transferred from the auxiliary unit to the main body and the balance is maintained by dynamic adjustment of the lifting force, i.e. while the auxiliary unit is being lowered.

Claims

1. 1. A wind turbine comprising: a tower; a nacelle (2) mounted on said tower (3); and a rotor defining a rotor axis (7) extending in a vertical central plane (8) and adapted to extract wind energy by rotation of blades (5) in a rotor rotation direction about said rotor axis, The nacelle includes a rotor support assembly including a main frame (40) that provides a load path from the rotor to the tower and receives some of the torque induced by the rotation of the rotor; The nacelle of the wind turbine has a center of gravity (COG) offset from the central plane (8) in a direction opposite to the direction of rotation of the rotor to counteract torque induced by the rotation of the rotor.

2. 2. The wind turbine of claim 1, wherein the direction of rotation of the rotor is clockwise when viewed from the wind side of the rotor, and the COG is offset to the left of center plane.

3. 3. A wind turbine according to claim 1 or 2, wherein one or more working components (34, 35) forming part of the power conversion system are arranged to have a resulting offset COG.

4. 4. A wind turbine according to claim 3, wherein the working components comprise a transformer and / or a converter.

5. 5. A wind turbine according to any one of claims 1 to 4, wherein the nacelle comprises a main unit (20) comprising the rotor support assembly and a first auxiliary unit (21) mounted to the main unit and housing one or more operating components.

6. 6. A wind turbine according to claim 5, wherein the first auxiliary unit houses a first transformer and a first converter.

7. 7. The wind turbine of claim 6, wherein a distance from the first converter to the central plane is greater than a distance from the first transformer to the central plane.

8. 7. A wind turbine according to claim 6, comprising a second auxiliary unit (22), the first and second auxiliary units being mounted on the main unit on opposite sides of the central plane.

9. 9. The wind turbine of claim 8, wherein the second auxiliary unit houses the operating components, and the operating components of the first auxiliary unit and the second auxiliary unit are asymmetrically disposed with respect to the central plane.

10. 10. A wind turbine according to claim 8 or 9, wherein the second auxiliary unit houses a second transformer and a second converter, and the distance from the first converter to the central plane is greater than the distance from the second converter to the central plane.

11. 11. A wind turbine according to any one of claims 3 to 10, wherein the nacelle is rotatably connected to the tower of the wind turbine for rotation about a yaw axis (9) extending in a transverse plane (10) perpendicular to the vertical central plane (8), the transverse plane being between the COG and the rotor.

12. 12. A wind turbine according to claim 3, wherein a first working component among the working components for power conversion is mounted to the rotor support assembly such that a first center of gravity (first COG) of the first working component is upwind with respect to a COG of the nacelle.

13. 13. A wind turbine according to claim 3, wherein a second center of gravity (second COG) of a second working component among the working components for power conversion is mounted to the rotor support assembly such that the second COG of the second working component is downwind with respect to the COG of the nacelle.

14. 14. The wind turbine of claim 3, wherein the rotor support assembly comprises a main frame and a main bearing housing (50) mounted to the main frame, the main bearing housing comprising main bearings that rotatably suspend a rotor shaft relative to the main frame, the main bearing housing forming part of a load path from the working components to the tower.

15. 15. A wind turbine as claimed in any one of claims 3 to 14, wherein working components are mounted directly to the rotor support assembly.

16. 15. A wind turbine according to any one of claims 3 to 14, wherein the working component is indirectly mounted to the rotor support assembly.

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