Support structure inside a nacelle of a wind turbine

Abstract

The present disclosure relates to a support structure (200, 240, 250) inside a nacelle (106) of a wind turbine (100) comprising a connecting portion (202) configured for attaching the support structure (200, 240, 250) to a main frame (210) of the wind turbine (100), a first supporting portion (204) for supporting at least a generator (216) of the wind turbine (100), and a second supporting portion (206) for supporting at least one other component of the wind turbine (100), in particular at least one electrical component of the wind turbine (100). In an attached state, the first supporting portion (204) adjoins the connecting portion (202), the second supporting portion (206) adjoins the connecting portion (202), and the second supporting portion (206) is arranged below the first supporting portion (204). The disclosure further relates to a wind turbine (100), comprising a tower (102), a nacelle (106) attached to the tower (102) and supporting a rotor (108), and a plurality of rotor blades (110) attached to the rotor (108).

Description

[0001] Description

[0002] Support structure inside a nacelle of a wind turbine

[0003] The invention relates to a support structure inside a nacelle of a wind turbine, and a wind turbine comprising a support structure.

[0004] Wind turbines are widely known from the prior art and are used to convert wind energy into mechanical output, and subsequently into electrical energy.

[0005] Figure 1 shows a schematic view of a wind turbine 100, which comprises a tower 102. The tower 102 is fixed to the ground by means of a foundation 104. At one end of the tower 102 opposite to the ground a nacelle 106 is rotatably mounted. The nacelle 106, for example, comprises a generator which is coupled to a rotor 108 via a rotor shaft (not shown). The rotor 108 comprises one or more (wind turbine) rotor blades 110, which are movably arranged on a rotor hub 112.

[0006] During operation, the rotor 108 is set in rotation by an air flow, in particular aerodynamic forces resulting from the interaction of wind with the blades. This rotational movement is transmitted to the generator via the rotor shaft, with or without a gearbox. The generator converts the mechanical energy of the rotor 108 into electrical energy.

[0007] Electrical equipment, including the generator and a transformer, is required to be placed close to the rotor 108 inside the nacelle 106 to keep mechanical and electrical transmission losses low and to protect the equipment from environmental influences. The mounting of relatively heavy equipment at an elevated position, i.e., operating height of the nacelle 106 above the tower 102, requires a strong and relatively stiff mounting structure to be attached at the upper end of the tower 102.

[0008] EP 3 447 283 B1 discloses a nacelle for a wind turbine and a generator frame.

[0009] The generator frame is part of a supporting structure comprising a machine frame and the generator frame. The generator frame is constructed as a y-shaped structure in such a way that a central support and two supporting arms, which directly adjoin the central support, form the y-shaped structure. The y-shaped structure stiffens the generator frame and allows heavy components to be placed above and along the generator frame perpendicular to an axis of the tower, thereby creating more useable space inside the nacelle.

[0010] As the size of wind turbines and their associated electrical equipment grows due to ever increasing demand for renewable energy, there is a continuous need for improved support structures inside a nacelle of a wind turbine. Preferably, such support structures should be strong enough to carry heavy equipment, small enough to be transported by road during pre-assembly and / or to the installation site, and enable safe and easy access to the nacelle for service personnel, once the support structure is attached to a tower. Another consideration is the dynamic effect such as the vibrational effect on the wind turbine, in particular, the tower, due to placement of heavy equipment on the generator frame. It is necessary to ensure that the positions of heavy equipment on the generator frame relative to the tower do not result in adverse vibrational characteristics, such as the resonance.

[0011] According to a first aspect of the present disclosure, a support structure inside a nacelle of a wind turbine is disclosed. The support structure comprises a connecting portion configured to be attached to a main frame of the wind turbine, a first supporting portion for supporting at least a generator of the wind turbine, and a second supporting portion for supporting at least one other component of the wind turbine, in particular at least one electrical component of the wind turbine. In an attached state, e.g., when the connecting portion is attached to the main frame of the wind turbine, the first supporting portion adjoins the connecting portion, the second supporting portion adjoins the connecting portion, and the second supporting portion is arranged below the first supporting portion.

[0012] Among other features, it was ascertained that space below a generator can be used to install at least one other component of a wind turbine, if a support structure comprises a first supporting portion and a second supporting portion arranged at different levels, e.g., vertically spaced apart. This in turn allows reduction in length of the individual supporting portions and, hence, the overall length of the support structure and the nacelle.

[0013] It also enables to bring the components supported by the support structure closer to the main frame and thus the tower. By arranging relatively heavy components, such as a generator and a transformer, closer to the main frame of the wind turbine, a natural frequency of the support structure getting closer to frequencies of vibrations caused by the wind and / or rotation of the rotor can be avoided, and therefore, the risk of unwanted resonance can be mitigated.

[0014] A relatively short support structure also allows heavier equipment to be mounted at different levels using beams or other structural parts having essentially the same strength. Inversely, the relatively short support structure with different levels allows the use of a slimmer, lighter structural parts for mounting components of a similar weight, the components which otherwise would be mounted further away from the main frame as in case of a conventional generator frame.

[0015] Using different portions or parts to form a support structure also enables modularity, and hence simplifies transportation and assembly of the nacelle and its components. Moreover, the support frame itself may be used for lifting or lowering of components, e.g., by using the upper, first supporting portion as support for ropes and winches for lifting or lowering components arranged on the lower, second supporting portion.

[0016] The provision of different levels also facilitates easy access to the generator and other equipment placed inside the nacelle. Among others, different access paths can be realized using the different levels. Moreover, large components such as the generator, converter, etc., can be accessed from different sides easily.

[0017] In at least one embodiment, the first supporting portion is arranged at a higher level than the connecting portion (i.e. , elevated with respect to the connecting portion), and the second supporting portion is arranged at a lower level than the connecting portion. In such an arrangement, part of the electrical equipment is arranged at an elevated height relative to the connecting portion forming an access point to the main frame, whereas at least one other component of the wind turbine is mounted at a lower level relative to the level of the connecting portion. Apart from gaining workspace due to the two-level arrangement, such an arrangement also simplifies access to the supporting portions from the connecting portion, as the height difference between, for example, floor levels of the three parts can be kept low. Put differently, the connecting portion may serve as an intermediate or mezzanine floor between an upper floor formed by the first supporting portion and a lower floor formed by the second supporting portion.

[0018] In yet another embodiment, the first supporting portion may lie in the same level or substantially same level as the connecting portion while the second supporting portion remains below the first supporting portion as well as the connecting portion. In still another embodiment, the second level may extend along the same level or substantially same level as the connecting portion while the first supporting portion is at an elevated height compared to both the second supporting portion and the connecting portion.

[0019] In at least one embodiment, the connecting portion further comprises at least one of a first access way, a second access way and / or an interconnecting pathway. A first access way, in particular a first gangway, ramp, stair and / or ladder, may interconnect the first supporting portion with at least one service entry of the main frame. In an embodiment, the at least one service entry may be a nacelle front entry (e.g., opening) defined at a frontal portion of the main frame. A second access way, in particular a second gangway, ramp, stair and / or ladder, may interconnect the second supporting portion with at least one service entry of the main frame (e.g., the nacelle front entry or another service entry of the main frame). An interconnecting pathway, in particular a third gangway, ramp, stair and / or ladder, may interconnect the second supporting portion with the first supporting portion and / or the connecting portion within the support structure. For example, the first access way may lead from the upper, first supporting portion down via a ramp or stairway to an upper surface of the connecting portion and, from there, around the outside of the main frame to its front entry for the nacelle in the main frame. A second, completely independent access way may lead from the second, lower supporting portion up a ramp or a gangway directly leading to a rear portion of the main frame. The interconnecting pathway may be, for example, a ladder, stairway or a ramp leading down from the second supporting portion directly to the first supporting portion and / or the connecting portion. Thus, the interconnecting pathway enables service personnel to change directly between the two service levels, or via the connecting portion. Thus, three different access ways to several working spaces inside nacelle can be provided. Among others, this enables a second escape route in case one of the first or second access ways should be blocked.

[0020] In at least one embodiment, the connecting portion comprises two or more supporting arms, each of the supporting arms configured to be attached, on a first end, to a respective attachment point of the main frame.

[0021] The two or more supporting arms may be arranged above each other, i.e. , vertically spread out, or besides each other, i.e., horizontally spread out. Moreover, separate supporting arms may be provided for each of the first supporting portion and the second supporting portion, or joint supporting arms may be provided to connect both the first supporting portion and the second supporting portion.

[0022] In some embodiments, for example, where the supporting arms are horizontally spread out, each of the two or more supporting arms is further configured to be attached, on a second end, to the first and second supporting portions. For example, the supporting arms may be attached on diametrically opposite sides of the main frame at the first end to form a Y-shaped structure, thereby strengthening the stiffness of the connecting portion. In other words, the first and the second supporting portions may branch out from each of the two or more supporting arms to form the two-level support structure. Further, the vertically spreading out supporting arms e.g., vertically spreading supporting arm pair, or the horizontally spreading out supporting arms, e.g., horizontally spreading supporting arm pair may be such that one supporting arm of the pair may extend in a parallel or a non-parallel (diverging or angular) relationship with the other supporting arm of the pair.

[0023] In one embodiment, the supporting arms may be attached to a common attachment point of the main frame, such that the supporting arms may branch out from the common attachment point.

[0024] In another embodiment, two supporting arms separated vertically may be attached, on their respective first ends, to the main frame at two attachment points, for example, at an upper attachment point and a lower attachment point, respectively.

[0025] In an embodiment, the two supporting arms separated vertically may be mechanically interconnected.

[0026] In at least one embodiment, the support structure further comprises a first joining portion of the first supporting portion or the connecting portion, and / or a second joining portion of the second supporting portion or the connecting portion. The first joining portion is inclined at a first angle with respect to a main direction of a main portion of the connecting portion, wherein the first angle lies within 30° and 150° relative to the to the main direction of the main portion of the connecting portion. The second joining portion is inclined at a second angle with respect to the main direction of the main portion, wherein the second angle lies within -30° and -150° relative to the to the main direction of the main portion of the connecting portion.

[0027] The first and second joining portions transmit the mechanical forces from the first and second supporting portions, respectively, to the main portion of the connecting portion and result in the described split-level arrangement of the two supporting portions. For example, the first joining portion may be inclined with a positive angle or not inclined at all with respect to a plane of the connecting portion, whereas the second joining portion may be inclined with a negative angle or not inclined at all with respect to the plane of the connecting portion, depending on the inclination of the first joining portion. To have a two-level configuration, one of the preferred orientations is that either the first joining portion or the second joining portion is always inclined (e.g., with at least an angle of 30°) relative to the plane of the connecting portion, or both the joining portions are inclined (e.g., with at least an angle of 30°) relative to the plane of the connecting portion.

[0028] In some embodiments, the angle of inclination of one of the first and the second joining portions may be greater than 90° relative to the plane of the connecting portion, depending on design features of the support structure and space availability. For example, the first and the second joining portions may be inclined at +135° and -135°, respectively, relative to the plane of the connecting portion. For angles greater than 90°, say between 110° and 150°, the connecting portion may serve as an intermediate supporting portion between the upper, first supporting portion and the lower, second supporting portion. The connecting portion serving as the intermediate supporting portion may support one or more components of the wind turbine, which may or may not be associated with the electrical components. This allows enhanced compactness within the nacelle with respect to mounting of the components.

[0029] In at least one embodiment, the first supporting portion is attached directly to an upper surface of each of the supporting arms, configured, for example, as a horizontal support beam extending from the main frame in a distal direction, and / or the second supporting portion is directly attached to a lower surface of each of the supporting arms.

[0030] Optionally, each of the supporting arms may extend to a distal end of the first supporting portion and / or of the second supporting portion along the distal direction. Such a support structure comprises only a small number of parts, provides two service floors and thus enables the simple construction of a relatively compact nacelle. The distal end may refer to a rear extremity or a rear end or a near rear end of the nacelle or the support structure itself. The distal direction is a longitudinal direction of the nacelle (or the rotor shaft axis) extending from the rotor till the distal end.

[0031] In an embodiment, the supporting arms configured as horizontal support beams comprises a frontal part for attaching to the main frame. A height of the frontal part may taper to at least a portion from a main part towards the main frame.

[0032] In at least one embodiment, at least one of the connecting portion and the first supporting portion is configured to support a portion of a drive train of the wind turbine. This enables forces originating from mechanical components of the wind turbine to be transmitted to the main frame.

[0033] In at least one embodiment, the support structure comprises two halves, which are detachably joined. Among others, this facilitates transportation of parts of a two- level support structure using conventional modes of transport, e.g., trucks, to the manufacturer of the support structure or to a construction site, at which the wind turbine is erected.

[0034] In at least one embodiment, each of the first supporting portion and the second supporting portion is structured as at least one of a plate, an array of interconnected bars, and an array of interconnected beams. For example, each supporting portion can be formed of a girder structure comprising longitudinal and cross metal beams, which are covered with a metal plate formed as a floor for mounting and accessing equipment in the respective service floor. Such structures can be easily manufactured and assembled and provide the required mechanical strength for holding heavy equipment.

[0035] In at least one embodiment, the second supporting portion comprises at least one base section for carrying the at least one other component, the at least one base section being detachable from the second supporting portion for loading and unloading the at least one other component in the attached state the support structure. Having a detachable section enables, amongst others, heavy components to be lowered from the second supporting portion to the ground below the nacelle.

[0036] In at least one embodiment, the first supporting portion comprises at least one load transmission point arranged above the at least one base section and configured such that the at least one base section and / or the at least one other component can be raised or lowered from the at least one load transmission point. In this way, the upper, first supporting portion can be used to support mechanical loads during raising or lowering of heavy equipment relative to (i.e. , from or to) the second, lower supporting portion.

[0037] In at least one embodiment, the support structure further comprises a transverse beam extending from the first supporting portion and configured such that the at least one other component can be lowered from the transverse beam. By having at least one transverse beam extending, for example, laterally or sideways beyond the first supporting portion, the at least one component can be hoisted on a side of the nacelle.

[0038] In at least one embodiment, the transverse beam comprises a first section attached to the first supporting portion, and at least one second section extendable, in particular in a telescopic manner, in a lateral direction of the nacelle, such that the at least one other component can be attached to the transverse beam in a retracted position of the second section and can be lowered from the support structure in an extended position of the second section.

[0039] In at least one embodiment, the connecting portion is manufactured in one or more parts as a steel or cast-iron construction, or any other metal or alloying combination. In addition, or alternatively, the first and second supporting portions are manufactured in one or more parts as a steel or cast-iron construction, or any other metal or alloying combination. Steel, cast-iron or similar metal materials provide the required strength and flexibility to transmit high mechanical forces for holding heavy equipment and attaching it firmly to the main frame. According to a second aspect of the present disclosure, a nacelle for a windturbine comprises a main frame, a support structure according to the first aspect, a generator, at least one other component, in particular at least one first electrical component electrically coupled to the generator, and a nacelle housing.

[0040] The main frame is configured to be attached to a tower of the wind turbine. The support structure is attached to the main frame. The generator is arranged on the first supporting portion of the support structure and is configured to be mechanically coupled to a rotor of the wind turbine. The at least one other component is arranged on the second supporting portion of the support structure. The nacelle housing encloses at least the main frame, the support structure, the generator and the at least one other component.

[0041] According to a third aspect of the present disclosure, a wind turbine comprising a tower, a nacelle according to the second aspect and attached to the tower and supporting a rotor, and a plurality of rotor blades attached to the rotor, is disclosed.

[0042] Such a nacelle and wind turbine enable the mounting of multiple, bulky and relatively heavy components close to the upper end of a tower supporting the nacelle and the rotor and, at the same time, enables easy access to all components.

[0043] In at least one embodiment, the nacelle resembles a compartment. That is to say, almost or all of the structural and operational components configured to reside inside the nacelle, in particular the entire support structure including the connecting portion, the first supporting portion and the second supporting portion, and, optionally the main frame, can be preassembled, before delivery or transportation of the nacelle to an installation site.

[0044] In at least one embodiment, the second supporting portion comprises at least one base section for carrying the at least one other component, the base section being detachable from the second supporting portion for loading and unloading the at least one other component in the attached state of the support structure, wherein the base section corresponds with, e.g., is arranged vertically above, an opening formed in a floor of the nacelle housing. In this way, components arranged on the second, lower supporting portion can be removed from inside the nacelle through the floor of the second supporting portion and the enclosing nacelle housing in a detached state of the base section, e.g., after removing a mechanical connection between the base section and the rest of the second supporting portion.

[0045] Further advantages, features and further developments are set out by the following exemplary embodiments, which are explained in conjunction with the attached figures. The same or similar elements or elements acting in the same way are provided with the same reference numerals in the following figures, even if they belong to different embodiments.

[0046] Figure 1 shows main components of a wind turbine.

[0047] Figure 2 shows a perspective view of a first support structure attached to a main frame of a wind turbine.

[0048] Figure 3 shows a cross-section through a nacelle comprising the support structure of Figure 2.

[0049] Figure 4A shows a perspective view of a second support structure attached to a main frame of a wind turbine.

[0050] Figures 4B to 4J show schematic cross-sections through further support structures.

[0051] Figure 5 shows a perspective view of a third support structure of a wind turbine.

[0052] Figures 6 to 8 show different perspective views of a support structure with multiple access and interconnecting ways. Figures 9 to 11 show perspective views of different support structures enabling hoisting loads.

[0053] Figure 12 shows a perspective view of a fourth support structure attached to a main frame of a wind turbine.

[0054] Figure 2 shows a perspective view of a first support structure 200 to be arranged inside a nacelle of a wind turbine, such as the wind turbine 100 shown in Figure 1 . The support structure 200 comprises a connecting portion 202, a first supporting portion 204 and a second supporting portion 206. The first supporting portion may be arranged elevated with respect to the connecting portion 202. For example, a floor level of the first supporting portion 204 may lie vertically above a floor level or upper level of the connecting portion 202. The second supporting portion 206 may be arranged vertically below the first supporting portion 204 to form a two-level structure with the upper first supporting portion 204. In the configuration shown in Figure 2, the second supporting portion 206 may be arranged lower with respect to the connecting portion 202. For example, a floor level of the second supporting portion 206 may lie vertically below a floor level or below a lower surface level of the connecting portion 202. Accordingly, the entire support structure 200 forms a split-level arrangement, with an upper floor formed by the first supporting portion 204, a lower floor formed by the second supporting portion 206, and an intermediate or mezzanine floor formed by the connecting portion 202. In an embodiment, the supporting levels of the first and second supporting portions 204, 206 may be parallel or substantially parallel.

[0055] The support structure 200 is attached, by means of the connecting portion 202, to a main frame 210 of the wind turbine. In other words, the connecting portion 202 may serve as a joining or attaching link between the main frame 210 and the first and the second supporting portions 204, 206. For this, the connecting portion 202 may extend in a longitudinal direction of the nacelle 106 between the main frame 210 and the first, second supporting portions 204, 206. In particular, the main frame 210 sits on the upper end of a tower (not shown in Figure 2), while the support structure 200 extends along the longitudinal direction of the nacelle to form a cantilever beam like arrangement. On top of the main frame 210, a rotor bearing assembly supports a rotor shaft 211 (e.g., at two positions) enclosed within a bearing housing 212. The rotor shaft 211 is connected to a drive train 214, which transmits the rotation of the rotor to a generator 216 arranged on the first supporting portion 204 forming an upper equipment level. In the depicted embodiment, the drive train 214 comprises a gearbox for connecting the main rotor shaft and with an axis of a rotor of the generator 216, which may be offset from one another. However, in other embodiments, the rotor shaft may be directly coupled with and arranged in line with an axis a rotor of the generator 216.

[0056] In a space at least partly below the generator 216 and / or the first supporting portion 204, other components of the wind turbine 100 are arranged on the second supporting portion 206 forming a lower equipment level. In particular, a transformer 218 for transforming the electrical energy provided by the generator 260 to a desired voltage range may be arranged at a back end of the second supporting portion 206 as shown. One or more further components, including, but not limited to electrical equipment such as a converter 220, an electrical cabinet 221 (shown in Figure 3), may also be arranged on the second supporting portion 206, for example, on one of its sides as shown in Figure 2. Apart from these components, other components associated with the wind turbine like the cooling lines, and equipment associated with cooling such as a heat exchanger, radiator, pump, valves, sensors, etc., may be supported on the second supporting portion 206. Further, the first supporting portion 204 and / or the connecting portion 202 may support a part of the drive train 214. For example, the connecting portion 202 may support a portion of the bearing housing 212 and / or gearbox.

[0057] In the embodiment shown in Figure 2, the connecting portion 202 may be formed as a relatively solid, metal or alloy part, for example, a cast-iron part. The first and second connecting portions 204 and 206 may also be formed by a metal or an alloy part, for example, as steel plates attached to the connecting portion 202. For this purpose, the connecting portion 202 comprises a first joining portion 222 which may be inclined upwards with respect to a main direction of a main portion 223 of the connecting portion 202. Moreover, the connecting portion 202 comprises a second joining portion 224 which may be inclined downwards with respect to the main direction of main portion 223 of the connecting portion 202. That is to say, a distal end of the connecting portion 202 facing away from the main frame 210 diverges into a vertically split structure for holding the structural members (e.g., steel plates) forming the first supporting portion 204 and the second supporting portion 206.

[0058] In an embodiment, the general plane of extension of the connecting portion 202 along the longitudinal direction of the nacelle may be horizontal (i.e., at 0°) or slightly inclined (i.e., greater than 0°) relative to the horizontal plane. At a proximal end, the connecting portion 202 comprises two (or more) supporting arms 226, which are attached to respective connection points 228 on opposite sides of the main frame 210. For example, first ends 226a of the two supporting arms 226 as shown in Fig. 2 may be attached to the main frame 210 on diametrically opposite sides for symmetric load distribution by both the supporting arms 206 to the main frame 210. In an embodiment, the supporting arms 226 may be attached to the main frame 210 by means including but not limited to fastening, welding, or any other mechanical and / or non-mechanical means. At an opposite second end 226b, the supporting arms 226 are attached to the supporting portions 204 and 206, e.g., by the first joining portion 222 and second joining portion 224, respectively. The two supporting arms 226 are spaced from one another in the horizontal plane, thereby forming an open space there between, and diverge towards the main frame 210. The described arrangement with diverging attachment points in a horizontal and vertical plane at both ends 226a and 226b of the connecting portion 202 leads to a relatively high stiffness of the connecting portion 202 and therefore allow relatively large forces and moments to be transmitted from the supporting portions 204 and 206 towards the main frame 210. In an embodiment, the supporting arms 206 may be structured as beams which have adept structural properties to transmit loads and moments between the supporting portions 205, 206 and the main frame 210.

[0059] In another embodiment, the geometry of the connecting portion 202 may be such that a height (or depth) of the connecting portion 202 may match with the height (or the depth) of a flange of the main frame 210 (best shown in Fig. 3). This results in the first supporting portion 204 to remain elevated relative to the main frame 210, and the second supporting portion 206 lie at a lower level than the main frame 210. This way, the height of the main frame 210 and the connecting portion 202 can still be kept minimal (e.g., optimal for strength and / or transportation), regardless of the dimensions and the orientation of the first and the second supporting portions 204, 206.

[0060] Although Fig. 2 depicts an upward and a downward inclination of the first and the second joining portions 222, 224, respectively, other arrangements may also be possible. For example, in one embodiment, the first joining portion 222 may lie in the same level (i.e. , have zero inclination) or substantially same level (i.e. , have a negligible inclination, e.g., of less than 5°) as the connecting portion 202, such that the first connecting portion 204 lies along the same plane as the connecting portion 202. In such a construction, the second joining portion 224 has an inclination (say 30° or higher) with respect to the main direction of the main portion 223 of the connecting portion 202, such that the second supporting portion 206 extends below the first supporting portion 204. Similarly, the second supporting portion 206 may extend along the same level or substantially same level as the connecting portion 202, such that the first supporting portion 204 is at an elevated height compared to both the second supporting portion 206 and the connecting portion 202. In such a construction, the first joining portion 222 has an inclination (say 30° or higher) with respect to the main direction of the main portion 223 of the connecting portion 202. In an embodiment, the first and the second joining portions 222, 224 may be reinforced by stiffeners and / or gusset plates.

[0061] Figure 3 shows a cross-section to a nacelle 106 comprising the support structure 200 and the main frame 210, explained with respect to Figure 2 above. It further shows that the support structure 200, the main frame 210, the rotor bearing housing 212, and the drive train 214, as well as the electrical components 216 to 221 , which are arranged slightly differently in the configuration of Figure 3, are enclosed by a nacelle housing 230 or cover. Figure 3 shows that room below the generator 216 supported by the first supporting portion 204 can be efficiently used to place several further components, including a transformer 218 and an electrical cabinet 221. This improves proximity of the heavier components like the transformer, converter, etc., to the tower and enhances space utility inside the nacelle. This also results in reduction of the overall length of the support structure 200 itself, as well as overall length of the nacelle 106 and the nacelle housing 230. As a result, the natural frequency of the support structure 200, when it is attached with its proximal end to the main frame 210 of a wind turbine, is optimized to create safe operating conditions. In an embodiment, the geometry of the nacelle cover may be adapted to meet the geometry, orientation and dimensions of the support structure 200, as shown in FIG. 3.

[0062] Figure 4A shows a second support structure 240 comprising a connection portion 202, a first supporting portion 204 and a second supporting portion 206. The relative arrangement and shapes of the various components are similar to those of the first support structure 200 and its components described above with respect to Figure 2. Accordingly, only the differences of the second support structure 240 are described in the following.

[0063] As can be seen in Figure 4A, the second support structure 206 may be formed from a lattice of longitudinal beams 242 and cross beams 244. Moreover, vertical beams 246 interconnect the lower, second supporting portion 206 with the upper, first supporting portion 204. The beam structure comprising beams 242 to 246 is relatively lightweight and further stiffens the support structure 240. Moreover, it enables a modular design and easy manufacturing of the first support structure 204 and the second support structure 206. In an embodiment, one of the first supporting portion 204 and the second supporting portion 206 may be composed of array of interconnecting beams, interconnecting bars or interconnecting closed structures like pipes, while the other of the first supporting portion 204 and the second supporting portion 206 may be a simple plate like structure. In the embodiment shown in Figure 4A, the connecting portion 202 comprises two supporting arms 226 attached to respective connection points 228 of the main frame 210. The two supporting arms 226 may be formed as cast-iron parts or any other metal or alloying combination and lie at a horizontal or an inclined level defined, for example, by a height of main frame 210. The first supporting portion 204 comprises a first joining portion 222, which may be formed as another cast- iron part or as a steel girder or from any other metal or alloying combination. Similarly, the lower supporting portion 206 comprises a second joining portion 224, which may be configured as a separate cast iron or steel girder part or any other metal or alloying combination. The first and second joining portions 222 and 224 adjoin the connecting portion 202 at a first (positive) angle a and second (negative) angle (3, respectively. Any one or both of the first angle a and second angle [3 may lie anywhere between 30° and 150° or -30° and -150°, respectively, as measured from the distal direction of a main direction (or plane) of the main portion 223 and indicated in Figure 4A. For example, if the first joining portion is at same level as the main direction (or plane) of the main portion 223 (i.e. , at 0° relative to the main direction), then the second joining portion 224 is inclined at - 30° (downwards) relative to both the main direction (or plane) of the main portion 223 and the first joining portion 222. When both of the first and second joining portions 222, 224 are inclined (upwards and downwards, respectively) with respect to main direction (or plane) of the main portion 223, then the minimum angle of each of the first and second joining portions 222, 224 between the main direction (or plane) of main portion 223 must be 30° and -30°, respectively. In the described embodiment, the first joining portion 222 is inclined upwards, for example, at about 35°, and the second joining portion 224 is inclined downwards at about -50° from the distal direction of a main direction (or plane) of the main portion 223. Thus, the total angle between the first and second joining portions 222 and 224 is about 85°.

[0064] In some embodiments, the angle of inclination of any one or both of the first and the second joining portions a, [3 may be absolutely greater than 90° and -90° relative to the main direction (or plane) of the main portion 223 of the connecting portion 202, depending on design features of the support structure 200 and space availability. For example, as shown in Figure 4B, the first joining portion and the second joining portion may be inclined at +135° and -135°, respectively, relative to the plane of the connecting portion 202 (e.g., to resemble a symbol). For angles greater than 90°, say between 110° and 150°, the connecting portion 202 may serve as an intermediate supporting portion between the upper, first supporting portion 204 and the lower, second supporting portion 206. The connecting portion 202 serving as the intermediate supporting portion may support one or more components of the wind turbine, which may be one of the aforementioned electrical components 220 or 221 , another electrical component or may not be an electrical component at all, e.g., a mechanical component. This allows enhanced stacking or mounting of the components, proximity of various components for interconnection, and overall compactness of the nacelle interior. In an embodiment, the first and the second joining portions 222, 224 inclining beyond 90° relative to the connecting portion 202 may be reinforced by stiffeners and / or gusset plates (not shown).

[0065] Figures 4C to 4J show several variations on the geometrical configuration of further support structures 410, 430, 440, 450, 460, 470, 480, and 490. In each case, an upper, first supporting portion 204 and a lower, second supporting portion 206 are attached to a main frame 210 of a nacelle by one or more supporting arms or supporting parts, forming the connecting portion 202. In the following, only the variations of the configuration of the connecting portion 202 and their attachment points are described. Otherwise, reference is made to the description of the further embodiments of the disclosed supporting structures described above and below.

[0066] In the supporting structure 410 of Figure 4C, an upper or first supporting arm 412 comprises a horizontal portion 416 and an upwards inclined portion 418 (the inclined portion 418, for example, may be the joining portion 222 described in earlier embodiments). A proximal, first end 412a of the first supporting arm 412 is attached to an upper attachment point 228a of the main frame 210. A distal, second end 412b of the first supporting arm 412 is connected to the first supporting portion 204. Similarly, a lower or second supporting arm 414 comprises a horizontal portion 420 and a downwards inclined portion 422 as shown. A proximal, first end 414a of the second supporting arm 414 is attached to a lower attachment point 228b of the main frame 210. A distal, second end 414b of the second supporting arm 414 is connected to the second supporting portion 206. As also indicated in Figure 4C, the first supporting arm 412 and the second supporting arm 422 may be mechanically interconnected by means of one or more essentially vertical load transfer elements 424, e.g., load transfer beams or a load transfer plates, arranged, for example, close to the respective bend or transition of the supporting arms 412 and 414.

[0067] In one embodiment, the one or more load transfer elements 424 may have shapes including, but not limited to an l-shape, a T-shape, an L-shape, a Y-shape, a bent profile such as a U-shape or a C-shape when viewed from the side of the nacelle as depicted in Figure 4C.

[0068] In another embodiment, a cross-sectional profile of the one or more load transfer elements 424 as viewed from front or rear of the nacelle may include, but not limited to H-shape, l-shape, X-shape, and T-shape.

[0069] In an embodiment, the one or more load transfer elements 424 may be spaced apart from the main frame 210 in the distal direction.

[0070] The supporting structure 430 according to Figure 4D differs from the previously described supporting structure 410 in that both the first supporting arm 412 and the second supporting arm 414 are connected to a common attachment point 228 of the main frame 210. In the specific embodiment, the common attachment point 228 is arranged towards an upper surface of the main frame 210, such that a surface of the horizontal portion 416 of the first supporting arm 412 is aligned with an upper surface of the main frame 410. The second supporting arm 414 consists solely of a downwards inclined portion 422. This helps, among others, to achieve a desired vertical distance between the first supporting portion 204 and the second supporting portion 206.

[0071] The common attachment point 228 may be anywhere along the height of the main frame 210 according to an embodiment. This allows the height of the main frame and the support structure to be customized depending on requirements or constraints.

[0072] In the support structure 440 shown in Figure 4E, both the first supporting arm 412 and the lower support arm 414 consist solely of an upwards inclined portion 418 and a downwards inclined portion 422, respectively. Accordingly, an upper attachment point 228a and a lower attachment point 228b of the main frame 210 can be arranged closer together compared with the embodiment shown in Figure 4C. Although not shown in Figure 4E, depending on the specific geometric configuration and requirements, the first supporting arm 412 and the second support arm 414 may also be connected to a common attachment point 228 arranged, for example, close to a center of the main frame 210.

[0073] The support structure 440 shown in Figure 4E may allow design and material optimization i.e., the excess portion or material of the main frame 210, especially closer to the attachment points 228a, 228b may be minimized or machined. This results in weight reduction and may create extra room for service access.

[0074] Figure 4F shows a support structure 450, wherein the first supporting portion 204 is attached to an intermediate attachment point 452 of a single supporting arm 454, for example by a weld joint or a screw joint. The single supporting arm 454 is configured in a similar way as the second supporting arm 414 of Figure 4C, except that the downward inclined portion 422 is longer, and that its first end 454a is attached, for example, at an attachment point 228 arranged towards an upper surface of the main frame 210.

[0075] Figure 4G shows a support structure 460 comprising two supporting arms 412 and 414, which are configured in an essentially mirror-symmetric fashion. Compared to the supporting arms described with respect to Figure 4C, the first supporting arm 412 further comprises a downwards inclined portion 462 arranged between a horizontal portion 416 and an upwards inclined portion 418. Inversely, the second supporting arm 414 comprises an additional upwards inclined portion 464 arranged between a horizontal portion 420 and a downwards inclined portion 422. As a result, the first supporting arm 412 and the second supporting arm 414 meet at a mechanical interconnection 466, which enables a further stiffening of and load transfer within the support structure 460.

[0076] In another embodiment, the mechanical interconnection 466 may be avoided to create a gap or an opening for access from the main frame to lower level of the support structure.

[0077] Figure 4H shows a further support structure 470, which combines an essentially straight connection of the first supporting portion 204 to the main frame 410 by means of a first supporting arm 412 consisting solely of a horizontal portion 416, and a vertically offset connection of the second supporting portion 206 using a second supporting arm 414, as previously described with respect to Figure 4C. As also described with reference to Figure 4C, the two supporting arms 412 and 414 may be mechanically interconnected by means of one or more load transfer beams 424 or a load transfer plate as described above.

[0078] The first supporting arm 412 and the second supporting arm 414, such as the horizontal portions 416 and 420 respectively described above, may be a beam or a bar intended to establish connection between the main frame 210 and the respective supporting portions 204, 206, while the supporting portions may have a framework of interconnected beams or bars, or a plate. In other words, the supporting portions 204, 206 may have enlarged width in comparison to the first supporting arm 412 and / or the second supporting arm 414 when viewed from the top.

[0079] Figure 4I shows a further supporting structure 480, wherein the connecting portion 202 is configured as a one-piece, U-shaped supporting part 482 comprising a first horizontal portion 416, a vertical portion 484 and a second horizontal portion 420 as shown. In the described embodiment, the upper first supporting portion 204 and the lower, second supporting portion 206 are attached to an upper corner 486 and a lower corner 488 of the vertical portion 482 as shown in Figure 4I, such that the respective surfaces of the horizontal portions 416 and 420 are aligned with respective surfaces of the supporting portions 204 und 206, respectively. The vertical portion 484 may have an aperture or an opening for movement or access between the main frame 210 and the lower floor defined by the second supporting portion 206.

[0080] In other embodiments, the connecting points 228a, 228b may have reduced vertical spacing such that such that the respective surfaces of the horizontal portions 416 and 420 are noy-aligned with respective surfaces of the supporting portions 204 und 206, respectively, to form a stepped like transition between the main frame 210 and the connecting portion 202.

[0081] Figure 4J shows a further supporting structure 490 whose connecting portion 202 consists solely of a one-piece, for example solid, block-shaped supporting part 492. The supporting part 492 serves to hold the first supporting portion 204 and the second supporting portion 206 prior to the attachment of the support structure 490 to the main frame 210. Note that the supporting part 492 may be attached to the main frame 210 either by means of multiple attachment points 228, for example screw or bolt joints, as shown, or by means of welding the supporting part 492 to a corresponding surface of a main frame 210.

[0082] Attention is drawn to the fact that various geometries shown in Figures 4A to 4J represent only a subset of possible geometries for attaching an upper, first supporting portion 204, and a second, lower supporting portion 206 to one or more attachment points 228 of a main frame 210.

[0083] Depending on a desired vertical difference between the supporting portions 204 and 206 and a height of the main frame 210, the intermediate connecting portion 202 may be configured in a tapered or inclined manner to adjust the distance between the first supporting portion 204 and the second supporting portion 206 with respect to respective attachment points 228, 228a and 228b of the main frame as shown, for example, in Figures 4A, 4C, 4D, 4E, 4G, and 4H. In other cases, where the height of the main frame 210 corresponds to, or even exceeds, the desired vertical distance between the first supporting portion 204 and the second supporting portion 206, no such widening may be required, as shown, for example, in Figures 41 and 4J.

[0084] Also, as shown and described above, depending on the expected load and desired stiffness of the supporting structure, a different number of supporting arms, supporting parts or attachment points may be used to attach the supporting portions 204 and 206 to the main frame 210. For example, for relatively light loads, a single attachment point 228 or a single arm 454 may be used, as shown, for example, in Figures 4B, 4D and 4F. For higher loads, two or more supporting arms 412 and 414, which are arranged vertically above each other, can be used as shown, for example, in Figures 4C, 4E, 4G, 4H. In case a load transfer between the first supporting portion 204 and the second supporting portion 206 is desired, additional mechanical interconnections may be provided, as shown, for example, in Figures 4C, 4G, 4I and 4J.

[0085] Figure 5 shows a third variant of a support structure 250 for a nacelle. The support structure 250 is similar to the support structure 240 shown in Figure 4A. Accordingly, only the differences will be described below.

[0086] As shown in Figure 5, the support structure 250 is formed from two mirror- symmetrical halves 252 and 254, which can be removably or permanently attached to one another at respective connection points 256 at a late stage of the assembly, for example during final assembly of the support structure 250 by the manufacturer of the nacelle 1006 and / or at the construction site for the wind turbine 100. This may be achieved, for example, by screwing, bolting or welding together corresponding flanges 258 at respective internal ends of cross beams 244 of the halves 252 and 254. In the embodiment shown in Figure 5, a total of six connection points 256 is shown, but this may vary depending on the configuration of the halves 252 and 254 and the required strength of the support structure 250. Also note that the halves 252 and 254 comprises separate right and left vertical beams 246, such that the respective parts of the first supporting portion 204 and the second supporting portion 206 are attached to one another even before the two halves 252 and 254 of the support structure 250 are attached to one another using the attachment points 256.

[0087] In another embodiment, the halves 252 and 254 may be asymmetrical in nature where the left half 254 and the right half 252 (when viewed from the main frame 210 side) have different number of longitudinal beams 242, and / or different sized longitudinal beams 242 and / or cross beams 244. Other possibilities that impart asymmetricity to the halves 252, 254 may also be realized. The symmetricity or asymmetricity may be decided depending on the number of components, nature of components, nacelle design, and so on.

[0088] Moreover, note that the lower, second supporting portion 206 of the third support structure 250 directly abuts the lower end of a connecting portion 202. In contrast, the upper, first supporting portion 204 is connected indirectly to the connecting portion 202 by respective joining portions 222 as shown. This may be attained through a tapered geometry of the connecting portions 202 resulting in elimination of materials required to be attached as joining portions corresponding to the lower, second supporting portion 206.

[0089] Figures 6 to 8 show different pathways for service personnel to access electrical components and other equipment arranged on a first and second supporting portions 204 and 206 of a support structure.

[0090] In particular, Figure 6 shows that the front side of a generator 216 may be accessed using a first access way 260, leading down from the first supporting portion 204 over a first ramp 262 formed by a first joining portion 222 to an upper surface 264 of the connecting portion 202. Although not shown in Figure 6, the first access path 260 continues around the outside of a main frame over stairs or a ladder towards at least one service entry, for example, a nacelle front entry 266 (shown, for example, in Figure 4A) defined at the frontal portion of the main frame 210. Additionally, access to the tower internal may be gained through another service entry, e.g., a service entry defined at a rear portion of the main frame 210 diametrically opposite to the service entry 266 (shown, for example, in Figure 7). Figure 7 shows a second access way 270 leading from the second supporting portion 206 via a second ramp 272 directly to a rear service entry 274 in the main fame 210. Note that the ramp 272 is arranged in a space formed between two supporting arms 226 of the connecting portion 202 through the joining portions 222, 224.

[0091] Moreover, Figure 7 also shows a ladder 276 interconnecting, in this case, the upper surface 264 of the connecting portion 202 with the floor level of the second supporting portion 206. Thus, in the case that the rear service entry 274 or the second ramp 272 is blocked, service personnel can leave the second supporting portion 206 by means of the ladder 276 forming an interconnecting pathway 278 to join the first pathway 260 as explained above with respect to Figure 6. Inversely, if a nacelle front entry 266 of the main frame 210 is blocked, service personnel can climb down from the upper surface 264 of the connecting portion 202 via the ladder 276 to the second supporting portion 206 and exit the nacelle 106 via the second ramp 272 and the rear service entry 274.

[0092] While not shown in the figures, an interconnecting pathway between the second access way 270 and the first access way 260 may also lead directly from the second supporting portion 206 to the first supporting portion 204. For example, a ladder and a corresponding manhole may interconnect the lower and upper equipment levels of the support structure.

[0093] The different access routes are also shown in Figure 8. Figure 8 further shows that an access opening 280 is arranged in the first supporting portion 204, which allows the generator 216 (not shown in Figures 7 and 8) to be accessed from below, and may also be used to form an interconnection pathway as detailed above.

[0094] Moreover, Figure 8 shows that the second supporting portion 206 has a lowered platform 282 for placement of particularly high electrical equipment, such as a bulky transformer (not shown in Figure 8). Figures 9 to 11 show three different configurations of a supporting structure for a nacelle for hoisting bulky and / or heavy components arranged on the second supporting portion 206. Attention is drawn to the fact that, due to the two-level arrangement, such components may not be easily maneuvered into the lower working space using external hoisting arrangements, such as a truck-mounted crane. Accordingly, the different supporting structures shown in Figures 9 to 11 include integrated hoisting arrangements, as further detailed below.

[0095] In the embodiment shown in Figure 9, the second supporting portion 206 comprises a supporting base section 284, which can be detached from the remaining parts of the second supporting portion 206. For example, retractable bolts may be used to fasten or unfasten the base section 284 to / from the remaining parts of a steel girder structure forming the load bearing part of the second supporting portion 206.

[0096] A heavy electrical component such as a transformer 218 or an electrical cabinet 221 or an electrical converter 220 may be mounted on a surface of the base section 284. In the embodiment shown in Figure 9, a lifting frame 286 is first attached to the base section 284 to transfer the weight of the electrical converter 220 to a central attachment point 288 for attaching a crane cable 290. The crane cable 290 is guided via one or more load transmission points 292 formed by or attached to respective cross beams of the first supporting portion 204. For example, secondary cable guideways or rollers may be attached to the cross beams, or the crane cable 290 may directly be guided by a suitably formed part of a cross beam. Once the crane cable 290 is secured, the base section 284 can be unfastened, and the component arranged on the base section 284 can be lowered from or raised to the second supporting portion 206 using an external winch via the crane cable 290.

[0097] Figure 10 shows an alternative arrangement for hoisting a heavy component. In this embodiment, a housing of the component is sufficiently strong to transfer the force generated by its own weight. Two crane cables 290 are attached directly to respective attachment points 288 of the converter 220. In this case, no support frame 286 is required. In this case, the heavy component 220 may be first lifted a little bit of the floor of the second supporting portion 206, giving easy access to the base section 284, e.g., for unfastening the base section 284 completely, or moving the base section 284 (e.g., hinged or sliding movement) relative to rest of the second supporting portion 206. In case of unfastening, the base section 284 may first be attached to bottom of the heavy component 220 before unfastening completely from rest of second supporting portion 206 so that both the heavy component 220 and the base section 284 may be lowered via the void formed in the second supporting portion 206 where the base section 284 was initially present. Alternately, the base section 284 may be moved, for example, swiveled via one or more hinges, so that the void may be formed in the second supporting portion 206 for lowering the heavy component 220. For the embodiments described with respect to Figures 9 and 10, an internal crane already present in the nacelle 106 may be used to lift or lower the components 218 and / or 220 into or out of the nacelle 106, respectively.

[0098] A nacelle housing 230, particularly the nacelle floor, may have a corresponding opening, e.g., a hatch, on its lower side, which corresponds to or aligns with the position of the base section 284. In this case, any component arranged on the base section 284 may be lowered from or raised to the second supporting portion 206 even after the nacelle housing 230 encloses the support structure. In the case that multiple electric or other bulky and / or heavy components are to be lowered from the second supporting portion 206, a plurality of openings in the nacelle housing 230 and a corresponding plurality of detachable base sections 284 may be formed in the support structure.

[0099] In a further variation, not shown in the figures, a winch for winding up one or more crane cable 290 may be arranged inside the nacelle 106, for example on the first or second support structure 204 or 206, respectively.

[0100] Figure 11 shows yet another way of hoisting loads into and out of the lower equipment space formed between the first and second supporting portions 204 and 206. In this case, rather than detaching a section of the second supporting portion 206, the first supporting portion 204 comprises a transverse beam 294 which extends beyond the side wall of the nacelle housing 230, thus facilitating winching up or down of the bulky and / or heavy components from a lateral side of the support structure. As detailed above, the nacelle side cover may be opened and removed to allow extension of the transverse beam 294 and corresponding transfer (i.e. , loading and unloading) of the heavy component 218 using the transverse beam 294.

[0101] In the depicted embodiment, the transverse beam 294 is configured as a telescopic crane arm, with a stationary first section 296 and an extendible second section 298. To remove a component from the second support structure 206, the component is first attached using corresponding crane cables 290 and respective attachment points of the component or a lifting frame (not shown) to the second section 298 of the transverse beam 294 in its retracted position. Then a corresponding side cover of the nacelle housing 230 is removed, and the second section 298 of the telescopic crane arm is extended in a telescopic manner in a lateral direction until the component to be lowered is outside the nacelle housing 230, as indicated by the upper box 218 in Figure 11 . Thereafter, the component can be lowered using the crane cables 290 as indicated by the lower box 218 in Figure 11 , for example using an external winch on the ground or a winch integrated into the nacelle 106 as described above. In the same way, new components can be hoisted into the nacelle 106, for example for replacing damaged components. In an embodiment, the first section 296 of the transverse beam 294 can be moved and adjusted longitudinally and fixed at a particular place depending on size and position of electrical components. Once the first section 296 is adjusted and fixed at a particular location, the second section 298 can extend telescopically to perform the described operation.

[0102] Figure 12 shows a further, fourth support structure 300 for a nacelle of a wind turbine. As previously described, the support structure 300 comprises a connecting portion 202, a first supporting portion 204 and a second supporting portion 206. Compared to the previously described embodiments, the connecting portion 202 extends, in a horizontal direction, between the upper, first supporting portion 204 and the lower, second supporting portion 206. That is to say, rather than providing an intermediate connecting portion 202 arranged in a horizontal direction between, i.e. , ending at, a main frame and proximal ends of the supporting portions 204 and 206, the connecting portion 202 of Figure 12 interconnects the first supporting portion 204 and the second supporting portion 206 along their entire length, or at least a significant proportion, e.g., more than 50%, of their length.

[0103] In the embodiment shown in Figure 12, the connecting portion 202 consists essentially of two main support beams 302. In the depicted embodiment, the two main support beams 302 are arranged in parallel to each other. The distance between the two main support beams 302 may correspond to the width of the main frame 210 as shown. Alternatively, they may diverge i.e., in a non-parallel manner in the distal direction. For example, they may extend from the main frame 210 in a radial direction relative to vertical central axis of the main frame 210 or the tower. The main support beams 302 extend in a horizontal direction outwards, i.e., perpendicular to the main axis of the tower (not shown), towards a rear end of the nacelle. Of course, it is also possible to provide one or more further main support beams between the outer support beams 302. The provision of two or more main support beams 302 improves a load distribution within the support structure 300 and can dissipate high mechanical forces, caused, for example, by a generator or by the weight of a transformer, to the main frame 210.

[0104] The main support beams 302 may be relatively thick, cast metal parts, or may be formed from steel profiles, such as H-profiles. The main support beams 302 are directly attached, at their proximal ends 302a, to respective attachment points 228 (228a and 228b) of the main frame 210. In the described embodiment, they may be attached by welding, screwing, or bolting. For example, the rear end of the main frame may comprise some connecting beams 312 protruding rearwards, i.e., towards the nacelle 106 in the fully assembled state, to form the connection points 228. Each connecting beam 312 has holes for bolting this portion of the main frame 210 to a corresponding main support beam 302 of the support structure 300. The bolts extend in a lengthwise direction of the beams 302 and 312, i.e., a distal or longitudinal direction. They can be accessed from the mainframe 310 or the support structure 300 (e.g., a rear frame).

[0105] Note that the distance between the first supporting portion 204 and the second supporting portion 206 is slightly larger than the height of the main frame 210. This is enabled by frontal parts 304 of the main support beams 302 as shown in Figure 12. The remaining part of each of the main support beams 302 has a uniform height, corresponding to the height of the lower floor of the nacelle.

[0106] The first support structure 204 is attached directly, for example by screwing, bolting or welding, to an upper surface 306 of the main support beams 302. The second supporting portion 206 is attached directly, for example by screwing, bolting or welding, to a lower surface 308 of the main support beams 302. As previously described, for example, with respect to Figure 5, both the first supporting portion 204 and the second supporting portion 206 may be formed from interconnected longitudinal beams and crossbeams, which may optionally be covered by a decking material, such as a metal sheet (not shown in Figure 12). Alternately, the first and second supporting portions may be composed of a thick plate which serves as a platform for mounting the components, e.g., the generator 216 and the transformer.

[0107] At least the second supporting portion 206 extends, in a lateral direction, beyond the outer edge of the main support beams 302. In the depicted embodiment, the first supporting portion 204 also extends, in the lateral direction, beyond the outer edge of the main support beams 302. The extra width of the lower floor provided by the second supporting portion 206 creates extra room on the lateral sides of the main support beams 302 for movement of service personnel, as well as allows mounting of equipment like internal crane (not shown in Figure 12), a converter (not shown in Figure 12), or a transformer.

[0108] In the embodiment shown in Figure 12, the upper supporting portion 204 carries, at least, a generator 216. The lower supporting portion 206 may carry other electrical equipment, such as a transformer 218 or a converter (not shown). The transformer 218 may be seated directly on the floor of the second supporting portion 206 (corresponding to the lower floor of the nacelle) as shown or may be hung or suspended from the first supporting portion 204 (corresponding to the upper floor of the nacelle), while still being accessed for service from the second supporting portion 206. It may be placed towards the distal end of the second supporting portion 206 as shown or in a lateral part as described above.

[0109] In the embodiment shown in Figure 12, the lower supporting portion 206 extends, in a vertical or distal direction, beyond the second, distal end 302b of the main support beams 302, as well as the distal end 204b of the first supporting portion 204. This enables the transformer 218 to be lifted off using a crane or similar lifting device, as previously described. In an alternative embodiment, the transformer 218 or another electrical component may not be directly placed on the second supporting portion 206, but may be arranged on a further, third supporting portion attached to the end of the second supporting portion 206 and / or to the second ends 302b of the main beam 302. In this case, the distal end 204b of the first supporting portion 204, the second ends 302b of the main support beams 302 and the distal end 206b of the second supporting portion 206 may be aligned with each other.

[0110] To enable access to both the upper, first supporting portion 204 and the lower, second supporting portion 206, one or more ladders, ramps, and manholes may be provided in the support structure. For example, as shown in the embodiment of Figure 12, the main support beams 302 may comprise several openings 310, which enable movement of service personnel, tools, and equipment between a left, a central and a right part of the second supporting portion 206. Note that such openings 310 also aid cooling by enabling natural convection or forced ventilation and reduce the weight and cost of the support structure 300. Several crossbeams or rungs extending in a horizontal direction between neighboring main support beams 302 may be provided, for example, at a front or rear end of the first supporting portion 204, which can serve as a ladder or stair between the first supporting portion 204 and the second supporting portion 206 (not shown). The various embodiments described above have a number of advantages over support structures of nacelles known from the prior art. In particular, the length of the supporting frame can be significantly reduced, leading to an improved (e.g., higher) eigenfrequency of the support structure in a mounted position. This also helps to move the eigenfrequency of the support structure away from the eigenfrequency of a tower 102 and / or rotor 108 and thereby reduces mechanical stress due to dynamic loads on the wind turbine 100. In this way, an undesired resonance can be avoided. It also reduces a bending moment and the stresses of the vertical loads.

[0111] At the same time, the described embodiments can be formed from relatively small, modular parts, which can be transported using conventional trucks, rather than exceptional heavy goods transports. This in turn greatly reduces manufacturing costs and additional effort when transporting components to a construction site. Moreover, the described design enables easy and safe access to all components based within the nacelle, using a plurality of different access routes. The modular design also allows the heavier components to be loaded into / unloaded from the nacelle using any of the known lifting and lowering arrangements, for e.g., a crane.

[0112] Reference signs

[0113] 100 wind turbine

[0114] 102 tower

[0115] 104 foundation

[0116] 106 nacelle

[0117] 108 rotor

[0118] 110 rotor blade

[0119] 112 rotor hub

[0120] 200 (first) support structure

[0121] 202 connecting portion

[0122] 204 first supporting portion

[0123] 206 second supporting portion

[0124] 210 main frame

[0125] 211 rotor shaft

[0126] 212 rotor bearing housing

[0127] 214 drive train

[0128] 216 generator

[0129] 218 transformer

[0130] 220 converter

[0131] 221 electrical cabinet

[0132] 222 first joining portion

[0133] 223 main portion

[0134] 224 second joining portion

[0135] 226 supporting arm

[0136] 228 attachment point230 nacelle housing

[0137] 240 (second) support structure

[0138] 242 longitudinal beams

[0139] 244 cross beams

[0140] 246 vertical beams

[0141] 248 second vertical beams

[0142] 250 (third) support structure

[0143] 252 (right) half (left) half attachment points flange first access way first ramp upper surface nacelle front entry second access way second ramp rear service entry ladder interconnecting pathway access opening lowered platform base section lifting frame attachment point crane cable load transmission point transverse beam (stationary) first section (extendible) second section (fourth) support structure main support beam frontal part upper surface lower surface opening connecting beams support structure first supporting arm second supporting arm horizontal portion upwards inclined portion horizontal portion downwards inclined portion load transfer element support structure support structure support structure intermediate attachment point supporting arm support structure downwards inclined portion upwards inclined portion mechanical interconnection support structure support structure U-shaped supporting part vertical portion upper corner lower corner support structure block-shaped supporting part

Claims

Claims1 . A support structure (200, 240, 250) inside a nacelle (106) of a wind turbine (100), the support structure (200, 240, 250) comprising:- a connecting portion (202) configured to be attached to a main frame (210) of the wind turbine (100);- a first supporting portion (204) for supporting at least a generator (216) of the wind turbine (100); and- a second supporting portion (206) for supporting at least one other component (218, 220, 221 ) of the wind turbine (100), in particular at least one electrical component of the wind turbine (100); wherein,- the first supporting portion (204) adjoins the connecting portion (202),- the second supporting portion (206) adjoins the connecting portion (202), and- the second supporting portion (206) is arranged below the first supporting portion (204).

2. The support structure (200, 240, 250) of claim 1 , wherein the first supporting portion (204) is arranged at a higher level than the connecting portion (202), and / or the second supporting portion (206) is arranged at a lower level than the connecting portion (206).

3. The support structure (200, 240, 250) of claim 1 or 2, further comprises at least one of the following:- a first access way (260), in particular a first gangway, ramp (262), stair and / or ladder, interconnecting the first supporting portion (204) with at least one service entry of the main frame (210); and- a second access way (270), in particular a second gangway, ramp (272), stair and / or ladder, interconnecting the second supporting portion (206) with at least one service entry of the main frame (210); and / or- an interconnecting pathway (278), in particular a third gangway, ramp, stair and / or ladder (276), interconnecting the second supporting portion (206) withthe first supporting portion (204) and / or the connecting portion (202) within the support structure (200, 240, 250).

4. The support structure (200, 240, 250) of any one of claims 1 to 3, wherein the connecting portion (202) comprises two or more supporting arms (226), each of the supporting arms (226) configured to be attached, on a first end (226a), to a respective attachment point (228) of the main frame (210).

5. The support structure (410, 430, 440, 460, 470) of claim 4, wherein the two or more supporting arms (226) comprise:- a first supporting arm (412) further configured to be attached, on a second end (412b), to the first supporting portion (204); and- a second supporting arm (414) arranged at least partially below the first supporting arm (412) and further configured to be attached, on a second end (414b), to the second supporting portion (206).

6. The support structure (430) of claim 5, wherein the first supporting arm (412) and the second supporting arm (414) are configured to be attached, on their first end (412a, 414a), to a common attachment point (228) of the main frame (210).

7. The support structure (410, 440, 460, 470) of claim 5, wherein the first supporting arm (412) is configured to be attached, on its first end (412a), to an upper attachment point (228a) of the main frame (210), and the second supporting arm (414) is configured to be attached, on its first end (414a), to a lower attachment point (228b) of the main frame (210).

8. The support structure (410, 460, 470) of claim 7, wherein the first supporting arm (412) and the second supporting arm (414) are mechanically interconnected to enable a load transfer between the upper attachment point (228a) and the lower attachment point (228b).

9. The support structure (200, 240, 250) of claim 4, wherein each of the two or more supporting arms (226) is further configured to be attached, on a second end (226b), to the first and the second supporting portions (204, 206).

10. The support structure (200, 240, 250) of any one of claims 4 to 9, further comprising:- a first joining portion (222) of the first supporting portion (204) or the connecting portion (202), wherein the first joining portion (222) is inclined at a first angle (a) with respect to a main direction of a main portion (223) of the connecting portion (202), wherein the first angle (a) lies within 30° and 150° relative to the to the main direction of the main portion (223) of the connecting portion (202); and / or- a second joining portion (224) of the second supporting portion (206) or the connecting portion (202), wherein the second joining portion (224) is inclined at a second angle (|3) with respect to the main direction of the main portion (223), wherein the second angle (|3) lies within -30° and -150° relative to the to the main direction of the main portion (223) of the connecting portion (202).11 . The support structure (300) of claim 4, wherein- the first supporting portion (204) is attached directly to an upper surface (306) of each of the supporting arms (226); and / or- the second supporting portion (206) is directly attached to a lower surface (308) of each of the supporting arms (226).

12. The support structure (300) of claim 11 , wherein each of the supporting arms (226) is configured as a horizontal support beam (302) extending from the main frame (210) in a distal direction.

13. The support structure (300) of claim 12, wherein- each horizontal support beam (302) comprises a main part for attaching the first supporting portion (204) and / or the second supporting portion (206), and a frontal part (304) for attaching the respective horizontal support beam (302) to the main frame (210);- the main part of each of the horizontal support beam (302) has a uniform height; and- a height of the frontal part (304) tapers to at least a portion from the main part towards the proximal end (302a).

14. The support structure (300) of any one of claims 11 to 13, wherein each of the supporting arms (226) extend to a distal end (204b) of the first supporting portion (204) and / or a distal end (206b) of the second supporting portion (206).

15. The support structure (300) of any one of claims 9 to 14, comprising a plurality of rungs or cross beams extending in a widthwise direction of the nacelle between two neighboring supporting arms (226), the plurality of rungs or cross beams arranged one above the to form a ladder-like arrangement between the first supporting portion (204) and / or the second supporting portion (206).

16. The support structure (300) of any one of claims 4 to 15, wherein each of the supporting arms (226) comprises one or more openings (310).

17. The support structure (200, 240, 250) of any one of claims 1 to 16, wherein at least one of the connecting portion (202) and the first supporting portion (204) is configured to support a portion of a drive train (214) of the wind turbine (100).

18. The support structure (250) of any one of claims 1 to 17, wherein the support structure (250) comprises two halves (252, 254), which are detachably joined.

19. The support structure (200, 240, 250) of any one of claims 1 to 18, wherein each of the first supporting portion (204) and the second supporting portion (206) is structured as at least one of a plate, an array of interconnected bars and an array of interconnected beams (242, 244).

20. The support structure (200, 240, 250) of any one of claims 1 to 19, wherein the second supporting portion (206) comprises at least one base section (284) for carrying the at least one other component, the at least one base section (284)being detachable from the second supporting portion (206) for loading and unloading the at least one other component in an attached state of the support structure (200, 240, 250).21 . The support structure (200, 240, 250) of claim 20, wherein the first supporting portion (204) comprises at least one load transmission point (292) arranged above the at least one base section (284) and configured such that the at least one base section (284) and / or the at least one other component can be raised or lowered from the at least one load transmission point (292).

22. The support structure (200, 240, 250) of any one of claims 1 to 21 , wherein the support structure (200, 240, 250) further comprises a transverse beam (294) extending from the first supporting portion (204) and configured such that the at least one other component can be lowered from the transverse beam (294).

23. The support structure of claim 22, wherein the transverse beam (294) comprises:- a first section (296) attached to the first supporting portion (204); and- at least one second section (298) extendible, in particular in a telescopic manner, in a lateral direction of the nacelle (106), such that the at least one other component can be attached to the transverse beam (294) in a retracted position of the second section (298), and can be lowered from the support structure (200, 240, 250) in an extended position of the second section (298).

24. The support structure (200, 240, 250) of any one of claims 1 to 23, wherein:- the connecting portion (202) is manufactured in one or more parts as a steel or cast-iron construction, or any other metal or alloying combination; and / or- the first and the second supporting portions (204, 206) are manufactured in one or more parts as a steel or cast- iron construction, or any other metal or alloying combination.

25. A nacelle (106) for a wind-turbine (100), comprising:- a main frame (210) configured to be attached to a tower (102) of the wind turbine (100);- a support structure (200, 240, 250, 300, 410, 430, 440, 460, 470, 480, 490) according to any one of claims 1 to 24, wherein the support structure (200, 240, 250, 300, 410, 430, 440, 460, 470, 480, 490) is attached to the main frame (210);- a generator (216) arranged on the first supporting portion (204) of the support structure (200, 240, 250) and being configured to be mechanically coupled to a rotor (108) of the wind turbine (100);- at least one other component (218, 220, 221 ), in particular at least one first electrical component electrically coupled to the generator (216), the at least one other component (218, 220, 221 ) being arranged on the second supporting portion (206) of the support structure (200, 240, 250); and- a nacelle housing (230) enclosing at least the main frame (210), the support structure (200, 240, 250), the generator (216), and the at least one other component (218, 220, 221 ).

26. The nacelle (106) of claim 25, wherein the nacelle (106) further comprises a transformer (218).

27. The nacelle (106) of claim 26, wherein the transformer (218) is suspended from the first supporting portion (204) or seated on the second supporting portion (206).

28. A wind turbine (100) comprising a tower (102), a nacelle (106) according to any one of claims 25 to 27 attached to the tower (102) and supporting a rotor (108), and a plurality of rotor blades (110) attached to the rotor (108).

29. The wind turbine (100) as claimed in claim 28, wherein the second supporting portion (206) comprises at least one base section (284) for carrying the at least one other component, the base section (284) being detachable from the second supporting portion (206) for loading and unloading the at least one othercomponent in the attached state of the support structure (200, 240, 250), and wherein the base section (284) corresponds with an opening formed in a floor of the nacelle housing (230).

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