Reinforcement of a wind turbine structure

Abstract

One aspect of the invention relates to a method of reinforcing a tubular wind turbine structure using a radially adjustable ring stiffener. The ring stiffener comprises a pair of adjacent ring segments coupled together by a coupling device configured to allow radial adjustment of the ring stiffener by changing the inter-segment spacing between adjacent ends of those ring segments. The method comprises the steps of positioning the ring stiffener at a reinforcement position within the tubular wind turbine structure; and adjusting the inter-segment spacing between the pair of adjacent ring segments to increase the radius of the ring stiffener; and thereby engaging the inner surface of the tubular wind turbine structure with a radial force that retains the ring stiffener at the reinforcement position by means of friction between the ring stiffener and the tubular wind turbine structure.

Description

Technical Field

[0001] This invention generally relates to wind turbine structures, and more particularly to methods for reinforcing tubular wind turbine structures. Background Technology

[0002] A typical design for a horizontal axis wind turbine includes a tower and a nacelle. The nacelle is mounted on top of the tower and supports a rotor with a set of blades and power generation equipment for converting the kinetic energy of the wind into electrical energy. The tower is typically composed of a series of tubular sections (usually made of steel or concrete) that are transported individually to the installation site, where they are stacked on top of each other and joined together to form the tower structure.

[0003] With the trend towards reducing total energy costs, the size of wind turbines has increased over the past few decades, presenting several significant design challenges. Larger nacelles and rotors require stronger support structures, which often means that the tubular segments of the wind turbine tower are manufactured with increased wall thickness. However, this increases the material cost of such towers and also challenges conventional installation methods. To reduce costs, known methods include minimizing the wall thickness of the tower's tubular segments to enable the production of lighter and more economical towers. However, the reduction in tower wall thickness must be done carefully, as this also reduces the tower's strength, which can lead to structural fragility.

[0004] One known method for reducing the mass of a wind turbine tower without compromising its strength involves constructing the tower with thicker tubular segments in areas identified as most vulnerable to structural weaknesses. However, this method is often too expensive because it potentially adds a significant amount of unnecessary material to the tower.

[0005] Another method is to reinforce the vulnerable parts of the tower by welding ring stiffeners to the inner or outer walls of the tower. This method effectively enlarges or strengthens the cross-section of critical areas of the tower. This, in turn, reduces the buckling length of tower segments and increases the tower's resistance to bending, thereby increasing the tower's strength and mitigating any structural vulnerabilities.

[0006] However, one problem with the second method is that the welding process heats the tower walls, and the hot spots that may be formed by the heat of the welding process could result in a reduction in the fatigue strength of the tower.

[0007] It was in this context that the present invention was designed. Summary of the Invention

[0008] According to one aspect of the invention, a method for reinforcing a tubular wind turbine structure using a radially adjustable ring reinforcement is provided. The ring reinforcement comprises a pair of adjacent ring segments joined together by coupling means configured to allow radial adjustment of the ring reinforcement by changing the intersegmental separation between adjacent ends of those ring segments. The method includes the steps of: positioning the ring reinforcement at a reinforced position within the tubular wind turbine structure; adjusting the intersegmental separation between the pair of adjacent ring segments to increase the radius of the ring reinforcement; and thereby engaging the inner surface of the tubular wind turbine structure with a radial force, the radial force holding the ring reinforcement in the reinforced position by means of friction between the ring reinforcement and the tubular wind turbine structure.

[0009] Advantageously, the method is configured such that the ring reinforcement attached to the tubular wind turbine structure remains in place (only) by means of friction, i.e., no fasteners or welds are placed between the ring reinforcement and the wind turbine structure.

[0010] Therefore, the method is advantageously configured to reinforce the wind turbine structure and, in particular, alleviate weak areas of the structure without reducing the fatigue strength of the wind turbine structure (e.g., by creating hot spots).

[0011] In one embodiment, the ring reinforcement is inserted into the tower after the wind turbine has been constructed. Furthermore, the wind turbine may have already been operating for some time.

[0012] In one embodiment, the ring reinforcement is inserted into the tower during partial repowering of the wind turbine, where the tower is reused. Partial repowering includes replacing and / or upgrading one or more components of the wind turbine. By installing the ring reinforcement at weak points, the tower's lifespan can be increased easily and economically. This location can be determined based on a tower strength assessment.

[0013] For example, the radius of the ring reinforcement can be increased to such an extent that an interference fit or friction fit is formed between the ring reinforcement and the inner surface of the wind turbine structure, thereby holding the ring reinforcement in place by means of friction. In other words, the radius of the ring reinforcement can be increased to be equal to or greater than the inner radius of the tubular wind turbine structure.

[0014] In the example, the connecting device may take the form of an adjustable connecting device, operable to control the inter-segment spacing between the pair of adjacent ring segments. "Control" means that the adjustable connecting device can selectively set, maintain, or otherwise sustain the inter-segment spacing as needed. The step of adjusting the inter-segment spacing between the pair of adjacent ring segments includes operating the adjustable connecting device.

[0015] For example, an adjustable coupling device may include an adjustable separating member or device that extends between adjacent ring segments, thereby keeping adjacent ends of those ring segments separated. Such an adjustable coupling device may be used in combination with an actuating device that forces the plurality of ring segments radially outward (in order to set an increased inter-segment spacing).

[0016] In the example, the adjustable coupling device may include a biasing device configured to cause adjacent ends of these ring segments to separate.

[0017] In the example, the adjustable coupling device may include an actuator operable to change the inter-segment spacing between adjacent ends of a ring segment. Adjusting the inter-segment spacing between the pair of adjacent ring segments may, for example, involve operating the actuator to cause the pair of adjacent ring segments to separate.

[0018] In other words, the actuator can be operated to generate actuation force that causes adjacent ends of the ring section to separate (against the resistance of the inner surface of the tubular wind turbine structure).

[0019] In the example, the actuator can be a linear actuator. For instance, actuation force can be generated by linear expansion of the actuator between adjacent ends of a ring segment. In other examples, the actuator can be a rotary actuator.

[0020] For example, the actuator can be one of the following: a pneumatic actuator; a mechanical actuator; a hydraulic actuator; or an electric actuator.

[0021] In the example, the linear actuator may include a lead screw mechanism connected between the pair of adjacent loop segments. This lead screw mechanism may, for example, be operable to cause the pair of adjacent loop segments to separate.

[0022] Alternatively, the lead screw mechanism may engage a pair of opposing walls at adjacent ends of the loop section.

[0023] In the example, the adjustable coupling device can take the form of a fastening arrangement. This fastening arrangement can include the lead screw mechanism, which may include, for example, a screw, a first fastening member, and a second fastening member. The first and second fastening members can be mounted on the lead screw between the pair of opposing walls, wherein the first fastening member abuts against a first wall of the opposing walls, and the second fastening member abuts against a second wall of the opposing walls. Operating the lead screw mechanism may include, for example, rotating at least one of the first and second fastening members along the lead screw to increase the distance between the first and second fastening members, thereby causing the pair of adjacent ring segments to separate.

[0024] In this way, the ring reinforcement can be adjusted by means of fastening devices between adjacent ring sections, which also serve to connect the adjacent ring sections together.

[0025] In the example, the method may further include the step of securing the engagement between the ring reinforcement and the tubular wind turbine structure by fixing the inter-segment spacing between the pair of adjacent ring segments. In this context, the inter-segment spacing can be rigidly fixed by a permanent device.

[0026] The step of fixing the inter-segment spacing between the pair of adjacent ring segments includes, for example, connecting a separating member between the pair of adjacent ring segments. The separating member can be configured to substantially inhibit relative movement between adjacent ring segments.

[0027] In one example, the step of connecting the separator between the pair of adjacent ring segments may include welding the separator to the adjacent ring segments. For example, opposite ends of the separator may be welded to the corresponding ring segments in the pair of adjacent ring segments. In another example, the separator may be connected between the pair of adjacent ring segments by bolts or other fasteners.

[0028] In one example, the method may further include the step of removing the connecting device from between the pair of adjacent ring segments after the inter-segment spacing between the pair of adjacent ring segments has been fixed. In this way, the connecting device can be reusable, for example, for use in further reinforcement of the tubular wind turbine structure or for use in reinforcement of another tubular wind turbine structure.

[0029] The step of adjusting the inter-segment spacing between the pair of adjacent ring segments may include, for example, using sufficient radial force to force the pair of adjacent ring segments to radially outward engage the inner surface of the tubular wind turbine structure in order to hold the ring reinforcement in the reinforced position.

[0030] In one example, the method further includes the step of assembling a radially adjustable ring reinforcement within the tubular wind turbine structure, wherein assembling the ring reinforcement includes connecting a pair of adjacent ring segments together using a coupling device. Advantageously, the ring segments can thus be introduced individually into the interior of the tubular wind turbine structure, allowing them to be inserted into the tubular wind turbine structure through smaller openings. This may be suitable, for example, in cases where the tubular wind turbine structure needs to be field-mounted on the assembled wind turbine.

[0031] In one example, the ring reinforcement may include multiple ring segments connected together by a set of coupling devices, the multiple ring segments including the pair of adjacent ring segments. Each coupling device in the coupling device may extend between a corresponding pair of adjacent ring segments in the multiple ring segments and may be configured to allow radial adjustment of the ring reinforcement by changing the inter-segment spacing between adjacent ends of those ring segments. The method may include the steps of: adjusting the inter-segment spacing between one or more pairs (or each pair) of adjacent ring segments to increase the radius of the ring reinforcement; and thereby using a radial force that holds the ring reinforcement in a reinforced position to engage the inner surface of the tubular wind turbine structure.

[0032] For example, the plurality of ring reinforcements may consist of three ring segments. The plurality of ring segments may be connected end-to-end in a circular arrangement by the set of connecting devices. The plurality of ring segments may have equal (arc-shaped) lengths, which may, for example, produce a symmetrical and balanced arrangement of forces.

[0033] In the example, the outer radius of each of the plurality of ring segments can be greater than or equal to the radius of the inner surface of the tubular wind turbine structure at the reinforced location. In this way, the plurality of ring segments can be complementary to the inner surface of the tubular wind turbine structure and configured to form an interference fit with it.

[0034] Optionally, the tubular wind turbine structure is selected from at least one of the following: a tubular segment of the wind turbine tower; and / or a tubular segment of the wind turbine blade.

[0035] Within the scope of this application, it is expressly intended that various aspects, embodiments, examples, and alternatives set forth in the preceding paragraphs, claims, and / or the following description and drawings, particularly their individual features, may be adopted independently or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination, unless such features are incompatible. The applicant reserves the right to accordingly amend any originally filed claim or to file any new claim, including the right to modify any originally filed claim to incorporate any feature dependent on and / or incorporated into any other claim, although not originally claimed in this manner. Attached Figure Description

[0036] The above and other aspects of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0037] Figure 1 This is a schematic diagram of an example wind turbine according to an embodiment of the present invention;

[0038] Figure 2 yes Figure 1 A schematic diagram of an example tower segment of a wind turbine is shown.

[0039] Figure 3A This is a schematic diagram of an example radially adjustable ring reinforcement according to an embodiment of the present invention;

[0040] Figure 3B yes Figure 3A A side view of an example ring segment among the multiple ring segments of the radially adjustable ring reinforcement shown;

[0041] Figure 4A and Figure 4B Examples Figure 3A The radially adjustable ring reinforcement shown is configured in the first state and the second state, respectively.

[0042] Figure 5 Examples are set as follows Figure 3A An example connection device between a pair of adjacent ring segments of the plurality of ring segments of the radially adjustable ring reinforcement shown;

[0043] Figure 6 An example is illustrated by the use of a radially adjustable ring reinforcement (such as...) according to an embodiment of the invention. Figure 3A The radially adjustable ring reinforcement shown is used to reinforce tubular wind turbine structures (such as...). Figure 2 Example method (shown for tower segments);

[0044] Figure 7 Examples Figure 6 The method shown will Figure 3AThe radially adjustable ring reinforcement shown moves to Figure 2 The steps for determining the location within the tower segment shown;

[0045] Figure 8 Examples Figure 6 The method shown is in Figure 2 The tower segment shown has been increased Figure 1 Another step in adjusting the radius of the radially adjustable ring reinforcement shown;

[0046] Figure 1 Examples Figure 2 The attached to Figure 2 The radially adjustable ring reinforcement of the tower segment shown; and

[0047] Figure 3A Examples Figure 3B The radially adjustable ring reinforcement shown is attached once... Figure 3A The tower segment shown represents the step of fixing the distance between the plurality of ring segments of the radially adjustable ring reinforcement.

[0048] In the accompanying drawings, the same reference numerals are used to indicate the same features throughout the drawings. Detailed Implementation

[0049] Embodiments of the present invention relate to a wind turbine structure and a method for reinforcing a tubular wind turbine structure using radially adjustable ring reinforcements. This method is envisioned for use in reinforcing tubular segments of wind turbine towers and / or wind turbine blades to mitigate structural weaknesses.

[0050] This method is configured to advantageously connect the ring reinforcement to the tubular segment using the radial adjustability of the ring reinforcement without conventional attachment means such as welding, adhesives, or fasteners. Alternatively, the method involves placing the ring reinforcement within the tubular segment and increasing the radius of the ring reinforcement to such an extent that the ring reinforcement engages the inner surface of the structure with sufficient radial force to hold the ring reinforcement in place.

[0051] For example, the radius of the ring reinforcement can be increased to such an extent that an interference fit is formed between the ring reinforcement and the inner surface of the wind turbine structure, thereby holding the ring reinforcement in place by means of friction.

[0052] Using this attachment method, ring reinforcements can effectively strengthen the cross-section of wind turbine structures and reduce the bending length of the structure, thus increasing its bending resistance. In this way, ring reinforcements can be attached to mitigate weak areas of the structure without reducing its fatigue strength.

[0053] Figure 3BA horizontal axis wind turbine 1 according to an embodiment of the present invention is shown. The wind turbine 1 includes a tower 2, a nacelle 4, and a set of blades 6.

[0054] The nacelle 4 is mounted on top of the tower 2, and in this example, the tower 2 is supported on a base on the ground (not shown). The nacelle 4 supports a rotor, which includes a rotor hub 5 to which the set of blades 6 is attached, and the nacelle 4 houses a power generation device (not shown) for converting the kinetic energy of the wind into electrical energy.

[0055] Tower 2 comprises a plurality of tower segments 10, which are stacked on top of each other and connected together to form a tower structure. The number of tower segments 10 is not critical to the invention, and in other examples, tower 2 may comprise a single tower segment 10, which still falls within the scope of the appended claims.

[0056] Each tower segment 10 is tubular and essentially cylindrical. However, as... Figure 3B As shown, each tower segment 10 can be slightly tapered along its length so that it has a slightly larger diameter at one end than at the other.

[0057] The plurality of tower segments 10 can be formed, for example, of steel or concrete. Typically, such tower segments can be about 10 to 30 meters high, about 3 to 6 meters in diameter, and have a wall thickness of about 10 to 40 millimeters for the context.

[0058] Now turn to Figure 3A The image shows an illustrative but slightly simplified view of one of the plurality of tower segments 10. In this example, the tower segment 10 includes a tower wall 12 that is substantially cylindrical and extends along the longitudinal axis of the tower segment 10 from a base 14 at one end to a top 16 at the other end.

[0059] The interior of tower segment 10 is defined by the inner surface 18 of tower wall 12, and the exterior of tower segment 10 is defined by the outer surface 20 of tower wall 12. Although tower wall 12 tapers inward, the thickness between the inner surface 18 and the outer surface 20 is substantially constant between the base 14 and the top 16.

[0060] Despite Figure 3B The tower segment 10 may include other components not described herein, such as access ladders, cable support brackets, and floor joists, as is conventional in the art, but those skilled in the art will appreciate that it may also include other components not described herein.

[0061] Those skilled in the art will recognize that the strength of tower segment 10 derives primarily from the thickness of tower wall 12. Therefore, a lighter tower segment 10 with a thinner tower wall 12 will inherently be more flexible. This means that a thin-walled tower segment 10 may be more susceptible to structural weaknesses (such as bending that may occur if the compressive load on one side of the tower segment 10 becomes excessive), leading to structural instability.

[0062] Therefore, if the tower wall 12 is too thin (as is the case with the vulnerable section of tower 2), the compressive load during extreme transient events may be large enough to cause the tower segment 10 to bend on the compressive side and move away from its equilibrium position. After bending, the structural integrity of the tower segment 10 and tower 2 itself may be compromised.

[0063] The method of the present invention attempts to mitigate this problem by reinforcing tower segment 10 and increasing the strength of tower 2 by installing radially adjustable ring reinforcements.

[0064] For example, a radially adjustable ring reinforcement can be installed at a reinforced location (generally indicated as 22), which is identified as a transversely structurally weak area within the tower 2 and / or tower segment 10 itself. This structurally weak area can be identified, for example, by a structural integrity assessment that identifies potential load-limiting locations. The location of the structurally weak area can depend on the design of the tower 2 and the corresponding loads applied to the tower segment 10, and can be identified, for example, based on the maximum expected load during a transient event. In this example, the reinforced location 22 can be positioned at the midpoint of the tower segment 10, where the tower segment 10 is relatively rigid near the base 14 and top 16.

[0065] Once installed, the adjustable ring reinforcement functions to enlarge the cross-section of tower segment 10 at the reinforced position 22, thereby effectively increasing the thickness of the tower wall 12. The increased wall thickness increases the strength of the tower segment 10 and mitigates any structural weaknesses that would otherwise have led to bending.

[0066] Figure 3A and Figure 4A An example of a radially adjustable ring reinforcement 30 according to an embodiment of the present invention is shown.

[0067] Figure 4B A plan view of the ring reinforcement 30 is shown. The ring reinforcement includes multiple ring segments 32a to 32c and a set of connecting devices 34a to 34c. Each of the multiple ring segments 32a to 32c has an arcuate length, and the multiple ring segments 32a to 32c are connected end-to-end by the set of connecting devices 34a to 34c to form a circular shape.

[0068] In this example, the plurality of ring segments 32a to 32c include: a first ring segment 32a, a second ring segment 32b, and a third ring segment 32c. However, it should be understood that in other examples, the plurality of ring segments may include two or more ring segments.

[0069] In this example, the first ring segment 32a, the second ring segment 32b, and the third ring segment 32c have equal (arc-shaped) lengths to create a balanced and symmetrical arrangement. However, in other examples, it is not necessary for the multiple ring segments to have equal lengths.

[0070] Figure 4A A side view of an example ring segment (such as the first ring segment 32a) is shown, which in this example has a T-shaped cross-section. Figure 4B (The cross-hatching is shown in the diagram). The T-shaped cross section is not necessary for this invention, and in other examples, the specific shape of each ring section can take other suitable forms to reinforce the tubular wind turbine structure, such as being characterized by an L-shaped, I-shaped, or box-shaped cross section.

[0071] The T-shaped cross-section is defined by a first wall 40 and a transverse second wall 42. The first wall 40 is configured to engage with the inner surface of a tubular wind turbine structure (such as tower segment 10) and extends substantially vertically above and below the outer edge 44 of the second wall 42, like a flange. The second wall 42 projects radially inward from the first wall 40 like a web and functions to increase the radial strength of the annular segment 32a.

[0072] In this example, the outer surface 46 of the first wall 40 defines the outer surface of the annular segment 32a, and thus it should be understood that the outer surface 46 of the first wall 40 can be configured to engage the tubular wind turbine structure. For example, the outer surface 46 of the first wall 40 can be shaped at the desired reinforcement location 22 in a manner complementary to the inner surface 18 of the tower segment 10.

[0073] More specifically, the outer surface 46 of the first wall 40 may have a radius greater than or equal to the radius of the inner surface 18 of the tower wall 12 (e.g., at the reinforced position 12), and thus complement it.

[0074] like Figure 4A and Figure 4B As shown, each ring segment 32a to 32c extends from the corresponding first end 48a to 48c to the corresponding second end 50a to 50c, and the ring segments 32a to 32c are connected end to end to form a ring reinforcement 30.

[0075] In order to support the connection of adjacent ring segments 32a to 32c together, in this example, each ring segment 32a to 32c includes a first end wall 49a to 49c at the first end 48a to 48c and a second end wall 51a to 51c at the second end 50a to 50c.

[0076] The first end walls 49a to 49c and the second end walls 51a to 51c of each annular segment 32a to 32c are substantially rectangular and extend substantially vertically from the inner radius of each annular segment 32a to 32c defined at the inner edge 52 of the second wall 42 to the outer radius of the annular segment 32a to 32c defined at the outer surface 46 of the first wall 40.

[0077] Once assembled, it should be considered that the adjacent end walls 49a to 49c of the first end walls and 51a to 51c of the adjacent ring segments 32a to 32c form multiple pairs of opposing walls 52a to 52c, such as Figure 4A As shown. For example, a first pair of opposing walls 52a are formed between the second end wall 51a of the first ring section 32a and the first end wall 49a of the second ring section 32b; a second pair of opposing walls 52b are formed between the second end wall 51b of the second ring section 32b and the first end wall 49c of the third ring section 32c; and a third pair of opposing walls 52c are formed between the second end wall 51c of the third ring section 32c and the first end wall 49a of the first ring section 32a.

[0078] Multiple pairs of opposing walls 52a to 52c can be adapted to use the set of connecting devices 34a to 34c to connect adjacent ring sections 32a to 32c together, as will become clear.

[0079] Considering the set of connecting devices 34a to 34c in more detail, each connecting device 34a to 34c is configured to connect a corresponding pair of adjacent ring segments 32a to 32c together, and allows radial adjustment of the ring reinforcement 30 by changing the spacing between adjacent ends of those ring segments 32a to 32c. Hereinafter, the spacing between adjacent ends of adjacent ring segments 32a to 32c will be referred to as the “inter-segment spacing”.

[0080] For this purpose, for example, the various connecting devices 34a to 34c can be conveniently arranged between and connected to a corresponding pair of walls in a plurality of pairs of opposing walls 52a to 52c.

[0081] supply Figure 4B and Figure 4A The radial adjustment of the ring reinforcement 30 is illustrated in more detail.

[0082] Figure 4B The ring reinforcement 30 is shown in its first configuration, and Figure 5The ring reinforcement 30 configured in the second state is shown, while the ring reinforcement 30 in the first state is also illustrated by dashed lines. Figure 5 and Figure 4A In the figure, the outer radius 54 of the ring reinforcement 30 is depicted and shown as extending from the center 56 of the ring reinforcement 30 to the outer surface of one of the plurality of ring segments 32a to 32c, such as the outer surface 46 of the first ring segment 32a.

[0083] Compare Figure 4B and Figure 4A It is clear that the outer radius 54 of the ring reinforcement 30 is shorter in the first state than in the second state. For example, in the second state, the outer radius 54 of the ring reinforcement 30 can be increased by at least 3% compared to the first state, and in other examples, it can be increased by at least 5% compared to the first state.

[0084] Therefore, in the first state, the ring reinforcement 30 can pass through a hole or opening with a smaller diameter than that possible in the second state.

[0085] As will become clear, during the installation process, the radius of the ring reinforcement 30 can therefore be advantageously reduced to move the ring reinforcement 30 to the reinforced position.

[0086] Between the first and second states, the ring reinforcement 30 is configured to expand radially outward, and it is evident that between each pair of adjacent ring segments 32a to 32c, the inter-segment spacing increases from a first length to a second length, as can be seen by comparison. Figures 6 to 9 and Figure 6 As shown.

[0087] For clarity, it should be understood that the plurality of ring segments 32a to 32c remain substantially unchanged between the first and second states. However, the connecting devices 34a to 34c allow for an increase in the inter-segment spacing between each pair of adjacent ring segments 32a to 32c. This has the effect of increasing the circumference of the ring reinforcement 30, and thus pushing the plurality of ring segments 32a to 32c radially outward, thereby causing the ring reinforcement 30 to expand.

[0088] As will become clear, within the scope of the appended claims, the connecting devices 34a to 34c may take various forms for connecting adjacent ring segments 32a to 32c together when the inter-segment spacing changes.

[0089] In the example, the connecting devices 34a to 34c can be configured to allow passive variation in the inter-segment spacing while connecting adjacent ring segments 32a to 32c together. For example, the connecting devices 34a to 34c can take the form of flexible connecting devices or mechanisms that can be configured to constrain relative movement of adjacent ring segments 32a to 32c, thereby allowing the inter-segment spacing to be changed by forcing other means of radially outward movement of adjacent ring segments 32a to 32c.

[0090] In another example, the connecting devices 34a to 34c may additionally or alternatively include a biasing device configured to cause adjacent ring segments 32a to 32c to separate. Therefore, a radially inward force is required to compress the biasing device and maintain the ring reinforcement 30 in a first state. Upon removal of the radially inward force, the biasing device can cause adjacent ring segments 32a to 32c to separate, thereby expanding the ring reinforcement 30 into a second state. It should be understood that the biasing device can simultaneously function to connect adjacent ring segments 32a to 32c together, thereby preventing them from separating from each other.

[0091] In another example, the connecting devices 34a to 34c may additionally or alternatively be adjustable and configured to set, maintain, or otherwise control the inter-segment spacing between adjacent ring segments 32a to 32c. For example, such an adjustable connecting device may take the form of an adjustable separating member or device that extends between adjacent ring segments 32a to 32c, thereby keeping adjacent ends of those ring segments 32a to 32c separated.

[0092] In yet another example, the connecting devices 34a to 34c may additionally or alternatively include means for actively changing the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c. For example, the connecting devices may include actuators or actuating mechanisms that can be operated to cause adjacent ring segments 32a to 32c to separate and change the inter-segment spacing. Such actuating mechanisms may, for example, include any of a mechanical actuator, a hydraulic actuator, an electric actuator, or a pneumatic actuator.

[0093] To provide a detailed example, Figures 7 to 9 A portion of an example ring reinforcement 30 is shown, representing a set of connecting devices 34a to 34c that are operable to change the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c.

[0094] For the sake of simplicity, Figure 5Only the connecting device 34a, which is located between the first ring section 32a and the second ring section 32b, is shown. However, it should be understood that the other connecting devices 34b, 34c in this group of connecting devices 34a to 34c can be substantially the same.

[0095] In this example, the connecting device 34a takes the form of a fastening device 60a, which is disposed between the pair of opposing walls 52a at the adjacent ends of the first adjacent ring segment 32a and the second adjacent ring segment 32b. As will become clear, the fastening device 60a can optionally operate as a lead screw mechanism to cause the pair of adjacent ring segments 32a, 32b to separate.

[0096] In this example, the fastening device 60a includes four substantially identical sub-devices 62a to 62d. These sub-devices 62a to 62d are functionally equivalent, and in other examples, any one of those sub-devices 62a to 62d can be fully operated as the coupling device 34a.

[0097] Consider in more detail one of the sub-devices 62a to 62d, sub-device 62a including a screw 64 and a complementary set of fastening components 66a to 66d.

[0098] The screw 64 extends from the first end 68 to the second end 70 and passes through a pair of complementary holes (not shown) formed in the pair of opposing walls 52a.

[0099] The fastening components 66a to 66d are mounted on the screw 64 to abut against the opposing walls 52a at the adjacent ends of the first ring section 32a and the second ring section 32b, thereby controlling the inter-segment spacing between them.

[0100] Therefore, in this example, the set of fastening components 66a to 66d includes: a first fastening component 66a, a second fastening component 66b, a third fastening component 66c, and a fourth fastening component 66d.

[0101] The first fastening member 66a and the second fastening member 66b are mounted on the screw 64 between the pair of opposing walls 52a and abut against the pair of opposing walls 52a, thereby keeping the adjacent ring sections 32a, 32b separated. For example, the first fastening member 66a can be configured to abut against the second end wall 51a of the first ring section 32a, and the second fastening member 66b can be configured to abut against the opposing first end wall 49b of the second ring section 32b.

[0102] With this construction, it is conceivable that the fastening device 60a can be operated as a screw mechanism capable of changing the inter-segment interval between the first ring segment 32a and the second ring segment 32b.

[0103] Specifically, the distance between the first fastening member 66a and the second fastening member 66b can be increased by rotating at least one of the first fastening member 66a and the second fastening member 66b along the screw 64, thereby moving the ring reinforcement 30 from... Figure 2 The first state shown is adjusted to Figure 4A The second state is shown.

[0104] As the distance between the first fastening member 66a and the second fastening member 66b increases, the pair of adjacent ring segments 32a and 32b are further separated, thereby increasing the inter-segment spacing between them.

[0105] The third fastening component 66c and the fourth fastening component 66d can be mounted on the first end 68 and the second end 70 of the screw 64, and the pair of opposing walls 52a can be disposed between them to ensure that the first ring section 32a and the second ring section 32b are fully connected together.

[0106] For example, the third fastening member 66c can be rotated to abut against the second end wall 51a of the first ring section 32a, thereby clamping the second end wall 51a against the first fastening member 66a. Similarly, the fourth fastening member 66d can be rotated to abut against the first end wall 49b of the second ring section 32b, thereby clamping the first end wall 49b against the second fastening member 66b.

[0107] This arrangement can be used to substantially prevent the first ring segment 32a and the second ring segment 32b from moving away from the first fastening member 66a and the second fastening member 66b. Without the third fastening member 66c and the fourth fastening member 66d, the first ring segment 32a and the second ring segment 32b may, for example, become disengaged during transport or installation.

[0108] It should also be considered that by operating the fastening device 60a to reduce the distance between the first fastening member 66a and the second fastening member 66b, the ring reinforcement 30 can return to... Figure 7 The first state is shown.

[0109] Now, refer to Figure 6 A method 100 for reinforcing a tubular wind turbine structure using a radially adjustable ring reinforcement according to an embodiment of the present invention is described.

[0110] Figure 4A A schematic illustration of method 100 is shown, and provides Figure 4B This illustrates one or more steps of the method.

[0111] For simplicity, the following examples involve using Figure 8 The radially adjustable ring reinforcement 30 is shown for reinforcement. Figure 8The method shown for tower segment 10.

[0112] Tower segment 10 is reinforced before assembling tower 2 (e.g., at the manufacturing facility), and in step 101, a radially adjustable ring reinforcement is located inside tower segment 10 in preparation for installation.

[0113] In step 102, the ring reinforcement 30 is moved to the reinforcement position 22 of the tower segment 10 in preparation for attachment to the tower wall 12. In other words, in step 102, the ring reinforcement 30 can be moved along the longitudinal axis of the tower segment 10 to the area requiring reinforcement.

[0114] Therefore, such as Figure 9 As shown, the ring reinforcement 30 can be set in the first state and positioned coaxially relative to the tower segment 10.

[0115] It should be understood that, in the first state, the ring reinforcement 30 can be sized to fit inside the tower segment 10, and has a certain gap between the outer surface 46 of each ring segment 32a to 32c and the inner surface of the tower wall 12.

[0116] For example, Figure 10 A plan view of the ring reinforcement 30 located at the reinforcement position 22 is shown.

[0117] With such a gap, the ring reinforcement 30 can move substantially unimpeded along the longitudinal axis of the tower segment 10 between the base 14 of the tower segment 10 and the reinforcement position 22.

[0118] Although not described in detail here, those skilled in the art will appreciate that the ring reinforcement 30 can be moved to the reinforced position 22 by various means, including suitable lifting mechanisms or machines (such as cranes).

[0119] In this example, the ring reinforcement 30 is designed to completely avoid contact with the tower wall 12 when set in the first state. However, in other examples, it should be considered that the ring reinforcement 30 may slightly engage the inner surface 18 of the tower wall 12 at the reinforced position 22, but the engagement force may not be sufficient to hold the ring reinforcement 30 in place.

[0120] Return to Figure 10 In order to fully connect the ring reinforcement 30 to the tower segment 10, in step 104, the radius of the ring reinforcement 30 may be increased to engage the inner surface 18 of the tower wall 12 with sufficient radial force, thereby holding the ring reinforcement 30 in place.

[0121] Therefore, it is necessary to increase the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c. Thus, for proper engagement, the ring reinforcement 30 can be...​ The first state shown is adjusted to ​ The second state is shown.

[0122] In this example, the radius of the ring reinforcement 30 can be increased by operating the adjustable coupling devices 34a to 34c to cause one or more pairs of adjacent ring segments 32a to 32c to separate.

[0123] For example, ​ The example illustrates the increase in the inter-segment spacing between the first ring segment 32a and the second ring segment 32b.

[0124] like ​ As shown, in this example, the adjustable coupling device 34a takes the form of a fastening device 60a (described previously) and can be operated as a lead screw mechanism in step 104 to cause the pair of adjacent ring segments 32a, 32b to separate.

[0125] In particular, the operation of the first sub-device 62a of the fastening device 60a is considered in more detail.

[0126] In step 104, the first fastening member 66a and the second fastening member 66b can be rotated along the screw 64 to increase the distance or interval between them.

[0127] As the distance between the first fastening member 66a and the second fastening member 66b increases, the pair of adjacent ring segments 32a, 32b are caused to separate and radially outward in order to engage the tower wall 12.

[0128] As the ring reinforcement 30 continues to expand from the first state to the second state, the increased radial force can be used to force the plurality of ring segments 32a to 32c against the tower wall 12, thereby enhancing the engagement between the ring reinforcement 30 and the tower segment 10.

[0129] Ultimately, the outer radius 54 or the ring reinforcement 30 can be increased to a degree greater than or equal to the radius of the inner surface 18 of the tower wall 12. Therefore, as... ​ As shown, an interference fit can be formed between the ring reinforcement 30 and the tower segment 10.

[0130] It should be understood that as the ring reinforcement 30 expands from the first state to the second state, the tower wall 12 will function to resist the expansion of the ring reinforcement 30. Therefore, the torque required to rotate the first fastening member 66a and the second fastening member 66b along the screw 64 can correspond to the corresponding radial force required to hold the ring reinforcement 30 in the reinforced position 22.

[0131] Once the ring reinforcement 30 has been properly expanded, the third fastening member 66c and the fourth fastening member 66d can rotate along the screw 64 toward the first fastening member 66a and the second fastening member 66b in order to clamp the pair of opposing walls 52a and fix the inter-segment spacing between adjacent ring segments 32a to 32c.

[0132] Subsequently, the ring reinforcement 30 can be effectively connected to the tower segment 10 by friction alone, without the need for additional supports, welding or other fasteners between the ring reinforcement 30 and the tower wall 12.

[0133] It should be understood that the expansion of the ring reinforcement 30 can be performed by simultaneously or one after another increasing the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c.

[0134] Advantageously, the attached ring reinforcement 30 effectively increases the wall thickness of the tower wall 12 at the reinforced position 22, thereby mitigating the structural weaknesses of the tower segment 10 without reducing its fatigue resistance.

[0135] Additionally, if necessary, the ring reinforcement 30 can be selectively detached from the tower wall 12 by repeating the above steps in reverse order and reducing the radius of the ring reinforcement 30 from the second state to the first state.

[0136] Those skilled in the art will also appreciate that the present invention can relate to the reinforcement of other tubular wind turbine structures (such as the tubular segments of wind turbine blades 6), which can be, for example, in the field (in the assembled wind turbine structure).

[0137] In another example, the method 100 for reinforcing a tubular wind turbine structure may further include the following steps: after the ring reinforcement 30 has expanded to the second state, ensuring the engagement between the ring reinforcement 30 and the tubular wind turbine structure by fixing the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c.

[0138] For example, the inter-segment spacing between each pair of adjacent ring segments 32a to 32c can be ensured by connecting corresponding separating members between the pairs of adjacent ring segments 32a to 32c. Once connected, the separating members can be configured to substantially inhibit relative movement of adjacent ring segments 32a to 32c.

[0139] like ​ As shown, after the ring reinforcement 30 has expanded to engage the tower segment 10 with sufficient radial force to remain in place, in step 104, the first separator 80a and the second separator 80b can be connected between the first ring segment 32a and the second ring segment 32b.

[0140] Specifically, in this example, the first partition 80a and the second partition 80b take the form of corresponding first elongate struts and second elongate struts, each strut extending from a corresponding first end 82a, 82b to a corresponding second end 84a, 84b.

[0141] The first ends 82a and 82b of each separating member 80a and 80b are connected to the first ring section 32a, and the second ends 84a and 84b of each separating member 80a and 80b are connected to the second ring section 32b. Specifically, in this example, the first separating member 80a is connected between the first ring section 32a and the second ring section 32b, and the ends 82a and 84a are welded to a corresponding wall of the opposing walls 52a located at adjacent ends of these ring sections 32a and 32b. Similarly, the second separating member 80b is also connected between the first ring section 32a and the second ring section 32b, and the ends 82b and 84b are welded to a corresponding wall of the pair of opposing walls 52a. Therefore, the first separating member 80a can be welded to the upper surface of the pair of opposing walls 52a, and the second separating member 80b can be welded to the lower surface of the pair of opposing walls 52a, as shown below. ​ As shown.

[0142] In this example, it should be understood that the welding is applied to the ring reinforcement 30, rather than to the surface of the tower wall 12, thereby mitigating the formation of any hot spots on the tower wall 12.

[0143] In other examples, the inter-segment spacing between adjacent ring segments 32a to 32c can be ensured by other means, such as bolted intermediate separators.

[0144] In another example, the method 100 for reinforcing a tubular wind turbine structure may further include the step of removing the connecting devices 34a to 34c from the ring reinforcement 30 after ensuring the inter-segment spacing. For example, once the separating components 80a and 80b have been fitted between the first adjacent ring segment 32a and the second adjacent ring segment 32b, the fastening device 60a can be loosened to remove the screw 64 and the set of fastening components 66a to 66d, and the separating components 80a and 80b can maintain the inter-segment spacing.

[0145] Advantageously, the connecting devices 34a to 34c can then be reused elsewhere, for example, when connecting the ring sections of another radially adjustable ring reinforcement.

[0146] In another example, the method 100 for reinforcing a tubular wind turbine structure may further include the following steps: before step 101 and before moving the ring reinforcement 30 to the reinforcement position in step 102, moving the radially adjustable ring reinforcement 30 into the tower segment 10.

[0147] For example, the ring reinforcement 30 can be adjusted to reduce the radius of the ring reinforcement 30 to a first state, and thereafter, the ring reinforcement 30 can be introduced into the tower segment 10 through an opening at the base 14 or top 16 of the tower segment 10.

[0148] Alternatively, the fact that the ring reinforcement 30 is an assembly of multiple components can be advantageously utilized, and the ring reinforcement 30 can be introduced into the internal volume of the tower section 10 in an unassembled form. For example, each of the plurality of ring sections 32a to 32c can be introduced into the tower section 10 individually, and then assembled together inside the tower section 10 by connecting the plurality of ring sections 32a to 32c end to end using the set of connecting devices 34a to 34c.

[0149] Advantageously, in this way, the ring reinforcement 30 can be introduced through a smaller hole and subsequently assembled inside the tubular wind turbine structure. This facilitates the field installation of the ring reinforcement 30 onto the assembled tubular wind turbine structure of the wind turbine 1. It should be understood that once the wind turbine 1 has been assembled, conventional ring reinforcements typically cannot be moved into the internal volume of the tower 2, and instead, conventional ring reinforcements must be assembled to the outer surface of the tower 2.

[0150] As previously mentioned, the connecting devices 34a to 34c between adjacent ring segments 32a to 32c of the ring reinforcement 30 can take various forms, all configured to connect adjacent ring segments 32a to 32c together while changing the inter-segment spacing. The following example illustrates an implementation of method 100, wherein the ring reinforcement 30 includes other such connecting devices 34a to 34c.

[0151] Therefore, in the example, the connecting devices 34a to 34c can take the form of the flexible connecting devices or mechanisms previously described, which are configured to passively allow changes in the inter-segment spacing while connecting adjacent ring segments 32a to 32c together.

[0152] In this case, the tubular wind turbine structure can be reinforced essentially as described in method 100 previously.

[0153] However, in order to increase the radius of the ring reinforcement 30, in step 104, the method may include the following step: applying a radially outward force to the plurality of ring segments 32a to 32c.

[0154] For example, one or more actuators can be coupled to the plurality of ring segments 32a to 32c, and the one or more actuators can be operated to cause the plurality of ring segments 32a to 32c to separate and radially outward. When a radially outward force is applied, the coupling devices 34a to 34c can allow the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c to be increased, expanding the ring reinforcement 30 from a first state to a second state, and engaging the tower wall 12 with sufficient radial force to hold the ring reinforcement 30 in place.

[0155] In this example, the connecting devices 34a to 34c can allow such expansion, but in order to maintain the engagement between the ring reinforcement 30 and the tower wall 12, it may be necessary to have one or more actuators to maintain the radially outward force, and / or to connect one or more separating members between adjacent ring sections 32a to 32c, as previously described.

[0156] In another example, the connecting devices 34a to 34c may additionally or alternatively include a biasing device as previously described, which is configured to connect adjacent ring segments 32a to 32c together while causing them to separate.

[0157] Therefore, the tubular wind turbine structure can be reinforced substantially as described in method 100 previously. However, in steps 101 and 102, the biasing device can be compressed by a radially inward force acting on the plurality of ring segments 32a to 32c to maintain the ring reinforcement 30 in a first state while moving the ring reinforcement to the reinforced position. For example, the ring reinforcement 30 can be radially compressed inward by one or more tension cables extending between adjacent ring segments 32a to 32c.

[0158] Once the ring reinforcement 30 has been moved to the reinforced position 22, in step 104, the radially inward force can be removed, for example, by decoupling one or more tension cables. In removing the radially inward force, the biasing device can cause adjacent ring segments 32a to 32c to separate, expanding the ring reinforcement 30 into a second state and thereby engaging the tower wall 12 with sufficient radial force to hold the ring reinforcement 30 in place. Thereafter, the joint between the ring reinforcement 30 and the tower segment 10 can be maintained by the biasing force of the coupling devices 34a to 34c.

[0159] In another example, the connecting devices 34a to 34c may additionally or alternatively be adjustable and configured to set, maintain, or otherwise control the inter-segment spacing between adjacent ring segments 32a to 32c, as previously described. For example, such an adjustable connecting device may take the form of an adjustable separating member or device extending between adjacent ring segments 32a to 32c to keep adjacent ends separated. For example, the adjustable connecting device may abut against the pair of opposing end walls to keep them separated.

[0160] The tubular wind turbine structure can be reinforced substantially as described in method 100 previously. However, in step 104, the method may include the step of applying a radially outward force to the plurality of ring segments 32a to 32c. For example, one or more actuators may be coupled to the plurality of ring segments 32a to 32c, and the one or more actuators may be operated to cause the plurality of ring segments 32a to 32c to separate and radially outward.

[0161] When a radially outward force is applied, the adjustable coupling devices 34a to 34c can allow the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c to be increased, expanding the ring reinforcement 30 from the first state to the second state, and engaging the tower wall 12 with sufficient radial force, thereby holding the ring reinforcement 30 in place.

[0162] Subsequently, the adjustable connecting devices 34a to 34c can be operated to maintain the inter-segment spacing and, without radial outward force, keep the ring reinforcement 30 in the expanded second state.

[0163] For example, after the adjustable coupling devices 34a to 34c have been set with inter-segment intervals, one or more actuators can be detached from and removed from the ring reinforcement 30.

[0164] In yet another example, the coupling devices 34a to 34c may additionally or alternatively include means (other than those previously described) for actively changing the inter-segment spacing between one or more pairs of adjacent ring segments 32a to 32c. For example, the coupling devices 34a to 34c may include actuators or actuation devices that may be disposed between adjacent ends of adjacent ring segments 32a to 32c and operable to cause adjacent ring segments 32a to 32c to separate. The actuators may be, for example, hydraulically actuated, pneumatically actuated, or electrically actuated, and may be, for example, linear or rotary actuators.

[0165] The tubular wind turbine structure can be reinforced essentially as described in method 100 previously. In step 104, the actuator can thus be operated (similar to the screw mechanism previously described) to cause adjacent ring sections 32a to 32c to separate and engage the tower wall 12 with sufficient radial force, thereby holding the ring reinforcement 30 in place.

[0166] In another example, tower segment 10 may include multiple structurally weak areas, which can be reinforced by corresponding radially adjustable ring reinforcements 30 according to the method described above.

[0167] The illustrative examples discussed above demonstrate various technical implementations of the inventive concept. However, those skilled in the art will appreciate that other variations may be made in addition to those detailed above, and still fall within the scope of the appended claims.

Claims

1. A method of reinforcing a tubular wind turbine structure using a radially adjustable ring stiffener, the radially adjustable ring stiffener comprising a pair of adjacent ring segments coupled together by a coupling device configured to allow radial adjustment of the radially adjustable ring stiffener by varying the inter-segment spacing between adjacent ends of those ring segments, the method comprising the steps of: positioning the radially adjustable ring stiffener at a reinforcing position within the tubular wind turbine structure; adjusting the inter-segment spacing between the pair of adjacent ring segments to increase the radius of the radially adjustable ring stiffener; and thereby engaging the inner surface of the tubular wind turbine structure with a radial force, the radial force retaining the radially adjustable ring stiffener at the reinforcing position by virtue of friction between the radially adjustable ring stiffener and the tubular wind turbine structure; and securing the engagement between the radially adjustable ring stiffener and the tubular wind turbine structure by fixing the inter-segment spacing between the pair of adjacent ring segments, wherein the inter-segment spacing is rigidly fixed by a permanent device.

2. The method of claim 1, wherein, the coupling device takes the form of an adjustable coupling device operable to control the inter-segment spacing between the pair of adjacent ring segments, and wherein the step of adjusting the inter-segment spacing between the pair of adjacent ring segments comprises operating the adjustable coupling device.

3. The method of claim 2, wherein, the adjustable coupling device comprises an actuator operable to vary the inter-segment spacing between the adjacent ends of the ring segments, and wherein the step of adjusting the inter-segment spacing between the pair of adjacent ring segments comprises operating the actuator to cause the pair of adjacent ring segments to separate.

4. The method of claim 3, wherein, the actuator is one of: a pneumatic actuator; a mechanical actuator; a hydraulic actuator; or an electric actuator.

5. The method of claim 3 or claim 4, wherein, the actuator is a linear actuator.

6. The method of claim 5, wherein, the linear actuator comprises a lead screw mechanism connected between the pair of adjacent ring segments, and wherein the lead screw mechanism is operable to cause the pair of adjacent ring segments to separate.

7. The method of claim 6, wherein, the lead screw mechanism engages a pair of opposing walls at the adjacent ends of the ring segments.

8. The method of claim 7, wherein, the adjustable coupling device takes the form of a fastening device, and the lead screw mechanism is a mechanical actuator comprising: a screw of the fastening device, a first fastening component, and a second fastening component; wherein the first and second fastening components are mounted on the screw between the pair of opposing walls, with the first fastening component bearing against a first of the opposing walls and the second fastening component bearing against a second of the opposing walls; and wherein the step of operating the lead screw mechanism comprises turning at least one of the first and second fastening components along the screw to increase the distance between the first and second fastening components, and thereby cause the pair of adjacent ring segments to separate.

9. The method of claim 8, wherein, The step of fixing the inter-segment spacing between the pair of adjacent ring segments comprises joining a separation component between the pair of adjacent ring segments, the separation component being configured to substantially inhibit relative movement of the adjacent ring segments.

10. The method of claim 9, wherein, The step of joining the separation component between the pair of adjacent ring segments comprises welding the separation component to the adjacent ring segments.

11. The method of claim 8, further comprising the step of: The coupling device is removed from between the pair of adjacent ring segments after the inter-segment spacing between the pair of adjacent ring segments has been fixed.

12. The method of claim 1, wherein, The step of adjusting the inter-segment spacing between the pair of adjacent ring segments comprises forcing the pair of adjacent ring segments radially outwardly into engagement with the inner surface of the tubular wind turbine structure with sufficient radial force to retain the radially adjustable ring reinforcement in the stiffened position.

13. The method of claim 1, further comprising the step of: The radially adjustable ring reinforcement is assembled inside the tubular wind turbine structure, wherein the step of assembling the radially adjustable ring reinforcement comprises coupling the pair of adjacent ring segments together using the coupling device.

14. The method of claim 1, wherein, The radially adjustable ring reinforcement comprises a plurality of ring segments coupled together by a set of the coupling devices, the plurality of ring segments including the pair of adjacent ring segments, each of the coupling devices extending between a respective pair of adjacent ring segments of the plurality of ring segments and being configured to allow radial adjustment of the radially adjustable ring reinforcement by changing the inter-segment spacing between adjacent ends of those ring segments, and The method comprises the steps of adjusting the inter-segment spacing between one or more pairs of adjacent ring segments to increase the radius of the radially adjustable ring reinforcement; and thereby engaging the inner surface of the tubular wind turbine structure with the radial force retaining the radially adjustable ring reinforcement in the stiffened position.

15. The method of claim 13, wherein, The plurality of radially adjustable ring reinforcements consists of three ring segments, and wherein the three ring segments are coupled together in a circular arrangement end-to-end by a set of the coupling devices, and optionally wherein the three ring segments have equal (arc) lengths.

16. The method of claim 1, wherein, An outer radius of each of the ring segments is greater than or equal to a radius of the inner surface of the tubular wind turbine structure at the stiffened position.

17. The method of claim 1, wherein, The tubular wind turbine structure is selected from at least one of: a tubular segment of a tower of the wind turbine; and / or a tubular segment of a blade of the wind turbine.

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