Temporary damper assembly

Abstract

A temporary damper assembly (1) for use during vertical storage and / or vertical transportation of a tower (2) is described, the damper assembly (1) comprising a liquid damper (10) tuned to the natural vibration frequency of the tower (2), a tower cover (11) realized to cover a ring-shaped upper opening (20) of the tower (2) during storage and / or transportation, a mounting interface (12) configured to suspend the liquid damper (10) from the ring-shaped upper opening (20) of the tower (2), and a load transfer interface (13) for transferring a load (F) between the liquid damper (10) and the tower (2). A method of suppressing vortex-induced vibrations in a tower (2) during vertical storage and / or vertical transportation of the tower (2) is also described.

Description

Technical Field

[0001] This invention describes a temporary damper assembly used during vertical storage and / or vertical transport on a tower. Background Technology

[0002] The installed wind turbine may be equipped with permanent dampers, such as tuned mass dampers mounted upstream of the tower. The dampers are configured to counteract oscillations at the tower's natural frequency (its "intrinsic frequency"). When the wind turbine tower oscillates, the tuned mass damper will also oscillate, but with a phase shift relative to the tower oscillations. Liquid dampers permanently mounted on the upper layer of the tower may be partially filled with sloshing fluid, the amount of which is selected based on the tower's intrinsic frequency. The function of permanent dampers is to suppress tower oscillations, keeping the amplitude within safe levels.

[0003] Offshore wind turbines can have tower heights of approximately 80-100 meters. Such towers typically consist of two or more generally cylindrical, hollow tower sections with circular flanges at both ends. The tower sections can be bolted to another tower section and / or additional structures such as transition pieces using bolts inserted through the flanges.

[0004] Wind turbine towers can be pre-assembled and temporarily stored before being loaded onto ships for transport to the installation site. While towers can be stored and transported horizontally, their own weight can cause significant deformation or ellipticing. Furthermore, the inverted operation of heavy and long towers can be hazardous. For these reasons, it may be preferable to store and transport pre-assembled towers in their vertical or upright orientation.

[0005] However, certain problems exist associated with the vertical storage and transport of high towers. The main problem is eddy-induced crosswind vibration. This is particularly relevant during transport by ship, as the tower stands upright on the deck and cannot be shielded from the wind. Eddy-induced crosswind vibration can structurally damage the tower. Furthermore, the resulting loads must be borne by the mounting fittings on the deck, and these can be damaged. Therefore, eddy-induced crosswind vibration during storage and transport leads to high costs. Permanent dampers used in wind turbine towers cannot be used to suppress this vibration during storage and transport because they are explicitly tuned to the natural frequencies of the completed wind turbine, including the nacelle, generator, aerodynamic rotor, etc.

[0006] Therefore, it is necessary to provide a method for suppressing or damping vortex-induced crosswind vibrations of pre-assembled towers during storage and transportation. In one method, a helical construction of vortex hoops is attached to the exterior of the tower before storage or transportation in an exposed environment. The vortex hoops alter the airflow over the tower surface, preventing the development of vortices and thus preventing vortex-induced vibrations. However, equipping towers with vortex hoops can be time-consuming, and removing them requires a similar amount of time. Furthermore, the work associated with installing vortex hoops is highly dependent on weather conditions and, due to the hazardous nature of the work, cannot typically be carried out under conditions of high winds or storms.

[0007] Therefore, the object of the present invention is to provide an improved method for storing and transporting vertical towers. Summary of the Invention

[0008] This objective is achieved by the temporary damper assembly according to the invention and by the method according to the invention for suppressing eddy current-induced vibrations in a tower.

[0009] According to the present invention, a temporary damper assembly is intended for use during storage and / or transport of a tower and includes: a liquid damper tuned to the natural frequency of vibration of the tower; a tower cover configured to cover an annular upper opening of the tower during storage and / or transport; a mounting interface configured to suspend the liquid damper from the annular upper opening of the tower; and a load transfer device for transferring a load between the liquid damper and the tower.

[0010] The advantage of the temporary damper assembly of the present invention is the reduction of offshore operation work, thereby lowering the overall cost. This is because the temporary damper of the present invention can be installed on the upper layer of the tower (and subsequently removed from the upper layer of the tower) with a relatively simple procedure. In contrast, preparing a tower with vortex ferrules can take a considerable amount of time, and removing the vortex ferrules requires a similar amount of time at the final destination of the tower. Furthermore, the operation of the temporary damper of the present invention is relatively independent of weather conditions compared to the operation of vortex ferrules, which is typically not possible under stormy conditions. Another advantage of the temporary damper assembly of the present invention is that, due to the fewer manual operation steps involved, it reduces the hazards involved in preparing the tower for storage and / or transport.

[0011] According to the present invention, a method for suppressing eddy current-induced vibrations in a tower during storage and / or transportation includes the following steps: determining the natural frequency (i.e., eigenfrequency) of the tower's vibration; tuning a liquid damper to the natural frequency; preparing a temporary damper assembly by attaching the tuned liquid damper to a tower cover and providing a load transfer device for transferring loads between the liquid damper and the tower; and installing the temporary damper assembly onto an annular upper opening of the tower prior to storage and / or transportation of the tower.

[0012] Particularly advantageous embodiments and features of the invention are given by the dependent claims, as disclosed in the following description. Features from different categories of claims may be suitably combined to give other embodiments not described herein.

[0013] In the following text, it may be assumed that the tower is intended for use in an offshore wind turbine. The tower of such a wind turbine typically has a narrow, tapered shape with a generally circular cross-section. The tower is widest at its base, where a transition piece to the offshore foundation can be installed. This tower may be assumed to comprise two or more tower sections, and that the tower is pre-assembled before being transported to the offshore installation site.

[0014] The liquid damper is preferably implemented as a tank or other container capable of being suspended inside the tower. In a preferred embodiment of the invention, the liquid damper is implemented as a generally cylindrical tank with a diameter of approximately 40%-50% of the tower's inner diameter. The tank may be partially filled with a fluid or a sloshing liquid, such as BASF Glysantin. ® G30 ® Its primary purpose is as an antifreeze. The liquid damper may include a fluid inlet / outlet, allowing adjustment of the fluid fill level. Preferably, the liquid damper is sized for use with a tower having a natural frequency in the range of 0.45 Hz to 0.9 Hz. The process of tuning the liquid damper involves adjusting the volume of liquid in the damper. For example, the volume of liquid present in the tank can be determined by weighing the liquid damper (alone or as part of an assembled temporary damper assembly).

[0015] The liquid damper can be installed using any suitable type of mounting interface. In a preferred embodiment of the invention, the mounting interface includes multiple brackets, such as removable adapter brackets. Each bracket extends between the outer surface of the liquid damper and the annular upper opening of the tower. The brackets are preferably configured such that the liquid damper is centrally positioned inside the tower. In a preferred embodiment of the invention, the mounting interface includes at least three brackets evenly distributed around the liquid damper at 120° intervals.

[0016] The support can be attached to the liquid damper in any suitable manner. In a preferred embodiment of the invention, boot-shaped members are provided on the outer surface of the liquid damper, and each boot-shaped member is shaped to receive the vertical side of the support. For example, the support can be inserted into the boot-shaped member and then fastened to the boot-shaped member using bolts, screws, or other fasteners.

[0017] To suspend the liquid damper in the tower, the mounting interface preferably extends to the upper edge of the tower, where it can be attached to a tower flange. As described above, the flange has a bolt ring through which bolts pass when the tower is attached to another tower or additional component. In a preferred embodiment of the invention, the mounting interface comprises a plurality of radial arms extending outward to the upper edge. In another preferred embodiment of the invention, each radial arm may terminate at an arc segment. The curvature of the arc segment preferably matches the curvature of the upper edge of the tower. Preferably, the length of the radial arms is adjustable and / or the arc segments are detachable, allowing the assembly to be adapted to a range of tower diameters. For example, the radial arm length can be extended or shortened as needed, and a set of arc segments with suitable curvature can be selected. Thus, a temporary damper assembly can be used for various tower diameters.

[0018] The temporary damper assembly is provided by mounting the liquid damper to the top cover, such that the liquid damper is suspended from the underside of the top cover. When the top cover is placed on the tower, the liquid damper will be positioned in the upper part of the tower interior.

[0019] To suppress eddy current-induced vibrations or other oscillations in the tower, a load transfer bridge is needed between the liquid damper and the tower wall. In one approach, the liquid damper and / or its mounting interface can be configured to achieve a form fit, i.e., physical contact between the inner wall of the tower and one or more surfaces of the liquid damper and / or its mounting interface. For example, each bracket may have an outer surface abutting against the inner surface of the tower. However, such a form-fit configuration limits the temporary damper assembly to a specific tower diameter. Therefore, in a preferred embodiment of the invention, the maximum diameter of the mounting interface can be smaller than the inner diameter of the tower, and the difference is bridged by multiple adjusting bolts. For example, adjusting bolts can be inserted into a bracket attached to the mounting interface or into a substantially horizontal threaded bushing arranged in the bracket of the mounting interface, such that the outer end of the adjusting bolt contacts the inner surface of the tower. Of course, the outer end of the adjusting bolt can terminate in a flat washer or plate, allowing the force to spread over a larger area, thereby avoiding damage to the tower surface. Various other methods exist for bridging the gap between the mounting interface and the tower, such as using a hydraulic cylinder arrangement to apply pressure to the inner surface of the tower.

[0020] The load transfer interface is adjusted or completed from within the tower. This provides access to the tower's interior for technicians. Once the temporary damper assemblies have been lowered into place so that the top cover rests on the upper annular surface of the tower, technicians can, for example, turn the adjusting bolts to apply sufficient pressure against the inner surface of the tower. Technicians can access the upper levels of the tower via, for example, a lift that is part of the tower assembly.

[0021] The temporary damper assembly is preferably lifted to the upper height of the tower by a crane. Suitable lifting fittings can be provided to keep the temporary damper assembly stable while it is suspended from the crane lifting trolley. The mounting interface preferably includes multiple connectors (e.g., eyelets) for connecting cables to the lifting fitting. The tower cover may have an opening through which the cables can pass, allowing the cables to be attached to a bracket of the mounting interface. In a preferred embodiment, the top cover includes multiple hatches that can be opened to receive the cables of the lifting fitting. Once the temporary damper assembly is in place, the cables are removed, and the hatches can be closed again, sealing the tower interior from the environment. In another preferred embodiment, the tower cover includes an elastomeric edge arranged to rest on the annular upper end of the tower. The elastomeric or rubber edge can act as a seal to prevent water from entering the tower interior. Attached Figure Description

[0022] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, it should be understood that the drawings are for illustrative purposes only and are not intended to define any limitation thereof.

[0023] Figure 1 An embodiment of the temporary damper assembly of the present invention is shown;

[0024] Figure 2 An embodiment of the temporary damper assembly of the present invention, lowered onto a tower, is shown;

[0025] Figure 3 An embodiment of the temporary damper assembly of the present invention in place on a tower is shown;

[0026] Figure 4 A perspective view showing an embodiment of the temporary damper assembly of the present invention in place on a tower;

[0027] Figure 5 An embodiment of the temporary damper assembly of the present invention is shown, which is parked on the cargo hold frame.

[0028] In the accompanying drawings, the same numbers always represent the same objects. The objects in the drawings are not necessarily drawn to scale. Detailed Implementation

[0029] Figure 1 An embodiment of the temporary damper assembly 1 of the present invention is shown, and a liquid damper 10 suspended from a tower top cover 11 is also shown. In an exemplary embodiment, the top cover 11 may have an arrangement of panels or fittings on its underside, to which the damper 10 may be bolted.

[0030] The diameter D10 of the damper 10 is significantly smaller than the inner diameter of the tower. In this exemplary embodiment, the mounting interface 12 includes three angular brackets 120 (two of which are visible in the figure) evenly distributed around the damper 10 and mounted in a boot-shaped member 121 disposed on the outer surface of the damper 10. An elastomeric seal or edge 112 is disposed on the outer edge of the top cover 11. One of several lifting brackets 16 is shown. These are configured to attach cables to the lifting accessories during lifting operations.

[0031] Figure 2 The temporary damper assembly 1 is shown being lowered toward the tower 2, such that the damper 10 will be positioned in the interior space at the upper level of the tower 1. A lifting fitting 3 is being used and is suspended from a lifting trolley of a crane (not shown). Several cables 30 extend from the lifting fitting 3 to the lifting support 16. During the lifting operation, the hatch 110 of the top cover is opened, and the cables 30 extend through the open hatch.

[0032] The upper level of tower 2 may be 80-100m above the ground, making it difficult or even impossible to assess the accuracy of the operation from the ground position. Therefore, in order to avoid damage to the temporary damper assembly 1 or tower 2, multiple cameras and / or sensors (not shown) can be deployed to provide feedback on the lifting operation, allowing for position adjustments as needed.

[0033] Figure 3An embodiment of the temporary damper assembly 1 of the present invention, positioned on a tower 2, is shown. An internal floor or platform 20P is shown. The tower can typically be configured to include a platform 20P near its upper end, allowing maintenance personnel to work at that height. An arc segment 122 at the outer end of the radial arm 123 rests on the circular edge of the tower 2. For simplicity, the figure shows two supports 120 on opposite sides of the damper 10 in the diametrical direction. However, it should be understood that at least three supports 120 can be deployed, preferably evenly spaced around the cylinder of the liquid damper 10. The figure shows a load transfer bridge including adjusting bolts 13, which are tightened such that their outer ends press against the inner surface 20S of the tower. Thus, the diameter D12 defined by the outer ends of the supports 120 can be smaller than the inner diameter D20 of the “smallest” tower (among a plurality of towers of different sizes), and the adjusting bolts 13 can bridge this gap. In this way, a type of temporary damper assembly 1 can be fabricated for towers of different diameters. Each of these towers can be vertically stored and / or transported using a single type of temporary damper assembly 1.

[0034] Figure 4 A perspective view of an embodiment of the temporary damper assembly 1 of the present invention in place on tower 2 is shown. The top cover 11 is not shown, but its presence should be assumed. The figure shows radial arms 123 (six in this embodiment) terminating in replaceable arc segments 122. Arc segments 122 are selected to match the curvature of the tower flange. The figure also shows several adjusting bolts 13 in the retracted position (not pressed against the tower wall).

[0035] Figure 5 An embodiment of the temporary damper assembly 1 of the present invention is shown, "parked" on the nacelle transport frame 4. After the tower is unloaded at the offshore installation site, the tower is installed onto the foundation, and the nacelle is installed onto the tower, the temporary damper assembly 1 used with the tower can be parked on the yaw support portion 40 of the nacelle transport frame, since the diameters are corresponding.

[0036] Although the invention has been disclosed in the form of preferred embodiments and variations thereof, it should be understood that many other modifications and variations may be made thereto without departing from the scope of the invention.

[0037] For clarity, it should be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “including” does not exclude other steps or elements.

Claims

1. A temporary damper assembly (1) for use during vertical storage and / or vertical transport on a tower (2), the temporary damper assembly (1) comprising: - Tower cover (11), which is implemented to cover the annular upper opening (20) of the tower (2) during storage and / or transportation. - A liquid damper (10), which is tuned to the natural vibration frequency of the tower (2) and suspended from the underside of the tower cover (11); - Mounting interface (12), which is configured to suspend the liquid damper (10) from the annular upper opening (20) of the tower (2); and - Load transfer interface (13) for transferring load (F) between the liquid damper (10) and the tower (2). in, The load transfer interface (13) includes a plurality of adjusting bolts, wherein the adjusting bolts extend between the mounting interface (12) and the inner surface (20S) of the tower (2).

2. The temporary damper assembly according to claim 1, wherein, The liquid damper (10) comprises a generally cylindrical tank, the diameter (D10) of which is at most 80% of the inner diameter (D20) of the tower (2).

3. The temporary damper assembly according to claim 1, wherein, The liquid damper (10) comprises a generally cylindrical tank, the diameter (D10) of which is at most 60% of the inner diameter (D20) of the tower (2).

4. The temporary damper assembly according to any one of claims 1-3, wherein, The mounting interface (12) includes a plurality of brackets (120) which are configured to extend between the liquid damper (10) and the inner surface (20S) of the tower (2).

5. The temporary damper assembly according to any one of claims 1-3, wherein, The mounting interface (12) includes a plurality of boot-shaped members (121) arranged on the liquid damper (10), wherein the boot-shaped members (121) are shaped as receiving brackets (120).

6. The temporary damper assembly according to any one of claims 1-3, wherein, The mounting interface (12) includes a plurality of radial arms (123), each radial arm (123) terminating at an arc segment (122), wherein the curvature of the arc segment (122) is based on the curvature of the annular upper opening (20) of the tower (2).

7. The temporary damper assembly according to any one of claims 1-3, wherein, The mounting interface (12) includes multiple connectors for connecting to the cables (30) of the lifting fitting (3).

8. The temporary damper assembly according to any one of claims 1-3, wherein, The tower cover (11) includes multiple hatches (110) that open to accommodate cables (30) for the lifting fitting (3).

9. The temporary damper assembly according to any one of claims 1-3, wherein, The dimensions of the liquid damper (10) are designed for use with towers (2) having a natural frequency in the range of 0.55 Hz to 0.8 Hz.

10. A method for suppressing eddy current-induced vibrations in a tower (2) during vertical storage and / or vertical transport of a tower (2) using a temporary damper assembly (1) according to claim 1, the method comprising: - Determine the natural frequency of the vibration of the tower (2); - Tune the liquid damper (10) to the natural frequency; - The temporary damper assembly (1) is prepared by attaching a tuned liquid damper (10) to the tower cover (11) such that the tuned liquid damper (10) is suspended from the underside of the tower cover (11) and providing the load transfer interface (13) for transferring the load (F) between the liquid damper (10) and the tower (2); and - Before vertical storage and / or vertical transport of the tower (2), the temporary damper assembly (1) is installed at the upper end of the tower (2) to suspend the liquid damper (10) from the annular upper opening (20) of the tower (2).

11. The method according to claim 10, wherein, The steps of preparing the temporary damper assembly (1) include selecting the elements of the mounting interface (12) based on the diameter (D20) of the tower (2).

12. The method of claim 11, comprising the steps of: attaching the selected arc segment (122) to each of the plurality of radial arms (123) of the mounting interface (12) and / or mounting the plurality of selected brackets (120) to the boot-shaped piece (121) on the exterior of the liquid damper (10).

13. The method according to any one of claims 10 to 12, comprising the step of: deploying lifting equipment to bring the temporary damper assembly (1) to the upper level of the tower (2).

14. The method according to any one of claims 10 to 12, wherein, The steps of installing the temporary damper assembly (1) include manually tightening the adjusting bolts of the load transfer interface (13) from inside the tower (2).

15. The method according to any one of claims 10 to 12, comprising the steps of: removing the temporary damper assembly (1) from the tower (2) and deploying lifting equipment to transfer the temporary damper assembly (1) to the cabin transport frame (4).

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