Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
  • F03D13/10—Assembly of wind motors; Arrangements for erecting wind motors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
  • F03D13/20—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03D—WIND MOTORS
  • F03D80/00—Details, components or accessories not provided for in groups F03D1/00 - F03D17/00
  • F03D80/80—Arrangement of components within nacelles or towers
  • F03D80/88—Arrangement of components within nacelles or towers of mechanical components
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
  • F05B2260/00—Function
  • F05B2260/96—Preventing, counteracting or reducing vibration or noise
  • F05B2260/964—Preventing, counteracting or reducing vibration or noise by damping means
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/70—Wind energy
  • Y02E10/72—Wind turbines with rotation axis in wind direction
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/70—Wind energy
  • Y02E10/728—Onshore wind turbines

Definitions

• the present invention relates to wind turbines, and in particular to methods of damping oscillations in towers of wind turbines.
• a horizontal-axis wind turbine typically includes a tower, a nacelle supported by the tower, and a rotor mounted to the nacelle. Over time there has been a significant increase in the overall size of these machines and their components. This increase in size presents many challenges, both before and during operation.
• wind turbine towers are tall, slender structures typically comprised of cylindrical and/or conical sections.
• vortices are shed alternately from opposite sides of the tower. This gives rise to a fluctuating force acting substantially perpendicular to the wind direction.
• the fluctuating force can lead to large oscillations when the periodic frequency of the vortex shedding is similar to one of the natural frequencies of the tower.
• a method of damping oscillations in a wind turbine tower comprises connecting a bag of material (e.g., sand) or liquid to a tower component at a first lateral distance away from a tower wall.
• the bag is also suspended from the tower component by a first vertical distance.
• the height of the tower component is known such that the first vertical distance corresponds to a particular height within the tower.
• the first lateral distance, first vertical distance, and mass of the bag are such that the bag is configured to act as a pendulum counteracting a fundamental mode of vibration of the tower.
• the invention also provides a method of installing a wind turbine comprising erecting a tower of the wind turbine and installing a damping system in the tower.
• the damping system is installed in the manner mentioned above. That is, by connecting a bag of material or liquid to a tower component at a first lateral distance from a tower wall and suspending the bag from the tower component by a vertical distance. Again the height of the tower component is known such that the vertical distance corresponds to a particular height within the tower.
• the method of installation further involves damping oscillations caused by vortices shed from the tower, wherein the first lateral distance, first vertical distance, and mass of the bag are such that the bag acts as a pendulum that counteracts a fundamental mode of vibration of the tower.
• the damping system is removed from the tower.
• FIG. 1 is a perspective view of an example of a wind turbine.
• Fig. 2 is a perspective view of a damping system installed in a tower of the wind turbine.
• Fig. 3 is a top elevation view the damping system of Fig. 2. Ref. No.: 2012P00066WO
• Fig. 4 is a perspective view showing a portion of the damping system of Fig. 2 in further detail.
• Fig. 5 is a cross-sectional view of a portion of tower with a damping system installed according to an alternative embodiment.
• Fig. 6 is a cross-sectional view of a portion of tower with a damping system installed according to another alternative embodiment.
• Fig. 7 is a cross-sectional view of a portion of tower with a damping system installed according to yet another alternative embodiment.
• Fig. 8 is a perspective view of a portion of a damping system according to an alternative embodiment.
• FIG. 1 shows one example of a wind turbine 2 having a rotor 4 mounted to a nacelle 6, which is supported on a tower 8.
• the rotor 4 serves as the prime mover for an electromechanical system. Wind causes the rotor 4 to rotate, and this rotational energy is delivered to a power transmission system housed within the nacelle 6.
• the power transmission system converts the rotational energy into electrical power.
• the tower 8 shown in Fig. 1 is a tubular steel tower comprised of multiple tower sections 8a, 8b.
• the tower sections 8a, 8b are cylindrical or slightly tapered (i.e., conical) and stacked on top of each other. Again, however, this is merely an example.
• the description below focuses damping tower oscillations and may apply to any wind turbine tower that is a tall, slender structure susceptible to oscillations. For example, the description may apply to steel towers having segmented tower sections, concrete towers, composite towers, hybrid towers (e.g., steel and concrete), wooden towers, etc.
• a damping system 10 for the tower 8 is shown.
• the damping system 10 in this embodiment is installed in one of the tower Ref. No.: 2012P00066WO sections (e.g., the uppermost tower section 8a).
• the tower section 8a includes various tower components, such as an upper platform 12, lower platform 14, and ladder 16 providing access to the upper and lower platforms 14, 16.
• the lower platform 14 is shaped to accommodate an elevator lift (not shown) and includes safety fencing 18 around the area for the elevator lift.
• the damping system 10 includes several sandbags 20 that are each suspended from a bracket 22 by a chain 24. More specifically, the sandbags 20 are each suspended from the hook of a ratchet wrench 26 (also referred to as a "ratchet chain hoist") positioned on the associated chain 24.
• the brackets 22 and sandbags 20 are distributed circumferentially about the tower section 8a in relation to a tower wall 28, as shown in Fig. 3. Although three sandbags 20 are shown, any number of sandbags or even a single sandbag may be used in alternative embodiments. There may also be multiple sandbags suspended from the same bracket in alternative embodiments.
• the bracket 22 in this embodiment comprises a vertical support 30, horizontal support 32, and cross beam 34.
• the vertical support 30 may be mounted to a tower wall 28 using known techniques.
• the bracket 22 may be bolted or otherwise secured to magnets 34, which in turn are magnetically attached to the tower wall 28. Examples such magnets and techniques are described in WO
• a safety cable 36 or the like may connect the bracket 22 to another, permanently-installed tower component, such as the upper platform 12, thereby providing a back-up means of support in the event the bracket 22 slips along or disengages from the tower wall 28 due to ineffective mounting.
• the horizontal support 32 of the bracket 22 includes different attachment points 40 for the chain 24. This allows the sandbag 20 to be connected to the bracket 22 at different lateral distances from the tower wall 28.
• the vertical distance by which the sandbag 20 is suspended from the bracket 22 may be adjusted using the ratchet wrench 26.
• the horizontal distance, vertical distance, and mass of each sandbag 20 are such that the sandbags 20 are configured to act as pendulums that counteract a fundamental mode of vibration of the tower 8.
• the damping system 10 has the advantage being easy to install and remove, which provides a great amount of flexibility in terms of its use.
• the damping system 10 may be installed as a permanent fixture intended to remain in the tower 8 after the wind turbine 2 has been fully erected, or as a retrofit or temporary solution for addressing tower oscillations as they arise. The latter situation is particularly advantageous during the installation process of a wind turbine because of the challenges mentioned in the background section above.
• one method of installing the wind turbine 2 may involve using the damping system 10 during one or more stages of the installation.
• Such a method first comprises partially or completely erecting the tower 8.
• the damping system 10 may be installed in the uppermost tower section 8a before or after the tower section 8a is erected.
• the brackets 22 may be mounted to the tower wall 28 and the sandbags 20 connected to the brackets 22 prior to transporting the tower section 8a to the site of installation.
• These steps may alternatively occur after mounting the tower section 8a to the other previously-installed tower section 8b (or a foundation in embodiments where the tower 8 only comprises one tower section).
• the sandbags 20 are eventually suspended from the brackets 22 by an initial distance. This distance is adjusted by operating the ratchet wrench 26 until a desired vertical distance is attained.
• the desired vertical distance depends on the height of the tower 8, as does the desired lateral distance from the tower wall 28 (determined by the attachment point 40 of the chain 24 to the bracket 22).
• the lateral distance, vertical distance, and mass of each sandbag 20 are selected such that the sandbags 20 are configured to act as pendulums that counteract a fundamental mode of vibration of the tower 8.
• the method is particularly advantageous if the fundamental mode of vibration is the first natural frequency of bending vibration of the tower 8. This frequency is the most susceptible to oscillations caused by vortex shedding because of the lower wind speeds at which vortex shedding can be in resonance with the frequency.
• tuning the damping system 10 to the first natural frequency of bending vibration maximizes its effectiveness at damping oscillations caused by vortex shedding.
• the tower 8 may remain standing for an extended period of time prior to installing the nacelle 6 or its components, whose significant weight changes the dynamics of the overall structure and makes vortex shedding less of a concern.
• the logistics of installing a wind farm with several wind turbines may be optimized to make the most efficient use of resources and equipment (e.g., cranes).
• the damping system 10 is removed from the tower 8. This may be done after positioning one or more nacelle components (or even an entire nacelle with all nacelle components) on the tower 8. Alternatively, it may be done shortly before positioning the one or more nacelle components such that the tower 8 is only susceptible to oscillations caused by vortex shedding for a short period of time.
• One way in which the damping system 10 may be removed is by positioning the sandbags 20 onto the lower platform 14 (e.g., by using the ratchet wrenches 26). Each sandbag 20 is then moved from the lower platform 14 onto the elevator lift, transported toward the bottom of the tower 8 using the elevator lift, and eventually removed through a door near the bottom of the tower 8. It may be necessary to repeat these steps one or more times depending on the number of sandbags used and the capacity of the elevator lift. Ref. No.: 2012P00066WO
• the damping system 10 may also be used earlier in the installation process, for example, when less than all of the tower sections have been erected. In that situation the damping system 10 is installed in the last tower section erected. The lateral distance and/or vertical distance of the sandbags 20 will be different from when the damping system 10 is used in the uppermost section of a
• the different attachment points 40 on the brackets 22 and the ratchet wrenches 26 facilitate the ability to set these distances according to the dynamics of the structure.
• the partially-erected tower may remain standing for an extended period of time without concerns that vortex shedding will lead to significant oscillations.
• the damping system 10 may first be removed by passing the sandbags 20 through an open top end of the tower section in which they were installed. It is also possible to remove the damping system 10 in the manner described above using the elevator lift. Alternatively, if the damping system 10 is to be used in the next tower section, it may remain in the tower until the next tower section is installed and then moved accordingly. In other words, the damping system 10 may be removed from one tower section and installed in the next.
• Figs. 5-8 Various alternatives to the above-described embodiments are shown in Figs. 5-8, where the same reference numbers are used to refer to corresponding structures.
• the brackets 22 in the above-described embodiments are merely representative tower components to which the sandbags 20 are connected via the ratchet wrenches 26 and chains 24. Other tower components may support the sandbags instead.
• Fig. 5 illustrates a sandbag 20 being connected to and suspended from a different type of bracket.
• the bracket shown is a beam 50 secured to a top flange 52 of a tower section 54 and extending inwardly away from a tower wall 56.
• Fig. 6 illustrates a sandbag 20 being connected to and suspended from a platform 60 (e.g., the upper platform 12 in Fig. 2).
• the connection occurs via the ratchet wrench 26 and chain 24, which is hooked onto or otherwise secured to an eye nut 62 that has been bolted to the platform 60.
• a platform 60 e.g., the upper platform 12 in Fig. 2.
• the connection occurs via the ratchet wrench 26 and chain 24, which is hooked onto or otherwise secured to an eye nut 62 that has been bolted to the platform 60.
• ratchet wrench 26 and chain 24 which is hooked onto or otherwise secured to an eye nut 62 that has been bolted to the platform 60.
• eye nut 62 that has been bolted to the platform 60.
• skilled persons will appreciate other ways of connecting and suspending the sandbags 20.
• Fig. 7 illustrates a variation of the embodiment shown in Fig. 6.
• the arrangement includes a frame 70 from which the chain 24 extends.
• the chain 24 may be engaged with one of several hooks 72 provided on the frame 70, which in turn is suspended from the eye nut 62 by a rope or cable 74.
• the rope 74 may be used like a sling and tied off to another tower component (not shown) after positioning the frame 70 at a desired height within the tower 8.
• the frame 70 offers the ability to suspend the sandbags at different vertical distances from the platform 60 without the need for a ratchet wrench or the like. However, ratchet wrenches may still be used if desired.
• FIG. 8 illustrates an alternative to the sandbags shown in other figures.
• a conventional bag 80 such as a tool bag, may be filled with a number of smaller sandbags 82 or other bags of liquid or material.
• the smaller bags 82 have the advantage of being easier to handle and transport compared to the sandbags 20 shown in Figs. 2-6.
• the bag 80 is filled with a sufficient number of the smaller bags 82 to provide the desired mass.
• any bag of liquid or material may be used according to the invention.
• the term "bag” is meant in a broad sense to include any receptacle, container, or other structure that holds the liquid or material.
• the sandbags are shown and described as being connected to the Ref. No.: 2012P00066WO tower component(s) via ratchet wrenches and chains, it is also possible to use cables, ropes, or other devices.
• the details of any particular embodiment should not be seen to necessarily limit the scope of the claims below.
• skilled persons will understand how features of the various embodiments may be combined in different ways.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Wind Motors (AREA)

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• 2012
  • 2012-12-07 WO PCT/DK2012/050450 patent/WO2014040598A1/en active Application Filing
  • 2012-12-07 EP EP12812513.5A patent/EP2895741A1/de not_active Withdrawn

Non-Patent Citations (2)

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