Method of damping wind turbine tower oscillations

Patent metadata

Field	Value
Publication number	US-9683556-B2
Application number	US-201415032918-A
Country	US
Kind code	B2
Filing date	Oct 20, 2014
Priority date	Oct 28, 2013
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

A method of damping oscillations in a wind turbine tower comprises connecting a bag of material 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 hit said tower wall during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

First claim

The invention claimed is:

1. A method of damping oscillations in a wind turbine tower, comprising:
suspending a bag of material or liquid from a tower component such that the bag is configured to hit a tower wall of said wind turbine tower during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

2. The method according to claim 1 , comprising:
connecting the bag of material or liquid to a tower component at a first lateral distance away from the tower wall;
suspending the bag from the tower component by a first vertical distance, wherein a height of the tower component is known such that the first vertical distance corresponds to a particular height within the tower, and further wherein the first lateral distance, first vertical distance, and mass of the bag are such that the bag is configured to hit said tower wall during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

3. The method according to claim 2 , wherein a ratio between said first vertical distance and said first lateral distance is between 5 and 20.

4. The method according to claim 3 , wherein the ratio between said first vertical distance and said first lateral distance is between 8 and 15.

5. The method according to claim 3 , wherein the ratio between said first vertical distance and said first lateral distance is between 10 and 12.

6. The method according to claim 2 , wherein the first lateral distance, first vertical distance, and mass of the bag are such that the bag during oscillation will act as a pendulum counteracting a fundamental mode of vibration of the tower prior to hitting said wind turbine tower.

7. The method according to claim 2 , wherein the bag is connected to and suspended from the tower component with a chain, cable, or rope, and wherein suspending the bag comprises:
suspending the bag an initial distance from the tower component; and
adjusting the distance by which the bag is suspended from the tower component until the first vertical distance is attained.

8. The method according to claim 2 , wherein the bag is connected to and suspended from the tower component with a chain and via a ratchet wrench positioned on the chain, and wherein suspending the bag comprises:
suspending the bag an initial distance from the tower component; and
adjusting the distance by which the bag is suspended from the tower component by operating the ratchet wrench to move the bag along the chain.

9. The method according to claim 1 , wherein a mass of said bag is between 20 kg and 300 kg.

10. The method according to claim 1 , whereby said damping of oscillations is at least partly obtained by converting kinetic energy into heat energy through plastic deformation of said bag.

11. The method according to claim 1 , further comprising:
mounting a bracket to the tower, the bracket extending away from the tower wall and serving as the tower component to which the bag is connected.

12. The method according to claim 11 , wherein mounting the bracket to the tower comprises securing the bracket to the tower wall without welding.

13. The method according to claim 11 , wherein mounting the bracket to the tower comprises securing the bracket to a flange of the tower.

14. The method according to claim 1 , wherein the bag is connected to and suspended from a platform in the tower.

15. The method according to claim 1 , further comprising:
providing a plurality of bags of material or liquid; and
connecting and suspending the bags to a common tower component or respective tower components, wherein at least some of the bags are distributed circumferentially in relation to the tower wall.

16. The method according to claim 1 , further comprising:
positioning the bag onto a platform in the tower;
moving the bag from the platform onto an elevator lift;
transporting the bag toward the bottom of the tower using the elevator lift; and
removing the bag through a door in the tower.

17. The method according to claim 1 , further comprising:
filling the bag with a plurality of smaller bags, wherein the smaller bags effectively provide an overall mass of the bag.

18. A system for damping oscillations experienced by a wind turbine tower, comprising:
one or more bags of material or liquid;
one or more tower components configured to be secured to the tower; and
one or more chains, cables, or ropes configured to suspend the one or more bags from the one or more tower components,
wherein said system is configured such that upon installation in the wind turbine tower, the bag is configured to hit a tower wall of said wind turbine tower during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

19. The system according to claim 18 ,
wherein said bag is connected to said one or more tower components at a first lateral distance away from a tower wall; and
wherein said bag is suspended from the tower component by a first vertical distance, wherein a height of the tower component is known such that the first vertical distance corresponds to a particular height within the tower, and further wherein the first lateral distance, first vertical distance, and mass of the bag are such that the bag is configured to hit said tower wall during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

20. The system according to claim 19 , wherein a ratio between said first vertical distance and said first lateral distance is between 5 and 20.

21. The system according to claim 19 , wherein the first lateral distance, first vertical distance, and mass of the bag are such that the bag during oscillation will act as a pendulum counteracting a fundamental mode of vibration of the tower prior to hitting said wind turbine tower.

22. The system according to claim 18 , wherein a mass of said bag is between 20 kg and 300 kg.

23. The system according to claim 18 , wherein the one or more tower components have multiple attachment points for the chains, cables, or ropes so that the bags can be positioned at different lateral distances from a wall of the wind turbine tower.

24. The system according to claim 18 , wherein each bag comprises at least one large bag filled with a number of smaller bags containing the material or liquid.

25. A wind turbine comprising:
a tower;
a nacelle supported by the tower;
a rotor mounted to the nacelle; and
a damping system for damping oscillations experienced by a wind turbine tower, the damping system comprising:
one or more bags of material or liquid;
one or more tower components configured to be secured to the tower; and
one or more chains, cables, or ropes configured to suspend the one or more bags from the one or more tower components,

wherein said damping system is configured such that upon installation in a wind turbine tower, the bag is configured to hit a tower wall of said wind turbine tower during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

26. A method of installing a wind turbine, comprising:
providing a tower of the wind turbine having at least one tower wall, one or more tower components configured to be secured to the tower, and a damping system, the damping system comprising one or more bags of material or liquid and one or more chains, cables, or

Assignees

• Vestas Wind Sys As

Inventors

• Ollgaard Borge
• Jensen Soren P

Classifications

• E04H9/0215

  involving active or passive dynamic mass damping systems · CPC title

• F05B2230/60

  Assembly methods · CPC title

• Y02E10/728

  Onshore wind turbines · CPC title

• F03D80/00

  Details, components or accessories not provided for in groups F03D1/00 - F03D17/00 · CPC title

• F05B2240/912

  on a tower · CPC title