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EP-4739907-A1 - A BASE FOR A WIND TURBINE, A WIND TURBINE INSTALLED ON A BASE, AND A METHOD FOR MAKING A BASE FOR A WIND TURBINE

EP4739907A1EP 4739907 A1EP4739907 A1EP 4739907A1EP-4739907-A1

Abstract

A base (10) for a wind turbine and a method for making a base is disclosed. The base comprises a side wall (11) enclosing an inner volume and having a circular cross-sectional shape. The side wall comprises a lower section (12) extending from a lower side towards an upper side, an upper section (14) extending from the upper side towards the lower side, and a centre section (13) extending from the lower section to the upper section, said centre section meeting the lower section in a first horizontal plane (P1) and meeting the upper section in a second horizontal plane (P2). The centre section has a first outer diameter (d1) at the first horizontal plane and a second outer diameter (d2) at the second horizontal plane, said first outer diameter being larger than said second outer diameter, and an outer pitch angle (α) of the centre section decreases in the height direction. The lower section, the centre section, and the upper section are made from concrete and integrally formed.

Inventors

  • HOLM, MICHAEL

Assignees

  • COBOD International A/S

Dates

Publication Date
20260513
Application Date
20230703

Claims (19)

  1. 1 . A base for a wind turbine comprising a side wall extending in a height direction from a lower side to an upper side, enclosing an inner volume, and having a circular cross- sectional shape, where an inner side of the side wall faces the inner volume and an outer side of the side wall faces away from the inner volume, where said side wall comprises a lower section extending from the lower side towards the upper side, an upper section extending from the upper side towards the lower side, and a centre section extending from the lower section to the upper section, said centre section meeting the lower section in a first horizontal plane and meeting the upper section in a second horizontal plane, where said centre section has a first outer diameter at the first horizontal plane and a second outer diameter at the second horizontal plane, said first outer diameter being larger than said second outer diameter, and where an outer pitch angle of the centre section decreases in the height direction, and where of the lower section, the centre section, and the upper section are made from concrete and integrally formed.
  2. 2. A base for a wind turbine according to claim 1 , where a total pitch angle of the base is 10-30 degrees, preferably at least 15 degrees.
  3. 3. A base for a wind turbine according to claim 1 or 2, where the lower section, the centre section, and the upper section are made by printing, each comprising a plurality of layers of concrete located on top of each other in the height direction.
  4. 4. A base for a wind turbine according to one or more of the preceding claims, where the lower section is conical with the outer side of the side wall extending at a first outer pitch angle.
  5. 5. A base for a wind turbine according to one or more of the preceding claims, where the upper section is cylindrical.
  6. 6. A base for a wind turbine according to one or more of the preceding claims, where the thickness of side walls decreases in the height direction.
  7. 7. A base for a wind turbine according to one or more of the preceding claims, further comprising reinforcement chosen from the group comprising: rods, rings, or fibres.
  8. 8. A base for a wind turbine according to one or more of the preceding claims, further comprising an inner support structure.
  9. 9. A wind turbine installed on a base according to one or more of claims 1 -8, said wind turbine comprising a rotor blades, a nacelle, and a tower, where the tower is supported by the base, and where the base is supported by a foundation.
  10. 10. A wind turbine according to claim 9, where reinforcement elements having two ends are attached to the tower at one end and to the foundation at the other end, and where the reinforcement elements extend through the inner volume of the base.
  11. 11 . A wind turbine according to claim 9 or 10, where the foundation is a strip foundation.
  12. 12. A wind turbine according to claim 9 or 10, where the foundation is a floating foundation.
  13. 13. A wind turbine according to claim 9, 10 or 12, where the foundation comprises a plurality of curved portions connected to the base by straight walls, and where the curved portions together from an outer side wall of the foundation enclosing the base.
  14. 14. A wind turbine according to claim 13, where the foundation further comprises an interior circular wall surrounding the base and interconnecting the straight walls.
  15. 15. A wind turbine according to claim 13 or 14, where the base is provided with local reinforcement where it meets the straight walls of the foundation.
  16. 16. A wind turbine according to one or more of claims 9-15, where the base is formed integrally with the foundation.
  17. 17. A method for making a base for a wind turbine where concrete is deposited along a circular path thereby forming a side wall extending in a height direction from a lower side to an upper side, enclosing an inner volume, and having an inner side of the side wall faces the inner volume and an outer side of the side wall faces away from the inner volume, said method comprising the following steps: I) Depositing concrete on a support surface thereby forming a lower section of the base, where a top of the lower section defines a first horizontal plane, II) Depositing concrete on the top of the lower section thereby forming a centre section of the base, where a top of the centre section defines a second horizontal plane, and III) Depositing concrete on the top of the centre section thereby forming an upper section of the base. where the lower section, the centre section, and the upper section are integrally formed, where a diameter of the circular path is gradually reduced during step II), and where a rate reduction of the diameter of the circular path is gradually decreased during step II).
  18. 18. A method according to claim 17, where the base is made by printing.
  19. 19. A method according to claim 17 or 18, where the base is formed integrally with a foundation.

Description

Title of Invention A base for a wind turbine, a wind turbine installed on a base, and a method for making a base for a wind turbine Technical Field The invention relates to the installation of wind turbines on-shore as well as off-shore and the provision of support for the wind turbines. Background Art With the increasing demand for sustainable energy, wind turbines have been optimised both with respect to power conversion and size. With an increased size the wings can become longer, which will increase the power production capacity, and it is also possible to reach levels, where wind speeds are high and there is less turbulence caused by landscape factors, such as hills, vegetation, and buildings. The need for transporting components from a production site to a site of installation has, however, set limits on the total size of wind turbines. Increasing the height has therefore necessitated still stronger towers and bigger foundations, which has added to the production costs. Summary of Invention With this background, it is an object of the invention to provide a means and a method by which it is possible to cost efficiently increase the height of a wind turbine. In a first aspect of the invention this and further objects are achieved with a base for a wind turbine comprising a side wall extending in a height direction from a lower side to an upper side, enclosing an inner volume, and having a circular cross-sectional shape, where an inner side of the side wall faces the inner volume and an outer side of the side wall faces away from the inner volume; where said side wall comprises a lower section extending from the lower side towards the upper side, an upper section extending from the upper side towards the lower side, and a centre section extending from the lower section to the upper section, said centre section meeting the lower section in a first horizontal plane and meeting the upper section in a second horizontal plane; where said centre section has a first outer diameter at the first horizontal plane and a second outer diameter at the second horizontal plane, said first outer diameter being larger than said second outer diameter, and where an outer pitch angle of the centre section decreases in the height direction; and where of the lower section, the centre section, and the upper section are made from concrete and integrally formed. With the outer pitch angle of the centre section decreasing in the height direction, the outer side becomes gradually steeper in the height direction, so that the centre section gets the shape of a trumpet, giving the base a relatively large footprint. This has several advantages, one being that with the trumpet shape concrete is applied where it is most needed from a structural point of view. Wind turbine towers experience large lateral loads from the turbine operation, and since they in principle act as a cantilever column under static and dynamic load, the sectional bending moment is largest at the tower bottom, i.e. in the base close to the lower side. With the large diameter at the lower side, the bending stress level in the side wall is reduced compared to a conical shape with a linear decrease in diameter from bottom to top, where the bending moment capacity is decreased at a slower rate than the decrease of the actual bending moment section force resulting from lateral loads. Another advantage is that the trumpet shape, allows the loads of the wind turbine to be distributed over a large area, and by forming the base from concrete, it can be formed on the installation site, eliminating the need for transportation of components from a production site. The use of concrete as compared to for example steel will in itself result in a thicker side wall which may also result in a relatively large footprint of the base and hence a good load distribution. The use of concrete may also result in that the base is relatively heavy, which may contribute to a stabilization of the finished wind turbine. The upper side and the lower side will typically be horizontal, when the wind turbine is to be installed off-shore or on a level terrain, but if the wind turbine is to be installed for example in a mountainous area, it may be advantageous that the base is capable of compensating for unevenness in the terrain, for example by the lower side being non-horizontal. Any reference to items being horizontal, vertical, upper, lower, or similar indications of direction used herein are to be understood as referring to the base in the installed use state. In some embodiments, the total pitch angle of the base, i.e. the angle of a line extending from the outer side of the side wall at the lower side to the outer side of the side wall at an upper side relative to vertical, is 10-30 degrees, preferably at least 15 degrees. It is presently considered advantageous that the lower section, the centre section, and the upper section are made by additive manufacturing, also called printing, each co