POST-TENSIONING SYSTEM FOR A TOWER OF A WIND TURBINE, POST-TENSIONED TOWER OF A WIND TURBINE AND METHOD OF POST-TENSIONING A TOWER OF A WIND TURBINE

Abstract

The present invention relates to a post-tensioning system for a tower of a wind turbine that manages the quasi-permanent loads on the tower to counter them, reducing their impact and making it possible to decrease the required amount of overall post-tension force in the tower of the wind turbine, also to a post-tensioned tower of a wind turbine comprising the post-tensioning system and to the method of post-tensioning a tower of a wind turbine.

Claims

1. A post-tensioning system for a tower of a wind turbine, wherein the tower (1) comprises at least: a vertical axis (2); a concrete tower part (3) comprising: an upwind side (4) and a downwind side (5), wherein the upwind side (4) and the downwind side (5) are defined, in use, from a first vertical plane (PV1) containing the vertical axis (2) and being perpendicular to a predominant wind direction (W), upwards and downwards respectively, from the first vertical plane (PV1); and the system comprising: an upper end (18) comprising a first surface (8) and a lower end (17) comprising a second surface (7); a plurality of tensioning elements (9), wherein each one of the tensioning elements (9) comprises a first end (10) located in the upper end (18) and a second end (11) located in the lower end (17); a first set of anchoring elements (12) configured to anchor the first ends (10) of the tensioning elements (9) towards the first surface (8); a second set of anchoring elements (13) configured to anchor the second ends (11) of the tensioning elements (9) towards the second surface (7); characterised in that the tensioning elements (9) are configured to exert a resultant post-tension force (P) comprising a line of action (D) which intersects with a horizontal plane (PH1) located at the lower end (17) in a first intersection point (I1) upwards from the first vertical plane (PV1).

2. The post-tensioning system for a tower of a wind turbine according to claim 1, characterised in that the first ends (10) and the second ends (11) of the tensioning elements (9) are disposed in a symmetrical way with respect to the first vertical plane (PV1).

3. The post-tensioning system for a tower of a wind turbine according to claim 1, characterised in that the first ends (10) of the tensioning elements (9) are disposed in a symmetrical way with respect to the first vertical plane (PV1), while the second ends (11) of the tensioning elements (9) are disposed in a non-symmetrical way with respect to the first vertical plane (PV1).

4. The post-tensioning system for a tower of a wind turbine according to claim 3, characterised in that the number of second ends (11) of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) is greater than the number of second ends (11) of the tensioning elements (9) disposed downwards from the first vertical plane (PV1).

5. The post-tensioning system for a tower of a wind turbine according to any one of the previous claims, characterised in that each tensioning element (9) comprises a set of strands (14).

6. The post-tensioning system for a tower of a wind turbine according to claim 5, characterised in that the number of strands (14) of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) is greater than the number of strands (14) of the tensioning elements (9) disposed downwards from the first vertical plane (PV1).

7. The post-tensioning system for a tower of a wind turbine according to any one of the previous claims, characterised in that a first post-tensioning force (P1) that exerts, in use, the tensioning elements (9) disposed upwards from the first vertical plane (PV1) is greater than a second post-tensioning force (P2) that exerts, in use, the tensioning elements (9) disposed downwards from the first vertical plane (PV1).

8. The post-tensioning system for a tower of a wind turbine according to any one of the previous claims, characterised in that the resultant post-tension force (P) is contained in a second vertical plane (PV2) perpendicular to the first vertical plane (PV1), the second vertical plane (PV2) containing the predominant wind direction (W).

9. The post-tensioning system for a tower of a wind turbine according to any one of the previous claims, characterised in that the resultant post-tension force (P) also intersects with an additional horizontal plane (PH2) located at the upper end (18) in a second intersection point (I2).

10. The post-tensioning system for a tower of a wind turbine according to claim 9, characterised in that the first intersection point (I1) and the second intersection point (I2) are located at the same distance from the first vertical plane (PV1).

11. The post-tensioning system for a tower of a wind turbine according to claim 9, characterised in that the first intersection point (I1) and the second intersection point (I2) are located at a different distance from the first vertical plane (PV1).

12. The post-tensioning system for a tower of a wind turbine according to any one of the claims 9 to 11, characterised in that the first intersection point (I1) and/or the second intersection point (I2) are located at a distance between 0.1 m and 3 m from the first vertical plane (PV1).

13. A post-tensioned tower of a wind turbine (1) comprising the post-tensioning system for a tower of a wind turbine of any one of the previous claims.

14. A wind turbine (1) comprising the post-tensioned tower of claim 13.

15. A method of post-tensioning a tower of a wind turbine, wherein the tower comprises at least: a vertical axis (2); a concrete tower part (3) comprising: an upwind side (4) and a downwind side (5), wherein the upwind side (4) and the downwind side (5) are defined, in use, from a first vertical plane (PV1) containing the vertical axis (2) and being perpendicular to a predominant wind direction (W), upwards and downwards respectively, from the first vertical plane (PV1); and the method carried out with the post-tensioning system of any one of claims 1 to 12 and comprising: a step of disposing in the concrete tower part (3) a plurality of tensioning elements (9), wherein each one of the tensioning elements (9) comprises a first end (10) located in the upper end (18) and a second end (11) located in the lower end (17); a step of anchoring a first set of anchoring elements (12) in the first ends (10) of the tensioning elements (9) towards the first surface (8); a step of anchoring a second set of anchoring elements (13) in the second ends (11) of the tensioning elements (9) towards the second surface (7); and a step of exerting a resultant post-tension force (P) comprising a line of action (D) which intersects with a horizontal plane (PH1) located at the lower end (17) in a first intersection point (I1) upwards from the first vertical plane (PV1), by means of the tensioning elements (9).

16. The method of post-tensioning a tower of a wind turbine according to claim 15, characterised in that the step of exerting a resultant post-tension force (P) comprising a line of action (D) which intersects with a horizontal plane (PH1) located at the lower end (17) in a first intersection point (I1) upwards from the first vertical plane (PV1) comprises a step of exerting a first post-tensioning force (P1) by means of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) and a second post-tensioning force (P2) by means of the tensioning elements (9) disposed downwards from the first vertical plane (PV1), wherein the first post-tensioning force (P1) is greater than the second post-tensioning force (P2).

17. The method of post-tensioning a tower of a wind turbine according to claim 15, characterised in that the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9), wherein each one of the tensioning elements (9) comprises a first end (10) located in the upper end (18) and a second end (11) located in the lower end (17) comprises a step of disposing at least one tensioning element (9) with fewer strands (14) in the downwind side (5) than in the upwind side (4).

18. The method of post-tensioning a tower of a wind turbine according to claim 15, characterised in that the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9), wherein each one of the tensioning elements (9) comprises a first end (10) located in the upper end (18) and a second end (11) located in the lower end (17) comprises disposing more tensioning elements (9) in the upwind side (4) than in the downwind side (5).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 shows a lateral view of a wind turbine with different constituent parts of the tower wherein the post-tensioning system of the present invention is disposed, according to the invention.

[0056] FIG. 2 shows a top view of the concrete tower part of the tower of a wind turbine wherein the post-tensioning system of the present invention is disposed.

[0057] FIG. 3 shows a lateral view of the concrete tower part shown in FIG. 2, wherein a first embodiment of the post-tensioning system of the present invention is represented.

[0058] FIG. 4 shows in the upper part, the upper end of the concrete tower part shown in FIG. 3 and in the lower part, the lower end of the concrete tower part shown in FIG. 3.

[0059] FIG. 5 shows the resultant post-tension force exerted by the tensioning elements of the system of FIG. 3.

[0060] FIG. 6 shows a detail of the anchoring elements of the tensioning elements, wherein each tensioning element comprises several strands.

[0061] FIG. 7 shows a lateral view of the concrete tower part shown in FIG. 2, wherein a second embodiment of the post-tensioning system of the present invention is represented.

[0062] FIG. 8 shows in the upper part, the upper end of the concrete tower part shown in FIG. 7 and in the lower part, the lower end of the concrete tower part shown in FIG. 7, showing how the tensioning elements disposed upwards from the first vertical plane comprises a greater number of strands than the number of strands of the tensioning elements disposed downwards from the first vertical plane (only represented in the lower end).

[0063] FIG. 9 shows the resultant post-tension force exerted by the tensioning elements in another embodiment of the system of the invention, wherein the line of action of the resultant post-tension force intersects the additional horizontal plane located at the upper end in a second intersection point displaced from the vertical axis of the tower.

[0064] FIG. 10 shows the resultant post-tension force exerted by the tensioning elements in another embodiment of the system of the invention, wherein the line of action of the resultant post-tension force is parallel to the vertical axis of the tower.

[0065] FIG. 11 shows a lateral view of the concrete tower part shown in FIG. 2, wherein a third embodiment of the post-tensioning system of the present invention is represented, being P1 greater than P2.

[0066] FIG. 12 shows the step of anchoring one anchoring element of the first set of anchoring elements in the first end of a tensioning element, wherein the tensioning element comprises several strands.

[0067] FIG. 13 shows the step of anchoring one anchoring element of the second set of anchoring elements in the second end of the tensioning element, wherein the tensioning element comprises several strands (not shown).

PREFERRED EMBODIMENT OF THE INVENTION

[0068] The invention is described in detail as follows. It relates to a post-tensioning system for a tower of a wind turbine, wherein the tower (1) comprises at least: [0069] a vertical axis (2); [0070] a concrete tower part (3) comprising: [0071] an upwind side (4) and a downwind side (5), wherein the upwind side (4) and the downwind side (5) are defined, in use, from a first vertical plane (PV1) containing the vertical axis (2) and being perpendicular to a predominant wind direction (W), upwards and downwards respectively, from the first vertical plane (PV1); and [0072] the system comprising: [0073] an upper end (18) comprising a first surface (8) and a lower end (17) comprising a second surface (7); [0074] a plurality of tensioning elements (9), wherein each one of the tensioning elements (9) comprises a first end (10) located in the upper end (18) and a second end (11) located in the lower end (17); [0075] a first set of anchoring elements (12) configured to anchor the first ends (10) of the tensioning elements (9) towards the first surface (8); [0076] a second set of anchoring elements (13) configured to anchor the second ends (11) of the tensioning elements (9) towards the second surface (7);

[0077] As can be seen in FIG. 5, the tensioning elements (9) are configured to exert a resultant post-tension force (P) comprising a line of action (D) which intersects with a horizontal plane (PH1) located at the lower end (17) in a first intersection point (I1) upwards from the first vertical plane (PV1), (contained in a space defined within the upwind side).

[0078] Preferably, the first surface (8) of the upper end (18) is located in an adaptor (16) of the tower (1), as shown in FIG. 12, being the upper end (18) of the post-tensioning system of the invention the adaptor.

[0079] Preferably, the second surface (7) of the lower end (17) is located in a tower foundation (15) of the tower (1), as shown in FIG. 13, being the lower end (17) of the post-tensioning system of the invention the tower foundation.

[0080] Preferably, as shown in FIGS. 3, 5, 7, 9, 10 and 11, the first surface (8) of the upper end (18) and/or the second surface (7) of the lower end (17) are located in a surface of the concrete tower part (3) of the tower, being the upper end (18) of the post-tensioning system of the invention an upper part of the concrete tower part (3) and the lower end (17) of the post-tensioning system of the invention a lower part of the concrete tower part (3).

[0081] In the preferred embodiment shown in FIGS. 3 and 4, the resultant post-tension force (P) comprises a line of action (D) which intersects with the horizontal plane (PH1) located at the lower end (17) in a first intersection point (I1) upwards from the first vertical plane (PV1), as can be seen in FIG. 5, wherein the number of strands (14) forming each tensioning element (9) is the same, and the first ends (10) of the tensioning elements (9) are disposed in a symmetrical way with respect to the first vertical plane (PV1) and to a second vertical plane (PV2) perpendicular to the first vertical plane (PV1), the second vertical plane (PV2) containing the predominant wind direction (W). Preferably, the second ends (11) of the tensioning elements (9) are disposed in an asymmetrical way with respect to the first vertical plane (PV1) and in a symmetrical way with respect to the second vertical plane (PV2).

[0082] In another embodiment, the first ends (10) and/or the second ends (11) of the tensioning elements (9) are disposed in a symmetrical way with respect to the first vertical plane (PV1).

[0083] As can be seen in FIG. 6, each tensioning element (9) comprises a set of strands (14).

[0084] In another embodiment shown in FIG. 8, the number of strands (14) of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) is greater than the number of strands (14) of the tensioning elements (9) disposed downwards from the first vertical plane (PV1) despite comprising the same number of tensioning elements (9) upwards than downwards from the first vertical plane (PV1).

[0085] In another embodiment, a first post-tensioning force (P1) that exerts, in use, the tensioning elements (9) disposed upwards from the first vertical plane (PV1) is greater than a second post-tensioning force (P2) that exerts, in use, the tensioning elements (9) disposed downwards from the first vertical plane (PV1).

[0086] In the embodiment shown in FIG. 4, the first ends (10) of the tensioning elements (9) are disposed in a symmetrical way with respect to the first vertical plane (PV1), while the second ends (11) of the tensioning elements (9) are disposed in a non-symmetrical way with respect to the first vertical plane (PV1). As can be seen in FIG. 4, the number of second ends (11) of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) may be greater than the number of second ends (11) of the tensioning elements (9) disposed downwards from the first vertical plane (PV1). In the embodiment shown in FIG. 4, the first ends (10) and the second ends (11) of the tensioning elements (9) are disposed in a symmetrical way with respect to the second vertical plane (PV2).

[0087] In another embodiment shown in FIGS. 9 and 10, the resultant post-tension force (P) also intersects with an additional horizontal plane (PH2) located at the upper end (18) in a second intersection point (I2). Preferably, as shown in FIG. 9, the first intersection point (I1) and the second intersection point (I2) are located at a different distance from the first vertical plane (PV1). Also preferably, as shown in FIG. 10, the first intersection point (I1) and the second intersection point (I2) are located at the same distance from the first vertical plane (PV1). In this embodiment, the same asymmetrical distribution in the upper end (18) and in the lower end (17) of the first ends (10) and the second ends (11), respectively, of the tensioning elements (9), as well as the tensioning elements (9) being disposed parallel to the vertical axis (2) of the tower (1), is given.

[0088] Preferably, the first intersection point (I1) and/or the second intersection point (I2) are located at a distance between 0.1 m and 3 m from the first vertical plane (PV1).

[0089] Preferably, the first set of anchoring elements (12) and/or the second set of anchoring elements (13) are nuts, bolts or a combination of them.

[0090] The invention also relates to a post-tensioned tower of a wind turbine (1) comprising the post-tensioning system for a tower of a wind turbine. Also, the invention relates to a wind turbine (1) comprising the post-tensioned tower.

[0091] Also, the invention relates to a method of post-tensioning a tower of a wind turbine, wherein the tower comprises at least: [0092] a vertical axis (2); [0093] a concrete tower part (3) comprising: [0094] an upwind side (4) and a downwind side (5), wherein the upwind side (4) and the downwind side (5) are defined, in use, from a first vertical plane (PV1) containing the vertical axis (2) and being perpendicular to a predominant wind direction (W), upwards and downwards respectively, from the first vertical plane (PV1); and [0095] the method carried out with the post-tensioning system described above and comprising: [0096] a step of disposing in the concrete tower part (3) a plurality of tensioning elements (9), wherein each one of the tensioning elements (9) comprises a first end (10) located in the upper end (18) and a second end (11) located in the lower end (17); [0097] a step of anchoring a first set of anchoring elements (12) in the first ends (10) of the tensioning elements (9) towards the first surface (8), as shown in FIG. 12; [0098] a step of anchoring a second set of anchoring elements (13) in the second ends (11) of the tensioning elements (9) towards the second surface (7), as shown in FIG. 13; and [0099] a step of exerting a resultant post-tension force (P) comprising a line of action (D) which intersects with a horizontal plane (PH1) located at the lower end (17) in a first intersection point (I1) upwards from the first vertical plane (PV1), by means of the tensioning elements (9).

[0100] In the embodiment shown in FIG. 4, the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9) comprises disposing the first ends (10) in a symmetrical way with respect to the first vertical plane (PV1), and the second ends (11) of the tensioning elements (9) in a non-symmetrical way with respect to the first vertical plane (PV1). Preferably, the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9) comprises disposing the first ends (10) in a symmetrical way with respect to the second vertical plane (PV2), and the second ends (11) of the tensioning elements (9) in a symmetrical way with respect to the second vertical plane (PV2).

[0101] In the embodiment shown in FIG. 8, the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9) comprises disposing the first ends (10) and the second ends (11) of the tensioning elements (9) in a symmetrical way with respect to the first vertical plane (PV1). Preferably, the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9) comprises disposing a greater number of strands (14) of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) than the number of strands (14) of the tensioning elements (9) disposed downwards from the first vertical plane (PV1). Preferably, the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9) comprises disposing the first ends (10) and the second ends (11) of the tensioning elements (9) in a symmetrical way with respect to the second vertical plane (PV2).

[0102] In another embodiment shown in FIG. 11, the step of exerting a resultant post-tension force (P) comprises a step of exerting a first post-tensioning force (P1) by means of the tensioning elements (9) disposed upwards from the first vertical plane (PV1) and a second post-tensioning force (P2) by means of the tensioning elements (9) disposed downwards from the first vertical plane (PV1), wherein the first post-tensioned force (P1) is greater than the second post-tensioned force (P2).

[0103] In the embodiment shown in FIG. 4, the step of disposing in the concrete tower part (3) a plurality of tensioning elements (9) comprises disposing a greater number of second ends (12) of the tensioning elements (9) upwards from the first vertical plane (PV1) than the number of second ends (12) of the tensioning elements (9) disposed downwards from the first vertical plane (PV1).

[0104] In the embodiment shown in FIG. 4, the step of exerting a resultant post-tension force (P) is carried out exerting the resultant post-tension force (P) in a line of action contained in a second vertical plane (PV2) perpendicular to the first vertical plane (PV1), the second vertical plane (PV2) containing the predominant wind direction (W).

[0105] Optionally, the step of exerting a resultant post-tension force is carried out exerting the resultant post-tension force in a line of action such that the first intersection point (I1) and/or the second intersection point (I2) are located at a distance between 0.1 m and 3 m from the first vertical plane (PV1).