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EP-4739909-A1 - FASTENING SYSTEM FOR A WIND TURBINE TOWER ASSEMBLY AND METHOD FOR USING SAME

EP4739909A1EP 4739909 A1EP4739909 A1EP 4739909A1EP-4739909-A1

Abstract

A fastening system (142) and method for connecting a flange (64) of one tower section (62) to a flange (74) of an adjacent tower section (72) is disclosed. The first and second flanges (64, 74) have aligned through holes (66, 76). The fastening system (142) includes a plurality of bolts (82) received in a plurality of aligned through holes (66, 76) in the respective flanges (64, 74) and first and second bolt extenders (144, 148). Each bolt extender (144, 148) has at least one extender bore (146, 150), each receiving one of the plurality of bolts (82). For each adjacent pair of extender bores (146, 150) one extender bore is threaded and the other is unthreaded. For each adjacent pair of bolts (82), one bolt (82) has a first orientation and the other bolt (82) has a second orientation opposite to the first orientation. The centerlines between two adjacent bolts (82) are spaced apart a centerline distance (C blt ) and the centerline distance (C blt ) may be in the range of 1.01 to 1.75 times a shaft diameter (D sh ) of the bolt (82).

Inventors

  • FYNBO, Peter
  • HØEG, Christian Elkjær
  • MADSEN, Søren Bøgelund

Assignees

  • VESTAS WIND SYSTEMS A/S

Dates

Publication Date
20260513
Application Date
20240704

Claims (19)

  1. 1 . A wind turbine tower assembly (12), comprising: a first tower section (62) including a first flange (64) with a plurality of through holes (66), the first flange (64) including an inner surface (68) and a mating surface (70); a second tower section (72) including a second flange (74) with a plurality of through holes (66), the second flange (74) including an inner surface (78) and a mating surface (80); and a fastening system (142) for connecting the first flange (64) and the second flange (74) at a connection interface (18a) such that the respective mating surfaces (70, 80) face toward each other, the respective inner surfaces (68, 78) face away from each other, and the plurality of through holes (66) in the first flange (64) and the plurality of through holes (76) in the second flange (74) respectively align with each other, the fastening system (142) comprising: a plurality of bolts (82), each of the plurality of bolts (82) having a head (84) and a shaft (86) extending from the head (84) and received in a respective one of the aligned plurality of through holes (66, 76) in the first and second flanges (64, 74); at least one first bolt extender (144) including at least one first extender bore (146) receiving one of the plurality of bolts (82), the at least one first bolt extender (144) contacting the inner surface (68) of the first flange (64); and at least one second bolt extender (148) including at least one second extender bore (150) receiving one of the plurality of bolts (82), the at least one second bolt extender (148) contacting the inner surface (78) of the second flange (74); and a plurality of nuts (154), each nut (154) being threadingly engaged to one of the plurality of bolts (82), wherein for each adjacent pair of the plurality of bolts (82), one bolt (82) has a first orientation and the other bolt (82) has a second orientation opposite to the first orientation, and wherein the shaft (86) of each of the plurality of bolts (82) has a shaft diameter (Dsh), wherein the centerlines between two adjacent bolts (82) are spaced apart a centerline distance (Cbit), and wherein the centerline distance (Cbit) is in the range of 1 .01 to 1 .75 times the shaft diameter (Dsh), and preferably 1 .25 times the shaft diameter (Dsh).
  2. 2. The wind turbine tower assembly (12) of claim 1 , wherein the at least one first bolt extender (144) includes two cutouts (152a, 152b) on opposed sides of the at least one first extender bore (146), and wherein each cutout (152a, 152b) receives at least part of the head (84) of the bolt (82) adjacent to the at least one first extender bore (146).
  3. 3. The wind turbine tower assembly (12) of claim 1 or 2, wherein the first flange (64) includes a first groove (172) in the inner surface (68), and wherein the at least one first bolt extender (144) contacts the inner surface (68) of the first flange (64) so as to span the first groove (172).
  4. 4. The wind turbine tower assembly (12) of any of the preceding claims, wherein for each bolt (82) of the plurality of bolts (82), at least one adjacent bolt (82) defines an overlap region (160) between the head (84) of the bolt (82) and the head (84) of the adjacent bolt (82).
  5. 5. The wind turbine tower assembly (12) of any of the preceding claims, wherein for each of the plurality of bolts (82), there is at least one adjacent bolt (82) that defines an overlap region (166a, 166b) between the nut (154) of the bolt (82) and the through hole (66) of the first flange (64) and/or the through hole (76) of the second flange (74) that receives the adjacent bolt (82).
  6. 6. The wind turbine tower assembly (12) of claim 5, wherein for each bolt (82) of the plurality of bolts (82), there is a first adjacent bolt (82) that defines a first overlap region (166a) between the nut (154) of the bolt (82) and the through hole (66) of the first flange (64) and/or the through hole (76) of the second flange (74) that receives the first adjacent bolt (82), and there is a second adjacent bolt (82) that defines a second overlap region (166b) between the nut (154) of the bolt (82) and the through hole (66) of the first flange (64) and/or the through hole (76) of the second flange (74) that receives the second adjacent bolt (82).
  7. 7. The wind turbine tower assembly (12) of any of the preceding claims, wherein the at least one first bolt extender (144) includes only one first extender bore (146).
  8. 8. The wind turbine tower assembly (12) of any of claims 1 -6, wherein the at least one first bolt extender (144) includes a plurality of first extender bores (146).
  9. 9. The wind turbine tower assembly (12) of any of the preceding claims, wherein the at least one first bolt extender (144) includes a plurality of first bolt extenders (144).
  10. 10. The wind turbine tower assembly (12) of any of the preceding claims, wherein the first tower section (62) includes a first tower wall (30a) extending from the first flange (64), wherein the at least one first bolt extender (144) includes a curved edge (162), and wherein the curved edge (162) is received within a corner (116) defined by an intersection of the first flange (64) and the first tower wall (30a).
  11. 11 . The wind turbine tower assembly (12) of any of the preceding claims, wherein the at least one first bolt extender (144) and the at least one second bolt extender (148) are identical to each other.
  12. 12. A wind turbine (10) comprising the wind turbine tower assembly (12) according to any of claims 1-11.
  13. 13. A method of assembling a wind turbine tower assembly (12), the wind turbine tower assembly (12) comprising: a first tower section (62) including a first flange (64) with a plurality of through holes (66), the first flange (64) including an inner surface (68) and a mating surface (70); a second tower section (72) including a second flange (74) with a plurality of through holes (76), the second flange (74) including an inner surface (78) and a mating surface (80), the method comprising: positioning the first flange (64) relative to the second flange (74) so that the respective mating surfaces (70, 80) face toward each other, the respective inner surfaces (68, 78) face away from each other, and the plurality of through holes (66) in the first flange (64) respectively align with the plurality of through holes (76) in the second flange (74); positioning on the inner surface (68) of the first flange (64) at least one first bolt extender (144) including at least one first extender bore (146) so that the at least one first extender bore (146) aligns with at least one of the plurality of through holes (66) in the first flange (64); positioning on the inner surface (78) of the second flange (74) at least one second bolt extender (148) including at least one second extender bore (150) so that the at least one second extender bore (150) aligns with at least one of the plurality of through holes (76) in the second flange (74); using a plurality of bolts (82): inserting one of the plurality of bolts (82) into the at least one first extender bore (146) of the at least one first bolt extender (144), and inserting one of the plurality of bolts (82) into the at least one second extender bore (150) of the at least one second bolt extender (148); engaging each of the plurality of bolts (82) with a nut (154); and tensioning each of the plurality of bolts (84) to connect the first flange (64) and the second flange (74), wherein the plurality of bolts (82) is inserted such that for each adjacent pair of the plurality of bolts (82), one bolt (82) has a first orientation and the other bolt (82) has a second orientation opposite to the first orientation, and wherein the shaft (86) of each of the plurality of bolts (82) has a shaft diameter (Dsh), wherein the centerlines between two adjacent bolts (82) are spaced apart a distance (Cbit), and wherein the distance (Cbit) is in the range of 1 .01 to 1 .75 times the shaft diameter (Dsh), and preferably 1.25 times the shaft diameter (Dsh).
  14. 14. The method of claim 13, wherein for each bolt (82) of the plurality of bolts (82), at least one adjacent bolt (82) defines an overlap region (160) between the head (84) of the bolt (82) and the head (84) of the adjacent bolt (82).
  15. 15. The method of claim 13, wherein: the first tower section (62) includes a first tower wall (30a) extending from the first flange (64) at an intersection that defines a corner (116), the at least one first bolt extender (144) includes a curved edge (162), and positioning the at least one first bolt extender (144) on the inner surface (68) of the first flange (64) includes positioning the at least one first bolt extender (144) such that the curved edge (162) is received in the corner (116); and the second tower section (72) includes a second tower wall (30b) extending from the second flange (74) at an intersection that defines a corner (118), the at least one second bolt extender (148) includes a curved edge (164), and positioning the at least one second bolt extender (148) on the inner surface (78) of the second flange (74) includes positioning the at least one second bolt extender (148) such that the curved edge (164) is received in the corner (118).
  16. 16. The method of any of claims 13-15, wherein: the first flange (64) includes a groove (172) on the inner surface (68), and positioning the at least one first bolt extender (144) on the inner surface (68) of the first flange (64) includes positioning the at least one first bolt extender (144) to span the groove (172); and the second flange (74) includes a groove (174) on the inner surface (78), and positioning the at least one second bolt extender (148) on the inner surface (78) of the second flange (74) includes positioning the at least one second bolt extender (148) to span the groove (174).
  17. 17. A method of retrofitting a fastening system (60, 130, 136) to a wind turbine tower assembly (12), the wind turbine tower assembly (12) comprising: a first tower section (18) including a first flange (32a) with a plurality of existing through holes (34), the first flange (32a) including an inner surface (68) and a mating surface (70); a second tower section (18) including a second flange (32b) with a plurality of existing through holes (34), the second flange (32b) including an inner surface (78) and a mating surface (80), wherein the first flange (32a) is connected to the second flange (32b) via a plurality of existing bolts (36) in the plurality of existing through holes (34) of the first and second flanges (32a, 32b) and the respective mating surfaces (70, 80) face toward each other and the respective inner surfaces (68, 78) face away from each other, the method comprising: removing a subset of the plurality of existing bolts (36) from the plurality of existing through holes (34) in the first and second flanges (64, 74); forming a plurality of intermediate through holes (190) in the first and second flanges (64, 74), each of the plurality of intermediate through holes (190) being positioned between adjacent pairs of existing through holes (34) in the first and second flanges (64,74); positioning on the inner surface (68) of the first flange (64) at least one first bolt extender (144) each including at least one first extender bore (146) so that the at least one first extender bore (146) aligns with one of the plurality of existing through holes (34) in the first flange (64) or with one of the plurality of intermediate through holes (190) in the first flange (64); positioning on the inner surface (78) of the second flange (74) at least one second bolt extender (148) each including at least one second extender bore (150) so that the at least one second extender bore (150) aligns with one of the plurality of existing through holes (34) in the second flange (74) or with one of the plurality of intermediate through holes (190) in the second flange (74); using a plurality of replacement bolts (82): inserting one of the plurality of replacement bolts (82) into the at least one first extender bore (146) of the at least one first bolt extender (144), and inserting one of the plurality of replacement bolts (82) into the at least one second extender bore (150) of the at least one second bolt extender (148); engaging each of the plurality of replacement bolts (82) with a nut (154); and tensioning each of the plurality of replacement bolts (82) to connect the first flange (64) and the second flanges (74), wherein the plurality of replacement bolts (82) is inserted such that for each adjacent pair of the plurality of replacement bolts (82), one replacement bolt (82) has a first orientation and the other replacement bolt (82) has a second orientation opposite to the first orientation, and wherein the shaft (86) of each of the plurality of bolts (82) has a shaft diameter (Dsh), wherein the centerlines between two adjacent bolts (82) are spaced apart a distance (Cbit), and wherein the distance (Cbit) is in the range of 1 .01 to 1 .75 times the shaft diameter (Dsh), and preferably 1.25 times the shaft diameter (Dsh).
  18. 18. The method of claim 17, wherein each of the plurality of the existing through holes (34) in the first and second flanges (32a, 32b) is positioned at a first radius (Ri) from a center of the first and second tower sections (18), and wherein each of the plurality of the intermediate through holes (190) is positioned at a second radius (R2) less than or equal to the first radius (R1).
  19. 19. The method of claim 17 or 18, wherein before removal, each of the plurality of existing bolts (36) is in the first orientation.

Description

FASTENING SYSTEM FOR A WIND TURBINE TOWER ASSEMBLY AND METHOD FOR USING SAME Technical Field This application relates generally to wind turbines, and more particularly to a fastening system for connecting wind turbine tower sections and a method for using that fastening system. Background Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A horizontal-axis wind turbine includes a tower, a nacelle located at the apex of the tower, and a rotor having a plurality of blades and supported in the nacelle by means of a shaft. The shaft couples the rotor either directly or indirectly with a generator, which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator. To this end, wind turbines may be located either on a land mass (onshore) or within a body of water (offshore). The tower of a wind turbine may be constructed from a plurality of tower sections stacked one on top of another. A tower section may have a circumferential flange at one or both of its ends where the flange will have a plurality of spaced-apart through holes for receiving respective bolts therethrough. In one configuration, the through holes are spaced equidistant from each other around the entire flange. During assembly, one tower section is stacked on top of another tower section such that the flange of the upper tower section rests upon the flange of the lower tower section. The through holes on both flanges are aligned and bolts are inserted into the through holes of the top flange and extend through the through holes of the lower flange where nuts are threaded onto the ends of the bolts. The nut may be tightened by placing a tool (e.g., a socket) over the nut and using a power tool to turn and thereby tighten the nut onto the bolt. The coupled flanges form a joint between the two adjacent tower sections. The tightened nuts and bolts create a clamping force between the two flanges at the joint. As wind turbines increase in size to produce even greater energy, the wind turbines and the corresponding towers increase in height to accommodate larger (longer) wind turbine blades. As the towers increase in height, they need greater strength at the joints between adjacent tower sections. One approach is to simply increase the diameter of the tower. This approach, however, has a number of drawbacks including increased material costs, transportation costs, and manufacturing limitations. Another approach to increasing the strength is to increase the number of bolts around the flanges of adjacent tower sections. For example, this may be achieved by spacing the bolts closer together around the circumference of the flange. However, the minimum distance the bolts may be spaced next to each other is often dictated by the size of the tool needed to engage the nut to tighten it onto the bolt. If the bolts are spaced too closely, the tool will be unable to positively engage the nut and, therefore, will be unable to tighten the nut onto the bolt. A washer is typically used with the nut. The through hole must be spaced radially inward from the wall of the tower section so that the washer does not contact the radiused fillet located by between the tower wall and the flange. The load transfer may be increased by moving the through holes radially as close as possible to the tower walls. The presence of the radiused fillet, however, limits how close the through holes and thus the bolts may be located next to the tower section walls. In light of the problems for decreasing bolt spacing and moving the bolts closer to the tower section walls, there is a need for a fastening system and method that allows the bolts to be spaced closer together but allow conventional tools to tighten the nuts on the bolts. The fastening system should further allow the bolts to be placed closer to the tower section walls even in the presence of a radiused fillet. Summary According to a first aspect of the invention, a wind turbine tower assembly includes a first tower section including a first flange with a plurality of through holes, where the first flange including an inner surface and a mating surface and a second tower section including a second flange with a plurality of through holes, where the second flange including an inner surface and a mating surface. The wind turbine tower assembly further includes a fastening system for connecting the first flange and the second flange at a connection interface such that the respective mating surfaces face toward each other, the respective inner surfaces face away from each other, and the plurality of through holes in the first flange and the plurality of through holes in the second flange respectively align with each other. The fastening system includes a plurality of bolts, each of the plurality of bolts having a hea