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EP-4739908-A1 - FASTENING SYSTEM FOR A WIND TURBINE TOWER ASSEMBLY AND METHOD FOR USING SAME

EP4739908A1EP 4739908 A1EP4739908 A1EP 4739908A1EP-4739908-A1

Abstract

A fastening system (60) 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 (60) 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 (100, 104, 198, 202, 210, 214). Each bolt extender (100, 104, 198, 202, 210, 214) has a plurality of extender bores (102, 106), each receiving one of the plurality of bolts (82). For each adjacent pair of extender bores (102, 106) 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.

Inventors

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

Assignees

  • VESTAS WIND SYSTEMS A/S

Dates

Publication Date
20260513
Application Date
20240704

Claims (20)

  1. Claims 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 (76), the second flange (74) including an inner surface (78) and a mating surface (80); and a fastening system (60) 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 (60) 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 (100, 198, 202, 210, 214) including a plurality of first extender bores (102) contacting the inner surface (68) of the first flange (64), wherein: for each adjacent pair of the plurality of first extender bores (102), one first extender bore (102) is threaded and the other first extender bore (102) is unthreaded, and each of the plurality of first extender bores (102) receives one of the plurality of bolts (82); and at least one second bolt extender (104, 198, 202, 210, 214) including a plurality of second extender bores (106) contacting the inner surface (78) of the second flange (74), wherein: for each adjacent pair of the plurality of second extender bores (106), one second extender bore (106) is threaded and the other second extender bore (106) is unthreaded, and each of the plurality of second extender bores (106) receives one of the plurality of bolts (82), and 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.
  2. 2. The wind turbine tower assembly (12) of claim 1, wherein for each bolt (82) of the plurality of bolts (82), at least one adjacent bolt (82) defines an overlap region (110) between the head (84) of the bolt (82) and the head (84) of the adjacent bolt (82).
  3. 3. The wind turbine tower assembly (12) of claim 1 or 2, wherein each bolt (82) of the plurality of the bolts (82) has a first adjacent bolt (82) and a second adjacent bolt (82) each having a centerline, wherein the centerlines of the bolt (82) and the first adjacent bolt (82) are spaced apart with a centerline distance (C 1 ), wherein the centerlines of the bolt (82) and the second adjacent bolt (82) are spaced apart with a second centerline distance (C2), and wherein the second distance (C2) is greater than or equal to the first distance (C 1 ).
  4. 4. The wind turbine assembly (12) of claim 4, wherein the shaft of each of the plurality of bolts (82) has a shaft diameter (D sh ) and the first centerline distance (C 1 ) is in the range of 1.01 to 1.75 times the shaft diameter (D sh ), and preferably 1.25 times the shaft diameter (Dsh).
  5. 5. The wind turbine tower assembly (12) of any of the preceding claims, wherein for each adjacent pair of the plurality of first extender bores (102), the unthreaded extender bore (102) is a through bore, and the threaded extender bore (102) is a through bore or a blind bore.
  6. 6. The wind turbine tower assembly (12) of any of the preceding claims, wherein the at least one first bolt extender (100, 198, 202, 210, 214) includes only two first extender bores (102).
  7. 7. The wind turbine tower assembly (12) of any of the preceding claims, wherein the at least one first bolt extender (100, 198, 202, 210, 214) of the fastening system (60) includes a plurality of first bolt extenders (100, 198, 202, 210, 214).
  8. 8. 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 (100, 198, 202, 210, 214) includes a curved edge (122), and wherein the curved edge (122) is received within a corner (118) defined by an intersection of the first flange (64) and the first tower wall (30a).
  9. 9. The wind turbine tower assembly (12) of any of the preceding claims, wherein the at least one first bolt extender (100, 198, 202, 210, 214) and the at least one second bolt extender (104, 198, 202, 210, 214) are identical to each other.
  10. 10. The wind turbine tower assembly (12) of any of the preceding claims, wherein each of the at least one first bolt extender (198, 210) and the at least one second bolt extender (198, 210) includes sidewalls (200, 204, 206) defining a trapezoidal perimeter.
  11. 11. The wind turbine assembly (12) of any of the preceding claims, wherein the at least one first and second bolt extenders (210) have sidewalls (204, 206), wherein each of the sidewalls (204) includes at least one of the plurality of extender bores (102), wherein the at least one of the plurality of extender bores (102) in each opposing sidewall (204) extends at least 50% of a complete extender bore circumference.
  12. 12. The wind turbine assembly (12) of any of claims 1-9, wherein each of the at least one first bolt extender (214) and the at least one second bolt extender (214) have first and second opposing sidewalls (218, 220), the first sidewall (218) being concave and the second sidewall (218) being convex, wherein the concave second sidewall (220) of the at least one first bolt extender (214) is configured to nest within the convex first sidewall (218) of an adjacent first bolt extender (214).
  13. 13. The wind turbine assembly (12) of claim 12, wherein the first sidewall (218) having a first curved portion (222) and the second sidewall (220) having a second curved portion (224), wherein the center of curvature of the second curved portion (224) is defined at a central axis of the one threaded first extender bore (102).
  14. 14. The wind turbine assembly (12) of claim 12, wherein the other unthreaded first extender bore (102) extends at least 70% of a complete extender bore circumference.
  15. 15. A wind turbine (10) comprising the wind turbine tower assembly (12) according to any of claims 1-9.
  16. 16. 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 (70), 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 (100) including a plurality of first extender bores (102) so that the plurality of first extender bores (102) align with respective ones of the plurality of through holes (66) in the first flange (64), wherein for each adjacent pair of the plurality of first extender bores (102), one first extender bore (102) is threaded and the other first extender bore (102) is unthreaded; positioning on the inner surface (78) of the second flange (74) at least one second bolt extender (104) including a plurality of second extender bores (106) so that the plurality of second extender bores (106) align with respective ones of the plurality of through holes (76) in the second flange (74), wherein for each adjacent pair of the plurality of second extender bores (106), one second extender bore (106) is threaded and the other second extender bore (106) is unthreaded; using a plurality of bolts (82): inserting one of the plurality of bolts (82) into each one of the unthreaded first extender bores (102) of the at least one first bolt extender (100) so as to be received in and engaged with one of the second threaded extender bores of the at least one second bolt extender (104); and inserting one of the plurality of bolts (82) into each one of the unthreaded second extender bores (106) of the at least one second bolt extender (104) so as to be received in and engaged with one of the threaded first extender bores (102) of the at least one first bolt extender (100); and tensioning each of the plurality of bolts (82) 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.
  17. 17. The method of claim 15, 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 (100) includes a curved edge (120), and positioning on the inner surface (68) of the first flange (64) the at least one first bolt extender (100) includes positioning the at least one first bolt extender (100) such that the curved edge (120) 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 (104) includes a curved edge (122), and positioning on the inner surface (78) of the second flange (74) the at least one second bolt extender (104) includes positioning the at least one second bolt extender (104) such that the curved edge (122) is received in the corner (118).
  18. 18. A method of retrofitting a fastening system (60) 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) such that 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 (100) including a plurality of first extender bores (102) so that at least one of the plurality of the first extender bores (102) aligns with one of the plurality of existing through holes (34) in the first flange (64) and an adjacent one of the plurality of first extender bores (100) aligns with the adjacent one of the plurality of intermediate through holes (190) in the first flange (64), wherein for each adjacent pair of the plurality of first extender bores (102), one first extender bore (102) is threaded and the other first extender bore (102) is unthreaded; positioning on the inner surface (78) of the second flange (74) at least one second bolt extender (104) including a plurality of second extender bores (106) so that at least one of the plurality of the second extender bores (106) aligns with one of the plurality of existing through holes (34) in the second flange (74) and an adjacent one of the plurality of second extender bores (104) aligns with an adjacent one of the plurality of the intermediate through holes (190) in the second flange (74), wherein for each adjacent pair of the plurality of second extender bores (106), one second extender bore (106) is threaded and the other second extender bore (106) is unthreaded; using a plurality of replacement bolts (82): inserting one of the plurality of replacement bolts (82) into each one of the unthreaded first extender bores (102) of the at least one first bolt extender (100) so as to be received in and engaged with one of the second threaded extender bores (106) of the at least one second bolt extender (140), and inserting one of the plurality of replacement bolts (82) into each one of the unthreaded second extender bores (106) of the at least one second bolt extender (104) so as to be received in and engaged with one of the first threaded extender bores (102) of the at least one first bolt extender (100); 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.
  19. 19. The method of claim 18, 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 (R1) 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 (R 2 ) less than or equal to the first radius (R1).
  20. 20. The method of claim 18 or 19, 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 includes 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 includes 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 head