Wind turbine tower

Abstract

A wind turbine tower is tethered by a number of cables, each cable extending between a first end anchored to an anchoring element and a second end attached to the tower at an attachment element. Two cables extending from two different anchoring elements are attached to the tower such that projection lines from the second ends of the two cables converge at a point which lies inside the tower wall thickness or within a distance of three wall thicknesses from the wall inner surface. A method of erecting a wind turbine tower includes positioning a first tower section, attaching at least some tethering cables to a second tower section while the second tower section is on the ground, lifting the second tower section with the attached cables onto the first tower section, and joining the second tower section to the first.

1 . A wind turbine tower configured to support a wind turbine nacelle and a rotor, comprising:
 a first elongate tower section having a first connection flange at an upper end thereof;   a second elongate tower section having a second connection flange at a lower end thereof;   a cable attachment section disposed between the first and second elongate tower sections and coupled to the first and second connection flanges, wherein the cable attachment section includes a plurality of attachment elements affixed to an outer surface of the cable attachment section, and wherein the cable attachment section has a length significantly shorter than a length of the first and second elongate tower sections;   a plurality of anchoring elements disposed at a lower end of the wind turbine tower and radially outboard thereof; and   two tethering cables extending from each of the plurality of anchoring elements to a respective one of the plurality of attachment elements on the cable attachment section.   
     
     
         2 . The wind turbine tower of  claim 1 , wherein the cable attachment section has a length slightly greater than a length the attachment elements extend along the cable attachment section. 
     
     
         3 . The wind turbine tower of  claim 2 , wherein the cable attachment section has a length less than about three times the length the attachment elements extend along the cable attachment section. 
     
     
         4 . The wind turbine tower of  claim 1 , wherein two tethering cables extending from two different anchoring elements are attached to the cable attachment section of the tower such that longitudinal projection lines from the ends of the two cables converge at a convergence point. 
     
     
         5 . The wind turbine tower of  claim 4 , wherein said convergence point lies at a location at a height and inside the tower within a distance of three wall thicknesses from the wall inner surface as measured at the height and in a direction perpendicular to a central longitudinal axis. 
     
     
         6 . The wind turbine tower of  claim 1 , wherein the two tethering cables extending from each anchoring element diverge from each other in a direction toward the anchoring elements on the cable attachment section. 
     
     
         7 . The wind turbine tower of  claim 1 , wherein the plurality of attachment elements forms an integral part of the cable attachment section. 
     
     
         8 . The wind turbine tower of  claim 1 , wherein the two tethering cables anchored to the same anchoring element extend to different positions at the tower at essentially the same height of the tower. 
     
     
         9 . A method of erecting a wind turbine tower configured to support a wind turbine nacelle and a rotor, comprising:
 providing a first elongate tower section having a first connection flange at an upper end thereof;   providing a second elongate tower section having a second connection flange at a lower end thereof,   providing a cable attachment section having a plurality of attachment elements affixed to an outer surface of the cable attachment section, wherein the cable attachment section has a length significantly shorter than a length of the first and second elongate tower sections;   attaching each of a plurality of tethering cables to a respective one of the plurality of attachment elements on the cable attachment section while the cable attachment section is on the ground;   attaching the cable attachment section to one of the first connection flange of the first tower section or the second connection flange of the second tower section while the respective first or second tower section is on the ground;   erecting the tower by attaching a lower end of the first elongate tower section to a wind turbine structure; and   further erecting the tower by attaching the cable attachment section to the other of the first connection flange of the first tower section or the second connection flange of the second tower section.   
     
     
         10 . The method of  claim 9 , further comprising attaching each of the plurality of tethering cables to one of a plurality of anchor elements disposed at a lower end of the wind turbine tower and radially outboard thereof, wherein the plurality of tethering cables are arranged such that two tethering cables extend from each of the plurality of anchoring elements to a respective one of the plurality of attachment elements on the cable attachment section. 
     
     
         11 . The method of  claim 10 , further comprising arranging the plurality of tethering cables such that two tethering cables extending from two different anchoring elements are attached to the cable attachment section of the tower such that longitudinal projection lines from the ends of the two tethering cables converge at a convergence point. 
     
     
         12 . The method of  claim 11 , wherein said convergence point lies at a location at a height and inside the tower within a distance of three wall thicknesses from the wall inner surface as measured at the height and in a direction perpendicular to a central longitudinal axis. 
     
     
         13 . The method of  claim 10 , further comprising arranging the plurality of tethering cables such that the two tethering cables extending from each anchoring element diverge from each other in a direction toward the anchoring elements on the cable attachment section. 
     
     
         14 . The method of  claim 10 , further comprising arranging the plurality of cables such that the two tethering cables anchored to the same anchoring element extend to different positions at the tower at essentially the same height of the tower.