Device and method for assembling wind turbine

A system for modifying a cross section of a tower section of a wind turbine, wherein the tower section comprises a flange located at an end of the tower section having a plurality of through holes spaced around its circumference for securing the tower section to another wind turbine section, the system comprising:

• a pair of devices, wherein each of the pair of devices comprises:
• an expandable securing member configured to be located within one of the plurality of through holes in the flange;
• and
• an expansion mechanism configured to expand the securing member so as to urge the securing member into contact with the one of the plurality of through holes such that the securing member is braced against an internal wall and removal of the expanded securing member from the one of the plurality of through holes is thereby inhibited by frictional resistance between the securing member and the internal wall;
• a tether configured to extend between generally opposing sides of the tower section, each end of the tether being configured to attach to a respective device of the pair of devices;
• and
• a tensioning mechanism configured to couple to each of the pair of devices via the tether and further configured to apply a tensile force between the pair of devices via the tether.