Method and yoke for lifting a wind turbine component

A method for lifting a wind turbine component using a lifting yoke, the lifting yoke comprising:

• a first structural body comprising a crane hook attachment point, a first connection point and a second connection point,
• a second structural body comprising a third connection point and a fourth connection point, the second structural body further comprising a first axis defined as being parallel to a longitudinal direction of the second structural body, a second axis defined as being perpendicular to the first axis and extending substantially in a transverse direction of the second structural body, the first axis and second axis defining a lifting plane, and a third axis defined as being perpendicular to the first axis and the second axis,
• a first tensional element connecting the first connection point and the third connection point,
• a second tensional element connecting the second connection point and the fourth connection point, wherein a length of the second tensional element is variable, such that an angle between the first and second structural bodies can be changed by changing the length of the second tensional element, and
• an inertial measurement unit positioned on the second structural body,
• wherein the method comprises:
• a) attaching a crane hook to the crane hook attachment point,
• b) attaching the wind turbine component to the second structural body of the lifting yoke,
• c) measuring at least one angle of rotation of the lifting plane about at least one of the first and/or second axis with respect to a horizontal plane using the inertial measurement unit,
• d) determining a distance, along at least one axis in the lifting plane perpendicular to the first and/or second axis about which the angle of rotation of the lifting plane, from the fourth connection point on the second structural body to an intersection between an axis extending vertically through a center of gravity of the wind turbine component and the lifting plane, and
• e) providing the distance determined, along at least one axis in the lifting plane perpendicular to the first and/or second axis about which the angle of rotation of the lifting plane, from the fourth connection point on the second structural body to the intersection between an axis extending vertically through the center of gravity of the wind turbine component and the lifting plane to a crane operator.