Patent ID: 8240044

Claim:
A method for adjusting an unevenness of a top flange of a wind turbine generator tower in which the unevenness of an upper surface of the top flange is adjusted by arranging shim plates on the upper surface of the top flange and by adjusting a thicknesses and/or number of the shim plates to be disposed at individual positions, the method comprising: a main measurement step of measuring roughness levels of the upper surface of the top flange at a plurality of measuring points in a state in which a nacelle of the wind turbine generator is not mounted on the tower which is vertically erected; a shim-plate-placement-plan determination step of determining the thicknesses and/or number of the shim plates to be disposed on the individual plurality of measuring points to adjust the unevenness of the upper surface of the top flange in accordance with the roughness levels of the upper surface of the top flange measured in the main measurement step; and a shim-plate placement step of placing the shim plates on the individual plurality of measuring points on the upper surface of the top flange in accordance with the thicknesses and/or number of the shim plates determined in the shim-plate-placement-plan determination step; an auxiliary measurement step of measuring the roughness levels of the upper surface of the top flange at the plurality of measuring points, prior to the main measurement step, in a state in which the nacelle is mounted on the tower, which is vertically erected; and a shim-plate-placement-plan estimation step of estimating, in advance, the thicknesses and/or number of the shim plates to be determined in the shim-plate-placement-plan determination step from the roughness levels of the upper surface of the top flange measured in the auxiliary measurement step.