Main problems that should be paid attention during installation of the ultra-supercritical1000MW air-cooled unit steam turbine were presented.Moreover

the steam flow excited vibration(SFEV)occurred during the debugging process was analyzed and several countermeasures were proposed.The bearing preload was increased to improve its dynamic specific pressure by changing its elevation.The system damping was increased to enhance the stability margin.Keep gap width of the diaphragm gland of the upper cylinder be about 0.06mm to 0.10mm smaller than that of the lower cylinder

the axial distance between the nozzle and the governing stage blade was shortened by about 0.20mm to 0.25mm.The original sequence of the control valve 1

2

3

4was changed into 2

1

4

3.After the improvement

the unit can start up successfully and run stably.