Abstract: The rotor of the ultra supercritical steam turbine operates under severe environment with high steam parameters. Especially, when the unit operates under variable condition, such as taking part in peak shaving, a great thermal stress may occur inside material of the rotor, and improper operation will damage the rotor seriously. Taking the HP rotor of 1 000 MW ultra supercritical steam turbine as research object, using the rotor thermal stress analysis theory, according to the site measured data, the various level steam parameters of the HP rotor and the heat transfer coefficient were calculated, and the boundary conditions of finite element calculation of rotor thermal stress were established. Using the software ANSYS, the temperature field and the stress field of the HP rotor during cold startup process and warm startup process were calculated respectively. The thermal stress spectrums of the HP rotor under the two conditions were compared. The results of calculation and analysis can be used as reference for 1 000 MW ultra supercritical turbine set in startup and operation under variable condition.

Key words: ultra supercritical unit, steam turbine, high pressure (HP) rotor, thermal stress, finite element analysis, cold startup, warm startup