Thermal field calculation for the rotor of large turbo-generator

An air-cooled turbo-generator rotor was taken as an example in this paper. According to the heat transfer theory, the 3D finite element model of rotor circumference 1/4 including slot insulation of rotor winding and slot wedge was established, meanwhile, basic assumptions and boundary conditions of the solution region were presented. Under the rated load condition, winding copper loss and stray loss on rotor surface were calculated. On this account, the 3D thermal fields of generator rotor were also calculated by using all losses and heat release coefficient calculated above as the solving condition. The accurate results of rotor thermal fields under rated load condition were attained, and the temperature distribution of the rotor was analyzed. At the same time, the influence of the stray loss and the slot insulation on thermal fields were analyzed quantitatively. The results showed that the temperature distribution of the windings and the iron core was uneven which was due to the uneven slotted rotor; the stray loss on rotor surface and slot insulation had influence on rotor thermal fields. These factors should be considered comprehensively on thermal field calculation of large turbo-generator. These results provided reference for structure design of large turbo-generator rotor and theory evidences for the department of generator running.