Theoretical Analysis And Calculation Of Eddy Losses In Stator Windings Of Large Synchronous Generator

Turbo-generators become more and more popular because of their many merits, such as, simple construction, high reliability and so on. As the increasing of the capacity of the turbogenerator, the accurate calculation of stray losses in stator coils, named eddy losses, is very important; which is also significant to electrical efficiency and thermal distribution in stator. Taking an air-cooled turbogenerator of 200 MW as an example, the eddy current losses in stator coils are studied profoundly.In this paper, the distribution characteristic of eddy current of stator windings in 200MW turbo-generator was analyzed firstly by using analysis method, and the mathematical representations of eddy current were presented from detailed derivation. The resistance enhancement coefficients and the value of eddy loss of stator windings in inphase and outphase slot were determined. The 2-D electromagnetic field calculation model of one stator slot with windings was established, and the distribution of current density in radial direction calculated by using finite element method. Then resistance enhancement coefficients and eddy loss in strands at different position in radical direction were determined, which were also compared with that from analysis method. Based on the electromagnetic field computation, the 3-dimensional temperature field mathematical model of stator windings were established. The influences of eddy loss on windings temperature distribution in inphase and out phase slot were analyzed. Lastly, some optimization designs of stator windings were developed based on the work above. Some useful conclusions were achieved and should benefit the design of turbo-generator.