Study on eddy current loss and heat-transfer character of stator windings in synchronous generator

The eddy loss of stator windings in synchronous generator was calculated using analysis method and finite-element method, the distributed characteristic of stator windings temperature field was studied. In this paper, the distribution characteristic of eddy current of windings in rectangular slot was analyzed first by using analytical method, and the mathematical representations of eddy current were presented. Taking a 200MW turbo-generator as an example, the resistance enhancement coefficients and the value of eddy loss of stator windings in inphase and out phase slot were determined. The 2-dimensional electromagnetic field calculation model of one stator slot with windings was established, and the distribution of current-density in radius direction was 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 analytical method. Based on the electromagnetic field computation, the 3-dimensional temperature field mathematical model of stator windings with corrugated plate was established. The effect of eddy loss on windings temperature distribution in inphase and out phase slot were analyzed, some useful conclusions were achieved and should be benefits to the design of turbo-generator.