Analysis And Calculation For Stator Transposition Bar And Circulating Current Loss In Large Hydro-generator

Due to the increasing capacity of hydro-generator, the circulating current andthe circulating current loss are larger and larger in stator strands. The accuratecalculation of circulating current losses in strands is very necessary in the designof large generator. This dissertation takes the180MW hydro-generator as theresearch object, the analytic method and numerical method are adopted tocalculate the circulating current and the circulating current loss in strands underdifferent transposition circumstances respectively, and a more accuratecalculation method can be provided to calculate the circulating current and thecirculating current loss in strands by comparing and analyzing the two kinds ofcalculation methods.First, the strands loop method and the leakage fields EMF method areintroduced to calculate the circulating current loss in strands briefly, and it isused to calculate the circulating current and the circulating current loss instrands under the cases of360complete transposition of stator strands,insufficient360transposition in different transposition angle,360emptytransposition in different transposition length, and the extended360transposition.Second, the numerical method is described to calculate the circulating currentand the circulating current loss in strands briefly, and the numerical method isused to calculate the circulating current and the circulating current loss instrands under the cases of360complete transposition, insufficient360transposition with leave empty three strands and360empty transposition withthe empty transposition length of434mm, in addition, the circulating currentand the circulating current loss in strands are analyzed under the cases of insufficient360transposition in different transposition angle,360emptytransposition in different transposition length, and empty transposition atdifferent location in the groove.Finally, the circulating current losses in strands calculated by the leakagefields EMF method and the numerical method are taken into compared, and theleakage magnetic field distribution of slot and end around strands are extractedto compare with that of the leakage fields EMF method under the assumedconditions, the inadequacy of the leakage fields EMF method and both thenecessity and accuracy of the numerical method are proved.