Analysis On The Transposed Connection And Calculation Of Temperature Field For Stator Bars Of Hydro-generator

The stator strands transposition is widely used to reduce the circulating currentloss of hydro-generator. However, in the transposition bar, the unequal magnetic fluxleakage at the end make the stator strands potential imbalance, which produces thecirculating current losses. With the increasing hydro-generator unit capacity, thecirculating current losses increases, resulting issues such as uneven generatortemperature rising and high local temperature rising, seriously affect the generatorefficiency and safe operation. Previous studies have shown that this part of thecirculating current losses can be greatly reduced by the end bars connecting withuniform group, but for some hydro-generator, the ends can not be connected withuniform group, and the technique of circulating current losses calculation for unevengroup has not been discussed yet, so the dissertation expands research for thisproblem.Firstly, on the base of potential leakage inductance method, the method ofcirculating current calculation for uneven group is derived, and the calculationmethod of circulating current losses about the large hydro-generator stator barstransposition end uneven grouping connection is given in the paper. Also, the papercalculates circulating current losses of hydro-generator, and contrasts the distributionof circulating current losses when the stator bars are grouped and are not grouped.Simultaneously, the paper integrates the stator bars transposition optimization designand the stator bar ends grouping connection, and develops an software of the statorbars optimization design and circulating current losses calculation using Visual Basic6.0.Secondly, the three-dimensional field-circuit coupling model of the stator bar isestablished. Leakage magnetic field of stator is analyzed in detail, and grouped joinof stator bar end is simulated by changing external circuit connection. Then,circulating current losses under different connection methods are analyzed.Furthermore, inhibition of circulating current loss by groups is verified. Finally, three-dimensional fluid-heat coupling model of stator ventilation ditch isestablished. Detailed analysis of fluid and temperature fields of stator ventilationditch is given, and the temperature rising of various components of stator ventilationditch model is analyzed comparatively in using different connection methods ofstator bar ends. Then, variation of temperature rising of different components issummarized.