Calculation Of Eddy Current Loss In The End Region Of Large Hydro-generator

The large-capacity generators are being used more and more with the inputting and upgrading of the long distance and high voltage power grid . The unit cost of the large generators has reduced as the increasing of the power density and the eddy current loss issue became especially prominent. In order to make sure the operation of large generators safe and reliable, there is a need for further studying of large generator in the internal eddy current field. This dissertation which is in view of a large hydro-generator with a capacity of 1000MW, using the calculation method of the state electromagnetic field and the constant eddy current, it carried on a deep research to the problem of eddy current loss on structure of the generator end region,and provided the basis for the further analysis of the large hydro-generator interior physics field.Calculation of eddy current loss is one of the important elements of designing the large generators.It is not only related to the safety and reliability of the generator's operation,but also the life of generator. The accurate calculation of the magnetic field is the prerequisite for the calculation accuracy of the eddy current loss. Based on the basic theory of electromagnetic field, using two-dimensional finite element method for solving nonlinear steady-state magnetic field under the condition of no-load and full-load, the dissertation obtained the air-gap flux density, , it also identified a fundamental component and harmonic component through Fourier transform. Then it carried on the computation of the rated excitation current according to the electromagnetism formula to the generator which is operating under the condition of no-load and full-load.The eddy current loss is appeared by Magnetic flux leakage of the structure of generator end region is one of the reasons for local overheating in motor. Based on the theory of time-varying electric magnetic field, with the foundation of the A-φmethod which descripts mathematics model of three dimensional sine eddy current field, for the structure characteristics of hydro-generator end region, This dissertation established three dimensional entity model of hydro-generator end region, and the magnetic field was calculated under the condition of no-load and full-load. then it obtained magnetic vector potential and scalar potential of the structure on generator end region under the condition of no load and full load, eddy current electricity dense and eddy current losses were find out by the Calculation formula of eddy current loss, and eddy current losses distribution of the structure of generator end region was given.