Influence of Magnetic Screen Material on Leakage Magnetic Field and Losses in the End Zone of Turbine Generator Based on Double Iterative Method

The overheating problem of the end components affects the safe and stable operation of the turbine generator. The magnetic screen layer can improve effectively the distribution of leakage magnetic field in the end zone. Taking the nonlinearity of the core material, rotor rotation, and the complex structure into consideration, mathematical model of nonlinear transient electromagnetic field is established in the end zone of 1407 MVA turbine generator. The influence of different materials of magnetic screen layer on the end leakage magnetic field is studied based on double iterative method. Current density distribution of screen plate and finger plate are determined. The losses of the end components are obtained under the different materials of magnetic screen layer, which are used as heat sources in the three-dimensional fluid-solid coupled heat transfer model. Complex fluid flow and temperature distribution of the end components are obtained in the end zone of the turbine generator. The calculation results are verified by experiments.