An Axisymmetric Finite-Element Model for Nonaxisymmetric Electromechanical Loads in Large Superconducting Generators

The present work was done as a part of the 300-MVA superconducting generator development project jointly funded by the Electric Power Research Institute and the authors´ company. The analytical developments necessary for a successful design included stress analyses due to electromagnetic and thermal loading as well as studying the dynamic behavior of the machine. This paper deals with the mechanical stresses induced in the armature of such machines due to electromagnetically induced loads during short circuit conditions. The basic structure of the armature is described first. The electromagnetic force patterns are then discussed. The corresponding stress analysis is made using an axisymmetric finite-element model with nonaxisymmetric loads. The orthotropic material properties are taken into account.