Investigation of Ideal Anisotropic Material Properties for Outer Corona Protection Systems in Large Rotating Machines

An essential component of the insulation system of large electric machines is the corona protection system. One important parameter in particular of the outer corona protection (OCP) is the ohmic resistance together with service related current and potential distributions as well as locally generated power losses. These parameters can be calculated and analyzed using finite element method (FEM). In this study the influence of the OCP material parameters on the electric field distributions in the insulation system are investigated. Real wrapped insulation system structures are modeled with a high level of detail by consideration of anisotropic material characteristics. A new approach to assess the ideal anisotropic OCP material properties is introduced with the process of the swarm optimization algorithm. The results of these examinations are used for the development of an ideal OCP system with the aim to minimize the electric and thermal field stresses in the insulation system. The results for one particular machine type are evaluated by analyzing the solution data to characterize the overall general OCP system behavior.