Full3D Eddy Current And Temperature Field Analysis Of Large Hydro-generators

Ventilation and cooling system design in large and giant hydro-generator has attracted more and more attentions from both academicians and engineers alike due to the complications arising from the increasing capacity. The full three dimensional (3D) coupled eddy current and temperature fields of a generator under different operating conditions has become one of the topical issues in this direction. In this point of view, this dissertation focuses on the comprehensive and extensive study of the numerical techniques for solving the full3D eddy and temperature fields of large hydrogenerators. More specially, the main works includes:The full3D finite element models are developed for numerical solutions of the coupled eddy current and temperature fields in the end region of large hydro-generator using a250MW hydro-generator as the prototype. The model is simplified on the premise of ensuring enough accuracy on the magnetic field and temperature distributions, providing a valuable methodology for the similar problems in engineering applications. Moreover, the boundary value problem for the3D harmonic eddy current fields is formulated. Also, the equivalent medium parameters used in the computations are comprehensively discussed. The spatial positions of Phase A of the Stator under rated and0.95leading phase operations are finally discussed.The grid matrix method is employed to calculate the ventilation system to determine the air volume and its distribution, resulting in the related model of the ventilation system. The differential equation of heat conduction of the3D temperature fields in steady state is developed. The boundary conditions of the temperature fields are also investigated, and the corresponding heat conductive and connective coefficients are finally determined.Based on the aforementioned models and methods, the full3D numerical analysis of the coupled eddy current and temperature fields in the end region of a large hydro-generator at no-load operation,0.95leading phase operation and rated operation are accomplished are comprehensively studied, and some guidelines for engineering applications are proposed.