Finite Element Analyses of Eddy Current Effects in Turbogenerators

About the book: This book, written by the author following his decades of research experience of dealing with eddy-current problems and their analyses, aims at a comprehensive study of various aspects of eddy currents, from a detailed account of the basic phenomenon to their utilisation in various applications, and their detrimental effects, esp. in large turbogenerators. The first part of the book describes in detail the theory and principles involved in the genesis of eddy currents, based on Maxwell's equations. There is a chapter describing applications of eddy currents in various forms. Later, an extensive description is given of eddy current power loss, heating and temperature rise in key regions of machines that may be detrimental to their operation and performance under steadystate and transient operating conditions, causing severe thermal stress and damage, esp. in to turbogenerators. The second part is devoted to the “basics” of finite elements and formulation of the methodology relevant to the solution of eddy-current problems in general, with special reference to requirements for finite-element solution of eddy-current problems. The technique is applied to a few representative problems to illustrate the various key aspects of FEM. In the third part, the technique is first applied to solve eddy-current problems related to an actual 2-pole turbogenerator. A case of particular importance, discussed in detail, is the significant effects of eddy currents in large turbo-generators during their unbalanced operation, leading to heating and temperature rise as a result of eddy-current power loss that can be unacceptably intense in some key parts. This is followed by two chapters related to a “model turbogenerator”, uniquely conceptualised and designed by the author during the course of experimental research, not easily feasible on actual generators. An important and unique feature of the model turbogenerator would be its very extensive and special instrumentation, employing a variety of hundreds of transducers to measure electromagnetic-field parameters and temperature rise due to eddy-current power loss. Later, a chapter is specifically devoted to the case study of two large turbogenerators, each of 500 MW rating, manufactured by two different world-class manufacturers, to substantiate the methodology of analysis developed by the author. The salient feature of the book, one of its kind available anywhere, is the detailed description of the finite-element technique(s) for analyses of the steadystate and transient heating of key regions of turbogenerators of ratings from 120 MW to 500 MW when exposed to “negative-sequence” currents under unbalanced fault conditions. The book is enriched by over a dozen appendices, dealing with special aspects pertaining to various chapters, to substantiate their contents. An elaborate list of symbols, a very comprehensive list of references (not easily available elsewhere) and bibliography related to eddy currents and finite elements and a detailed index form important assets of the book. Contents: Part-A: Eddy Currents I. The Eddy Currents II. Eddy-current and Power Loss III. Utilisation of Eddy Currents IV. Eddy Currents and Turbogenerators Part-B: Finite Elements for Eddy Current Analyses V. Finite Elements: General VI. Finite Element Solution of Representative Problems Part-C: Finite Elements for Turbogenerator Problems VII. Finite Element Analysis Applied to Turbogenerators VIII. Finite Element Analysis of Eddy Currents in TG and Temperature Rise IX. The Model Turbogenerator – General X. The Model Turbogenerator – Representative Studies XI. Case Studies of Large Turbogenerators