Calculation And Analysis Of Electromagnetic Field And Eddy Current Loss In End For Large Hydro-generator

Hydro-generator rated steady-state operation, the generator in addition to the mainmagnetic field exists, and part of leakage magnetic field through to the structure of thepress board and press fingers causes the unnecessary of eddy current loss. for smallcapacity of the generator, the loss could not give too much attention, but for the largecapacity generator, the loss cannot be ignored. Line capacity of winding is higher, andleakage magnetic field that through to the structure of the press board and press fingersis higher, so the loss of the press board and fingers is very big. At the same time it causeslocal overheating and other problems. That is to say, the calculation of generatormagnetic field and eddy current loss is directly related to the feasibility analysis for thegenerator, and the generator power factor, efficiency, operation time, temperature riseand its stability performance is of great significance. More importantly, the eddy currentloss calculation can accurately predicting the rise of temperature of the generator, so asto control the temperature rise is beneficial to improve the efficiency of the generatorvery well.In this paper, based on the basic theory of transient electromagnetic field of thegenerator, in a1000mw large hydro-generator, for example, first of all, according tocharacteristics of hydro-generator end model, and do the corresponding assumptions;The three-dimensional finite element model of hydro-generator end is established.Secondly, the paper accurately calculated the generator end the three-dimensionaltransient electromagnetic field, got the no-load and the rated load condition on thedistribution of each structure distribution of magnetic field and eddy current loss. At thesame time, the accurate calculation the press board and press fingers specific numericaleddy current loss.Finally, according to the end the overall structure, this paper improve the structure of the press board and press fingers, and to the whole model was calculated and comparedwith the original model results, analysis the advantages and disadvantages of the newstructure. At the same time, the change of end material magnetic permeability andelectric conductivity, recalculate, analyses its effect on the eddy current loss.