Multi-physical Field Calculation And Analysis Of The Doubly-fed Hydro-generator

With the improvement of technology and economic, Doubly-Fed Hydro-Generator’s capacities are gradually increasing. It will lead to loss increasesignificantly. Temperature increase will affect the lifetime of the generator aswell as the operational reliability. However, in recent years the emphases studyof Doubly-fed Hydro-Generator is on the control system. The study of harmoniccontent, loss distribution, and temperature rise are not completed for generatorontology. Therefore, it is very necessary to research electromagnetic field,temperature field, and fluid field of the generator and study its tooth harmoniccontent, loss distribution, and temperature rise condition.In view of the above problems, this paper takes6.5MW Doubly-Fed Hydro-Generator as an example. The physical model of finite element calculation ofelectromagnetic field is created. Time-stepping finite element method was usedto calculate the flux density distribution characteristic when the generator isunder no-load condition. Harmonic amplitude was obtained from the Fourierdecomposition of air-gap flux density waveform. Characteristics of the generatorharmonic content and loss distribution in different situations were analyzedemphatically. In this paper a method was proposed that connect externalequivalent impedance to simulate rated load condition. Then get the generator’sloss; output power; power factor; phase voltage waveform. At last, themathematical, physical model of3-D fluid flow and heat transfer coupled wasestablished according to the entity structure of generator cooling system,fundamental assumptions and corresponding boundary conditions were given.The fluid flow and temperature coupled field on the rated condition werecalculated using finite volume method, by which the distribution of fluid flowand temperature rise were obtained, which compared with the test value. And then temperature distribution after using magnetic slot wedge was calculated andthe temperature rise of generator was got.In this paper,6.5MW Doubly-Fed Hydro-Generator’s electromagnetic field,temperature field, and fluid field were calculated. Then get harmonic content,harmonic amplitude, copper loss, iron loss, temperature distribution and analyzethem detailed. The results of this paper can provide the theory for largercapacity’s optimum structure and its temperature field calculation.