Analysis On Eddy Current Loss And Thermal Field Of Auto-transformer

As one of the important equipment in power generation, transmission,distribution and substation system, transformer plays a very significant role in thestabilized transmission, rational distribution, economic operation and safe use ofelectric energy. With the development of modern power network, transformer isdeveloping towards the trend of large capacity and extra-high voltage, then theensuing transformer thermal issues is becoming more and more prominent. Oncethe phenomenon of too much eddy current loss or excessive concentration on lossdistribution appears in transformer, it will cause the local overheating andreduced insulation character, and then the safe operation and service life oftransformer will be affected. At present, the problems that how to reduce energyconsumption and control transformer overheating is one of the important problemfor current transformer manufacturing industry to be solved urgently, and it isalso the key to guarantee the safe and stable operation of transformer. Therefore,further study of the transformer loss and temperature field has great significance.This dissertation based on the related theory of electromagnetism and finiteelement, as an example of ODFS-334000/500auto-transformer, establish theactual model of transformer core window at the high voltage-medium working atrated situation by using field-circuit coupled method for transformer windingdistribution of magnetic flux leakage, and carefully analysis the magnetic fluxleakage simulation results, afterwards extract the leakage flux density value ofeach wire in the unit and calculate the eddy current loss of each wire, and then getthe loss distribution trend and the sum loss in winding. Secondly the model ofsolving the three-dimensional leakage magnetic field and eddy current field isestablished, applying reasonable load and boundary conditions to solve themagnetic flux leakage and the distribution of the eddy current loss of metalstructure, and puts forward more reasonable measures of improving the distribution of loss aimed at the metal structure. Finally, according to the relatedtheory of temperature field and flow field, the model of solving the transformertemperature field is established by the FLUENT software, the whole temperaturefield distribution is obtained, and compares the influence of different orientedarea number, load factor and center heights of radiator on the transformertemperature field and flow field, then provides certain reference basis onreducing the winding hot spot temperature rise.In this dissertation, through calculating and analyzing the leakage magneticfield, the eddy current field and temperature field of transformer, the eddy currentloss distribution of winding and metal structure and the distribution oftransformer temperature field are obtained, then get the conclusion that themagnetic shielding and slot can reduce the loss of metal structure, increasing theappropriate oil baffle plate and center height of radiator can reduce transformertemperature, which has certain guiding significance for the engineering designand the structure optimization of transformer.