Influence Of Magnetic Shielding On Magnetic Field And Temperature Field Of Large Power Transformer

Large power transformer plays an important role in high voltage transmissionline, whether it works safely and efficiently or not is the key issue for electricalenergy transferring. But in practical application, the larger leakage magnetic fluxbecause of the increasing of transformer capacity leads to more leakage flux in thestructural parts, which declines the efficiency and quality of transformer working.Therefore, how to reduce the leakage magnetic flux of transformer in thestructural parts has been a hot spot in the study of transformer workers both athome and abroad.Aiming at the phenomenon that too much leakage magnetic flux is foundaround transformer core, and considering the actual structure of the transformer,this paper puts forward to a method of installing magnetic shielding in leakagemagnetic shielding, to reduce leakage magnetic flux within the structural parts.Based on the study of theory and practice, it is found that installing magneticshielding appropriately around iron core can be helpful to restrain leakagemagnetic circuit and reduce the loss of structural parts.To illustrate the necessity and advantage of magnetic shielding installed, thispaper elaborated the following aspects. First of all, the construction of large powertransformer needed magnetic shielding was described in detail, as well as thematerials and the locations adopted by magnetic shielding, and the role ofmagnetic shielding playing, etc. Secondly, using the3-D finite element method,mathematical model of a500kV large power transformer was established. Fromthe perspective of the theory of analyzing large power transformer，magnetic fieldof transformer was discussed. Thirdly, according to the influence of the differentinstalled positions of magnetic shielding on the magnetic field of transformer iron core, different analysis models were established respectively for analyzingmagnetic field. The distribution of main magnetic flux of iron core and leakagemagnetic field of the structural parts was analyzed. Through the analyzing andcomparing the changing rule of magnetic field distribution, the advantages of thenew type of magnetic shielding mentioned by this paper was obtained. Finally, thetemperature field model of the transformer was established to calculate thetemperature field. Through studying the change tendency of temperature fieldmodel with or without magnetic shielding installed respectively, it is indicated thatthe increase of this type of magnetic shielding can reduce structure loss, andreduce the temperature rise of structural parts. The research result is of practicalvalue for the selection and optimization design of large power transformermagnetic shielding, and provides an important theoretical basis.