变压器磁热耦合计算与局部过热屏蔽措施

Magnetic-thermal coupling calculation and shielding measure of local overheating for transformer

针对大型电力变压器涡流损耗及局部过热问题,采用三维有限元涡流场计算得出变压器油箱及夹件的涡流损耗及其分布,进一步采用磁热耦合方法计算出油箱和夹件温度场分布以及热点温度.在此基础上,分析局部过热问题,找出最热点并采取相应磁屏蔽来降低油箱和夹件涡流损耗及热温升,分析了磁屏蔽结构尺寸对油箱及夹件涡流损耗和最热点温度的影响.采取磁屏蔽措施后,油箱和夹件涡流损耗及热点温度明显降低,有效防止了局部过热现象,为电力变压器的优化设计提供了参考依据.

In order to solve the problems concerning both eddy current loss and local overheating in large power transformer, the three-dimensional （3D） finite element calculation of eddy current field was adopted to obtain the eddy current loss and its distribution for the fuel tank and clamps of transformer, and a magnetic-thermal coupling method was used to calculate the temperature field distribution and hot spot temperature of the fuel tank and clamps. And thus, the local overheating problem was analyzed, and the hottest spot was found out. In addition, the corresponding magnetic shielding was applied to reduce the eddy current loss and temperature rise of the fuel tank and clamps. Finally, the influence of the size of the magnetic shielding structure on both eddy current loss and hottest spot temperature of the fuel tank and clamps was analyzed. After adopting the magnetic shieding measure, the eddy current loss and hot spot temperature of the fuel tank and clamps decrease significantly, and the local overheating phenomenon is prevented efficiently, which can provide the references for the optimization design of power transfomler.