基于Comsol多物理场仿真的短路工况下变压器轴向电磁力的计算

过大的短路电磁力会影响变压器的安全运行及电网的稳定性。为了计算研究短路条件下变压器绕组的轴向电磁力,本文建立了110 kV/38.5 kV/10.5 kV的变压器“磁场-电路”耦合模型,使用Comsol Multiphysics软件对三相高压对中压绕组短路工况下的变压器进行了仿真,并得到了铁心磁密和内部辐向漏磁磁密的分布,B相高压中压绕组所受的轴向电磁力,以及在不同电流载荷下绕组所受轴向电磁力的变化规律。结果表明,变压器内部辐向漏磁磁密主要集中在绕组端部,峰值可达0.03 T,绕组中间位置,辐向漏磁磁密为0。绕组所受轴向电磁力的频率主要为50 Hz和100 Hz,且随着短路时间的增加,其二倍频特性愈加明显。随着短路励磁电流增加,绕组受到的轴向电磁力也会增大,且轴向电磁力增幅等于电流增幅的平方。

Research on the Calculation of Axial Electromagnetic Force of Transformer Under Short Circuit Condition Based on COMSOL Multi-physical Field Simulation

Huge short circuit electromagnetic force will affect the safe operation of the transformer and the stability of the power grid. In order to calculate and study the axial electromagnetic force of the transformer winding under the condition of short circuit, the "field-circuit" coupling model of the transformer of 110kV/38.5kV/10.5kV is established in this paper. The condition of short circuit of the three-phase high voltage to medium voltage winding is simulated based on Comsol Multiphysics, and the distribution of magnetic density of the core and internal radial leakage magnetic density. The axial electromagnetic force of B-phase high voltage medium voltage winding, and the change law of axial electromagnetic force of the winding under different current load are obtained. The results show that the radial magnetic flux leakage density in the transformer is mainly concentrated at the end of the winding, where the peak value is up to 0.03T. And the radial magnetic flux leakage density in the middle of the winding is 0. The main frequency of the axial electromagnetic force on the winding is 50Hz and 100Hz, and with short circuit time going by, the double frequency characteristic becomes more and more obvious. With the increase of the short-circuit excitation current, the axial electromagnetic force of the winding will also increase, and the increase of the axial electromagnetic force is equal to the square of the current increase.