重合闸短路冲击下变压器绕组轴向强度计算与分析

Calculation and Analysis of Axial Strength of Transformer Windings under Reclosing Short Circuit Shock

本文中作者以一台型号为SSZ11-50MVA/110kV电力变压器为研究对象,首先搭建了变压器短路故障模型,计算其在初次短路及重合闸后短路电流瞬变过程,研究不同重合闸初相角、剩磁下变压器短路电流瞬变特点;然后,基于有限元法,对其漏磁场进行分析与计算,得到绕组轴向力变化规律;最后,通过模态分析,计算变压器绕组固有频率,给出变压器可作静态校核的依据,进一步计算短路及重合闸后绕组线饼在轴向力分别作用下的位移分布特点。计算结果表明,初次短路和重合闸短路下,高压绕组最大轴向位移分别为1.56mm和3.32mm,中压绕组的最大轴向位移分别为2.37mm和3.14mm,在重合闸短路冲击下变压器绕组稳定性有所降低,其位移形变量更大,易发生轴向失稳。

ln this paper,a model SSZ11-50MVA/110kV power transformer is used as the research object.Firstly,a transformer short-circuit fault model is built to calculate the short-circuit current transient process after the initial short-circuit and reclosing,and to study the characteristics of transformer short-circuit current transient under different reclosing initial phase angle and remanent magnetism.Finally,through the modal analysis,the inherent frequency of the transformer winding is calculated,and the basis for static calibration of the transformer is given,and the displacement distribution characteristics of the winding bobbin under the action of axial force after short circuit and reclosing are further calculated.The calculation results show that the maximum axial displacement of the high-voltage winding is 1.56mm and 3.32mm under the initial short circuit and reclosing short circuit respectively,and the maximum axial displacement of the mediumvoltage winding is 2.37mm and 3.14mm respectively,and the stability of the transformer winding is reduced under the shock of reclosing short circuit,and its displacement deformation is larger and prone to axial instability.