变压器环形铁芯建模和剩磁测量

Toroidal iron core modeling of transformer and residual flux density measurement

大型电力变压器进行空载合闸操作时,铁芯中的剩磁可能会引起励磁涌流,导致变压器无法正常投入运行。文章介绍了一种新的分析和测量剩磁的方法,该方法是在外加正反向直流电压激励的基础上实现的。通过分析剩磁产生的原理,建立了基于Jiles-Atherton磁滞理论模型的变压器环形铁芯仿真模型。在环形铁芯绕组上先后施加大小相等方向相反的直流电压,可以得到两个不同的响应电流,结合场路暂态分析,可以判断剩磁的方向,并且找到响应电流和剩磁之间的关系。该方法可以在对变压器铁芯中原有剩磁影响不大的情况下准确测量剩磁的大小和方向。通过自主搭建的实验平台对环形铁芯中的剩磁进行了测量,验证了仿真结果的合理性。

When the large transformer performs no-load closing operation,magnetizing inrush current may be resulted for the residual flux exists in the iron core,and thus the transformer perhaps fail to connect with the power grid.A novel method for analyzing and measuring residual flux in the closed iron core is proposed in this paper,which is based on the positive and negative DC voltage excitation method.The principle of residual flux generation is introduced,and then,considering the hysteresis characteristic of magnetic material,a toroidal iron core simulation model is established based on Jiles-Atherton(J-A)model.By applying DC voltage with the same magnitude but different polarity to the winding on the toroidal iron core,two different response currents can be obtained.Based on magnetic field and circuit transient analysis method,the residual flux direction can be determined,and then,the corresponding relationship between the response current and the residual flux can be also found.This method can accurately measure the value and direction of the residual flux when it has little effect on the initial residual flux in iron core.Finally,the residual flux in toroidal iron core is measured by the self-built experimental platform,and the rationality of the simulation results are verified.