直流偏磁下单相变压器铁心实验模型局部磁致形变测量与模拟

Measurement and Modelling of Local Deformation Caused by Magnetism in the Single-phase Transformer Core Experimental Model Under DC Bias

电工钢片的磁致伸缩效应是变压器振动噪声的主要来源之一,实际工况下变压器铁心的磁致伸缩特性比单片电工钢片的特性更为复杂,而直流偏磁的存在会加剧铁心的形变。为了进一步掌握变压器铁心的磁致形变特征,该文直接对单相变压器铁心局部应变进行实验测试,开发并搭建叠片结构的单相双柱变压器铁心磁致伸缩测试系统,测试并分析不同磁化方式下不同局部区域的磁致伸缩特性,讨论直流偏磁磁场对铁轭以及芯柱磁致伸缩性能的影响,分析夹件位置和夹紧力对变压器铁心磁致伸缩的影响。基于实验测试数据,从工程应用角度提出直流偏磁下基于BP神经网络的叠片铁心磁致伸缩模拟方法。研究结果表明,实际工况下变压器铁心拐角区域由于旋转磁场的存在导致磁致伸缩增大,适当的夹紧位置和夹紧力可有效降低铁心磁致伸缩应变,神经网络法能较好的模拟直流偏磁下变压器铁心局部的磁致形变特性,更适用于工程实践。

The magnetostrictive effect of electrical steel sheet is one of the main sources of transformer vibration and noise. The magnetostrictive property of transformer core under practical working conditions is more complex than that of single sheet electrical steel sheet. Meanwhile, the existence of direct current(DC) bias will aggravate the deformation of the core. In order to further grasp the magnetic deformation properties of the core, in this paper, the local strain in the single-phase transformer core was directly tested. A magnetostrictive testing system for a single-phase double column transformer core structure was developed and built. The magnetostrictive characteristics of different local regions under different magnetization modes were tested and analyzed. The influence of DC bias magnetic field on the magnetostrictive properties of yoke and limb was compared and discussed. The influence of clamping position and clamping force on the magnetostriction of transformer core was studied. Based on the experimental data, a magnetostrictive modeling method of laminated core using BP neural network under DC bias was proposed from the viewpoint of engineering application. The research results show that the magnetostriction increases at the corner of core due to the existence of rotating magnetic field, and the suitable clamping position and clamping force can reduce the magnetostrictive strain of core effectively. The neural network method can model the characteristics of local magnetic deformation of transformer core under DC bias so that it is more suitable for engineering application.