中文摘要：

直流偏磁条件下电力变压器铁心的振动噪声明显加剧，铁心的磁致伸缩效应是其主要原因之一。目前有关直流偏磁磁场对硅钢片磁致伸缩特性的影响规律尚不完全清楚，亟需从实验测量角度定性地分析其影响规律，为建立有效地减小电力变压器铁心振动噪声的方法提供参考。该文在一台精度为10nm／m的激光位移磁致伸缩测试系统上，对不同直流偏磁磁场下取向硅钢片的磁致伸缩特性进行实验研究，对比分析交变磁化及直流偏磁磁化在磁场饱和前后对磁致伸缩波形形状、峰峰值的影响规律，并将测量结果应用于一台电力变压器铁心的振动位移分析。结果表明：直流偏磁磁场使磁致伸缩回环失去原有的对称性，这种影响会随着磁场饱和程度的增加逐渐减弱：随着偏磁磁场的增加，磁致伸缩峰峰值增大，硅钢片的形变加剧。

英文摘要：

When the power transformer is running under the condition of direct current （DC） bias, the noise and vibration of the transformer core increase obviously and one of the main reasons is the magnetostriction effect of core. At present, the law about the influence of DC biased magnetic field on the magnetostrictive property of silicon steel sheet has not been clearly explained. It is necessary to analyze the law by means of experimental test qualitatively, which can provide a reference for putting forward methods of reducing the vibration and noise of transformer cores. Based on a laser displacement magnetostrictive measurement system with ＇accuracy of 10nm/m, the magnetostrictive property of grain-oriented silicon steel was studied experimentally under different DC biased magnetic fields. The influence law of alternating and DC biased magnetizations on magnetostrictive waveform shape and peak-to-peak value before and after magnetic saturation was comparatively investigated, and the measured results was applied to the vibration displacement simulation of a power transformer. The results show that DC biased field makes the magnetostrictive loop to lose its original symmetry, which will gradually die down with the increase of magnetic saturation, and the peak-to-peak value of magnetostriction increases with the increase of biased magnetic field, which makes the deformation of silicon steel serious.