直流偏磁下变压器绕组及垫块振动特性分析

直流偏磁使得变压器绕组振动加剧,目前采用将绕组简化为忽略垫块结构的圆柱模型的建模方法误差较大.建立包含垫块的线饼式绕组精细化模型,通过电磁场-结构场-流体场多物理场耦合的方法,在对直流偏磁下变压器磁场分布进行分析的基础上,对绕组及垫块的振动位移特性进行研究且进行实验验证.结果表明:直流偏磁下变压器漏磁增加且在特定角度分布集中,绕组在对应位置出现新的不平衡单边振动模式,绕组局部位移的不平衡使得垫块脱落的可能性增加,变压器抗突发能力下降.此研究可为变压器直流偏磁下运行状态监测提供理论指导.

Analysis of Influence of DC Bias on Transformer Short Circuit Withstand Ability

DC bias will aggravate the transformer vibration. Usually, a simplified model is used to calculate the winding vibration to simplify the winding to a cylindrical model that ignores the block structure. Although it saves the calculation time, it makes the calculation result have a large error from the real situation. This paper establishes a refined model of wire-pie-type windings including pads. Based on the analysis of the excitation characteristics of the transformer under DC bias, through the coupling of electromagnetic field, structure field, and fluid field with multiple physical fields, The vibration displacement characteristics are studied and experimentally verified. The results show that the magnetic flux leakage of the transformer increases under the DC bias, and the distribution is concentrated at a specific angle. A new unilateral vibration mode appears at the corresponding position of the winding. The imbalance in the local displacement of the winding increases the possibility of the pad falling off, and the anti-burst ability of the transformer decreases. . This research can provide theoretical guidance for fault monitoring of DC bias operation.