多次短路下变压器绕组短路强度与稳定性研究

发布时间：2018-01-29 19:43

本文关键词： 变压器绕组多次短路强度累积形变稳定性　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文在全面深入地总结了变压器绕组短路强度和稳定性研究现状的基础上,从变压器短路试验模型入手,采用有限元法对模型进行多物理场耦合分析,掌握绕组电磁分布,电磁力变化规律和绕组形变规律。分别对多次短路下变压器绕组辐向强度和稳定性进行了仿真计算,求解出了绕组的累积形变和临界失稳载荷,并且进一步探讨了短路电流和撑条结构对绕组强度的影响。通过结构力场分析,计算了多次短路下变压器绕组的端圈应力,在此基础上进一步计算了绕组的自然频率,并且探讨了绕组垫块的预压处理对多次短路下变压器绕组自然频率的影响。首先,基于电磁分析和结构分析的基本原理,选取变压器短路试验模型作为基本研究模型,对变压器短路下的绕组电磁场、结构力场等多物理场进行了分析。利用简化模型对短路模型进行了详细的电磁过程分析,并对绕组受力及其运动方程进行了推导。重点采用ANSYS多物理场耦合软件,建立了该变压器短路试验模型的三维有限元模型,并对其进行了多物理场耦合计算分析。其次,全面分析了变压器绕组在多次短路下产生累积形变的原因及过程,并且提出了多次短路下变压器绕组辐向强度的有限元计算方法,通过对变压器试验模型的试验测量,验证了有限元计算方法的有效性和可靠性。对比分析了绕组在不同短路电流峰值下,短路冲击次数和峰值持续时间对变压器绕组累积形变过程的影响。针对变压器绕组的撑条特性,研究了不同撑条个数、不同撑条宽度下绕组辐向形变规律。另外,基于弹支梁模型对变压器绕组在多次短路下的辐向稳定性进行了计算分析,讨论了绕组的辐向累积形变对绕组临界失稳载荷的影响。最后,基于变压器绕组轴向振动的基本原理,采用“质量-弹簧模型”,针对实例变压器绕组进行了结构力场计算分析,得出了多次短路下变压器绕组各线饼和端圈的应力分布规律。通过模态分析,对比分析了绕组在短路前后的前六阶振型,并且计算了绕组在短路前后的自然振动频率。采用瞬态激振法和频谱分析法对绕组自然振动频率进行了试验测量,验证了有限元计算方法的有效性和可靠性。最后重点探讨了垫块预压处理对绕组自然频率的影响。
[Abstract]:On the basis of summarizing the research status of short circuit strength and stability of transformer windings in an all-round way, this paper starts with transformer short-circuit test model and uses finite element method to analyze the multi-physical field coupling of the model. The electromagnetic distribution of windings, the law of electromagnetic force variation and the law of winding deformation are grasped. The radial strength and stability of transformer windings under multiple short-circuit are simulated and calculated respectively. The cumulative deformation and critical instability load of the windings are solved, and the influence of the short circuit current and the strut structure on the winding strength is further discussed. The end coil stress of transformer winding under multiple short circuit is calculated, and the natural frequency of the winding is further calculated. The influence of preloading on the natural frequency of transformer windings is discussed. Firstly, based on the basic principles of electromagnetic analysis and structure analysis. The transformer short-circuit test model is selected as the basic research model to study the electromagnetic field of the transformer windings under short circuit. The structure force field and other multi-physical fields are analyzed, and the electromagnetic process of the short-circuit model is analyzed in detail by using the simplified model. The stress on the winding and its equation of motion are deduced, and the 3D finite element model of the short-circuit test model of the transformer is established by using the ANSYS multi-physical field coupling software. And the multi-physical field coupling analysis is carried out. Secondly, the cause and process of cumulative deformation of transformer windings under multiple short-circuit are analyzed. A finite element method for calculating the radial strength of transformer windings under multiple short circuits is proposed. The transformer test model is tested and measured. The validity and reliability of the finite element method are verified. The influence of short circuit impact times and peak duration on the cumulative deformation process of transformer windings. In addition, based on the elastic beam model, the radial stability of transformer windings under multiple short circuits is calculated and analyzed. The influence of the cumulative radial deformation of the winding on the critical unstable load of the winding is discussed. Finally, based on the basic principle of the axial vibration of the transformer winding, the mass-spring model is adopted. Based on the calculation and analysis of the structural force field of transformer windings, the stress distribution law of each wire cake and end ring of transformer windings under multiple short circuit is obtained, and the modal analysis is carried out. The first six vibration modes of the winding before and after the short circuit are compared and the natural vibration frequency of the winding before and after the short circuit is calculated. The natural vibration frequency of the winding is measured by the transient excitation method and the spectrum analysis method. The validity and reliability of the finite element method are verified. Finally, the influence of preloading on the natural frequency of winding is discussed.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41

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