电力变压器绕组短路电动力计算

发布时间：2018-01-05 10:25

本文关键词：电力变压器绕组短路电动力计算　出处：《哈尔滨理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：电力变压器在电网中主要起到能量转换和传输的作用，是发电厂和变电所的重要设备之一，其承受短路能力的大小直接关系到电网是否能够安全可靠的运行。随着国民经济的快速发展以及国家对电网的不断投建和改造，使得越来越多的大型电力变压器在电网中被投入使用，但在其运行过程中当变压器受到短路冲击电流作用时因绕组的机械强度不足而引起的事故屡见不鲜。因此，提高大型电力变压器绕组抗短路能力是需要解决的问题。本文以一台三相五柱式电力变压器为例，对其内部瞬态电磁场、绕组短路电动力以及线圈的机械强度问题进行了深入的分析研究。介绍了本课题的研究背景和意义，阐述了大型电力变压器内部电磁场、绕组短路电动力以及绕组机械强度问题的国内外发展情况。对样机建立三维有限元模型，利用场路耦合方法计算了此模型在额定运行和短路运行两种不同情况下变压器三维瞬态电磁场的磁密分布及绕组静态时轴向和辐向的受力大小，并给出其分布规律。与此同时，针对电力变压器绕组在其高度方向上的机械强度问题进行了商讨，建立了变压器低压绕组在Z轴方向上的模态振动数学模型，计算了在短路冲击力的作用下绕组线饼轴向上产生的位移变化及引起的共振频率大小，并针对绕组的短路电动力进行了校核。此课题为加强绕组承受短路能力的设计提供了一定的理论依据，，为今后类似的研究提供了参考依据，具有一定的理论和工程应用价值。
[Abstract]:Power transformers play an important role in energy conversion and transmission in power grid, and are one of the important equipments in power plants and substations. Its ability to bear short circuit is directly related to whether the power grid can operate safely and reliably. With the rapid development of the national economy and the continuous investment and reconstruction of the power grid. As a result, more and more large power transformers are put into use in the power grid. However, when the transformer is affected by short-circuit impact current during its operation, accidents caused by insufficient mechanical strength of windings are common. To improve the short-circuit resistance of large power transformer windings is a problem to be solved. Taking a three-phase five-column power transformer as an example, the transient electromagnetic field inside the transformer is studied. The short circuit electromotive force of winding and the mechanical strength of the winding are deeply analyzed and studied. The research background and significance of this subject are introduced, and the electromagnetic field inside the large power transformer is expounded. The development of windings short circuit electromotive force and winding mechanical strength at home and abroad. The 3D finite element model of the prototype is established. The field circuit coupling method is used to calculate the magnetic density distribution of the three dimensional transient electromagnetic field of the transformer and the axial and radial force under static winding under two different conditions of rated operation and short circuit operation. At the same time, the mechanical strength of the power transformer winding in the direction of its height is discussed, and the mathematical model of the modal vibration of the low-voltage winding of the transformer in the Z-axis direction is established. The displacement change and resonance frequency caused by the axial direction of the winding wire cake under the action of short circuit impact force are calculated. The short circuit electromotive force of the winding is checked. This subject provides a certain theoretical basis for the design of strengthening the short circuit bearing capacity of the winding, and provides a reference basis for similar research in the future. It has certain theory and engineering application value.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM41

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