Affiliations: [a] College of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin, China | [b] Jiamusi Electric Machinery Co., Ltd, Jiamusi, China
Correspondence:
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Corresponding author: Mengmeng Ai, College of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, Heilongjiang Province, China. Tel.: +86 187 2460 5449; E-mail: aimengmeng@hrbust.edu.cn
Abstract: The safety and reliable operation of power grid is directly related to the ability of power transformer to withstand short-circuit, therefore, it is a problem to be solved to improve the ability of large power transformer windings to withstand short-circuit. Taking a three-phase five-limb power transformer as an example, the transient electromagnetic field, short-circuit electrodynamics force of windings and mechanical strength of coils are analyzed in depth. Firstly, the three-dimensional finite element model of the prototype is established, and the magnetic flux density distribution of the three-dimensional transient electromagnetic field of transformer under short-circuit operation and the axial and radial static force magnitude of the winding are calculated by using the field-circuit coupling method, and the distribution law can be obtained. At the same time, the mechanical strength of power transformer winding in its height direction is discussed, and the modal vibration mathematical model of transformer low-voltage winding in Z-axis direction is established. The displacement change and resonance frequency of the winding wire cake in the axial direction caused by short-circuit are calculated, and the short-circuit electrodynamics force of the winding is also checked. The research in this paper provides a theoretical basis for strengthening the design of short-circuit withstanding capacity of windings, and has a certain theoretical and engineering application value.
Keywords: DC power transformer, field-circuit coupling, short-circuit electrodynamics force, winding mechanical strength
