大型电力变压器杂散损耗的研究

发布时间：2018-04-15 08:17

本文选题：变压器 + 漏磁场　；参考：《华北电力大学》2017年硕士论文

【摘要】：在大容量变压器中,负载电流产生的漏磁通非常大,这些漏磁通穿过绕组空道沿着铁心夹件、主柱铁心或经过油箱形成闭合回路,漏磁通通过铁磁性材料时,形成众多涡流,产生涡流损耗,并且散发出热量。无论这些损耗还是热量,对变压器都是无无益的,不但会降低变压器的效率,还会破坏变压器的绝缘,影响变压器的安全运行,缩短变压器的使用寿命。漏磁通在变压器金属结构件中形成的损耗,称为杂散损耗,油箱的涡流损耗占杂散损耗的大部分。变压器的杂散损耗不可避免,且随容量的增长而增加。工程上研究杂散损耗,一方面控制其在允许的范围内,满足用户要求;另一方面控制漏磁通密度,避免局部过热,保证变压器的安全运行。经过专家和学者的研究试验,工程中最有效的减少金属结构件的漏磁通方法是,在漏磁通密集的地方安装屏蔽板或开漏磁槽。油箱的结构对杂散损耗也有一定影响,当变压器的参数不是常规时,设计者需要分析金属结构件和油箱的漏磁场,避免局部过热。基于变压器漏磁场对上述问题的影响,因此需要全面的分析。本文是从以下方面对课题进行论述的:通过研究电磁场的基本理论,导出适用于计算的电磁场方程。介绍了本课题计算用到的有限元法、建模软件Pro/ENGINEER和电磁场仿真计算软件Mag Net。还进一步分析了漏磁场产生的原因和危害。本文以一台SFP-410000/220变压器为例,采利用Mag Net软件对该变压器进行漏磁场计算,通过分析金属结构件的磁通密度和杂散损耗密度,得出结论不会出现过热点。为了进一步探究油箱顶部角度的改变带来的漏磁效应,论文分析了高压侧35度箱盖和45度箱盖的漏磁场。通过比较两种箱盖角度的漏磁带来的杂散损耗和热效应,得出了45度的箱盖杂散损耗略大于35度箱盖,但并未形成过热点。
[Abstract]:In large capacity transformers, the leakage flux generated by the load current is very large. These flux leakage fluxes pass through the windings along the iron core, and the core of the main column or through the oil tank forms a closed loop. When the leakage flux passes through the ferromagnetic material, a large number of eddy currents are formed.Causes eddy current loss and emits heat.Whether these losses or heat are not beneficial to the transformer, it will not only reduce the efficiency of the transformer, but also damage the insulation of the transformer, affect the safe operation of the transformer, shorten the service life of the transformer.The loss of flux leakage in the metal structure of transformer is called stray loss, and the eddy current loss of fuel tank accounts for most of the stray loss.The stray loss of transformer is inevitable and increases with the increase of capacity.On the one hand, the stray loss can be controlled within the allowable range to meet the requirements of the users; on the other hand, the flux leakage density will be controlled to avoid local overheating and ensure the safe operation of the transformer.Through the research and test by experts and scholars, the most effective method to reduce the leakage flux of metal structure in engineering is to install shielding plate or flux-leakage slot in the place where the flux leakage is dense.The structure of fuel tank also has a certain influence on stray loss. When the transformer parameters are not conventional, the designer needs to analyze the leakage magnetic field of metal structure and fuel tank to avoid local overheating.Based on the influence of transformer flux leakage on the above problems, a comprehensive analysis is needed.This paper discusses the subject from the following aspects: by studying the basic theory of electromagnetic field, the equation of electromagnetic field suitable for calculation is derived.The finite element method, modeling software Pro/ENGINEER and electromagnetic field simulation software Mag net are introduced in this paper.The cause and harm of leakage magnetic field are also analyzed.Taking a SFP-410000/220 transformer as an example, the magnetic flux leakage of the transformer is calculated by using Mag Net software. By analyzing the flux density and stray loss density of metal structure, it is concluded that there is no hot spot.In order to further explore the magnetic leakage effect caused by the change of the top angle of the tank, the magnetic leakage field of the 35 degree tank cap and the 45 degree tank cover on the high pressure side are analyzed in this paper.By comparing the stray loss and thermal effect of two kinds of leaky tape with different cover angle, it is concluded that the stray loss of 45 degree box cover is slightly greater than that of 35 degrees box cover, but no hot spot has been formed.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41

【参考文献】