高阻抗变压器的杂散损耗及热问题计算与分析

发布时间：2018-04-24 20:03

本文选题：高阻抗变压器 + 漏磁场　；参考：《沈阳工业大学》2017年硕士论文

【摘要】：随着电网装机容量的逐渐增大,为了限制电力系统的短路电流,提高电力系统运行的稳定性,越来越多的高阻抗变压器应用于坚强电网建设。与常规的变压器相比,高阻抗变压器的漏磁密更大并且分布不均匀,导致结构件的损耗增大。对于箔式绕组,因漏磁通分布不均匀而产生挤流效应,导致绕组端部的损耗密度过大,加快绝缘的老化速度,缩短了变压器的使用寿命。随着电力电子技术的快速发展,电力系统采用了大量的非线性元器件,虽然可以提高能源利用率,但是带来了谐波污染问题。高次谐波的存在使得通过结构件的漏磁通分布更复杂,杂散损耗进一步增大。因此,深入研究高阻抗变压器的杂散损耗及热问题,具有一定的现实意义。首先,以型号为SCBH15-2500/10/0.48的高阻抗变压器研究对象,对其进行合理的简化,建立了三维计算模型。使用电磁场软件Magnet对模型进行有限元计算,分别得到铁心中的磁密分布,结构件和绕组的漏磁密分布以及各部件的损耗。分别采用磁路法和能量法对高阻抗变压器的短路阻抗进行计算。通过对Team Problem 21b模型进行计算,验证了Magnet软件求解磁密和损耗的准确性。其次,基于场路耦合法,采用三维非线性时谐场求解器计算结构件的损耗值。分别采用解析法和有限元法对箔式绕组的涡流损耗进行计算,对计算结果进行对比与分析。采用频域分析法,计算在不同次数的谐波条件下,高阻抗变压器的损耗并分析对其影响较大的谐波次数。最后,阐述了高阻抗变压器的散热过程和求解流体场和温度场的原理。基于间接耦合法,将高阻抗变压器各部件的单位体积生热率作为热载荷施加到计算模型中,使用Ansys CFX软件对高阻抗变压器的多物理场进行求解,分析各部件的流体场和温度场的分布情况并对不同分接电压下,高压绕组的温升进行计算。
[Abstract]:As the installed capacity of power network increases gradually, in order to limit the short-circuit current of power system and improve the stability of power system, more and more high-impedance transformers are used in the construction of strong power network. Compared with conventional transformers, high impedance transformers have higher flux leakage density and uneven distribution, which leads to the increase of loss of structural parts. For foil windings, due to the uneven distribution of leakage flux, the squeezing effect is produced, which leads to the excessive loss density at the end of the winding, speeds up the aging of insulation and shortens the service life of the transformer. With the rapid development of power electronics technology, a large number of nonlinear components are used in power system, which can improve energy efficiency, but bring harmonic pollution. The distribution of flux leakage through the structure is more complicated and the stray loss is further increased due to the existence of high order harmonics. Therefore, it is of practical significance to study the stray loss and heat of high impedance transformer. Firstly, the research object of high impedance transformer based on SCBH15-2500/10/0.48 is simplified reasonably, and a three-dimensional calculation model is established. The electromagnetic field software Magnet is used to calculate the finite element of the model, and the magnetic density distribution of the core, the leakage density distribution of the structure and windings and the loss of each component are obtained respectively. The short circuit impedance of high impedance transformer is calculated by magnetic circuit method and energy method respectively. The calculation of Team Problem 21b model verifies the accuracy of Magnet software in solving magnetic density and loss. Secondly, based on the field-circuit coupling method, a three-dimensional nonlinear time-harmonic field solver is used to calculate the loss value of the structure. The eddy current loss of foil winding is calculated by analytic method and finite element method, and the calculated results are compared and analyzed. The frequency domain analysis method is used to calculate the loss of high impedance transformer under the condition of different harmonics and to analyze the number of harmonics which have a great influence on it. Finally, the heat dissipation process of high impedance transformer and the principle of solving fluid field and temperature field are described. Based on indirect coupling method, the unit volume heat generation rate of each component of high impedance transformer is applied to the calculation model as thermal load, and the multi-physical field of high impedance transformer is solved by Ansys CFX software. The distribution of fluid field and temperature field of each component is analyzed and the temperature rise of high voltage winding is calculated under different demultiplexing voltages.
【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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