不同温度下变压器绕组材料弹性模量及短路轴向力学性能研究
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摘要
变压器绕组材料弹性模量对其短路轴向力学性能及动稳定性有重要影响。采用动态热机械分析仪测量分析了绕组垫块弹性模量随温度的变化规律,并通过理论计算得到了铜导线弹性模量随温度的变化规律。在此基础上,以一台110kV电压等级的变压器为例,基于有限元电磁-结构耦合计算,研究了短路电流峰值时刻绕组漏磁场分布及轴向力学性能。结果表明:垫块和铜导线的弹性模量均随温度的升高而减小;在轴向短路电磁力的作用下,高、低压绕组同时受到从两端向中部的压缩作用,绕组两端的轴向位移最大,中部线饼的位移较小,应力最大值出现在中部线饼处,且高压绕组的最大位移和最大应力均小于低压绕组;突发短路时绕组的平均温度越高,其最大轴向位移越大,最大应力越小。
The elastic modulus of transformer winding material has an important influence on its axial mechanical properties and dynamic stability at short circuit. The change rule of elastic modulus of windings spacers with temperature was measured via dynamic thermal mechanical analyzer, and the change rule of elastic modulus of copper conductor with temperature was obtained by theoretical calculation.Based on finite element electromagnetism-structure coupling calculation, the leakage magnetic field distribution and axial mechanical properties of windings at the time of peak short-circuit current were calculated for an 110kV power transformer. The results show that the elastic modulus of the spacer and copper conductor decreases with the increase of temperature. Under the effect of axial short-circuit electromagnetic force, the high and low voltage windings are subject to compression effect from both ends to the middle part. The axial displacement of the both ends is the biggest, and the displacement of the middle part is the smallest, and the maximum stress occurs at the middle part. The maximum displacement and maximum stress of the high voltage windings are smaller than those of low voltage windings. The higher the average temperature of the windings at sudden short circuit fault, the greater the maximum axial displacement, the smaller the maximum stress is.
The elastic modulus of transformer winding material has an important influence on its axial mechanical properties and dynamic stability at short circuit. The change rule of elastic modulus of windings spacers with temperature was measured via dynamic thermal mechanical analyzer, and the change rule of elastic modulus of copper conductor with temperature was obtained by theoretical calculation.Based on finite element electromagnetism-structure coupling calculation, the leakage magnetic field distribution and axial mechanical properties of windings at the time of peak short-circuit current were calculated for an 110kV power transformer. The results show that the elastic modulus of the spacer and copper conductor decreases with the increase of temperature. Under the effect of axial short-circuit electromagnetic force, the high and low voltage windings are subject to compression effect from both ends to the middle part. The axial displacement of the both ends is the biggest, and the displacement of the middle part is the smallest, and the maximum stress occurs at the middle part. The maximum displacement and maximum stress of the high voltage windings are smaller than those of low voltage windings. The higher the average temperature of the windings at sudden short circuit fault, the greater the maximum axial displacement, the smaller the maximum stress is.
引文
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[2]杨静,盛慧慧,魏晓伟.500k V变压器内部短路损坏事故分析[J].高压电器,2010,46(6):74-78.
[3]朱维璐,贾永江,杜深慧.电力变压器绕组短路轴向稳定性分析[J].变压器,2009,46(9):17-19.
[4]郭健,林鹤云,徐子宏,等.用有限元方法分析电力变压器绕组轴向稳定性[J].高电压技术,2007,33(11):209-212.
[5]刘晓丽,刘文里,王明.基于“场-路”耦合法的电缆变压器轴向短路电磁力的计算[J].黑龙江电力,2008,30(1):7-12.
[6]闫振华,马波,马飞越,等.220k V电力变压器短路动力学性能分析[J].高压电器,2014,50(3):79-87.
[7]孙定华,许宪中.论材料特性与变压器的抗短路能力—写在新世纪到来之际[J].变压器,2000,37(2):15-21.
[8]Kozlowski M,Pewca W.Short-circuit Performance of a Stretched Transformer Winding with Regard to Its Actual Mechanical Characteristics[J].European Transactions on Electrical Power,1996,6(4):259-265.
[9]Zhang H,Yang B,Xu W,et al.Dynamic Deformation Analysis of Power Transformer Windings in Short-circuit Fault by FEM[J].IEEE Transactions on Applied Superconductivity,2014,24(3):1-4.
[10]张浩波,王莉艳.晶体Cu和Ar弹性模量随压强和温度的变化关系[J].西南师范大学学报(自然科学版),2004,29(1):67-70.
[11]郑瑞伦.面心立方晶体热力学性质的非简谐效应[J].西南师范大学学报(自然科学版),1991,16(4):432-439.
[12]冯端.金属物理学[M].北京:科学出版社,1987.
[13]杜宜谨,王向斌,杜卓宁,等.固体体积弹性模量与温度的关系[J].安徽大学学报(自然科学版),1992,16(2):49-51.