高压自耦变压器的涡流损耗计算与屏蔽措施

为应对大型电力变压器漏磁场及杂散损耗问题,采用三维非线性涡流场有限元分析方法,以1台高压自耦变压器为研究对象,引入B-H曲线来描述非线性材料的磁特性,对变压器结构件进行了漏磁场及涡流损耗计算。采用屏蔽措施之前,油箱及夹件等结构件涡流损耗及涡流损耗密度较大,容易引起局部过热问题并且影响变压器正常运行。通过进一步分析,给出了油箱磁屏蔽、夹件L型磁屏蔽和肺叶式磁屏蔽等降低杂散损耗的措施,以及多种屏蔽形式对漏磁场及结构件涡流损耗的影响。结果表明对电力变压器油箱、夹件等结构件采取合理的磁屏蔽措施能够有效地降低杂散损耗并消除热点,不同屏蔽形式对其周围结构件涡流损耗及漏磁场具有不同影响。

Eddy Current Losses Calculation and Shields of High Voltage Auto-transformer

In order to analyze the leakage magnetic field and eddy current losses in large-scale power transformer,taking the nonlinear magnetic B-H characteristics of core,tank and magnetic shield material into account,we computed the leakage magnetic field and eddy current loss in tank,yoke clamps,and other conductive construction parts of high voltage auto-transformer by three-dimensional(3D)nonlinear time harmonic finite element method.The results show that eddy current losses and loss density in tank wall and yoke clamps are large,may cause local overheating,and affect normal operation of the transformer.The magnetic shields added to tank wall and yoke clamps were used to reduce the eddy current loss in tank wall and yoke clamps of power transformer,and effects of those shields on leakage magnetic field and eddy current loss of construction parts were discussed.The results show that eddy current losses and hot spots can be reduced and eliminated effectively by adding magnetic shield to tank wall and yoke clamps.The different types of shields have different influences on leakage magnetic field and eddy current losses in construction parts of transformer.