一种基于有限元建模仿真的变压器抗短路能力校核方法及其运用研究

A checking method and application of transformer short-circuit ability based on finite element modeling and simulation

本文介绍了一种基于有限元二维仿真建模的变压器抗短路能力校核方法。运用该方法对一台发生故障的110kV SX变1号主变进行抗短路能力动稳定校核,通过有限元仿真计算其漏磁分布、短路冲击电流,然后根据漏磁与短路电流大小计算得到外线圈平均环形拉伸应力、内线圈平均环形压缩应力、幅向弯曲应力等的分布情况,并与国标推荐值对比,结果表明该主变抗辐向弯曲能力不满足GB 1094.5-2008要求,低压线圈采用扁铜线并绕,扁铜线的抗倾斜能力较弱。解体检查后发现其低压b相线圈有明显炭黑、熔断点、严重变形。低压c相线圈有明显变形、a相线圈有轻微变形。验证了其因抗短路能力不足而发生损坏。另外,用同样的方法对于该主变同厂同型的4台变压器进行校核,发现4台主变存在同样问题,未通过校核;最后给出了相应的运维建议。

This paper introduces a checking method of transformer anti-short-circuit ability based on finite element two-dimensional simulation modeling.Using this method,the anti-short-circuit capability of a 110 kV SX Substation No.1 main transformer is checked dynamically,and the distribution of leakage flux and short-circuit impulse current are calculated by finite element simulation,then,according to the magnetic flux leakage and short-circuit current,the average ring tensile stress of the outer coil,the average ring compressive stress of the inner coil and the amplitude bending stress of the inner coil are calculated,the results show that the radial bending resistance of the main transformer can not meet the requirements of GB 1094.5-2008.The low-voltage coil is wound by flat copper wire,and the anti-inclination ability of flat copper wire is weak.After disassembling,it was found that the low-voltage B phase coil had obvious carbon black,fuse point and severe deformation.The low-voltage c-phase coil has obvious deformation,and the a-phase coil has slight deformation.It is verified that the device is damaged due to the insufficient ability of anti-short circuit.In addition,the same method is used to check four transformers of the same type in the same plant,and the same problems are found in the four transformers,which have not been checked.