摘要
变压器长期运行过程中,绝缘纸板的力学性能在热应力作用下发生变化,进而引起其短路承受能力的变化。该文对绝缘纸板进行加速老化试验,获得不同老化纸板的力学性能;建立考虑支撑刚度的内线圈有限元模型,分析不同支撑刚度对应的内线圈幅向弯曲应力和屈曲临界载荷;并对1台110kV退运变压器的短路承受能力进行评估和试验。结果表明,纸板老化后弹性模量下降;考虑线圈支撑刚度后,辐向弯曲应力和临界载荷分别为直梁模型为两铰支圆弧拱模型计算结果的1/5和1/4;随着线圈的老化,弯曲应力的安全系数提高,临界载荷的安全系数降低,表明老化变压器出现屈曲的可能性增大。研究结果可为老化变压器短路承受能力评估提供重要依据。
During the service life of transformers,thermal stresses can change the mechanical properties of pressboards,and consequently change windings’withstand ability to short circuits(WASC).In this paper,the accelerated aging experiments were conducted firstly to obtain the mechanical properties of aging pressboards.Secondly,radial bending stresses and critical loads of inner windings were analyzed by establishing the finite element model,where the stiffness of stays was considered.Finally,the proposed model was used to evaluate the WASC of a 110 kV out-of-service power transformer,and short-circuit tests were carried out.The results show that the elastic modulus of pressboards drops with the increasing aging degree.Based on the proposed model,the radial bending stresses and the critical load are one-fifth and a quarter of the results calculated from the beam model and the two-hinged arch model,respectively.With the increasing degree of aging,the safety factor of radial bending stresses increases,while the safety factor of critical load decreases,indicating that the aged windings are easily to have buckling deformation.The conclusions can provide an important basis for evaluating the WASC of aging transformers.
作者
张凡
李秀广
朱筱瑜
庄哲
师愉航
汲胜昌
ZHANG Fan;LI Xiuguang;ZHU Xiaoyu;ZHUANG Zhe;SHI Yuhang;JI Shengchang(State Key Laboratory of Electrical Insulation and Power Equipment(Xi’an Jiaotong University),Xi’an 710049,Shaanxi Province,China;Electric Power Research Institute of State Grid Shaanxi Electric Power Co.,Ltd.,Xi’an 710049,Shaanxi Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2022年第10期3836-3845,共10页
Proceedings of the CSEE
基金
中国博士后科学基金项目(2020M673398)
国家自然科学基金项目(52007145)。
关键词
变压器
热老化
内线圈
短路承受能力
transformer
thermal aging
inner windings
withstand ability to short circuits
