摘要
变压器线圈在短路电动力的作用下产生强烈的轴向振动,影响线圈强度。为了深入研究线圈的短路振动特性及其对轴向强度的影响规律,该文首先建立绕组轴向的非线性振动模型,提出线圈、垫块、压板动态压缩力以及导线轴向弯曲应力的计算方法;然后,对一台SZ-50000/110kV变压器的动态轴向强度进行评估,并与传统的静态计算结果进行对比;最后,分析电流幅值、压紧力和固有频率对轴向强度的影响规律。研究结果表明,采用动态模型计算的线圈、垫块、压板压缩力和导线的轴向弯曲应力均大于静态计算结果。针对该文所研究的变压器,绕组二阶固有频率接近电动力频率时,线圈压缩力可增加10~25kN,压板最大应力可增加8MPa,轴向弯曲应力可分别增加5~10MPa。所提模型和计算方法对于提升变压器短路强度评估水平非常关键。
Excited by the magnetic forces under the action of short-circuit current,transformer coils vibrate strongly in axial direction to affect their mechanical strength.To further investigate windings’vibration characteristics during short-circuits and their influence on the axial mechanical strength,this paper firstly establishes a nonlinear axial vibration model and proposes methodologies to calculate dynamic compressive forces of coils,spacers,clamping rings,and axial bending stresses in conductors.Then,the proposed models are used to assess the dynamic axial mechanical strength of an SZ-50000/110kV power transformer,and the obtained results are compared with that from the traditional static assessment.Finally,the influences of current amplitude,clamping pressure,and natural frequencies on axial strength are discussed.The results show that the calculated compressive forces and stresses of winding disk,spacers,clamping rings and axial bending stress in conductors from the dynamic assessment are slightly higher than those of the static assessment.For the transformer used in this paper,when the second-order natural frequency gets close to the forces’frequency,the compressive force of disk increase by 10kN to 25kN,stresses of clamping rings increase by 8MPa,and axial bending stresses increase by 5MPa to 10MPa.The proposed model and methodology are valuable in improving the assessment of windings’mechanical strength.
作者
张凡
马程
李秀广
朱筱瑜
汲胜昌
ZHANG Fan;MA Cheng;LI Xiuguang;ZHU Xiaoyu;JI Shengchang(State Key Laboratory of Electrical Insulation and Power Equipment(Xi’an Jiaotong University),Xi’an 710049,Shaanxi Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2023年第16期6494-6504,共11页
Proceedings of the CSEE
基金
国家自然科学基金项目(52007145)
中国博士后科学基金资助项目(2020M673398)。
关键词
电力变压器
外部短路
绕组机械强度
动态评估
非线性振动
power transformer
external short-circuit
windings’mechanical strength
dynamic assessment
non-linear vibration
