|
|
|
| Study on the Influence of Geomagnetically Induced Current on the Thermal Aging of Transformer Inter-Turn Insulation |
| Zhu Lihua1,2, Zhang Xiaojie1, Duan Nana2, Yang Qingxin1 |
1. School of Electrical Engineering and AutomationTianjin University of Technology Tianjin 300382 China;
2. State Key Laboratory of Electrical Insulation and Power Equipment Xi'anJiaotong University Xi'an 710049 China |
|
|
|
|
|
|
Received: 01 June 2026
|
|
|
|
Corresponding Authors:
AbstractGeomagnetically induced current (GIC) introduces quasi-direct current bias into oil-immersed power transformers during geomagnetic disturbances, leading to core saturation, abnormal loss increase, and accelerated thermal aging of inter-turn insulation. The hotspot temperature rise is a key factor governing insulation degradation and lifetime reduction. Quantitative evaluation of the coupled electromagnetic-thermal behavior and insulation aging characteristics under different GIC levels is required for transformers operating under rated load conditions. The objective is to characterize the influence of GIC on loss distribution, hotspot temperature evolution, and thermal aging behavior of transformer insulation systems.++++A three-dimensional coupled electromagnetic-thermal-fluid model is established for a SFSZ-100000/220 oil-immersed transformer operating under rated load. GIC levels are set as 0 A, 30 A, and 50 A. The nonlinear magnetic characteristics of the core are represented using a B-H curve to capture saturation behavior under DC bias. Electromagnetic losses include core hysteresis loss, eddy current loss, winding copper loss, and additional stray losses caused by leakage flux distortion. These losses are mapped as heat sources into the thermal field. A conjugate heat transfer model is used to solve the temperature field, considering solid conduction and natural convection of transformer oil. The inter-turn insulation is modeled as an equivalent thermal thin layer to represent radial thermal resistance. Temperature-dependent oil properties are included to improve flow accuracy. The coupled electromagnetic and thermal fields are iteratively solved to obtain transient temperature distribution and winding hotspot temperature. The hotspot temperature is then introduced into the Arrhenius thermal aging model, and the aging acceleration factor is calculated. Equivalent aging time is obtained through time integration, and insulation life consumption is evaluated based on a reference lifetime of 180,000 h.++++The results show that GIC significantly increases core magnetic saturation and alters loss distribution. The maximum flux density increases from approximately 1.6 T at 0 A to 2.0 T at 50 A. Correspondingly, core loss and winding loss both increase due to intensified saturation and distorted leakage flux. The hotspot temperature of the medium-voltage winding increases from 361.2 K under normal operation to 378.1 K at 30 A and 390.2 K at 50 A. Under 30 A and 50 A conditions, the hotspot temperature exceeds the standard thermal limit, indicating a reduction of thermal margin and increased insulation stress in upper winding regions. The thermal aging process exhibits strong nonlinear acceleration characteristics. The aging acceleration factor increases from 0.094 at 0 A to 0.602 at 30 A and reaches 2.06 at 50 A, indicating that the aging rate under strong GIC conditions is nearly twice the baseline level. Over a 24-hour operating period, equivalent aging time increases from 2.3 h to 14.4 h and 49.4 h for 0 A, 30 A, and 50 A respectively. Long-term evaluation shows that annual insulation life loss increases from 0.457% to 1.067%,which is 1.33 times higher than the no-GIC condition.++++GIC induces core saturation and loss redistribution in oil-immersed transformers, resulting in increased hotspot temperature and accelerated thermal aging of inter-turn insulation. The coupling between electromagnetic distortion and thermal accumulation leads to significant reduction of insulation lifetime margin. The proposed electromagnetic-thermal-aging framework enables quantitative evaluation of hotspot temperature rise and insulation life consumption under different GIC conditions, providing a basis for insulation aging assessment and operational evaluation of transformers under geomagnetic disturbance environments.
|
|
|
|
[1] 王泽忠, 黄天超. 变压器地磁感应电流-无功功率动态关系分析[J]. 电工技术学报, 2021, 36(9): 1948-1955.
Wang Zezhong, Huang Tianchao.Analysis of geomagnetically induction current-reactive power dynamic relationship of transformer[J]. Transactions of China Electrotechnical Society, 2021, 36(9): 1948-1955.
[2] 王泽忠, 董博, 刘春明, 等. 地磁暴感应地电场的大地电性结构建模方法[J]. 科学技术与工程, 2015, 15(13): 72-76.
Wang Zezhong, Dong Bo, Liu Chunming, et al.Earth conductivity modelling technique for calculating geoelectric field during geomagnetic storms[J]. Science Technology and Engineering, 2015, 15(13): 72-76.
[3] 王泽忠, 李宇妍. 地磁感应电流作用下三相五柱变压器无功功率定量分析[J]. 华北电力大学学报(自然科学版), 2024, 51(3): 1-9, 19.
Wang Zezhong, Li Yuyan.Quantitative analysis of reactive power of three-phase five limbs transformer under the action of geomagnetically induced current[J]. Journal of North China Electric Power University, 2024, 51(3): 1-9, 19.
[4] 朱涛, 王丰华. 地磁感应电流作用下大型变压器的温升特性计算[J]. 电工技术学报, 2022, 37(8): 1915-1925.
Zhu Tao, Wang Fenghua.Calculation of temperature rise of large transformer under geomagnetically induced current[J]. Transactions of China Electro-technical Society, 2022, 37(8): 1915-1925.
[5] Fatima R, Birchfield A B.Impact of time-dependent transformer thermal model on assessment of GICs in large power systems[C]//2023 North American Power Symposium (NAPS), Asheville, NC, USA, 2023: 1-6.
[6] 王泽忠, 李明洋, 宣梦真, 等. 单相四柱式变压器直流偏磁下的温升试验及仿真分析[J]. 电工技术学报, 2021, 36(5): 1006-1013.
Wang Zezhong, Li Mingyang, Xuan Mengzhen, et al.Temperature rise test and simulation of single-phase four-column transformer under DC-bias[J]. Transactions of China Electrotechnical Society, 2021, 36(5): 1006-1013.
[7] 杨帆, 胡星宇, 王鹏博. 油浸式电力变压器温升计算场路耦合和降阶模型研究[J]. 电工技术学报, 2025, 40(13): 4071-4084.
Yang Fan, Hu Xingyu, Wang Pengbo.Study on temperature rise calculation and reduced-order model of oil-immersed transformer with field-circuit coupling[J]. Transactions of China Electrotechnical Society, 2025, 40(13): 4071-4084.
[8] 王古玥, 王泽忠, 刘春明. 高空电磁脉冲晚期成分作用下变压器的等效电感及无功损耗特性[J]. 电工技术学报, 2025, 40(18): 5728-5741.
Wang Guyue, Wang Zezhong, Liu Chunming.Equivalent inductance and reactive power loss characteristics of transformer under late-time high-altitude electromagnetic pulse[J]. Transactions of China Electrotechnical Society, 2025, 40(18): 5728-5741.
[9] Yan Xiaoli, Dong Xia, Han Guozheng, et al.Research on electromagnetic characteristics of single-phase transformer under DC bias[C]//2022 IEEE/IAS Industrial and Commercial Power System Asia (I&CPS Asia), Shanghai, China, 2022: 34-38.
[10] Shi Baidi, Jiang Yongfeng, Xiao Wei, et al.Power transformer vibration analysis model based on ensemble learning algorithm[J]. IEEE Access, 2025, 13: 37812-37827.
[11] Behjat V, Mostafaei M, Rezaei-Zare A, et al.Analysis of power transformers under geomag- netically induced currents[C]//2023 IEEE Kansas Power and Energy Conference (KPEC), Manhattan, KS, USA, 2023: 1-5.
[12] 李明洋, 张俊双, 李海明, 等. 500kV单相变压器直流偏磁下损耗及绕组热点温度的计算分析[J]. 电工电能新技术, 2021, 40(8): 51-59.
Li Mingyang, Zhang Junshuang, Li Haiming, et al.Calculation and analysis of loss and winding hot spot temperature under DC bias of 500 kV single-phase transformer[J]. Advanced Technology of Electrical Engineering and Energy, 2021, 40(8): 51-59.
[13] 刘尧, 刘刚, 李琳, 等. 匝间绝缘对变压器绕组温升及热点影响的仿真分析[J]. 华北电力大学学报(自然科学版), 2020, 47(2): 64-73.
Liu Yao, Liu Gang, Li Lin, et al.Simulation and analysis of turn-insulation on temperature rise and hot spots of transformer windings[J]. Journal of North China Electric Power University, 2020, 47(2): 64-73.
[14] 沈楠, 刘刚, 王晓晗, 等. 基于最小热阻力法则的油浸式变压器绕组等效导热系数计算方法及应用[J]. 华北电力大学学报(自然科学版), 2023, 50(4): 60-68.
Shen Nan, Liu Gang, Wang Xiaohan, et al.Calculation and application of equivalent thermal conductivity of oil-immersed transformer windings based on the law of least thermal resistance[J]. Journal of North China Electric Power University (Natural Science Edition), 2023, 50(4): 60-68.
[15] 王远, 唐桢馥, 牛飞宇, 等. 220 kV天然酯变压器绕组温度分布三维仿真计算分析[J]. 绝缘材料, 2025, 58(8): 50-56.
Wang Yuan, Tang Zhenfu, Niu Feiyu, et al.3D simulation calculation and analysis of winding temperature distribution in a 220 kV natural ester transformer[J]. Insulating Materials, 2025, 58(8): 50-56.
[16] Akbari M, Mostafaei M, Rezaei-Zare A.Estimation of hot-spot heating in OIP transformer bushings due to geomagnetically induced current[J]. IEEE Transactions on Power Delivery, 2023, 38(2): 1277-1285.
[17] 黄菁雯, 杜志叶, 徐箭, 等. 计及新能源出力和谐波的变压器热点温度修正模型[J]. 电力系统自动化, 2025, 49(16): 132-141.
Huang Jingwen, Du Zhiye, Xu Jian, et al.Modified hotspot temperature model for transformers considering renewable energy output and harmonics[J]. Automation of Electric Power Systems, 2025, 49(16): 132-141.
[18] 于文旭, 关向雨, 赵俊义, 等. 基于格子玻耳兹曼的油浸式变压器瞬态温升模拟与负载能力评估[J]. 电工技术学报, 2025, 40(10): 3315-3325.
Yu Wenxu, Guan Xiangyu, Zhao Junyi, et al.Transient temperature rise simulation and load capacity evaluation of oil-immersed transformer based on lattice Boltzmann method[J]. Transactions of China Electrotechnical Society, 2025, 40(10): 3315-3325.
[19] 袁帅. 电-热场耦合条件下变压器油纸绝缘损伤特性与评估方法研究[D]. 重庆: 重庆理工大学, 2025.
Yuan Shuai.Study on damage characteristics and evaluation method of transformer oil-paper insulation under the coupling condition of electric-thermal field[D]. Chongqing: Chongqing University of Tech-nology, 2025.
[20] 林智勇, 李荣华, 黄国泰, 等. 基于频域二次微分解谱法的油纸绝缘等效电路参数辨识[J]. 电工技术学报, 2025, 40(15): 4966-4975.
Lin Zhiyong, Li Ronghua, Huang Guotai, et al.Identification of dielectric response equivalent circuit of transformer's oil-paper insulation based on quadratic differential decomposition spectroscopy of frequency domain spectroscopy[J]. Transactions of China Electrotechnical Society, 2025, 40(15): 4966-4975.
[21] Qin Chunxu, Lin Wenjie, Huang Yongxiang, et al.Study on thermal aging insulation characteristics of transformer oil-paper insulation[C]//2024 IEEE 4th International Conference on Power, Electronics and Computer Applications (ICPECA), Shenyang, China, 2024: 744-748.
[22] 国家质量监督检验检疫总局, 中国国家标准化管理委员会. 电力变压器第2部分:液浸式变压器的温升: GB/T 1094.2—2013[S]. 北京: 中国标准出版社, 2014. |
|
|
|
2026, Vol. 41 
