Abstract：In recent years, frequency domain spectroscopy (FDS) has been widely used in the insulation status diagnosis of oil-paper bushing. However, at present, FDS testing can only be realized at steady temperature. The environment under actual working conditions is complex. Especially affected by external factors such as region and climate, the equipment is often in a dynamic cooling process when it is out of service for maintenance. In addition, due to the short “time window” of on-site maintenance, the time for FDS testing is limited. Therefore, it is impossible to conduct dielectric response assessment after the bushing temperature is stabilized, and the obtained FDS curves are quite different from the constant temperature curves. In order to solve these problems, this paper obtains the equivalent temperature of each frequency point of the FDS curves under the condition of time-varying temperature based on Havriliak-Negami (H-N) model, so as to realize FDS curve correction and improve the accuracy of insulation state evaluation. Firstly, the heat dissipation simulation model was constructed with full consideration of the real structure of the casing. On this basis, the conduction heat dissipation inside the bushing capacitor core, the external convection heat dissipation of the vertical wall and horizontal wall, and the radiation heat dissipation of the outer sheath surface to the environment were studied, and the temperature distribution characteristics of the bushing under different heat dissipation times were obtained. It is found that with the increase of heat dissipation time, the insulation temperature inside the bushing does not decrease at a constant rate, but shows an exponential downward trend, and the heat dissipation rate changes from fast to slow. In addition, the experiment shows that the error between the temperature curve of bushing oil temperature changing with time and the simulation curve is less than 6%, which verifies the accuracy of simulation. Furthermore, the FDS curves of several groups at constant temperature were obtained through testing. H-N relaxation function can accurately describe the relaxation process including interface polarization. Therefore, the nonlinear relationship between the characteristic parameters of the H-N dielectric relaxation model of the constant temperature FDS curves and temperature was inversed by using the particle swarm optimization (PSO) algorithm. Since the equivalent temperature cannot be expressed as an explicit expression, and the known data are more than the number of parameters to be solved, this paper uses the least square method (LS) to calculate the equivalent temperature of each frequency point in the FDS curves under the condition of time-varying temperature. Finally, the Arrhenius formula was used to achieve accurate correction of frequency point by point data under transient temperature. With 30℃, 60℃ and 90℃ as the reference temperature, the time-varying temperature curves under three different conditions were corrected. The results show that compared with the test results under 30℃, 60℃ and 90℃, the test results under time-varying temperature conditions are distorted in the low frequency part, and the curve shows a downward shift trend. The calibration results under three conditions are basically consistent with the test results under 30℃, 60℃ and 90℃, and the curve overlap well, which verifies the accuracy of the calibration model. Therefore, it can be concluded that the proposed correction method can effectively correct the test results under time-varying temperature conditions, which is helpful to the accurate evaluation of the insulation status of power equipment.
姚欢民, 穆海宝, 张大宁, 赵浩翔, 丁宁. 时变温度下油纸绝缘频域介电谱曲线校正方法研究[J]. 电工技术学报, 2023, 38(1): 246-257.
Yao Huanmin, Mu Haibao, Zhang Daning, Zhao Haoxiang, Ding Ning. Study on the Frequency Domain Spectroscopy Curves Correction Method of Oil-Paper Insulation at Time-Varying Temperature. Transactions of China Electrotechnical Society, 2023, 38(1): 246-257.
[1] 杨峰, 唐超, 周渠, 等. 基于等效电路的油纸绝缘系统受潮状态分析[J]. 电工技术学报, 2020, 35(21): 4586-4596. Yang Feng, Tang Chao, Zhou Qu, et al.Analyzing the moisture state of oil-paper insulation system using an equivalent circuital model[J]. Transactions of China Electrotechnical Society, 2020, 35(21): 4586-4596. [2] 范贤浩, 刘捷丰, 张镱议, 等. 融合频域介电谱及支持向量机的变压器油浸纸绝缘老化状态评估[J]. 电工技术学报, 2021, 36(10): 2161-2168. Fan Xianhao, Liu Jiefeng, Zhang Yiyi, et al.Aging evaluation of transformer oil-immersed insulation combining frequency domain spectroscopy and support vector machine[J]. Transactions of China Electrotechnical Society, 2021, 36(10): 2161-2168. [3] 邓映鑫, 杨丽君, 燕飞东, 等. 受潮油纸绝缘的非线性介电响应特性及H-W模型在时-频转换中的应用[J]. 电工技术学报, 2020, 35(21): 4609-4619. Deng Yingxin, Yang Lijun, Yan Feidong, et al.Nonlinear dielectric response characteristics of damp oil-impregnated pressboard insulation and application of H-W model in time-frequency conversion[J]. Transactions of China Electrotechnical Society, 2020, 35(21): 4609-4619. [4] Yao Huanmin, Mu Haibao, Ding Ning, et al.Evaluation method for moisture content of oil-paper insulation based on segmented frequency domain spectroscopy: from curve fitting to machine learning[J]. IET Science, Measurement & Technology, 2021, 15(6): 517-526. [5] Bandara K, Ekanayake C, Saha T K.Analysis of frequency domain dielectric response of pressboard insulation impregnated with different insulating liquids[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2016, 23(4): 2042-2050. [6] Zhang Daning, Yun Hao, Zhan Jiangyang, et al.Insulation condition diagnosis of oil-immersed paper insulation based on non-linear frequency-domain dielectric response[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2018, 25(5): 1980-1988. [7] Gutten M, Korenciak D, Brncal P, et al.Frequency diagnostics of insulating system of power transformers[J]. Electrical, Control and Communication Engineering, 2020, 16(1): 1-7. [8] Chakravorti S, Dey D, Chatterjee B. recent trends in the condition monitoring of transformers[M]. London: Springer London, 2013. [9] Fofana I, Hemmatjou H, Meghnefi F, et al.On the frequency domain dielectric response of oil-paper insulation at low temperatures[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2010, 17(3): 799-807. [10] Zukowski P, Rogalski P, Koltunowicz T N, et al.Influence of temperature on phase shift angle and admittance of moistened composite of cellulose and insulating oil[J]. Measurement, 2021, 185: 110041. [11] Wang Dongyang, Zhou Lijun, Wang Lujia, et al.Frequency domain dielectric response of oil gap in time-varying temperature conditions[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2017, 24(2): 964-973. [12] Liu Jiefeng, Fan Xianhao, Zhang Yiyi, et al.Frequency domain spectroscopy prediction of oil-immersed cellulose insulation under diverse temperature and moisture[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2020, 27(6): 1820-1828. [13] 冀田. 油纸电容式套管电场及温度场分析[D]. 沈阳: 沈阳工业大学, 2015. [14] Montsinger V M.Loading transformers by temperature[J]. Transactions of the American Institute of Electrical Engineers, 1930, 49(2): 776-790. [15] 王青于, 杨熙, 彭宗仁, 等. 应用三维电磁-热-流耦合场分析法计算换流变压器干式套管的温度场分布[J]. 中国电机工程学报, 2016, 36(22): 6269-6275. Wang Qingyu, Yang Xi, Peng Zongren, et al.3D coupled electromagnetic-thermal-fluid method for computation of temperature field of converter transformer RIP bushings[J]. Proceedings of the CSEE, 2016, 36(22): 6269-6275. [16] Bergman T L, Incropera F P, DeWitt D P, et al. Fundamentals of heat and mass transfer[M]. 7th ed. Hoboken, NJ: John Wiley, 2011 [17] 周利军, 李先浪, 王东阳, 等. 基于Havriliak-Negami介电弛豫模型的油纸绝缘状态评估[J]. 高电压技术, 2016, 42(1): 153-162. Zhou Lijun, Li Xianlang, Wang Dongyang, et al.Status assessment of oil-paper insulation based on Havriliak Negami dielectric relaxation model[J]. High Voltage Engineering, 2016, 42(1): 153-162. [18] Shan Zhiduo, Chen Qingguo, Fu Qiang.Analysis of dielectric response of epoxy-mica insulation with temperature normalization[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2020, 27(2): 574-580. [19] Dong Ming, Ren Ming, Wen Fuxin, et al.Explanation and analysis of oil-paper insulation based on frequency-domain dielectric spectroscopy[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2015, 22(5): 2684-2693. [20] Scaife B K P. Principles of dielectrics[M]. New York: Oxford University Press, 1989. [21] 赵孔双. 介电谱方法及应用[M]. 北京: 化学工业出版社, 2008. [22] 王力衡. 介质的热刺激理论及其应用[M]. 北京: 科学出版社, 1988. [23] Shroff D H, Stannett A W.A review of paper aging in power transformers[J]. IEE Proceedings C (Generation, Transmission and Distribution), 1985, 132(6): 312-319. [24] 胡一卓, 董明, 谢佳成, 等. 空间电荷引起的油纸绝缘低频弛豫现象研究[J]. 中国电机工程学报, 2020, 40(6): 2026-2038. Hu Yizhuo, Dong Ming, Xie Jiacheng, et al.Study of low frequency domain relaxation of oil-paper insulation caused by space charge[J]. Proceedings of the CSEE, 2020, 40(6): 2026-2038. [25] 赵小军, 徐华伟, 刘小娜, 等. 基于PSO-Powell混合算法的软磁复合材料二维矢量磁滞特性模拟[J]. 电工技术学报, 2021, 36(14): 2893-2903. Zhao Xiaojun, Xu Huawei, Liu Xiaona, et al.Two-dimensional vector hysteresis simulation of soft magnetic composite materials based on the hybrid algorithm of PSO-Powell[J]. Transactions of China Electrotechnical Society, 2021, 36(14): 2893-2903. [26] 任京攀, 马宏伟, 姚明清. 基于粒子群算法的飞轮阵列协调控制策略[J]. 电工技术学报, 2021, 36(增刊1): 381-388. Ren Jingpan, Ma Hongwei, Yao Mingqing.A coordinated control strategy of flywheel array based on particle swarm optimization algorithm[J]. Transactions of China Electrotechnical Society, 2021, 36(S1): 381-388. [27] Clerc M.Particle swarm optimization[M]. London: ISTE, 2006. [28] de Campos Souza P V. Pruning method in the architecture of extreme learning machines based on partial least squares regression[J]. IEEE Latin America Transactions, 2018, 16(12): 2864-2871. [29] Emsley A M, Stevens G C.Review of chemical indicators of degradation of cellulosic electrical paper insulation in oil-filled transformers[J]. IEE Proceedings - Science, Measurement and Technology, 1994, 141(5): 324-334.
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