油浸式变压器匝间纸绝缘中水分扩散特性
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摘要
匝间纸绝缘是决定油浸式变压器纵绝缘水平的重要绝缘结构之一,因其常由多层绝缘纸绕制而成,故水分在其中的扩散特性与在厚纸板中的有所不同。另外,相比于其他部位的固体绝缘,匝间纸绝缘要承受更高的温度和更快的温度变化,因此其内部水分的扩散更为明显。论文首先探讨了匝间纸绝缘与厚纸板在结构方面的差异,并在已有理论的基础上对典型匝间纸绝缘中水分的扩散过程建立了数学模型;然后设计了三类相同厚度、不同层数的纸绝缘模型,通过实验研究了典型纸绝缘在厚度方向上的水分分布特征及其随时间的变化规律,并研究了温度对水分分布和扩散速度的影响;最后将实验数据转化为离散形式并代入模型求解,获得了模型中特征系数与水分、温度的函数关系,研究了绝缘纸层数对水分扩散速度的影响。实验结果表明:温度对水分在多层绝缘纸中扩散速度的影响较为显著,同等厚度纸绝缘的层数越多,水分扩散就越慢。进一步分析发现,不同层数的纸绝缘模型所对应的特征系数之间存在差异,结合典型纸绝缘的结构特征分析表明,相邻纸层间微油隙的存在是造成这一差异的主要原因。
In oil-impregnated transformers, paper insulation between turns determines the series insulation strength of the facility. For the multilayer structure of the paper insulation, the diffusion process of moisture in it differs from that in thick pressboard. Besides, compared to the solid insulation elsewhere in the facility, paper insulation between turns endures higher temperature with faster rising speed, which leads to an obvious moisture diffusion. We comparatively investigated the difference in structure between multilayer paper and thick-pressboard. Based on the existing theory, a discrete mathematical model was set up to simulate the migration process of moisture in turn-to-turn paper insulation. Thereafter, we designed three types of paper insulation models with the same thickness and different layers. In the experiment, we investigated the characteristic of moisture distribution in paper layers in the thickness direction and its variation with time and the influence of temperature on moisture distribution and its diffusion speed were experimentally studied. The experiment results were discretized and put in the mathematical model, and the relevant characteristic coefficients related to the moisture content and temperature were obtained. Relations between the layer of insulation paper and the moisture migration process were also experimentally studied. Results show that temperature significantly influences the moisture diffusion speed in multilayer paper insulation. Besides, the speed of moisture diffusion speed decreases with increasing layers of the paper insulation with the same thickness. Further analysis show that the characteristic coefficients related to moisture diffusion differ among different models. Finally, taking the structure features of typical paper insulation into consideration, we have found that micro oil gap existing between paper layers leads to the difference of moisture diffusion speed in different models.
In oil-impregnated transformers, paper insulation between turns determines the series insulation strength of the facility. For the multilayer structure of the paper insulation, the diffusion process of moisture in it differs from that in thick pressboard. Besides, compared to the solid insulation elsewhere in the facility, paper insulation between turns endures higher temperature with faster rising speed, which leads to an obvious moisture diffusion. We comparatively investigated the difference in structure between multilayer paper and thick-pressboard. Based on the existing theory, a discrete mathematical model was set up to simulate the migration process of moisture in turn-to-turn paper insulation. Thereafter, we designed three types of paper insulation models with the same thickness and different layers. In the experiment, we investigated the characteristic of moisture distribution in paper layers in the thickness direction and its variation with time and the influence of temperature on moisture distribution and its diffusion speed were experimentally studied. The experiment results were discretized and put in the mathematical model, and the relevant characteristic coefficients related to the moisture content and temperature were obtained. Relations between the layer of insulation paper and the moisture migration process were also experimentally studied. Results show that temperature significantly influences the moisture diffusion speed in multilayer paper insulation. Besides, the speed of moisture diffusion speed decreases with increasing layers of the paper insulation with the same thickness. Further analysis show that the characteristic coefficients related to moisture diffusion differ among different models. Finally, taking the structure features of typical paper insulation into consideration, we have found that micro oil gap existing between paper layers leads to the difference of moisture diffusion speed in different models.
引文
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[10]TU Y,CHEN J,WANG S,et al.Moisture migration in oil-impregnated film insulation under thermal ageing[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,23(2):1135-1141..
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[13]OOMMEN T V.Moisture equilibrium charts for transformer insulation drying practice[J].IEEE Transactions on Power Apparatus and Systems,1984,4(10):3062-3067.
[14]林元棣,廖瑞金,夏桓桓,等.油纸绝缘微水二次扩散过渡过程的分析[J].电工技术学报,2016,31(10):16-25.LIN Yuandi,LIAO Ruijin,XIA Huanhuan,et al.Analysis of transition process during secondary diffusion of moisture in oil-paper insulation[J].Transactions of China Electrotechnical Society,2016,31(10):16-25.
[15]徐征宇,程涣超,汪可,等.高寒条件下变压器油击穿特性试验[J].高电压技术,2015,41(4):1342-1348.XU Zhengyu,CHENG Huanchao,WANG Ke,et al.Experimental research on breakdown characteristics of transformer oil at extremely-low temperature[J].High Voltage Engineering,2015,41(4):1342-1348.
[16]PRZYBYLEK P,NADOLNY Z,MOSCICKA-GRZESIAK H.Bubble effect as a consequence of dielectric losses in cellulose insulation[J].IEEE Transactions on Dielectrics and Electrical Insulation,2010,17(3):913-919.
[17]OOMMEN T V,LINDGREN S R.Bubble evolution from transformer overload[C]∥Transmission and Distribution Conference and Exposition.[S.l.]:IEEE,2001,1:137-142.
[18]VILLARROEL R,GARCíA B,BURGOS J C,et al.Experimental study on moisture dynamics in transformers insulated with natural-esters[C]∥2013 IEEE International Conference on Solid Dielectrics.Bologna,Italy:IEEE,2013:545-548.
[19]LI J,ZHANG Z,GRZYBOWSKI S,et al.Characteristics of moisture diffusion in vegetable oil-paper insulation[J].IEEE Transactions on Dielectrics and Electrical Insulation,2012,19(5):1650-1656.
[20]PREVOST T A,OOMMEN T V.Cellulose insulation in oil-filled power transformers:part I-history and development[J].IEEE electrical insulation magazine,2006,1(22):28-35.
[21]OOMMEN T V,PREVOST T A.Cellulose insulation in oil-filled power transformers:part II-maintaining insulation integrity and life[J].IEEE Electrical Insulation Magazine,2006,22(2):5-14.
[22]LIAO R J,ZHU M Z,YANG L J,et al.Molecular dynamics study of water molecule diffusion in oil-paper insulation materials[J].Physica B:Condensed Matter,2011,406(5):1162-1168.
[23]ZHU C Y,DUAN Z Q,GAO X Q,et al.Diffusion of amino acids in non-Newtonian fluids[J].Chinese Journal of Chemical Engineering,2006,14(4):450-455.
[24]GARCIA B,BURGOS J C,ALONSOáM,et al.A moisture-in-oil model for power transformer monitoring-part II:experimental verification[J].IEEE Transactions on Power Delivery,2005,20(2):1423-1429.
[25]方晓鹏,宣益民,李强.纳米流体传质扩散系数的测定[J].工程热物理学报,2011,32(2):277-280.FANG Xiaopeng,XUAN Yimin,LI Qiang.Measurements of mass diffusivity of nanoliquids[J].Journal of Engineering Thermophysics,2011,32(2):277-280.
[26]BAGHERI M,NADERI M S,BLACKBURN T,et al.Dean-Stark vs FDS and KFT methods in moisture content recognition of transformers[C]∥2012 IEEE International Conference on Power and Energy.Kota Kinabalu,Malaysia:IEEE,2012:712-717.
[27]PIPER J D.Moisture equilibrium between gas space and fibrous materials in enclosed electric equipment[J].Electrical Engineering,1946,65(12):791-797.
[28]廖瑞金,严家明,杨丽君,等.局部放电对油浸绝缘纸表面损伤特性研究[J].中国电机工程学报,2011,31(10):129-137.LIAO Ruijin,YAN Jiaming,YANG Lijun,et al.Characteristics of partial dis-charge-caused surface damage for oil-impregnated insulation paper[J].Proceedings of the CSEE,2011,31(10):129-137.
[29]邹平,李剑,孙才新,等.植物绝缘油纸浸渍模型与试验研究[J].中国电机工程学报,2011,31(25):125-131.ZOU Ping,LI Jian,SUN Caixin,et al.Impregnation model and experimental investigation of vegetable insulating oil-paper insulation[J].Proceedings of the Chinese Society of Electrical Engineering,2011,31(25):125-131.
[30]SUZUKI T,TAKAGI M.Oil impregnation in transformer boards(1)measurement of impregnation depth and internal pressure[J].IEEETransactions on Electrical Insulation,1984,19(4):340-343.
[31]SUZUKI T,TAKAGI M.Oil impregnation in transformer boards(2)theoretical analysis of changes in impregnation depth[J].IEEE Transactions on Electrical Insulation,1984,19(4):344-349.
[32]MAGDA J J,TIRRELL M,DAVIS H T.Molecular dynamics of narrow,liquid-filled pores[J].The Journal of Chemical Physics,1985,83(4):1888-1901.
[2]周远翔,戴超,黄猛,等.热老化过程中老化温度对油纸绝缘空间电荷特性的影响[J].高电压技术,2016,42(3):868-875.ZHOU Yuanxiang,DAI Chao,HUANG Meng,et al.Effect of aging temperature on space charge characteristics in process of thermal aging[J].High Voltage Engineering,2016,42(3):868-875.
[3]YI X,WANG Z D.The influences of solid surface on the propagation of creepage discharge in insulating liquids[J].IEEE Transactions on Dielectrics and Electrical Insulation,2015,22(1):303-312.
[4]杨丽君,廖瑞金,孙会刚,等.油纸绝缘热老化特性及生成物的对比分析[J].中国电机工程学报,2008,28(22):53-58.YANG Lijun,LIAO Ruijin,SUN Huigang,et al.Contrasting analysis and investigation on properties and products of oil-paper during thermal aging process[J].Proceedings of the CSEE,2008,28(22):53-58.
[5]廖瑞金,汪可,尹建国,等.初始水分含量对油纸绝缘热老化特性的影响[J].高电压技术,2012,38(5):1172-1178.LIAO Ruijin,WANG Ke,YIN Jianguo,et al.Influence of Initial moisture on thermal aging characteristics of oil-paper insulation[J].High Voltage Engineering,2012,38(5):1172-1178.
[6]ARALKELLIAN V G,FOFANA I.Water in oil-filled,high-voltage equipment,part I:states,solubility,and equilibrium in insulating materials[J].IEEE Electrical Insulation Magazine,2007,23(4):15-27.
[7]ARAKELIAN V G,FOFANA I.Water in oil-filled high-voltage equipment part II:water content as physicochemical tools for insulation condition diagnostic[J].IEEE Electrical Insulation Magazine,2007,23(5):15-24.
[8]SHUKLA P,SOOD Y R,JARIA R K.Experimental evaluation of water content in transformer oil[J].International Journal of Innovative Research of Science Engineering Technology,2013,2(1):284-291.
[9]PUDIPEDDI M,SERAJUDDIN A T M,GRANT D J W,et al.Solubility and dissolution of weak acids,bases,and salts[M].Handbook of pharmaceutical salts,properties,selection,and use.Zurich,Switzerland:Verlag Helvetica Chimica Acta and Weinheim,Wiley-VCH,Weinheim,Federal Republic of Germany:Wiley-VCH,2002.
[10]TU Y,CHEN J,WANG S,et al.Moisture migration in oil-impregnated film insulation under thermal ageing[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,23(2):1135-1141..
[11]IOELOVICH M,LEYKIN A.Study of sorption properties of cellulose and its derivatives[J].BioResources,2010,6(1):178-195.
[12]PRZYBYLEK P.The influence of temperature and aging of cellulose on water distribution in oil-paper insulation[J].IEEE Transactions on Dielectrics and Electrical Insulation,2013,20(2):552-556.
[13]OOMMEN T V.Moisture equilibrium charts for transformer insulation drying practice[J].IEEE Transactions on Power Apparatus and Systems,1984,4(10):3062-3067.
[14]林元棣,廖瑞金,夏桓桓,等.油纸绝缘微水二次扩散过渡过程的分析[J].电工技术学报,2016,31(10):16-25.LIN Yuandi,LIAO Ruijin,XIA Huanhuan,et al.Analysis of transition process during secondary diffusion of moisture in oil-paper insulation[J].Transactions of China Electrotechnical Society,2016,31(10):16-25.
[15]徐征宇,程涣超,汪可,等.高寒条件下变压器油击穿特性试验[J].高电压技术,2015,41(4):1342-1348.XU Zhengyu,CHENG Huanchao,WANG Ke,et al.Experimental research on breakdown characteristics of transformer oil at extremely-low temperature[J].High Voltage Engineering,2015,41(4):1342-1348.
[16]PRZYBYLEK P,NADOLNY Z,MOSCICKA-GRZESIAK H.Bubble effect as a consequence of dielectric losses in cellulose insulation[J].IEEE Transactions on Dielectrics and Electrical Insulation,2010,17(3):913-919.
[17]OOMMEN T V,LINDGREN S R.Bubble evolution from transformer overload[C]∥Transmission and Distribution Conference and Exposition.[S.l.]:IEEE,2001,1:137-142.
[18]VILLARROEL R,GARCíA B,BURGOS J C,et al.Experimental study on moisture dynamics in transformers insulated with natural-esters[C]∥2013 IEEE International Conference on Solid Dielectrics.Bologna,Italy:IEEE,2013:545-548.
[19]LI J,ZHANG Z,GRZYBOWSKI S,et al.Characteristics of moisture diffusion in vegetable oil-paper insulation[J].IEEE Transactions on Dielectrics and Electrical Insulation,2012,19(5):1650-1656.
[20]PREVOST T A,OOMMEN T V.Cellulose insulation in oil-filled power transformers:part I-history and development[J].IEEE electrical insulation magazine,2006,1(22):28-35.
[21]OOMMEN T V,PREVOST T A.Cellulose insulation in oil-filled power transformers:part II-maintaining insulation integrity and life[J].IEEE Electrical Insulation Magazine,2006,22(2):5-14.
[22]LIAO R J,ZHU M Z,YANG L J,et al.Molecular dynamics study of water molecule diffusion in oil-paper insulation materials[J].Physica B:Condensed Matter,2011,406(5):1162-1168.
[23]ZHU C Y,DUAN Z Q,GAO X Q,et al.Diffusion of amino acids in non-Newtonian fluids[J].Chinese Journal of Chemical Engineering,2006,14(4):450-455.
[24]GARCIA B,BURGOS J C,ALONSOáM,et al.A moisture-in-oil model for power transformer monitoring-part II:experimental verification[J].IEEE Transactions on Power Delivery,2005,20(2):1423-1429.
[25]方晓鹏,宣益民,李强.纳米流体传质扩散系数的测定[J].工程热物理学报,2011,32(2):277-280.FANG Xiaopeng,XUAN Yimin,LI Qiang.Measurements of mass diffusivity of nanoliquids[J].Journal of Engineering Thermophysics,2011,32(2):277-280.
[26]BAGHERI M,NADERI M S,BLACKBURN T,et al.Dean-Stark vs FDS and KFT methods in moisture content recognition of transformers[C]∥2012 IEEE International Conference on Power and Energy.Kota Kinabalu,Malaysia:IEEE,2012:712-717.
[27]PIPER J D.Moisture equilibrium between gas space and fibrous materials in enclosed electric equipment[J].Electrical Engineering,1946,65(12):791-797.
[28]廖瑞金,严家明,杨丽君,等.局部放电对油浸绝缘纸表面损伤特性研究[J].中国电机工程学报,2011,31(10):129-137.LIAO Ruijin,YAN Jiaming,YANG Lijun,et al.Characteristics of partial dis-charge-caused surface damage for oil-impregnated insulation paper[J].Proceedings of the CSEE,2011,31(10):129-137.
[29]邹平,李剑,孙才新,等.植物绝缘油纸浸渍模型与试验研究[J].中国电机工程学报,2011,31(25):125-131.ZOU Ping,LI Jian,SUN Caixin,et al.Impregnation model and experimental investigation of vegetable insulating oil-paper insulation[J].Proceedings of the Chinese Society of Electrical Engineering,2011,31(25):125-131.
[30]SUZUKI T,TAKAGI M.Oil impregnation in transformer boards(1)measurement of impregnation depth and internal pressure[J].IEEETransactions on Electrical Insulation,1984,19(4):340-343.
[31]SUZUKI T,TAKAGI M.Oil impregnation in transformer boards(2)theoretical analysis of changes in impregnation depth[J].IEEE Transactions on Electrical Insulation,1984,19(4):344-349.
[32]MAGDA J J,TIRRELL M,DAVIS H T.Molecular dynamics of narrow,liquid-filled pores[J].The Journal of Chemical Physics,1985,83(4):1888-1901.