机–热效应对换流变绝缘纸机械性能劣化影响的实验研究
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摘要
换流变压器的油纸绝缘系统处于强机械振动与热老化的综合作用环境中,其绝缘纸的劣化特性尚未引起足够重视。为研究机-热老化对绝缘纸机械性能劣化的协同作用,文中设计了高温振动老化箱,在130℃时添加频率为10Hz,振幅分别为0、1.99mm和2.64mm的加速老化试验,并对试品依次进行了抗拉强度测试、X射线衍射和扫描电镜分析以及聚合度测量。研究结果表明,机-热效应对绝缘纸机械性能劣化的促进作用显著高于热老化,且振幅越高,绝缘纸抗拉强度及聚合度的下降越明显。纤维素大分子链的取向使得纤维素的轴向机械强度远优于其径向机械强度,而外施力沿垂直于绝缘纸表面的分量大于平行于绝缘纸表面的分量,两因素共同加速机-热协同老化作用下绝缘纸机械性能的劣化。XRD和SEM分析显示,机-热协同老化使得绝缘纸微观结构中纤维的相对结晶度和晶粒尺寸变小,而微晶类型没有改变。同时,机-热协同作用促进了纤维的细化、分叉和断裂以及孔洞的出现、增加与发展,诸因素对绝缘纸机械性能的劣化共同起着促进作用。本研究可为分析换流变绝缘纸机-热综合作用下的劣化机理提供参考作用。
Oil-paper insulation system of converter transformer lies in a combination environment under which strong mechanical vibration and thermal are coupling, but the deterioration characteristics of insulation paper has not been paid enough attention. To study the mechanical-thermal synergy on the deterioration of insulation paper mechanical properties, thermal-vibration ageing box was designed. A series of accelerated ageing experiments were carried out under conditions of 130℃ thermal aging, added with vibration amplitude of 0, 1.99 mm and 2.64 mm at frequency 10 Hz, and ageing duration was 48 h, 96 h and 144 h respectively. The tensile strength(TS), X-ray diffraction(XRD) and scanning electron microscopy(SEM) analysis and the degree of polymerization(DP) were measured for the specimen. The results show that the promotion of mechanical-thermal synergy is sharper than that of thermal ageing, and the higher the amplitude, the more obvious the decrease of TS and DP of the insulation paper. Orientation of cellulose macromolecule chain makes the fiber axial mechanical strength is far superior to the radial one, and the perpendicular component of the applied force is higher than the one along to the surface of the insulation paper, the above two factors play a key synergy role to accelerate the deterioration of the insulation paper mechanical properties. XRD and SEM analysis indicate that, from a microstructure point, the relative crystallinity and microcrystal size of the cellulose fiber become smaller, whichindicates the type of microcrystalline doesn't change with ageing conditions. At the same time, the phenomena of refinement, bifurcation and breakage of fiber, and appearance, increase and development of holes, were found and they promoted the mechanical properties deterioration of the insulation paper. The study can provide a reference for the deterioration mechanism research of converter transformer insulation paper under the complex mechanical-thermal condition.
Oil-paper insulation system of converter transformer lies in a combination environment under which strong mechanical vibration and thermal are coupling, but the deterioration characteristics of insulation paper has not been paid enough attention. To study the mechanical-thermal synergy on the deterioration of insulation paper mechanical properties, thermal-vibration ageing box was designed. A series of accelerated ageing experiments were carried out under conditions of 130℃ thermal aging, added with vibration amplitude of 0, 1.99 mm and 2.64 mm at frequency 10 Hz, and ageing duration was 48 h, 96 h and 144 h respectively. The tensile strength(TS), X-ray diffraction(XRD) and scanning electron microscopy(SEM) analysis and the degree of polymerization(DP) were measured for the specimen. The results show that the promotion of mechanical-thermal synergy is sharper than that of thermal ageing, and the higher the amplitude, the more obvious the decrease of TS and DP of the insulation paper. Orientation of cellulose macromolecule chain makes the fiber axial mechanical strength is far superior to the radial one, and the perpendicular component of the applied force is higher than the one along to the surface of the insulation paper, the above two factors play a key synergy role to accelerate the deterioration of the insulation paper mechanical properties. XRD and SEM analysis indicate that, from a microstructure point, the relative crystallinity and microcrystal size of the cellulose fiber become smaller, whichindicates the type of microcrystalline doesn't change with ageing conditions. At the same time, the phenomena of refinement, bifurcation and breakage of fiber, and appearance, increase and development of holes, were found and they promoted the mechanical properties deterioration of the insulation paper. The study can provide a reference for the deterioration mechanism research of converter transformer insulation paper under the complex mechanical-thermal condition.
引文
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[17]Hill D J T,Le T T,Darveniza M,et al.A study of degradation of cellulosic insulation materials in a power transformer.Part 2:tensile strength of cellulose insulation paper[J].Polymer Degradation and Stability,1995,49(3):429-435.
[18]向彬,廖瑞金,张勇,等.电力变压器用绝缘纸热老化微观机理的X射线衍射分析[J].高压电器,2012,48(3):40-45,51.Xiang Bin,Liao Ruijin,Zhang Yong,et al.Aging micro-mechanism of oil-paper insulation in power transformers by XRD analysis[J].High Voltage Apparatus,2012,48(3):40-45,51(in Chinese).
[19]王世强,胡海燕,刘全桢,等.热老化对变压器绝缘纸微观结构影响的实验研究[J].高压电器,2016,52(2):93-96,102.Wang Shiqiang,Hu Haiyan,Liu Quanzhen,et al.Experimental research on thermal aging effects on microstructure of transformer paper[J].High Voltage Apparatus,2016,52(2):93-96,102(in Chinese).
[20]Oommen T V,Arnold L N.Cellulose insulation materials evaluated by degree of polymerization measurements[C]//Proceedings of the 15th Electrical Electronics Insulation Conference.USA,1981:257-261.
[21]Ekenstam A.The behavior of cellulose in mineral acid solutions:kinetic study of the decomposition of cellulose in acid solutions[J].Berichte der Deutschen Chemischen Gesellschaft,1936,69:553-559.
[22]Emsley A M.The kinetics and mechanisms of degradation of cellulosic insulation in power transformers[J].Polymer Degradation and Stability,1994,44(3):343-349.
[23]中华人民共和国国家质量监督检验检疫总局,中国国家标准化管理委员会.GB/T 1548-2004纸浆粘度的测定[S].北京:中国标准出版社,2004.General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China,Standardization Administration of China.GB/T 1548-2004 Pulps-Determination of viscosity[S].Beijing:China Standard Press,2004.
[24]Emsley A M,Heywood R J,Ali M,et al.Degradation of cellulosic insulation in power transformers.4.Effects of ageing on the tensile strength of paper[J].IEEProceedings-Science,Measurement and Technology,2000,147(6):285-290.
[25]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.
[26]Zou X,Uesaka T,Gurnagul N.Prediction of paper permanence by accelerated aging I.Kinetic analysis of the aging process[J].Cellulose,1996,3(1):243-267.
[27]Franklin A M.Simpler measurement of relative humidity in electrical insulating oils[J].Electrical Review,1974,194:373-375.
[28]Saha T K,Darveniza M,Yao Z T,et al.Investigating the effects of oxidation and thermal degradation on electrical and chemical properties of power transformers insulation[J].IEEE Transactions on Power Delivery,1999,14(4):1359-1367.
[29]高洁,汤烈贵.纤维素科学[M].北京:科学出版社,1996.Gao Jie,Tang Liegui.Cellulose science[M].Beijing:Science Press,1996.
[30]詹怀宇.纤维化学与物理[M].北京:科学出版社,2005.Zhan Huaiyu.Chemistry and physics of fibers[M].Beijing:Science Press,1996(in Chinese).
[31]马礼敦.近代X射线多晶体衍射-实验技术与数据分析[M].北京:化学工业出版社,2004.Ma Lidun.Modern X-ray polycrystal diffractionexperimental technology and data analysis[M].Beijing:Science Press,2004(in Chinese).
[32]Verma P,Roy M,Verma A,et al.Assessment of degradation of transformer insulation paper by SEM and X-RD techniques[C]//Proceedings of the 2004 IEEEInternational Conference on Solid Dielectrics,Toulouse,France:IEEE,2004:657-660.
[2]廖瑞金,解兵,杨丽君,等.油纸绝缘电-热联合老化寿命模型的比较与分析[J].电工技术学报,2006,21(2):17-21.Liao Ruijin,Xie Bing,Yang Lijun,et al.Analysis and selection of electrothermal life models used in oil-paper insulation[J].Transactions of China Electrotechnical Society,2006,21(2):17-21(in Chinese).
[3]廖瑞金,唐超,杨丽君,等.电力变压器用绝缘纸热老化的微观结构及形貌研究[J].中国电机工程学报,2007,27(33):59-64.Liao Ruijin,Tang Chao,Yang Lijun,et al.Research on the microstructure and morphology of power transformer insulation paper after thermal aging[J].Proceedings of the CSEE,2007,27(33):59-64(in Chinese).
[4]速水敏幸.电力设备的绝缘诊断[M].刘晓萱,译.北京:科学出版社,2003.Hayami Miyuki.Insulation diagnosis of electric power equipment[M].LIU Xiaoxuan,Translation.Beijing:Science Press,2003.
[5]Lessard M C,Van Nifterik L,Masse M,et al.Thermal aging study of insulating papers used in power transformers[C]//Proceedings of Conference on Electrical Insulation and Dielectric Phenomena-CEIDP'96.Millbrae,CA,USA:IEEE,1996:854-859.
[6]刘玉仙.变压器油纸绝缘的含湿分析及其对运行安全的影响[J].变压器,2002,39(5):1-6.Liu Yuxian.Moisture content analysis of oil-paper insulation in transformer and its influence on operation safety[J].Transformer,2002,39(5):1-6(in Chinese).
[7]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.
[8]赵畹君.高压直流输电工程技术[M].北京:中国电力出版社,2005:318-324.Zhao Wanjun.HVDC transmission engineering technology[J].Beijing:china electric power press,2005:318-324.
[9]He Jinliang,Yu Zhanqing,Zeng Rong,et al.Vibration and audible noise characteristics of AC transformer caused by HVDC system under monopole operation[J].IEEETransactions on Power Delivery,2012,27(4):1835-1842.
[10]Price P R.Geomagnetically induced current effects on transformers[J].IEEE Power Engineering Review,2002,22(6):62.
[11]Albertson V D,Bozoki B,Feero W E,et al.Geomagnetic disturbance effects on power systems[J].IEEETransactions on Power Delivery,1993,8(3):1206-1216.
[12]高沛,王丰华,苏磊,等.直流偏磁下电力变压器的振动特性[J].电网技术,2014,38(6):1536-1541.Gao Pei,Wang Fenghua,Su Lei,et al.Analysis on vibration characteristics of power transformer under DCbias[J].Power System Technology,2014,38(6):1536-1541(in Chinese).
[13]郭洁,黄海,唐昕,等.500 kV电力变压器偏磁振动分析[J].电网技术,2012,36(3):70-75.Guo Jie,Huang Hai,Tang Xin,et al.Analysis on 500 kVpower transformer vibration under DC magnetic biasing[J].Power System Technology,2012,36(3):70-75(in Chinese).
[14]Liu Zehong,Gao Liying,Wang Zuli,et al.R&D progress of±1100k V UHVDC technology[R].CIGREB4_201_2012,2012.
[15]?str?m U,Lescale V F,Menzies D,et al.The XiangjiabaShanghai 800 k V UHVDC project,status and special aspects[C]//2010 International Conference on Power System Technology.Hangzhou:IEEE,2010.
[16]李长云,王铮.机-热协同作用下绝缘纸机械性能的劣化机理[J].电工技术学报,2018,33(21):5090-5097.Li Changyun,Wang Zheng.The degradation mechanism of insulation paper mechanical properties with mechanical-thermal synergy[J].Transactions of China Electrotechnical Society,2018,33(21):5090-5097(in Chinese).
[17]Hill D J T,Le T T,Darveniza M,et al.A study of degradation of cellulosic insulation materials in a power transformer.Part 2:tensile strength of cellulose insulation paper[J].Polymer Degradation and Stability,1995,49(3):429-435.
[18]向彬,廖瑞金,张勇,等.电力变压器用绝缘纸热老化微观机理的X射线衍射分析[J].高压电器,2012,48(3):40-45,51.Xiang Bin,Liao Ruijin,Zhang Yong,et al.Aging micro-mechanism of oil-paper insulation in power transformers by XRD analysis[J].High Voltage Apparatus,2012,48(3):40-45,51(in Chinese).
[19]王世强,胡海燕,刘全桢,等.热老化对变压器绝缘纸微观结构影响的实验研究[J].高压电器,2016,52(2):93-96,102.Wang Shiqiang,Hu Haiyan,Liu Quanzhen,et al.Experimental research on thermal aging effects on microstructure of transformer paper[J].High Voltage Apparatus,2016,52(2):93-96,102(in Chinese).
[20]Oommen T V,Arnold L N.Cellulose insulation materials evaluated by degree of polymerization measurements[C]//Proceedings of the 15th Electrical Electronics Insulation Conference.USA,1981:257-261.
[21]Ekenstam A.The behavior of cellulose in mineral acid solutions:kinetic study of the decomposition of cellulose in acid solutions[J].Berichte der Deutschen Chemischen Gesellschaft,1936,69:553-559.
[22]Emsley A M.The kinetics and mechanisms of degradation of cellulosic insulation in power transformers[J].Polymer Degradation and Stability,1994,44(3):343-349.
[23]中华人民共和国国家质量监督检验检疫总局,中国国家标准化管理委员会.GB/T 1548-2004纸浆粘度的测定[S].北京:中国标准出版社,2004.General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China,Standardization Administration of China.GB/T 1548-2004 Pulps-Determination of viscosity[S].Beijing:China Standard Press,2004.
[24]Emsley A M,Heywood R J,Ali M,et al.Degradation of cellulosic insulation in power transformers.4.Effects of ageing on the tensile strength of paper[J].IEEProceedings-Science,Measurement and Technology,2000,147(6):285-290.
[25]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.
[26]Zou X,Uesaka T,Gurnagul N.Prediction of paper permanence by accelerated aging I.Kinetic analysis of the aging process[J].Cellulose,1996,3(1):243-267.
[27]Franklin A M.Simpler measurement of relative humidity in electrical insulating oils[J].Electrical Review,1974,194:373-375.
[28]Saha T K,Darveniza M,Yao Z T,et al.Investigating the effects of oxidation and thermal degradation on electrical and chemical properties of power transformers insulation[J].IEEE Transactions on Power Delivery,1999,14(4):1359-1367.
[29]高洁,汤烈贵.纤维素科学[M].北京:科学出版社,1996.Gao Jie,Tang Liegui.Cellulose science[M].Beijing:Science Press,1996.
[30]詹怀宇.纤维化学与物理[M].北京:科学出版社,2005.Zhan Huaiyu.Chemistry and physics of fibers[M].Beijing:Science Press,1996(in Chinese).
[31]马礼敦.近代X射线多晶体衍射-实验技术与数据分析[M].北京:化学工业出版社,2004.Ma Lidun.Modern X-ray polycrystal diffractionexperimental technology and data analysis[M].Beijing:Science Press,2004(in Chinese).
[32]Verma P,Roy M,Verma A,et al.Assessment of degradation of transformer insulation paper by SEM and X-RD techniques[C]//Proceedings of the 2004 IEEEInternational Conference on Solid Dielectrics,Toulouse,France:IEEE,2004:657-660.