摘要
六氟化硫(SF_6)气体具有优良的绝缘和灭弧性能,作为绝缘介质又可以大大减小设备尺寸,提高绝缘强度,已广泛地应用于气体绝缘组合电器(Gas Insulated Switchgear,简称GIS)中。纯净的SF_6气体化学性能稳定,不易分解。但局部放电、火花放电、电弧放电和过热作用会导致SF_6发生分解。通过分析气体分解组分来诊断SF_6气体绝缘电气设备的绝缘状况,目前已成为本领域研究的热点。
局部放电(Partial Discharge,简称PD)是表征设备绝缘性能的主要指标之一,而传统的电测法难以摆脱现场电磁信号的干扰,存在局限性。研究表明PD会导致SF_6气体发生分解,并且不同的PD原因下SF_6的分解特性不同。深入开展对SF_6分解产物的形成过程、相对含量关系、影响因素等的研究,提出以气体组分定量检测评判绝缘状况的理论与方法,对实现GIS绝缘缺陷引起突发性故障的早期诊断和预测有着重大意义。本文主要针对GIS早期绝缘缺陷产生的PD导致SF_6气体分解问题进行基础研究。
GIS内部常见的绝缘缺陷有高压导体突出物、自由导电微粒、绝缘子金属污染及气隙缺陷。本文利用建立的SF_6气体放电分解试验装置,并结合电气测量技术和气相色谱分析技术跟踪检测不同PD原因下SF_6的分解情况,研究GIS内部不同PD下SF_6分解特性及影响因素,寻找能有效表征绝缘故障类型的特征参量。
为此,本文构建了四种GIS典型绝缘缺陷物理模型,并对缺陷模型进行电场分布仿真,仿真结果表明四种缺陷模型在预定部位和可接受的电压阈值内均能产生PD。同时,建立了能有效分离SF_6放电分解组分的气相色谱定量检测系统,在此基础上,对不同绝缘缺陷PD下的SF_6分解气体进行96h跟踪检测,测量结果显示:SF_6局放分解的特征组分有SOF_2、SO_2F_2、CF_4和CO_2,且不同PD下SF_6的分解特性和产气规律存在明显差异。
研究发现,高压导体突出物PD稳定、放电能量大,SF_6产气量和分解速率高;自由导电微粒单次PD强度高,SOF_2/SO_2F_2较高;绝缘子表面金属污染由于PD涉及固体绝缘材料CF_4含量逐渐增加;绝缘子外气隙虽然PD强度较高,但产气量小。分析得出可以通过SOF_2/SO_2F_2、CO_2/CF_4、(SOF_2+SO_2F_2)/(CO_2+CF_4)三组含量比值初步判定四种绝缘缺陷类型,利用SOF_2/SO_2F_2监测PD强度及发展趋势,CF_4的含量变化在一定程度上反映GIS内绝缘材料的劣化情况。
For the excellent insulating and arc-quenching performance, SF_6 can significantly reduce the equipment size and improve the dielectric strength. It has been widely used in gas-insulated switchgear (hereinafter referred to as GIS) as insulating medium. Pure SF_6 is non-toxic and non-flammable inert gas. It has good stability and is difficult to decompose. However, partial discharge, spark discharge, electric arc and local overheating can cause SF_6 decomposition. At present, it has become a hot area of research that by way of analyzing the decomposition components to diagnose the insulation condition of SF_6 gas-insulated electrical equipment.
PD (Partial Discharge, referred to as PD) is the main indicator of insulation performance of equipment. However, the traditional measurement method is difficult to get rid of the electromagnetic disturbance in field. There are limitations. Researches show that PD can course SF_6 decomposition. And the decomposition characteristics has differences under various PD. Intensive study on the formation, mechanism and the relative content of SF_6 decomposition products in order to propose the judgments theory and method of insulation condition based on quantitative detection of decomposition components is significant to the realization of early diagnosis and prediction of GIS catastrophic failure caused by insulation defects. This paper mainly research on SF_6 decomposition characteristics under various PD of different insulation defects in GIS.
The typical insulation defects in GIS include high voltage metallic outshoot, free conductive particles, metallic contamination on insulator, insulator external gas-gap, insulator internal bubble defects. Based on the SF_6 discharge decomposition test equipment and combined with electrical measurement techniques and gas chromate- graphic analysis, SF_6 decomposition compositions under different PD were tracked and measured in this paper. The SF_6 decomposition characteristics, the development of insulation defects and influencing factors under different PD were studied in order to find effective characteristic parameters of fault types. Therefore, five kinds of physical model of typical insulation defects were constructed and the distribution of electric field of these models was analyzed by Finite Element Simulation. Simulation results showed that the defect models can raise PD in scheduled location and acceptable threshold voltage.
96 hours PD test was conducted for different insulation defects to cause SF_6 decomposition. The results showed that: The characteristic decomposition components of SF_6 under PD were CF_4, CO_2, SOF_2, and SO_2F_2, and due to different discharge energy, intensity, location, etc. in various PD the decomposition quantity and rate had significant differences. High voltage metallic outshoot PD had stable frequency and large energy. The decomposition rate of SF_6 was rapid and the gas production rate was high. Under high PD intensity of free conductive particles defect, SOF_2/SO_2F_2 was higher; Owing to involving solid insulating material in metallic contamination on insulator PD, CF_4 content increased gradually; In insulator external gas-gap defect PD intensity was high, but the total production was low. SOF_2 content is lower than SO_2F_2. Insulation defects can be preliminarily identified by analyzing SOF_2/SO_2F_2, CO_2/CF_4 and (SOF_2+SO_2F_2)/(CO_2+CF_4). Further, use SOF_2/SO_2F_2 to assess intensity and development trend of PD. Changes of CF_4 content can reflect degradation of the insulating material in GIS to some extent.
引文
[1]邱毓昌. GIS装置及其绝缘技术[M].水利水电出版社,1994.06.
[2] H. M. Heise, R. Kurte, P. Fischer, et al.“Gas analysis by infrared spectroscopy as a tool for electrical fault diagnostics in SF6 insulated equipment[J]. Fresenius Journal of Analytical Chemistry, Vol.358, No.7-8, Mar. 1997:793-799.
[3]苏舜. GIS内部放电监测方法的分析[J].东北电力技术. 1997.7, No.7: 7-11.
[4] M. Piemontesi, L. Niemeyer. Sorption of SF6 and SF6 decomposition products by activated alumina and molecular sieve 13X[C]. IEEE International Symposium on Electrical Insulation, Montreal, Quebec, Canada, Jun. 16-19, 1996:828-838.
[5] C.Beyer,H.Jenett and D.KFOCKOW. Influence of Reactive SFX Gases on Electrode Surfaces after Electrical Discharge ender SF6 Atmosphere[J]. IEEE Transactions on Dielectrics and Electrical Insulation, Vol.7, No.2, April 2000:234-240.
[6]国际电工委员会标准IEC60480-2004[S],中国电机工程学会高压专委会,2004.
[7]孙军彦.一起GIS设备放电事故的分析及处理[J].广西电力,2008,31(2):32-33.
[8]李英奇.渭南变电站330kV GIS历次事故简况及对策探讨[J].西安电力高等专科学校学报, 2008,3(1):53-55.
[9]梁之林,朱大铭,张英杰等.两起GIS组合电器事故原因分析及建议[J].电力设备,2007, 8(7):63-65.
[10]唐炬,李涛,万凌云等. SF6气体分解组分的多功能试验装置研制[J].高电压技术,2008, 34(8):52-57.
[11]张晓星,姚尧,唐炬等. SF6放电分解气体组分分析的现状和发展[J].高电压技术,2008, 34(4):37-42.
[12]连鸿松.根据SF6气体分解产物诊断电气设备故障[J].福建电力与电工, 2005, (3):21-24.
[13]刘有为,吴立远,肖燕等.输变电设备特征参量的研究[R].北京:中国电力科学研究院, 2009.
[14]刘卫东,金立军等.日本SF6电器局部放电监测技术研究近况[J].高电压技术, 2001, Vol.27, No.2: 76-77.
[15] D. Edelson, et al..Electrical Decomposition of SF6"[J]. Industrial and Engineering Chemistry, Vol.45, NO.19, September 1953:2094-2096.
[16] W. Leeds, F. Browne, and A. Strom.The Use of SF6 -Cor High Power Arc Quenching[J]. Power Apparatus and Systems, Part III. Transactions of the American Institute of Electrical Engineers.Vol. 76, NO.6, 1957:906-909.
[17] B. Gerasimov and T. Sidorkina.Kinetics and mechanism of crack growth during stress corrosi- on cracking of zirconium alloys[J]. Materials and Corrosion.Vol. 32, NO.11,1982:485-488.
[18] W. Becher and J. Massonne.Contribution to the Study of the Decomposition of SF6 in Electric Arcs and Sparks[J].Power Apparatus and Systems, Part III. Transactions of the American Institute of Electrical Engineers,Vol. 91, No. 11.1970:605-610.
[19] C. Boudene, J-L Cluet, G. Keib, and G. Wind,"Identification and Study of Some Properties of Compounds Resulting from the Decomposition of SF6 under the Effect of Electrical Arcing in Circuit-Breakers[J] Revue Generale Electricite– Special Issue, June 1974:45-78.
[20] B. Bartakova, J. Krump and V. Vosahlik. Effect of Electric Partial Discharge in SF6[C]. Electrotechnichy Obzor, Prague, 67, 1978:230-233.
[21] J. Kulseta, A. Rein, and P. A. Holt.Arcing in SF6 Insulated Equipment, Decomposition Products and Pressure Rise[J].Proc. Nordic Insulation Symposium, NORD-IS, Vol. 78, June 1978.
[22] H. Grasselt, W. Ecknig, and H. J. Polster,"Applications of Gas Chromatography for the Development of SF6 Insulated Switchgear and Equipment[J] Elektrie, Vol. 32, 1978:369-371.
[23] A. Baker, R. Dethlefsen, J. Dodds, N. Oswalt and P. Vouros.Study of Arc By-Products in Gas-Insulated Equipment[C].EPRI Report No. EL-1646, December 1980.
[24] R.Thorburn.Permanent Dissociation of SF6 in Corona Discharge[J]. Nature, Vol. 175, 1955:423.
[25] J. Manion, J. Philosophos, and M. Robinson.Arc Stability of Electronegative Gases[J]. IEEE Transactions on Dielectrics and Electrical Insulation.Vol.1, No.1 1967:1-10.
[26] J. Castonguay.Kinetics of the Arc Decomposition of SF6-Gas Mixtures[S].Proc. IEEE Intl. Symp. On Elect. Insulation, June 1980.
[27] F. Y. Chu, H. Stuckless, and J. M. Braun,"Generation and Effects of Low Level Contamination in SF6 Insulated Equipment[M].Gaseous Dielectrics IV, L. G. Christophorou and M. O. Pace (Eds.) Pergamon Press, 1984:462-472.
[28] L. C. Frees, I. Sauers, H. W. Ellis, and L. G. Christophorou.Positive Ions in Spark Breakdown of SF6[J].Journal of Physics D: Applied Physics,Vol.14, NO.9, 1981:1629-1642.
[29] I. Sauers, L. G. Christophorou, L. C. Frees, and H. W. Ellis.Aspects of Environmental Effects of Dielectric Gases[M]. Gaseous Dielectrics III, L.G.Christophorou (Ed.) Pergamon Press, 1982:387.
[30] I. Sauers, H. W. Ellis, L. C. Frees, and L. G.Christophorou.Studies of Spark Decomposition Products of SF6 and SF6 Perfluorocarbon Mixtures"[M].Gaseous Dielectrics III, L. G. Christophorou(Ed.) Pergamon Press,1982:387-401.
[31] I.Sauers, L.G. Christophorou and S.M. Spyrou. "Negative Ion Formation in SF6 Spark- By-Products[M].Gaseous Dielectrics IV, L. G. Christophorou and M. O. Pace (Eds.) PergamonPress, 1984:292-309.
[32] K. Hirooka and M. Shirai.Thermal Characteristics of SF6[J]. Chem. Soc. Japan, Vol.2, NO.25, 1980:165-169.
[33] P. G. Ashbaugh, D. W. McAdam and M. F. James,"SF6 - Its Properties and Uses as a Gaseous Insulator in Van der Graaf Accelerators"[J].IEEE Trans on Nuclear Science, NS-12, June 1965:266.
[34] R. R. Smardzewski, R. E. Noftle, and W. B. Fox,"Argon Matric Raman and Infrared Spectra of SF5Cl, SF5Br and S2Fl0[J].Journal of Molecular Spectroscopy, Vol.62, NO.12, 1976:449-457.
[35] B. Bartakova, J. Krump and V. Vosahlik.Effect of Electric Partial Discharge in SF6[J]. Electrotechnichy Obzor, Prague, 67, 1978:230.
[36] R, J. Van Brunt and D. A. Leep.Corona-Induced decomposition of SF6 [M].Gaseous Dielectrics IV,L. G. Christophorou and M. O. Pace (Eds.) Pergamon Press, N.Y,1982: 402-409.
[37] R. J. Van Brunt and M. Mashikian.Mechanisms for Inception of DC and 60-Hz AC Corona in SF6[J]. IEEE Transaction on Electrical Insulation, Vol.17, No.2, 1982: 106-120.
[38] R. J. Van Brunt and M. Mashikian.Role of Photodetachment in Initiation of Electric Discharges in SF6 and O2[J].Journal of Applied Physics Vol.54,NO.6, June 1983: 3074-3079.
[39] R. J. Van Brunt, T. C. Lazo, and W. E. Anderson,"Production Rates for Discharge Generated SOF2, SO2F2 and SO2 in SF6 and SF6/H2O Mixtures[M].Gaseous Dielectrics IV, L. G. Christophorou and M. O. Pace (Eds.) Pergamon Press, 1984: 276-285.
[40] R. J. Van Brunt.Production Rates for Oxy-fluorides SOF2, SO2F2 and SOF4 in SF6 Corona Discharge [J] National Bureau of Standards of Reserach,Vol. 90, No. 3, May 1985:229-253.
[41] F. Y. Chu, H. Stuckless, and J. M. Braun,"Generation and Effects of Low Level Contamination in SF6 Insulated Equipment[M].Gaseous Dielectrics IV, L. G. Christophorou and M. O. Pace (Eds.) Pergamon Press, 1984:462-472.
[42] S. Kusumoto, S. Itoh, Y. Tsuchiya, H. Mukae, and K. Takahashi.Diagnostic Technique of Gas Insulated Substation by Partial Discharge Detection[J].IEEE Transactions on Power Apparatus and Systems, Vol.99,No.4, July/August 1980: 1456.
[43] L.M.Babcock and G.E. Streit. Negative Ion-Molecule Reactions of SF4[J]. Chem.Phys, Vol.75, No.8, 1981:3864-3870.
[44] R, J. Van Brunt and I, T. Herron. Plasma chemical model for decomposition of SF6 in a negative glow corona discharge[J], Phys.Scripta, Vol.53,1994:9-29.
[45] Belarbi, A., C. Praday:rol, J. Casanovas and A.M. Casanovas. Influence of Discharge Production Conditions, as Pressure, Current Intensity and Voltage Type on SF6 Dissociation under Point-Plane Corona Discharges[J]. Appl. Phys, Vol. 77, No.4, February 1995:1398-1406.
[46] L.G. Christophorou and J.K. Olthoff. Electron interactions with SF6[J]. Phys. Chem. Ref.Data, Vol.29,2000:267-330.
[47] R. J. Van Brunt. Physics and chemistry of partial discharge and corona-Recent advances and future challenges. IEEE Trans. Dielectrics Electrical Insulation, Vol.1,1994.Oct:761-784.
[48]刘有为,吴立远,弓艳朋. GIS设备气体分解物及其影响因素研究[J].电网技术, 2009.3,33(5): 58-61.
[49] L. J. Jin, J.Q.Huang, W.D.Liu, J.L.Qian. Diagnosis of Partial Discharge in GIS based on UHF Sensing Technique[C]. Proceedings of 2001 International Symposium on Electrical Insulating Materials, November, 2001, Himeji, Japan: 251~253.
[50] Masatake Kawada, Zen-Ichiro Kawasaki and Kenji Matsu-ura. A New on-line Insulation Diagnostic Technique for Power Apparatus by Detecting Electromagnetic Signals Emitted frim PD[C]. 1996 Asian International Conference on Dielectrics and Electrical Insulation, 4th Japan-China Conference on Electrical Insulation Diagnosis, Xi'an, China, October, 1996: 325~328.
[51] Uwe Schichler, J?rg Gorablenkow. Experience with UHF PD Detection in GIS Substations[C]. Proceedings of the 6th International Conference on Properties and Applications of Dielectric Materials, Xi’an, China, June, 2000: 286~289.
[52]罗学琛. SF6气体绝缘全封闭组合电器[M].中国电力出版社,1998.11.
[53] I.J. Kemp. Partical discharge plant-monitoring technology:Present and future developments[J] IEE Proc.-Sci. Mens. Technol, Vol.142, No.1, January 1995:4-10.
[54] R.Kurte.C. Beyer H. M. Heise D. Klockow Application of infrared spectroscopy to monitoring gas insulated high-voltage equipment:electrode material-dependent SF6 decomposition[J] Anal Bioanal Chem.(2002)373:639-646.
[55]陈家斌. SF6断路器实用技术[M].中国水利水电出版社, 2004,4.
[56] D. Edelson, K. B. McAffe.Notes on the Infrared Spectrum of SF6,[J].Chem. Phys, Vol.19, No.10, October 1951:1311.
[57]黎明. SF6气体及气体绝缘变电站的运行[M].水利水电出版神, 1993.12.
[58] A.Derdouri and J.Casanovas. Spark Decomposition Mixtures of SF6/H2O[J]. IEEE Transactions on Electrical Insulation, Vol.24, No.6, December 1989:1147-1157.
[59] Piemontesi, M. and W.Zaengl. Analysis of Decomposition Products of Sulfur Hexafluroride by Spark Discharge at Different Spark Energies[C]. 9th International Symposium on High Voltage Engineering, August 28-September 1, 1995,Graz:2283-1-2283-4.
[60] S. A. Boggs, F. Y. Chu, and N. Fujimoto.Disconnect Switch Induced Transients and Trapped Charge in GIS[J].IEEE Transection on Power and Systems, Vol.101, October 1982.
[61] B. Belmadani et al. SF6 Decomposition under Power Arcs: Physical Aspects. IEEE Transactions on Electrical Insulation, Vol.26, No.6, December 1991:1163-1176.
[62] N. Fujimoto, S.J. Croall and S.M. Foty,"Techniques for the protention of GIS-insulated of substation to cable interfaces[J].IEEE Transactions on Power Delivery, Vol. 3, No. 4, October 1988:1650-1655.
[63] E. Schulz-Guide.Temperature Determination for Arcs in SF6 Accounting for Demixing[J]. Journal of Physics D: Applied Physics, Vol.13, No.5, 1980: 793-803.
[64] ASTM.Specification D 2472-81[S].Annual Books of ASTM Standards, 1984.
[65] F. Y. Chu, J. M. Braun, R. Seethapathy, and L.Gonzalex.A New Approach to Moisture Measurement and Control in Gas Insulated Switchgear[C]. Proc.of Canadian Electrical Association Spring Meeting, Toronto, March 1986.
[66] J. J. Dodds.Moisture Measurements in GIS[C].Doble Client Conference, Boston, 1985.
[67] J. P. McGeehan, B. C. O'Neill, A. N. Prasad, and J. D. Craggs.Negative Ion/Molecule Reactions in SF6 [J].Journal of Physics D: Applied Physics, Vol. 8, 1975:153.
[68] M. Goldman and A. Goldman. The Effects of Pulsed Corona Discharge on SO2 Absorption into Water"[J].Ind. Eng. Chem. Res.Vol.40, No.24,2001:5822–5830.
[69] Prakash K S , Srivastava K D, Morcos M M. Movement of particles in compressed SF6 GIS with dielectric coated enclosure[J] .IEEE Trans on Dielectrics and Eelectrical Insulation , 1997 , 4(3) : 344-347.
[70] Brunt R J V,Sauers I. Gas-phase hydrolysisof SOF2 and SOF4 [J]. Chem Phys, 1986, 85(8): 4377-4380.
[71] Rapp D, Englander-Golden P. Ionization by electron impact [J]. Chem Phys,1965,43 (5): 1464
[72] G. Camilli, G. S. Gordon, and R. E. Plump,"Gaseous Insulation for High-Voltage Transformers [J].Trans.of AIEE, January 1952: 348-357.
[73] G. D. Griffin, I. Sauers, L. G. Christophorou,C. E. Easterly, and P. J. Walsh.On the Toxicity of Sparked SF6[J].IEEE Transactions on Electrical Insulation,Vol. EL-18, No.5, October 1983: 551-552.
[74] S.Okabe, T.Kawashima, H. Wada.“Deterioration characteristics of insulation subjected to partial discharge in SF6 gas[C]. IEEE Transmission and Distribution Conference and Exhibition: Asia Pacific. Vol.2, Oct. 6-10 2002:792-797.
[75] M. Honda, H. Aoyagi, M. Koya, N. Kobayashi, and S. Nemju. Deterioration of Eposy Mold Insulators due to Voltage Endurance[M].Gaseous Dielectrics III. L. G. Christophorou (Ed.) Pergamon Press, 1982:322-326.
[76] S. Fukuda. Current-Carrying and Short Circuit Tests on EHV Cables Insulated with SF6Gas[J].IEEE Trans. PAS, PAS-88, No. 2, February 1969:147-156.
[77] Y. Murakami and S. Menju. Fundamental Techniques in Gas-Insulated Apparatus[J].Toshiba Review, Vol.117, September 1978:5.
[78]金立军,刘卫东等. GIS金属颗粒局部放电的试验研究[J]. 2002.6, 38(3):10-13.
[79]张国强,张元录,崔翔.高压套管均压球电极形状优化的研究[J].中国电机工程学报,1999, 19 (1): 37-40.
[80]傅若农.色谱分析概论[M].北京:化学工程出版社.2005.
[81]梁汉昌.气相色谱法在气体分析中的应用[M].化学工业出版社.2008.