中压配电网新型接地方式应用研究
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摘要
中压配电网中性点接地方式是个综合性的技术问题,它关系到系统过电压、绝缘配合、通信干扰、故障选线、系统可靠性和安全性等很多方面。
近年来,随着经济的快速发展,电网规模的不断扩大,电力电缆的大量使用,使得配电网系统对地等效电容电流增加,传统接地方式在新形势的发展下呈现出诸多问题。例如采用消弧线圈补偿配电网对地等效电容电流后带来选线困难和无法有效抑制过电压,配电网系统规模的变化,原有消弧线圈不再满足补偿要求等问题。针对以上问题,灵活接地方式(消弧线圈并联小电阻)和分布式补偿方式这两种新型接地方式被提出。
灵活接地方式在单相接地故障时补偿系统电容电流,并联小电阻后可抑制过电压同时提供有效的故障选线依据,集合了中性点经消弧线圈接地和小电阻接地两种接地方式的优点;分布式补偿方式通过在线路末端分布安装消弧线圈,解决了系统消弧线圈增容改造中空间不够等多方面问题,同时可减小故障残流,降低安装成本。
本文在简要分析灵活接地方式理论的基础上,利用PSCAD/EMTDC建立20kV配电网典型模型,包括电弧接地故障模型和故障多次重复计算模型等,考虑故障类型、小电阻并入时间和故障发生时刻等因素影响,对灵活接地方式下发生单相接地故障后系统过电压做了仿真计算。结果表明:可根据故障相电压波形对故障类型进行判断,在中性点电压为0左右并入小电阻时系统过电压最小。
本文介绍了分布式补偿方式的特点之后,利用PSCAD/EMTDC建立20kV配电网典型模型,从安装位置和补偿容量方面,与主站消弧线圈配合等方面研究了单相接地故障电流分布式补偿的特性,以及进行分布式补偿对系统发生断线过电压的影响。结果表明:分布式补偿装置安装在最大电容电流线路末端,且补偿容量与该线路的电容电流相对应时,故障点的残流最小;分布式补偿线路的断线过电压可通过主站消弧线圈过补偿和增加阻尼电阻的方法来抑制。
结合理论研究,本文从结构、原理等方面介绍了适合分布式补偿方式的接地变压器兼消弧线圈一体化装置,并将该装置进行了变电站现场调试。结果表明:适合于分布安装的接地变压器兼消弧线圈一体化装置结构简单,成本较小,易于分布安装,与系统对地等效电容、主站消弧线圈共同构成了零序电流回路,现场实际应用证明其能满足系统单相接地的补偿要求。
灵活接地方式和分布式补偿方式针对配电网发展带来的新问题,能将故障电流补偿至允许的范围,将系统过电压抑制在有效范围,提高系统安全性和可靠性,为配电网服务。
Neutral grounding of medium voltage level distribution networks is a comprehensive technical problem, which is important to the system’s overvoltage, insulation coordination, communication jamming, fault line selection, reliability and safety .
Recently, with the rapid development of the economy, increasing of the expansion of power system, the vast amount of using of electric cable, the traditional grounding encountered a lot of new challenges because of the capacitance current distribution in phase short circuit to ground increasing sharply. For example, there are difficulties in fault line selection and overvoltage suppression, and the old Petersen Coil no longer meet the current. In view of the questions mentioned above, flexible grounding and distributed compensation come up.
Capacitive current is compensated by the flexible grounding, and overvoltage is reducing by a parallel low resistance. At the same time, it can be helpful for fault line selection, which includes the advantages of neutral earthing via Petersen Coil and neutral grounded with Low-resistance. Installing the Petersen Coil at the end of line, distributed compensation could fix up the problems in expanding the capacity of Petersen Coil, lower cost.
After introducing the brief theories of flexible grounding, based on the PSCAD software, a simulation model on the neutral flexible grounded in distribution network is presented, which includes intermittent arc earthing model, multiple runs model, and so on. The overvoltage of system is calculated by the model, thinking about single phase-to-ground type, the time of paralleling resistor, and the moment of fault occurring. The results indicate that, fault type can be determined by the curve of faulty feeder, the overvoltage of system would be smallest if the small resistor is paralleled when neutral voltage is zero.
After introducing the brief characteristics of distributed compensation, flexibility of distributed arc suppression coil is studied by the location and capacity, and cooperation with arc extinction coil of principal station, and a simulation model is calculated. The result shows that fault current is smallest when distributed compensated at the end of line with suitable capacity. Broken line overvoltage can be restrained by over compensation and adding damping resistor.
Combined with the theoretical research, this paper introduces the Structure and Principle of the grounding transformer and the arc suppression coil integrated devices, and does an experiment. This device has features such as simple structure, low cost, convenient installment. Through test and actual application shows that i t can fulfill the requirement.
Flexible grounding and distributed compensation could compensate the fault current, improve the security and reliability of the system, servicing for the distribution network.
近年来,随着经济的快速发展,电网规模的不断扩大,电力电缆的大量使用,使得配电网系统对地等效电容电流增加,传统接地方式在新形势的发展下呈现出诸多问题。例如采用消弧线圈补偿配电网对地等效电容电流后带来选线困难和无法有效抑制过电压,配电网系统规模的变化,原有消弧线圈不再满足补偿要求等问题。针对以上问题,灵活接地方式(消弧线圈并联小电阻)和分布式补偿方式这两种新型接地方式被提出。
灵活接地方式在单相接地故障时补偿系统电容电流,并联小电阻后可抑制过电压同时提供有效的故障选线依据,集合了中性点经消弧线圈接地和小电阻接地两种接地方式的优点;分布式补偿方式通过在线路末端分布安装消弧线圈,解决了系统消弧线圈增容改造中空间不够等多方面问题,同时可减小故障残流,降低安装成本。
本文在简要分析灵活接地方式理论的基础上,利用PSCAD/EMTDC建立20kV配电网典型模型,包括电弧接地故障模型和故障多次重复计算模型等,考虑故障类型、小电阻并入时间和故障发生时刻等因素影响,对灵活接地方式下发生单相接地故障后系统过电压做了仿真计算。结果表明:可根据故障相电压波形对故障类型进行判断,在中性点电压为0左右并入小电阻时系统过电压最小。
本文介绍了分布式补偿方式的特点之后,利用PSCAD/EMTDC建立20kV配电网典型模型,从安装位置和补偿容量方面,与主站消弧线圈配合等方面研究了单相接地故障电流分布式补偿的特性,以及进行分布式补偿对系统发生断线过电压的影响。结果表明:分布式补偿装置安装在最大电容电流线路末端,且补偿容量与该线路的电容电流相对应时,故障点的残流最小;分布式补偿线路的断线过电压可通过主站消弧线圈过补偿和增加阻尼电阻的方法来抑制。
结合理论研究,本文从结构、原理等方面介绍了适合分布式补偿方式的接地变压器兼消弧线圈一体化装置,并将该装置进行了变电站现场调试。结果表明:适合于分布安装的接地变压器兼消弧线圈一体化装置结构简单,成本较小,易于分布安装,与系统对地等效电容、主站消弧线圈共同构成了零序电流回路,现场实际应用证明其能满足系统单相接地的补偿要求。
灵活接地方式和分布式补偿方式针对配电网发展带来的新问题,能将故障电流补偿至允许的范围,将系统过电压抑制在有效范围,提高系统安全性和可靠性,为配电网服务。
Neutral grounding of medium voltage level distribution networks is a comprehensive technical problem, which is important to the system’s overvoltage, insulation coordination, communication jamming, fault line selection, reliability and safety .
Recently, with the rapid development of the economy, increasing of the expansion of power system, the vast amount of using of electric cable, the traditional grounding encountered a lot of new challenges because of the capacitance current distribution in phase short circuit to ground increasing sharply. For example, there are difficulties in fault line selection and overvoltage suppression, and the old Petersen Coil no longer meet the current. In view of the questions mentioned above, flexible grounding and distributed compensation come up.
Capacitive current is compensated by the flexible grounding, and overvoltage is reducing by a parallel low resistance. At the same time, it can be helpful for fault line selection, which includes the advantages of neutral earthing via Petersen Coil and neutral grounded with Low-resistance. Installing the Petersen Coil at the end of line, distributed compensation could fix up the problems in expanding the capacity of Petersen Coil, lower cost.
After introducing the brief theories of flexible grounding, based on the PSCAD software, a simulation model on the neutral flexible grounded in distribution network is presented, which includes intermittent arc earthing model, multiple runs model, and so on. The overvoltage of system is calculated by the model, thinking about single phase-to-ground type, the time of paralleling resistor, and the moment of fault occurring. The results indicate that, fault type can be determined by the curve of faulty feeder, the overvoltage of system would be smallest if the small resistor is paralleled when neutral voltage is zero.
After introducing the brief characteristics of distributed compensation, flexibility of distributed arc suppression coil is studied by the location and capacity, and cooperation with arc extinction coil of principal station, and a simulation model is calculated. The result shows that fault current is smallest when distributed compensated at the end of line with suitable capacity. Broken line overvoltage can be restrained by over compensation and adding damping resistor.
Combined with the theoretical research, this paper introduces the Structure and Principle of the grounding transformer and the arc suppression coil integrated devices, and does an experiment. This device has features such as simple structure, low cost, convenient installment. Through test and actual application shows that i t can fulfill the requirement.
Flexible grounding and distributed compensation could compensate the fault current, improve the security and reliability of the system, servicing for the distribution network.
引文
[1]杜忠宝. 10千伏配电网中性点接地方式的选择[D].河海大学, 2006.
[2] Zhang Y, Jin Z, Dai F, et al. Analysis and Selection of Neutral Grounding Modes in Cable Distribution Network[C]. Nanjing, China: 2008.
[3] Osman Z H, El-Morshedy A M K. General Considerations in Grounding the Neutral of Power Systems[J]. Modelling, Measurement and Control A. 1989, 24(3): 1-40.
[4] Oka K, Koizumi S, Oishi K, et al. analysis of a neutral grounding method for a three-phase four-wire 11.4 kv distribution system[C]. Yokohama, Japan: 2002.
[5] Ji Y, Hou Y. Approach on the neutral grounding modes of 20kV distribution networks[C]. Guangzhou, China: 2008.
[6]熊信银,张步涵.电气工程基础[M].武汉:华中科技大学出版社, 2005.
[7]要焕年,曹梅月.电力系统谐振接地[M].北京:中国电力出版社, 2001.
[8] Pang Q. Rough set neural network based fault line detection for neutral non-effectively grounded system[C]. Chongqing, China: 2008.
[9] Longhua M, Qinghai M. Ground-fault protection based on active component of zero-sequence current in resistance neutral grounded distribution systems[C]. Beijing, China: 2002.
[10]邓传妍,安耀军. 35KV中性点灵活接地方案研究[J].中小企业管理与科技(下旬刊). 2009(05): 271.
[11]张海,徐玉琴,白嘉,等. 10 kV配电网中性点灵活接地方式在单相金属性接地故障下的ATP仿真及其研究[J].继电器. 2006(07): 18-23.
[12]罗泽捷.中性点经小电阻、经消弧线圈接地方式分析[J].广东科技. 2009(6): 152-153.
[13]蔡雅萍. 10kV配电网中性点灵活接地方式及接地故障检测系统的研究[D].中国电力科学研究院, 2002.
[14]孙鸣,王世勇.消弧线圈短时并联小电阻的单相接地选线方案[J].煤炭学报. 2006(02): 268-272.
[15] Givelberg M, Lysenko E, Zelichonok R. Zero sequence directional earth-fault protection with improved characteristics for compensated distribution networks[J]. Electric Power Systems Research. 1999, 52(3): 217-222.
[16] Folliot P, Boyer J M, Bolle S. Neutral grounding reactor for medium voltage networks[C]. Amsterdam, Netherlands: 2001.
[17] Nikander A, Lakervi E. A philosophy and algorithms for extinguishing earth fault arcs in suppressed medium voltage networks[C]. Birmingham, UK: 1997.
[18]谷双魁.一种中性点接地新方法及其实现技术研究[D].华中科技大学, 2006.
[19]张海. 6～35kV电网中性点灵活接地及其控制的研究[D].华北电力大学(河北), 2006.
[20]张圣建,平绍勋.高电阻与消弧线圈并联的接地方式[J].高电压技术. 2006(02): 117-118.
[21] Longhua M, Qinghai M. Ground-fault protection based on active component of zero-sequence current in resistance neutral grounded distribution systems[C]. Beijing, China: 2002.
[22] Hanninen S, Lehtonen M. Characteristics of earth faults in electrical distribution networks with high impedance earthing[J]. Electr. Power Syst. Res. (Switzerland). 1998, 44(3): 155-161.
[23] Izadfar H R, Shokri S, Sheibani A. Step up Transformers Neutral grounding Resistor Effect on an Industrial Network Transient Stability[C]. Nanjing, China: 2005.
[24] Oka K, Yoshinaga J, Koizumi S, et al. study of neutral grounding for 22 kV distribution system[C]. Proceedings Asia Pacific Conference and Exhibition of the IEEE-Power Engineering Society on Transmission and Distribution: 2002.
[25]王杰.独立电力系统中压电网接地方式和过电压问题研究[D].华中科技大学, 2008.
[26]戴靖波.浅析中性点经小电阻接地电网中Z形接地变压器[J].变压器. 2005(02): 18-21.
[27]刘同钦.中性点经小电阻接地电网接地变压器容量的选择[C].中国杭州: 2005.
[28]韩爱芝,刘莘昱,曾定文,等.配电网间歇性电弧接地过电压的仿真计算研究[J].河南电力. 2008(01): 28-30.
[29]周燕莉.配电网间歇性电弧接地过电压抑制措施的仿真研究[J].青海电力. 2002(04): 9-14.
[30]谢彦斌.山区35kV电网中性点新型运行方式研究[D].重庆大学, 2008.
[31]夏成军,张尧,邹俊雄.合空线统计过电压的建模与仿真[J].高电压技术. 2007(10): 11-15.
[32]金恩淑,杨明芳,陈韬. 10kV系统中性点不同接地方式下工频弧光过电压的仿真研究[C].中国山东烟台: 2008.
[33]齐波.中性点经高阻接地方式下配电网零序电流测量的研究[D].华北电力大学(北京), 2006.
[34]张新慧,潘贞存,徐丙垠,等.基于暂态零序电流的小电流接地故障选线仿真[J].继电器. 2008(03): 5-9.
[35]周志成,付慧,凌建,等.消弧线圈并联中阻选线的单相接地试验及分析[J].高电压技术. 2009(05): 1054-1058.
[36]纪鸿彬.谐振接地系统单相接地故障并联电阻选线的优化[J].高电压技术. 2006(08): 124-126.
[37] Ji T, Pang Q, Liu X. Study on Fault Line Detection Based on Genetic Artificial Neural Network in Compensated Distribution System[C]. Weihai, Shandong, China: 2006.
[38] Hanninen S, Lehtonen M, Hakola T. Earth faults and related disturbances in distribution networks[J]. IEE Proc., Gener. Transm. Distrib. (UK). 2002, 149(3): 283-288.
[39]赵建文,侯媛彬.配电网电容电流的准确预测[J].电工电能新技术. 2008(03): 49-53.
[40]李建华. 10kV小电阻接地系统断线接地故障仿真计算[J].上海电力. 2006(01): 61-63.
[41]唐轶,陈庆.一种新的适合分布安装的消弧线圈[J].电力自动化设备. 2007(11): 87-90.
[42]唐轶.接地变压器式消弧线圈[J].中国矿业大学学报. 1995(04): 36-40.
[43]陈庆,唐轶.接地变压器式消弧线圈的电气性能[J].中国电力. 2005(10): 25-28.
[44]姜宏伟,宋国福,王耕,等.气隙调感式消弧线圈结构设计及计算[J].变压器. 2002(02): 5-7.
[45]唐轶,黄显华.三相五柱式消弧电抗器[J].变压器. 1995, 32(4): 15-17.
[2] Zhang Y, Jin Z, Dai F, et al. Analysis and Selection of Neutral Grounding Modes in Cable Distribution Network[C]. Nanjing, China: 2008.
[3] Osman Z H, El-Morshedy A M K. General Considerations in Grounding the Neutral of Power Systems[J]. Modelling, Measurement and Control A. 1989, 24(3): 1-40.
[4] Oka K, Koizumi S, Oishi K, et al. analysis of a neutral grounding method for a three-phase four-wire 11.4 kv distribution system[C]. Yokohama, Japan: 2002.
[5] Ji Y, Hou Y. Approach on the neutral grounding modes of 20kV distribution networks[C]. Guangzhou, China: 2008.
[6]熊信银,张步涵.电气工程基础[M].武汉:华中科技大学出版社, 2005.
[7]要焕年,曹梅月.电力系统谐振接地[M].北京:中国电力出版社, 2001.
[8] Pang Q. Rough set neural network based fault line detection for neutral non-effectively grounded system[C]. Chongqing, China: 2008.
[9] Longhua M, Qinghai M. Ground-fault protection based on active component of zero-sequence current in resistance neutral grounded distribution systems[C]. Beijing, China: 2002.
[10]邓传妍,安耀军. 35KV中性点灵活接地方案研究[J].中小企业管理与科技(下旬刊). 2009(05): 271.
[11]张海,徐玉琴,白嘉,等. 10 kV配电网中性点灵活接地方式在单相金属性接地故障下的ATP仿真及其研究[J].继电器. 2006(07): 18-23.
[12]罗泽捷.中性点经小电阻、经消弧线圈接地方式分析[J].广东科技. 2009(6): 152-153.
[13]蔡雅萍. 10kV配电网中性点灵活接地方式及接地故障检测系统的研究[D].中国电力科学研究院, 2002.
[14]孙鸣,王世勇.消弧线圈短时并联小电阻的单相接地选线方案[J].煤炭学报. 2006(02): 268-272.
[15] Givelberg M, Lysenko E, Zelichonok R. Zero sequence directional earth-fault protection with improved characteristics for compensated distribution networks[J]. Electric Power Systems Research. 1999, 52(3): 217-222.
[16] Folliot P, Boyer J M, Bolle S. Neutral grounding reactor for medium voltage networks[C]. Amsterdam, Netherlands: 2001.
[17] Nikander A, Lakervi E. A philosophy and algorithms for extinguishing earth fault arcs in suppressed medium voltage networks[C]. Birmingham, UK: 1997.
[18]谷双魁.一种中性点接地新方法及其实现技术研究[D].华中科技大学, 2006.
[19]张海. 6～35kV电网中性点灵活接地及其控制的研究[D].华北电力大学(河北), 2006.
[20]张圣建,平绍勋.高电阻与消弧线圈并联的接地方式[J].高电压技术. 2006(02): 117-118.
[21] Longhua M, Qinghai M. Ground-fault protection based on active component of zero-sequence current in resistance neutral grounded distribution systems[C]. Beijing, China: 2002.
[22] Hanninen S, Lehtonen M. Characteristics of earth faults in electrical distribution networks with high impedance earthing[J]. Electr. Power Syst. Res. (Switzerland). 1998, 44(3): 155-161.
[23] Izadfar H R, Shokri S, Sheibani A. Step up Transformers Neutral grounding Resistor Effect on an Industrial Network Transient Stability[C]. Nanjing, China: 2005.
[24] Oka K, Yoshinaga J, Koizumi S, et al. study of neutral grounding for 22 kV distribution system[C]. Proceedings Asia Pacific Conference and Exhibition of the IEEE-Power Engineering Society on Transmission and Distribution: 2002.
[25]王杰.独立电力系统中压电网接地方式和过电压问题研究[D].华中科技大学, 2008.
[26]戴靖波.浅析中性点经小电阻接地电网中Z形接地变压器[J].变压器. 2005(02): 18-21.
[27]刘同钦.中性点经小电阻接地电网接地变压器容量的选择[C].中国杭州: 2005.
[28]韩爱芝,刘莘昱,曾定文,等.配电网间歇性电弧接地过电压的仿真计算研究[J].河南电力. 2008(01): 28-30.
[29]周燕莉.配电网间歇性电弧接地过电压抑制措施的仿真研究[J].青海电力. 2002(04): 9-14.
[30]谢彦斌.山区35kV电网中性点新型运行方式研究[D].重庆大学, 2008.
[31]夏成军,张尧,邹俊雄.合空线统计过电压的建模与仿真[J].高电压技术. 2007(10): 11-15.
[32]金恩淑,杨明芳,陈韬. 10kV系统中性点不同接地方式下工频弧光过电压的仿真研究[C].中国山东烟台: 2008.
[33]齐波.中性点经高阻接地方式下配电网零序电流测量的研究[D].华北电力大学(北京), 2006.
[34]张新慧,潘贞存,徐丙垠,等.基于暂态零序电流的小电流接地故障选线仿真[J].继电器. 2008(03): 5-9.
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