小电阻接地配电网多回线故障分析与自适应零序电流保护
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摘要
当小电阻接地配电网发生同母多回线接地故障时,每条馈线的零序电流相比于单回线故障时有较大差别,馈线零序电流保护可能不正确动作。为此,首先推导了发生多回线同名相单相接地与单回线单相接地故障时馈线零序电流间的关系,揭示了保护不正确动作机理。提出了考虑负荷且能适用于不同类型多回线接地故障的零序电流计算方法。基于实际变电站参数搭建RTDS仿真模型,分析了不同类型多回线接地故障对零序电流保护的影响。在此基础上,提出了自适应馈线零序电流保护方案,利用故障前电压等参数将发生多回线接地故障时的零序电流修正为发生单回线接地故障时的零序电流,在不改变原有保护定值的情况下使零序电流保护能够自主适应于不同类型的多回线接地故障。基于RTDS和自主研发的保护测控装置的测试结果表明,所提保护方案不受负荷电流的影响,能够在不同类型的多回线接地故障发生时正确动作,且能够提高馈线零序电流保护对过渡电阻的耐受能力。
When grounding fault occurs on multiple feeders of the same bus,the zero-sequence current of each feeder will be greatly different from that when single-feeder grounding fault occurs. Therefore,the zero-sequence current relay protection of feeder may operate improperly. The relationship of zero-sequence current between single-phase grounding fault of same phase on multi-feeder and single-phase grounding fault on single-feeder is deduced to reveal the mechanism of improper operation of protection. A zero-sequence current calculation method considering load and suitable to various types of multi-feeder grounding fault is proposed. Then,the influence of multi-feeder grounding fault on zero-sequence current protection is analyzed by RTDS simulation model based on parameters of actual substation. On this basis,a self-adaptive zero-sequence current protection scheme of feeder is proposed,which modifies the zero-sequence current under multi-feeder grounding fault to the zero-sequence current under single-feeder grounding fault by using the pre-fault voltage and other parameters. This self-adaptive zero-sequence current protection scheme can autonomously adapt to different types of multi-feeders grounding faults without changing the original protection settings. Test results based on RTDS and the self-designed protection device show that the proposed protection scheme is immune to load current,and can operate correctly when different types of multi-feeder grounding faults occur. In addition,the fault resistance endurance of zero-sequence current protection can be improved by the proposed protection scheme.
When grounding fault occurs on multiple feeders of the same bus,the zero-sequence current of each feeder will be greatly different from that when single-feeder grounding fault occurs. Therefore,the zero-sequence current relay protection of feeder may operate improperly. The relationship of zero-sequence current between single-phase grounding fault of same phase on multi-feeder and single-phase grounding fault on single-feeder is deduced to reveal the mechanism of improper operation of protection. A zero-sequence current calculation method considering load and suitable to various types of multi-feeder grounding fault is proposed. Then,the influence of multi-feeder grounding fault on zero-sequence current protection is analyzed by RTDS simulation model based on parameters of actual substation. On this basis,a self-adaptive zero-sequence current protection scheme of feeder is proposed,which modifies the zero-sequence current under multi-feeder grounding fault to the zero-sequence current under single-feeder grounding fault by using the pre-fault voltage and other parameters. This self-adaptive zero-sequence current protection scheme can autonomously adapt to different types of multi-feeders grounding faults without changing the original protection settings. Test results based on RTDS and the self-designed protection device show that the proposed protection scheme is immune to load current,and can operate correctly when different types of multi-feeder grounding faults occur. In addition,the fault resistance endurance of zero-sequence current protection can be improved by the proposed protection scheme.
引文
[1] 薛永端,郭丽伟,张林利,等.有源配电网中性点接地方式的选择问题[J].电力系统自动化,2015,39(13):129-136.XUE Yongduan,GUO Liwei,ZHANG Linli,et al.Selection problem of neutral grounding mode in active distributed networks[J].Automation of Electric Power System,2015,39(13):129-136.
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[4] 刘明岩.配电网中性点接地方式选择[J].电网技术,2004,28(16):86-89.LIU Mingyan.Selection of neutral grounding modes in power distribution network[J].Power System Technology,2004,28(16):86-89.
[5] 王辉.10 kV配电网小电阻接地方式的研究[D].天津:天津大学,2006.WANG Hui.Study on neutral grounding mode for 10 kV power distribution network[D].Tianjin:Tianjin University,2006.
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[7] 郭丽伟,薛永端,徐丙垠,等.中性点接地方式对供电可靠性的影响分析[J].电网技术,2015,39(8):2340-2345.GUO Liwei,XUE Yongduan,XU Bingyin,et al.Research on effects of neutral grounding modes on power supply reliability in distribution networks[J].Power Systems Technology,2015,39(8):2340-2345.
[8] 吴争荣,蔡颖倩,张俊潇,等.消弧线圈接地系统同母多回线相继故障分析[J].高电压技术,2017,43(7):2402-2409.WU Zhengrong,CAI Yingqian,ZHANG Junxiao,et al.Fault analysis on successive fault of multi-feeders connected to the same bus in resonant grounding system[J].High Voltage Engineering,2017,43(7):2402-2409.
[9] HUANG J K,WU J Y,WANG G,et al.Study on zero-sequence current distribution characteristics in low resistance grounding mode[C]//2011 International Conference on Advanced Power System Automation and Protection(APAP).Beijing,China:IEEE,2011:1039-1043.
[10] 袁勇,李凌.10 kV小电阻接地系统接地变压器零序电流保护误动分析[J].华东电力,2003,31(6):31-33.YUAN Yong,LI Ling.Analysis of malfunction of grounding trans-formers's zero-sequence current protection in 10 kV low resistance grounding system[J].East China Electric Power,2003,31(6):31-33.
[11] 宁国丽,房亚囡,邢立功,等.小电阻接地系统中接地变压器零序电流保护改进[J].电力自动化设备,2011,31(5):141-144.NING Guoli,FANG Yanan,XING Ligong,et al.Improvement of zero-sequence over-current protection for grounding transformers in low-resistance groungding power system[J].Electric Power Automation Equipment,2011,31(5):141-144.
[12] 江文东.10 kV小电阻接地系统零序过流定值的探讨[J].电力自动化设备,2002,22(10):73-75.JIANG Wendong.Discussion on zero sequence overcurrent setting for 10 kV low resistance grounding system[J].Electric Power Automation Equipment,2002,22(10):73-75.
[13] 喻磊,郭晓斌,韩博文,等.小电阻接地系统馈线自适应零序电流保护原理及装置实现[J].电力自动化设备,2017,37(11):125-137.YU Lei,GUO Xiaobin,HAN Bowen,et al.Principle of adaptive zero-sequence current protection and implementation of its device for feeder of low resistance grounding system[J].Electric Power Automation Equipment,2017,37(11):125-137.
[14] 刘万顺,黄少锋,徐玉琴.电力系统故障分析[M].3版.北京:中国电力出版社,2010:275-279.
[15] 范春菊,丁蕾,郁惟镛.电力电缆的零序电流保护方案[J].电力系统自动化,2006,30(8):61-64.FAN Chunju,DING Lei,YU Weiyong.Zero sequence current protection for power cable[J].Automation of Electric Power Systems,2006,30(8):61-64.
[16] 陈念,吕艳萍,周凯,等.110 kV电阻接地系统零序方向电流保护的整定研究[J].电力系统保护与控制,2017,45(13):91-96.CHEN Nian,Lü Yanping,ZHOU Kai,et al.Research on setting calculation of zero sequence directional overcurrent protection for 110 kV neutral point grounding via resistance system[J].Power System Protection and Control,2017,45(13):91-96.
[2] 郭丽伟,薛永端,徐丙垠,等.中性点接地方式对供电可靠性的影响分析[J].电网技术,2015,39(8):2340-2345.GUO Liwei,XUE Yongduan,XU Bingyin,et al.Research on effects of neutral grounding modes on power supply reliability in distribu-tion networks[J].Power System Technology,2015,39(8):2340-2345.
[3] 刘渝根,王建南,米宏伟,等.10 kV配电网中性点接地方式的优化研究[J].高电压技术,2015,41(10):3355-3362.LIU Yugen,WANG Jiannan,MI Hongwei,et al.Optimization research on neutral grounding mode of 10 kV distribution network[J].High Voltage Engineering,2013,33(34):3355-3362.
[4] 刘明岩.配电网中性点接地方式选择[J].电网技术,2004,28(16):86-89.LIU Mingyan.Selection of neutral grounding modes in power distribution network[J].Power System Technology,2004,28(16):86-89.
[5] 王辉.10 kV配电网小电阻接地方式的研究[D].天津:天津大学,2006.WANG Hui.Study on neutral grounding mode for 10 kV power distribution network[D].Tianjin:Tianjin University,2006.
[6] MITOLO M.Grounding the neutral of electrical systems through low-resistance groundingtesistors:an application case[J].IEEE Transactions on Industry Applications,2008,44(5):1311-1316.
[7] 郭丽伟,薛永端,徐丙垠,等.中性点接地方式对供电可靠性的影响分析[J].电网技术,2015,39(8):2340-2345.GUO Liwei,XUE Yongduan,XU Bingyin,et al.Research on effects of neutral grounding modes on power supply reliability in distribution networks[J].Power Systems Technology,2015,39(8):2340-2345.
[8] 吴争荣,蔡颖倩,张俊潇,等.消弧线圈接地系统同母多回线相继故障分析[J].高电压技术,2017,43(7):2402-2409.WU Zhengrong,CAI Yingqian,ZHANG Junxiao,et al.Fault analysis on successive fault of multi-feeders connected to the same bus in resonant grounding system[J].High Voltage Engineering,2017,43(7):2402-2409.
[9] HUANG J K,WU J Y,WANG G,et al.Study on zero-sequence current distribution characteristics in low resistance grounding mode[C]//2011 International Conference on Advanced Power System Automation and Protection(APAP).Beijing,China:IEEE,2011:1039-1043.
[10] 袁勇,李凌.10 kV小电阻接地系统接地变压器零序电流保护误动分析[J].华东电力,2003,31(6):31-33.YUAN Yong,LI Ling.Analysis of malfunction of grounding trans-formers's zero-sequence current protection in 10 kV low resistance grounding system[J].East China Electric Power,2003,31(6):31-33.
[11] 宁国丽,房亚囡,邢立功,等.小电阻接地系统中接地变压器零序电流保护改进[J].电力自动化设备,2011,31(5):141-144.NING Guoli,FANG Yanan,XING Ligong,et al.Improvement of zero-sequence over-current protection for grounding transformers in low-resistance groungding power system[J].Electric Power Automation Equipment,2011,31(5):141-144.
[12] 江文东.10 kV小电阻接地系统零序过流定值的探讨[J].电力自动化设备,2002,22(10):73-75.JIANG Wendong.Discussion on zero sequence overcurrent setting for 10 kV low resistance grounding system[J].Electric Power Automation Equipment,2002,22(10):73-75.
[13] 喻磊,郭晓斌,韩博文,等.小电阻接地系统馈线自适应零序电流保护原理及装置实现[J].电力自动化设备,2017,37(11):125-137.YU Lei,GUO Xiaobin,HAN Bowen,et al.Principle of adaptive zero-sequence current protection and implementation of its device for feeder of low resistance grounding system[J].Electric Power Automation Equipment,2017,37(11):125-137.
[14] 刘万顺,黄少锋,徐玉琴.电力系统故障分析[M].3版.北京:中国电力出版社,2010:275-279.
[15] 范春菊,丁蕾,郁惟镛.电力电缆的零序电流保护方案[J].电力系统自动化,2006,30(8):61-64.FAN Chunju,DING Lei,YU Weiyong.Zero sequence current protection for power cable[J].Automation of Electric Power Systems,2006,30(8):61-64.
[16] 陈念,吕艳萍,周凯,等.110 kV电阻接地系统零序方向电流保护的整定研究[J].电力系统保护与控制,2017,45(13):91-96.CHEN Nian,Lü Yanping,ZHOU Kai,et al.Research on setting calculation of zero sequence directional overcurrent protection for 110 kV neutral point grounding via resistance system[J].Power System Protection and Control,2017,45(13):91-96.