MMC直流输电网线路短路故障电流的近似计算方法
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摘要
柔性直流电网可灵活消纳大规模可再生能源,但直流线路故障后严重的过电流问题是制约其发展的重要因素之一。短路故障电流的分析和计算对于系统参数的设计和选取具有重要意义,但是由于换流站是高度复杂的非线性系统,无法得到故障电流的精确解析表达式,因此短路故障电流往往通过仿真得到。对于故障电流近似表达式的研究也往往只能针对双端直流系统进行,对于直流电网下的线路短路故障电流则无能为力。该文根据模块化多电平换流器(modular multilevel converter,MMC)柔性直流电网系统参数的基本特点对其进行合理的简化,得到线路短路故障电流的近似解析解的求解方法,可以在故障后一段时间内较为准确的描述故障电流的整体趋势,可为直流线路保护定值和直流断路器相关参数的选取和整定提供一定的依据。
VSC-HVDC grid can flexibly absorb large-scale renewable energy, but the severe overcurrent problem after transmission line fault is one of the most important factors which restrict its development. Calculation and analysis of short circuit fault current is meaningful to the design and selection of system parameters. However, converter is a complex nonlinear system which makes it impossible to get exact analytical solution of fault current, so the fault current is always obtained from simulation. Research concerning approximate expression of fault current is always based on two-terminal HVDC systems, but incapable of HVDC grid. This paper reasonably simplified the MMC-HVDC grid based on the feature of its parameters, in order to get an approximate way to calculate fault current. The proposed method can describe the general trend of fault current in a relatively accurate way during a certain period after fault occurs. This method can provide a basis for the selection of the setting value of transmission line protection and the parameters relevant to DC circuit breakers.
VSC-HVDC grid can flexibly absorb large-scale renewable energy, but the severe overcurrent problem after transmission line fault is one of the most important factors which restrict its development. Calculation and analysis of short circuit fault current is meaningful to the design and selection of system parameters. However, converter is a complex nonlinear system which makes it impossible to get exact analytical solution of fault current, so the fault current is always obtained from simulation. Research concerning approximate expression of fault current is always based on two-terminal HVDC systems, but incapable of HVDC grid. This paper reasonably simplified the MMC-HVDC grid based on the feature of its parameters, in order to get an approximate way to calculate fault current. The proposed method can describe the general trend of fault current in a relatively accurate way during a certain period after fault occurs. This method can provide a basis for the selection of the setting value of transmission line protection and the parameters relevant to DC circuit breakers.
引文
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[13]张哲任.适用于架空线的MMC型直流输电若干问题研究[D].杭州:浙江大学,2016.Zhang Zheren.Research on several issues in MMC-HVDC for overhead line transmission[J].Hangzhou:Zhejiang University,2016.
[14]滕松,宋新立,李广凯,等.模块化多电平换流器型高压直流输电综述[J].电网与清洁能源,2012,28(8):43-50.Teng Song,Song Xinli,Li Guangkai,et al.A survey on HVDC transmission with modular multilevel converters[J].Power System and Clean Energy,2012,28(8):43-50(in Chinese).
[15]徐政,肖晃庆,张哲任,等.柔性直流输电系统[M].2版.北京:机械工业出版社,2017.
[16]徐政,刘高任,张哲任.柔性直流输电网的故障保护原理研究[J].高电压技术,2017,43(1):1-8.Xu Zheng,Liu Gaoren,Zhang Zheren.Research on fault protection principle of DC grids[J].High Voltage Engineering,2017,43(1):1-8(in Chinese).
[17]Dommel H W.Digital computer solution of electromagnetic transients in single-and multiphase networks[J].IEEE Transactions on Power Apparatus and Systems,1969,PAS-88(4):388-399.
[18]葛耀中.新型继电保护和故障测距的原理与技术[M].2版.西安:西安交通大学出版社,2007.
[19]林圣,武骁,何正友,等.基于行波固有频率的电网故障定位方法[J].电网技术,2013,37(1):270-275.Lin Sheng,Wu Xiao,He Zhengyou,et al.A power system fault location method based on natural frequencies of traveling waves[J].Power System Technology,2013,37(1):270-275(in Chinese).
[20]蔡新雷,宋国兵,高淑萍,等.利用电流固有频率的VSC-HVDC直流输电线路故障定位[J].中国电机工程学报,2011,31(28):112-119.Cai Xinlei,Song Guobing,Gao Shuping.A novel fault-location method for VSC-HVDC transmission lines based on natural frequency of current[J].Proceedings of the CSEE,2011,31(28):112-119(in Chinese).
[2]CIGRE B4-52 Working Group.HVDC grid feasibility study[R].Melbourne:International Council on Large Electric Systems,2011.
[3]汤广福,罗湘,魏晓光.多端直流输电与直流电网技术[J].中国电机工程学报,2013,33(10):8-17.Tang Guangfu,Luo Xiang,Wei Xiaoguang.Multiterminal HVDC and DC-grid technology[J].Proceedings of the CSEE,2013,33(10):8-17(in Chinese).
[4]温家良,吴锐,彭畅,等.直流电网在中国的应用前景分析[J].中国电机工程学报,2012,32(13):7-12.Wen Jialiang,Wu Rui,Peng Chang,et al.Analysis of DCgrid prospects in China[J].Proceedings of the CSEE,2012,32(13):7-12(in Chinese).
[5]徐政,薛英林,张哲任.大容量架空线柔性直流输电关键技术及前景展望[J].中国电机工程学报,2014,34(29):5051-5062.Xu Zheng,Xue Yinglin,Zhang Zheren.VSC-HVDCtechnology suitable for bulk power overhead line transmission[J].Proceedings of the CSEE,2014,34(29):5051-5062(in Chinese).
[6]李斌,何佳伟,冯亚东,等.多端柔性直流电网保护关键技术[J].电力系统自动化,2016,40(21):2-12.Li Bin,He Jiawei,Feng Yadong,et al.Key techniques for protection of multi-terminal flexible DC grid[J].Automation of Electric Power Systems,2016,40(21):2-12(in Chinese).
[7]Franck C M.HVDC circuit breakers:a review identifying future research needs[J].IEEE Transactions on Power Delivery,2011,26(2):998-1007.
[8]史宗谦,贾申利.高压直流断路器研究综述[J].高压电器,2015,51(11):1-9.Shi Zongqian,Jia Shenli.Research on high-voltage direct current circuit breaker:a review[J].High Voltage Apparatus,2015,51(11):1-9(in Chinese).
[9]董新洲,汤兰西,施慎行,等.柔性直流输电网线路保护配置方案[J].电网技术,2018,42(6):1752-1759.Dong Xinzhou,Tang Lanxi,Shi Shenxing,et al.Configuration scheme of transmission line protection for flexible HVDC grid[J].Power System Technology,2018,42(6):1752-1759(in Chinese).
[10]张国驹,祁新春,陈瑶,等.模块化多电平换流器直流双极短路特性分析[J].电力系统自动化,2016,40(12):151-157,199.Zhang Guoju,Qi Xinchun,Chen Yao,et al.Characteristic analysis of modular multilevel converter under DCpole-to-pole short-circuit fault[J].Automation of Electric Power Systems,2016,40(12):151-157,199(in Chinese).
[11]杨海倩,王玮,荆龙,等.MMC-HVDC系统直流侧故障暂态特性分析[J].电网技术,2016,40(1):40-46.Yang Haiqian,Wang Wei,Jing Long,et al.Analysis on transient characteristic of DC transmission line fault in MMC based HVDC transmission system[J].Power System Technology,2016,40(1):40-46(in Chinese).
[12]郭晓茜,崔翔,齐磊.架空线双极MMC-HVDC系统直流短路故障分析和保护[J].中国电机工程学报,2017,37(8):2177-2184.Guo Xiaoqian,Cui Xiang,Qi Lei.DC short-circuit fault analysis and protection for the overhead line bipolar MMC-HVDC system[J].Proceedings of the CSEE,2017,37(8):2177-2184(in Chinese).
[13]张哲任.适用于架空线的MMC型直流输电若干问题研究[D].杭州:浙江大学,2016.Zhang Zheren.Research on several issues in MMC-HVDC for overhead line transmission[J].Hangzhou:Zhejiang University,2016.
[14]滕松,宋新立,李广凯,等.模块化多电平换流器型高压直流输电综述[J].电网与清洁能源,2012,28(8):43-50.Teng Song,Song Xinli,Li Guangkai,et al.A survey on HVDC transmission with modular multilevel converters[J].Power System and Clean Energy,2012,28(8):43-50(in Chinese).
[15]徐政,肖晃庆,张哲任,等.柔性直流输电系统[M].2版.北京:机械工业出版社,2017.
[16]徐政,刘高任,张哲任.柔性直流输电网的故障保护原理研究[J].高电压技术,2017,43(1):1-8.Xu Zheng,Liu Gaoren,Zhang Zheren.Research on fault protection principle of DC grids[J].High Voltage Engineering,2017,43(1):1-8(in Chinese).
[17]Dommel H W.Digital computer solution of electromagnetic transients in single-and multiphase networks[J].IEEE Transactions on Power Apparatus and Systems,1969,PAS-88(4):388-399.
[18]葛耀中.新型继电保护和故障测距的原理与技术[M].2版.西安:西安交通大学出版社,2007.
[19]林圣,武骁,何正友,等.基于行波固有频率的电网故障定位方法[J].电网技术,2013,37(1):270-275.Lin Sheng,Wu Xiao,He Zhengyou,et al.A power system fault location method based on natural frequencies of traveling waves[J].Power System Technology,2013,37(1):270-275(in Chinese).
[20]蔡新雷,宋国兵,高淑萍,等.利用电流固有频率的VSC-HVDC直流输电线路故障定位[J].中国电机工程学报,2011,31(28):112-119.Cai Xinlei,Song Guobing,Gao Shuping.A novel fault-location method for VSC-HVDC transmission lines based on natural frequency of current[J].Proceedings of the CSEE,2011,31(28):112-119(in Chinese).