潘武略,钱政旭,孙志攀,洪丰,曹文斌,王松,方愉冬
PAN Wulue,QIAN Zhengxu,SUN Zhipan,HONG Feng,CAO Wenbin,WANG Song,FANG Yudong

• 1:国网浙江省电力有限公司电力科学研究院
• 2:南瑞集团有限公司
• 3:国电南瑞南京控制系统有限公司

摘要(Abstract)：

低频输电线路发生区内故障时，因线路两端M3C（模块化多电平矩阵变换器）对故障电流幅值、相位的限制，使得两侧电流呈现穿越特性，进而造成传统基于相量的线路差动保护灵敏度降低甚至拒动。为解决上述问题，首先基于低频输电系统架构分析了线路故障后的电气特征及相量差动保护适应性；随后结合采样值差动原理，给出了3个基于采样值的逻辑判据，与稳态量差流门槛及低比率制动方程共同构成适用于低频输电线路的差动保护实现方法；最后在RTDS（实时数字仿真系统）中搭建了低频输电系统模型，通过对低频线路区内、区外不同类型故障的仿真分析，验证了该方法在低频输电线路中的有效性，为后续工程应用奠定了基础。
As a fault occurs in a low-frequency transmission line zone, the modular multilevel matrix converters(M3Cs) at both ends of the line limit the fault current amplitude and phase. Under such a circumstance, the current on both sides displays the characteristics of through current, which in turn leads to poor sensitivity or even failure to operate of the traditional phase-based line differential protection. To solve the above problems, the electrical characteristics of the line after a fault and the adaptability of the phase differential protection are analyzed first based on the architecture of the low-frequency transmission system. Then three logical criteria based on the sampling values are given in combination with the differential principle of sampling values, which together with the steady-state differential threshold current and the low ratio braking equation constitute a differential protection method applicable to low-frequency transmission lines. Finally, a model of the low-frequency transmission system is built in RTDS(realtime digital simulation) system, and the effectiveness of the method used in low-frequency transmission lines is verified through the simulation analysis of different types of faults within and outside the lines, which lays the foundation for subsequent engineering applications.

关键词(KeyWords)： 低频输电;线路保护;差动保护;采样值差动
low-frequency transmission;line protection;differential protection;sampling value differential

Abstract:

Keywords:

基金项目(Foundation): 国网浙江省电力有限公司科技项目（2021ZK07）

作者(Author): 潘武略,钱政旭,孙志攀,洪丰,曹文斌,王松,方愉冬
PAN Wulue,QIAN Zhengxu,SUN Zhipan,HONG Feng,CAO Wenbin,WANG Song,FANG Yudong

DOI: 10.19585/j.zjdl.202302005

参考文献(References)：

• [1]黄明煌，王秀丽，刘沈全，等.分频输电应用于深远海风电并网的技术经济性分析[J].电力系统自动化，2019,43(5):167-174.HUANG Minghuang,WANG Xiuli,LIU Shenquan,et al.Technical and economic analysis on fractional frequency transmission system for integration of long-distance offshore wind farm[J]. Automation of Electric Power Systems,2019,43(5):167-174.
• [2]王秀丽，张小亮，宁联辉，等.分频输电在海上风电并网应用中的前景和挑战[J].电力工程技术，2017,36(1):15-19.WANG Xiuli,ZHANG Xiaoliang,NING Lianhui,et al.Application prospects and challenges of fractional frequency transmission system in offshore wind power integration[J].Electric Power Engineering Technology,2017,36(1):15-19.
• [3]王秀丽，赵勃扬，黄明煌，等.大规模深远海风电送出方式比较及集成设计关键技术研究[J].全球能源互联网，2019,2(2):138-145.WANG Xiuli,ZHAO Boyang,HUANG Minghuang,et al.Research of integration methods comparison and key design technologies for large scale long distance offshore wind power[J].Journal of Global Energy Interconnection,2019,2(2):138-145.
• [4]林进钿，倪晓军，裘鹏.柔性低频交流输电技术研究综述[J].浙江电力，2021,40(10):42-50.LIN Jintian,NI Xiaojun,QIU Peng. Review of flexible low-frequency AC transmission technology[J]. Zhejiang Electric Power,2021,40(10):42-50.
• [5]宁联辉，王锡凡，滕予非，等.风力发电经分频输电接入系统的实验[J].中国电机工程学报，2011,31(21):9-16.NING Lianhui,WANG Xifan,TENG Yufei,et al.Experiment on wind power grid integration via fractional frequency transmission system[J].Proceedings of the CSEE,2011,31(21):9-16.
• [6]吴小丹，朱海勇，董云龙，等.面向柔性低频输电的模块化多电平矩阵变换器分频分层控制[J].电力系统自动化，2021,45(18):131-140.WU Xiaodan,ZHU Haiyong,DONG Yunlong,et al.Frequency-division and hierarchical control of modular multilevel matrix converter for flexible low-frequency transmission[J].Automation of Electric Power Systems,2021,45(18):131-140.
• [7]范慧敏.城市电网柔性低频电缆输电系统稳态特性研究[D].北京：华北电力大学，2017.FAN Huimin. Research on steady-state characteristics of the flexible low frequency AC cable transmission system for urban grid[D]. Beijing:North China Electric Power University,2017.
• [8]赵勃扬，王锡凡，宁联辉，等.分频海上风电系统的不对称故障穿越控制[J/OL].中国电机工程学报：1-12[2023-01-30]. http：//kns. cnki. net/kcms/detail/11.2107. tm.20220622.1606.005.html.DOI:10.13334/j.0258-8013.pcsee.220598.ZHAO Boyang,WANG Xifan,NING Lianhui,et al.Ridethrough control of fractional frequency offshore wind power system during unsymmetrical grid faults[J/OL].Proceedings of the CSEE,1-12[2023-01-30].http：//kns.cnki. net/kcms/detail/11.2107. tm. 20220622.1606.005.html.
• [9]王邦彦，王秀丽，王碧阳，等.海上风电分频送出系统可靠性评估模型及方法[J].电网技术，2022,46(8):2899-2909.WANG Bangyan,WANG Xiuli,WANG Biyang,et al.Reliability evaluation model and method of offshore wind power fractional frequency delivery system[J].Power System Technology,2022,46(8):2899-2909.
• [10]段子越，孟永庆，孔颖，等.分频输电系统高频隔离型换流器拓扑与经济性研究[J].浙江电力，2022,41(1):71-79.DUAN Ziyue,MENG Yongqing,KONG Ying,et al.Research on topology and economy of high-frequency isolated AC/AC converter in fractional frequency transmission system[J]. Zhejiang Electric Power,2022,41(1):71-79.
• [11]陈德树，马天皓，刘沛，等.采样值电流差动微机保护的一些问题[J].电力自动化设备，1996,16(4):3-8.CHEN Deshu,MA Tianhao,LIU Pei,et al.Problems in realization of microcomputer based differential current protection by-sampled values[J].Electric Power Automation Equipment,1996,16(4):3-8.
• [12]陈德树，尹项根，张哲.再谈采样值差动保护的一些问题[J].电力自动化设备，2000,20(4):1-3.CHEN Deshu,YIN Xianggen,ZHANG Zhe.On problems about sampling value differential protection[J]. Electric Power Automation Equipment,2000,20(4):1-3.
• [13]林湘宁，何战虎，刘世明，等.电流采样值差动保护若干问题的探讨[J].电力系统自动化，2001,25(19):27-33.LIN Xiangning,HE Zhanhu,LIU Shiming,et al.Discussionson some aspectsof sampling value differential current protection[J]. Automation of Electric Power Systems,2001,25(19):27-33.
• [14]袁荣湘，陈德树，马天皓，等.采样值电流差动保护原理的研究[J].电力自动化设备，2000,20(1):1-3.YUAN Rongxiang,CHEN Deshu,MA Tianhao,et al.Study on the principle of current differential protection based on sampled values[J]. Electric Power Automation Equipment,2000,20(1):1-3.
• [15]胡玉峰，陈德树，尹项根.采样值差动及其应用[J].电力系统自动化，2000,24(10):40-44.HU Yufeng,CHEN Deshu,YIN Xianggen.New differential protection of power apparatus based onsampled values and its application[J].Automation of Electric Power Systems,2000,24(10):40-44.
• [16]乔斌强，王永胜，刘斌，等.变压器差动保护误跳闸故障原因排查[J].内蒙古电力技术，2019,37(5):98-100.QIAO Binqiang,WANG Yongsheng,LIU Bin,et al.Cause analysis of differential relaying false tripping of transformer[J]. Inner Mongolia Electric Power,2019,37(5):98-100.