Line Protection Method of Three-Terminal Hybrid DC Transmission System Based on Control and Protection Coordination
Dai Zhihui1, Niu Baoyi1, Li Tiecheng2, Xi Xiaorui1, Li Hangze1
1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Resources North China Electric Power University Baoding 071003 China; 2. State Grid Hebei Electric Power Company Electric Power Research Institute Shijiazhuang 050021 China
Abstract：The hybrid DC transmission system integrates the advantages of conventional DC transmission systems and flexible DC transmission systems, gradually becoming a development trend of long-distance and large-capacity power transmission. However, its topology structure is complex and the operation mode is flexible. And it commonly employs overhead lines, the fault probability of the overhead lines is high and the fault current will be several times the rated current within a short time after the DC-side fault. Therefore, studying sensitive and reliable protection methods for DC transmission lines is of great significance. Most of the existing protection methods proposed for DC transmission lines have overlooked the coordination between control and protection. Therefore, this paper proposes a protection method for DC transmission lines utilizing control characteristic quantities. First, the three-terminal hybrid DC transmission system is modeled. On this basis, the direction of the short-circuit current fault component after the DC-side fault is analyzed, and the fault area can be determined based on the direction change. Second, based on the superimposed network and the Laplace transformation, the time-domain expression of the DC current fault component is calculated, revealing the negative correlation with the equivalent inductance value in the fault circuit. By utilizing the relationship between the port voltage and the DC current fault component, the DC voltage variation is obtained. By substituting it into the expression of direct-axis reference current variation integral, it is found that the direct-axis reference current variation integral is also negatively correlated with the equivalent inductance value in the fault circuit. Subsequently, the difference of the equivalent inductance value in the fault circuit of internal and external faults is analyzed, and it can be seen that the maximum equivalent inductance value during internal faults is less than the minimum equivalent inductance value during external faults. Therefore, it can be deduced that the minimum integral value of the direct-axis reference current variation during internal faults is larger than that during external faults. Based on this characteristic, the protection method is constructed by using the integral value of the direct-axis reference current variation. Finally, extensive simulation analysis, taking into account various influencing factors such as fault location, fault type, sampling frequency and fault resistance, is carried out on PSCAD/EMTDC to verify the reliability and sensitivity of the proposed protection method. The conclusions can be drawn as follows: When the three-terminal hybrid DC transmission lines have an internal fault, the integral value of the direct-axis reference current variation of the T-zone converter station is always greater than that during external fault. This paper fully makes use of the characteristics of the direct-axis reference current variation integral value of the T-zone converter station after DC-side faults to propose a protection method for DC transmission lines based on the coordination of control and protection. The proposed protection method is easy to implement and its settings value can adapt to control parameters. In addition, compared with the traveling wave protection method, the proposed protection method requires lower sampling frequency and less data communication.
戴志辉, 牛宝仪, 李铁成, 奚潇睿, 李杭泽. 基于控保协同的三端混合直流输电系统线路保护[J]. 电工技术学报, 2025, 40(1): 108-121.
Dai Zhihui, Niu Baoyi, Li Tiecheng, Xi Xiaorui, Li Hangze. Line Protection Method of Three-Terminal Hybrid DC Transmission System Based on Control and Protection Coordination. Transactions of China Electrotechnical Society, 2025, 40(1): 108-121.
[1] 王雪芹, 张大海, 李猛, 等. 基于小波能量谱和SSA-GRU的混合直流输电系统故障测距方法[J]. 电力系统保护与控制, 2023, 51(12): 14-24. Wang Xueqin, Zhang Dahai, Li Meng, et al.Fault location method for a hybrid DC transmission system based on wavelet energy spectrum and SSA-GRU[J]. Power System Protection and Control, 2023, 51(12): 14-24. [2] 李志川, 兰生, 魏柯. 基于MRSVD-GRU的混合三端特高压直流输电线路单极接地故障定位方法[J]. 电气技术, 2023, 24(3): 1-8, 63. Li Zhichuan, Lan Sheng, Wei Ke.Single-pole grounding fault location method of hybrid three-terminal ultra-high voltage direct current transmission line based on MRSVD and GRU[J]. Electrical Engineering, 2023, 24(3): 1-8, 63. [3] 李杭泽, 戴志辉, 石旭, 等. 计及控制响应的多端混合直流输电系统短路电流近似计算方法[J]. 电工技术学报, 2024, 39(9): 2810-2824. Li Hangze, Dai Zhihui, Shi Xu, et al.Approximate calculation method of short-circuit current of multi-terminal hybrid DC transmission system considering control strategy[J]. Transactions of China Electro-technical Society, 2024, 39(9): 2810-2824. [4] 梁远升, 黄泽杰, 李海锋, 等. 基于行波相位特性的三端混合直流线路行波保护原理[J]. 中国电机工程学报, 2021, 41(13): 4525-4543. Liang Yuansheng, Huang Zejie, Li Haifeng, et al.Phase characteristics based travelling wave protection for transmission line of three-terminal hybrid HVDC system[J]. Proceedings of the CSEE, 2021, 41(13): 4525-4543. [5] 杨亚宇, 邰能灵, 谢卫, 等. 利用单端边界能量的直流输电线路全线速动保护[J]. 电工技术学报, 2023, 38(9): 2403-2417. Yang Yayu, Tai Nengling, Xie Wei, et al.A whole-line fast protection scheme for HVDC transmission line based on single-ended boundary energy[J]. Transactions of China Electrotechnical Society, 2023, 38(9): 2403-2417. [6] Yu Xiuyong, Xiao Liye.A DC fault protection scheme for MMC-HVDC grids using new directional criterion[J]. IEEE Transactions on Power Delivery, 2021, 36(1): 441-451. [7] Zhang Chenhao, Song Guobing, Dong Xinzhou.Non-unit ultra-high-speed DC line protection method for HVDC grids using first peak time of voltage[J]. IEEE Transactions on Power Delivery, 2021, 36(3): 1683-1693. [8] 高淑萍, 宋晓辰, 宋国兵. 基于VMD能量熵的混合双端直流输电线路纵联保护方案[J]. 电力系统保护与控制, 2022, 50(14): 123-132. Gao Shuping, Song Xiaochen, Song Guobing.Longitudinal protection scheme of hybrid double-terminal DC transmission lines based on VMD energy entropy[J]. Power System Protection and Control, 2022, 50(14): 123-132. [9] 束洪春, 王广雪, 田鑫萃, 等. 基于随机矩阵理论的混合三端直流线路非单元式纵联保护[J]. 电力系统自动化, 2022, 46(19): 162-171. Shu Hongchun, Wang Guangxue, Tian Xincui, et al.Non-unit pilot protection for hybrid three-terminal DC lines based on random matrix theory[J]. Automation of Electric Power Systems, 2022, 46(19): 162-171. [10] 戴志辉, 牛宝仪, 邱宏逸, 等. 基于初始电流行波相位的多端混合直流线路单端保护方案[J]. 高电压技术, 2024, 50(2): 649-659. Dai Zhihui, Niu Baoyi, Qiu Hongyi, et al.Single-ended protection scheme for multi-terminal hybrid DC lines based on initial current traveling wave phase[J]. High Voltage Engineering, 2024, 50(2): 649-659. [11] 李晔, 李斌, 刘晓明, 等. 基于反向行波幅值比的对称单极柔性直流系统行波方向保护[J]. 电工技术学报, 2023, 38(9): 2418-2434. Li Ye, Li Bin, Liu Xiaoming, et al.The direction protection based on the amplitude ratio of the backward traveling wave for the symmetrical monopole flexible DC system[J]. Transactions of China Electrotechnical Society, 2023, 38(9): 2418-2434. [12] Liang Yuansheng, Jiang Liantao, Li Haifeng, et al.Fault analysis and traveling wave protection based on phase characteristics for hybrid multiterminal HVDC systems[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2022, 10(1): 575-588. [13] 陈淼, 贾科, 姚昆鹏, 等. 基于故障前行波极值时间的柔性直流线路单端量保护方法[J]. 中国电机工程学报, 2023, 43(10): 3742-3758. Chen Miao, Jia Ke, Yao Kunpeng, et al.Single-ended protection method of flexible DC line based on extremum time of fault forward traveling wave[J]. Proceedings of the CSEE, 2023, 43(10): 3742-3758. [14] Zhang Chenhao, Huang Jinhai, Song Guobing, et al.Non-unit ultra-high-speed line protection for multi-terminal hybrid LCC/MMC HVDC system and its application research[J]. IEEE Transactions on Power Delivery, 2021, 36(5): 2825-2838. [15] 杨赛昭, 向往, 文劲宇. 架空柔性直流电网线路故障保护综述[J]. 中国电机工程学报, 2019, 39(22): 6600-6617. Yang Saizhao, Xiang Wang, Wen Jinyu.Review of DC fault protection methods for the MMC based DC grid[J]. Proceedings of the CSEE, 2019, 39(22): 6600-6617. [16] 李海锋, 许灿雄, 梁远升, 等. 计及换流站控制响应的多端混合直流线路后备保护设计[J]. 电力系统保护与控制, 2023, 51(3): 155-163. Li Haifeng, Xu Canxiong, Liang Yuansheng, et al.Backup protection design for multi-terminal hybrid HVDC lines considering control response[J]. Power System Protection and Control, 2023, 51(3): 155-163. [17] 刘思奇, 胡鹏飞, 王栋, 等. 基于MMC主动限流的VSC-HVDC双极短路故障控保协同策略[J]. 电力系统自动化, 2024: 48(10): 192-202. Liu Siqi, Hu Pengfei, Wang Dong, et al.Collaborative control and protection strategy for bipolar short-circuit fault in VSC-HVDC based on active MMC current limiting[J]. Automation of Electric Power Systems, 2024: 48(10): 192-202. [18] 曹虹, 周泽昕, 吕鹏飞, 等. 高压直流输电线路故障初始阶段解析方法研究[J]. 电力系统及其自动化学报, 2022, 34(7): 137-147. Cao Hong, Zhou Zexin, Lü Pengfei, et al.Study on analysis method for HVDC transmission line faults at initial stage[J]. Proceedings of the CSU-EPSA, 2022, 34(7): 137-147. [19] 吴丽丽, 茆美琴, 施永. 含主动限流控制的MMC-HVDC电网直流短路故障电流解析计算[J]. 电工技术学报, 2024, 39(3): 785-797. Wu Lili, Mao Meiqin, Shi Yong.Analytical calculation of DC short-circuit fault current of modular multi-level converter-HVDC grid with active current limiting control[J]. Transactions of China Electrotechnical Society, 2024, 39(3): 785-797. [20] 王蕾, 孙孝峰, 王宝诚, 等. LCC-MMC混合高压直流输电系统直流线路故障保护方案研究[J]. 中国电机工程学报, 2021, 41(21): 7339-7352. Wang Lei, Sun Xiaofeng, Wang Baocheng, et al.Research on protection scheme of DC line fault in LCC-MMC hybrid HVDC system[J]. Proceedings of the CSEE, 2021, 41(21): 7339-7352. [21] 辛业春, 刘熠, 江守其, 等. 计及零直流电压控制的混合型MMC-HVDC输电系统短路电流计算方法[J]. 电网技术, 2023, 47(7): 2820-2828. Xin Yechun, Liu Yi, Jiang Shouqi, et al.Short-circuit current calculation method for FHMMC-HVDC transmission systems with zero DC voltage control[J]. Power System Technology, 2023, 47(7): 2820-2828. [22] 束洪春, 代月, 安娜, 等. 基于线性回归的柔性直流电网纵联保护方法[J]. 电工技术学报, 2022, 37(13): 3213-3226, 3288. Shu Hongchun, Dai Yue, An Na, et al.Pilot protection method of flexible DC grid based on linear regression[J]. Transactions of China Electrotechnical Society, 2022, 37(13): 3213-3226, 3288. [23] 黄旭, 刘轶超, 朱汉卿, 等. 基于平均电容的MMC直流故障电流计算方法研究[J]. 电气传动, 2022, 52(17): 46-51. Huang Xu, Liu Yichao, Zhu Hanqing, et al.Research on MMC DC fault current calculation method based on average capacitance[J]. Electric Drive, 2022, 52(17): 46-51. [24] 邢超, 蔡旺, 毕贵红, 等. 昆柳龙特高压三端混合直流输电线路边界频率特性研究[J]. 电力自动化设备, 2023, 43(2): 135-141. Xing Chao, Cai Wang, Bi Guihong, et al.Research on boundary frequency characteristics of Kunliulong hybrid three-terminal UHVDC transmission line[J]. Electric Power Automation Equipment, 2023, 43(2): 135-141. [25] 陈仕龙, 吴涛, 王朋林, 等. 基于深度学习的特高压三端混合直流输电线路波形特征故障区域判别方法[J]. 电力系统及其自动化学报, 2024, 36(1): 24-36. Chen Shilong, Wu Tao, Wang Penglin, et al.Fault zone identification method for three-terminal hybrid UHVDC transmission lines based on deep learning and waveform characteristics[J]. Proceedings of the CSU-EPSA, 2024, 36(1): 24-36. [26] 周家培, 赵成勇, 李承昱, 等. 采用电流突变量夹角余弦的直流电网线路纵联保护方法[J]. 电力系统自动化, 2018, 42(14): 165-171. Zhou Jiapei, Zhao Chengyong, Li Chengyu, et al.Pilot protection method for DC lines based on included angle cosine of fault current component[J]. Auto-mation of Electric Power Systems, 2018, 42(14): 165-171. [27] 汤兰西, 董新洲. MMC直流输电网线路短路故障电流的近似计算方法[J]. 中国电机工程学报, 2019, 39(2): 490-498, 646. Tang Lanxi, Dong Xinzhou.An approximate method for the calculation of transmission line fault current in MMC-HVDC grid[J]. Proceedings of the CSEE, 2019, 39(2): 490-498, 646. [28] 孙吉波, 王宇, 刘崇茹, 等. 基于MMC的多端直流电网双极短路故障电流计算[J]. 电力自动化设备, 2018, 38(11): 72-78. Sun Jibo, Wang Yu, Liu Chongru, et al.Pole-to-pole short circuit current calculation of multi-terminal DC grid based on MMC[J]. Electric Power Automation Equipment, 2018, 38(11): 72-78. [29] 黄宇. 电力系统电流互感器饱和特性及其对继电保护的影响与对策研究[D]. 成都: 西南交通大学, 2018.Huang Yu. Research on the saturation characteristics of current transformer in power system and its influence on relay protection and countermeasures[D]. Chengdu: Southwest Jiaotong University, 2018. [30] 祝新驰, 李海锋, 黄炟超, 等. 基于触发角变化特性的高压直流线路纵联保护[J]. 电力自动化设备, 2020, 40(6): 163-171. Zhu Xinchi, Li Haifeng, Huang Dachao, et al.Pilot protection of HVDC power transmission lines based on variation characteristics of firing angle[J]. Electric Power Automation Equipment, 2020, 40(6): 163-171. [31] 陈继开, 孙川, 李国庆, 等. 双极MMC-HVDC系统直流故障特性研究[J]. 电工技术学报, 2017, 32(10): 53-60, 68. Chen Jikai, Sun Chuan, Li Guoqing, et al.Study on characteristics of DC fault in bipolar MMC-HVDC system[J]. Transactions of China Electrotechnical Society, 2017, 32(10): 53-60, 68. [32] 高飘, 郑晓冬, 晁晨栩, 等. 基于边界暂态能量的多端柔性直流输电线路保护[J]. 电力系统自动化, 2021, 45(17): 171-179. Gao Piao, Zheng Xiaodong, Chao Chenxu, et al.Protection for multi-terminal flexible DC transmission lines based on boundary transient energy[J]. Auto-mation of Electric Power Systems, 2021, 45(17): 171-179. [33] 郑伟, 张楠, 杨光源. 西门子及ABB直流线路行波保护对比和改进研究[J]. 电力系统保护与控制, 2015, 43(24): 149-154. Zheng Wei, Zhang Nan, Yang Guangyuan.Comparative and improvement investigation on the DC transmission line traveling wave protections of Siemens and ABB[J]. Power System Protection and Control, 2015, 43(24): 149-154. [34] 邢超, 牛元有, 王龙, 等. 特高压多端混合直流线路经验模式分解单端保护[J]. 电力系统及其自动化学报, 2024, 36(7): 122-132. Xing Chao, Niu Yuanyou, Wang Long, et al.Single-end protection for UHV multi-terminal hybrid DC transmission line and CEEMDAN[J]. Proceedings of the CSU-EPSA, 2024, 36(7): 122-132. [35] Yang Qingqing, Le Blond S, Aggarwal R, et al.New ANN method for multi-terminal HVDC protection relaying[J]. Electric Power Systems Research, 2017, 148: 192-201.
2025, Vol. 40 
