基于等效故障区段的柔性直流输电线路单端量保护方案  

Single Terminal Protection Scheme for Flexible DC Transmission Lines Based on Equivalent Fault Section

作　　者：郑涛 李紫肖 陈云飞 宋祥艳 Zheng Tao;Li Zixiao;Chen Yunfei;Song Xiangyan(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University,Beijing 102206 China;Tangshan Power Supply Company State Grid Jibei Electric Power Company,Tangshan 063000 China)

机构地区：[1]新能源电力系统全国重点实验室(华北电力大学),北京102206 [2]国网冀北电力有限公司唐山供电公司,唐山063000

出　　处：《电工技术学报》2025年第3期771-785,共15页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金联合基金资助项目(U2166205)。

摘　　要：行波保护动作速度快,具有不依赖线路边界元件以及不受新能源控制策略影响等优点,是目前解决柔性直流输电线路中单端暂态量保护方案在弱边界情况下难以适用的有效途径之一。然而现有基于行波特征的单端量保护方案多为欠范围式保护,存在难以保护线路全长的问题。对此,该文首先通过分析线路不同位置故障时反向电流行波的传播路径,推导出在首个反极性波到达前,保护检测到同极性波的数量与故障位置的关系;在此基础上,考虑近端或末端故障时的“漏波”现象以及线路长度的影响,定义并引入“等效故障区段”的概念,以增大零线模时差在区内外故障时的差异,进而提出了基于等效故障区段的柔性直流输电线路单端量保护方案。该方案解决了现有单端量保护方案难以保护线路全长的问题,并考虑了近端或末端故障时采样率受限的影响,具有一定的容错性。最后,基于PSCAD/EMTDC的仿真实验,验证了所提保护方案的可行性。Flexible HVDC transmission systems have demonstrated significant advantages in addressing the challenges of large-scale and distant renewable energy integration,representing a key trend in the future transformation and development of power systems.However,flexible HVDC transmission systems comprise numerous power electronic devices,exhibiting characteristics such as low inertia and weak damping,thereby imposing higher demands on the speed of fault isolation and protection.Currently,to minimize the economic investments and enhance the grid dynamic performance,limiting reactors are often centrally installed at the converter station exits,resulting in a lack of clear boundary elements between DC transmission lines.This installation method leads to the possibility that existing protection schemes based on characteristics of line boundary elements may no longer be applicable.On the contrary,traveling-wave-based protection,with its inherent ultra-high speed and independence from line boundary elements,emerges as an effective approach to address the challenges of applying single ended transient protection schemes in flexible HVDC transmission lines under weak boundary conditions or no boundary conditions.However,existing traveling-wave-based single ended protection schemes often fail to effectively differentiate between faults occurring inside and outside the protected section,leading to undersized protection and difficulty in protecting the entire length of the line.Moreover,traveling-wave-based protection is susceptible to device sampling rates,especially when faults occur at the near end or remote end of the line,resulting in frequent wave reflections between the fault point and the busbar,which may reduce protection reliability.To address these issues,this paper first analyzes the propagation paths of reverse current waves during faults at different locations along the line,deriving the relationship between the number of same-polarity waves detected at the relay location before the arrival of the first reverse-polar

关 键 词：柔性直流输电线路 单端量保护 行波极性 零线模时差 等效故障区段 容错性 

分 类 号：TM77[电气工程—电力系统及自动化]