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基于电压反行波的特高压直流输电单端量线路保护
戴志辉1,2, 刘宁宁1, 刘媛1, 鲁浩1, 曹虹2
1.华北电力大学 电气与电子工程学院,河北 保定 071003;2.中国电力科学院有限公司 电网安全与节能国家重点实验室,北京 100192
摘要:
针对传统特高压直流输电线路电流差动保护快速性差、耐受过渡电阻能力有限等问题,提出一种基于电压反行波的单端电气量直流线路保护。综合考虑线路边界和直流输电线路对高频故障电压行波的衰减作用,结合发生区内、区外故障时故障行波传输特性发现:发生区内故障时,整流侧保护元件测得的高频电压反行波较大;发生区外故障时,保护元件在研究时段内测得的高频电压反行波较小,甚至近似为0。据此,可判别区内、区外故障。采用改进电压梯度法实现保护的快速、可靠启动。大量仿真结果表明,该保护方案能快速识别区内、区外故障,无需通信,能可靠保护线路全长,且耐过渡电阻能力强,不受分布电容影响。
关键词:  特高压直流输电  单端量保护  线路保护  电压反行波  线路边界  高阻接地故障
DOI:10.16081/j.epae.201909004
分类号:TM773;TM721.1
基金项目:国家自然科学基金资助项目(51877084);河北省自然科学基金资助项目(E2018502063);电网安全与节能国家重点实验室(中国电力科学院有限公司)开放基金资助项目(EPRI4124-191054);中央高校基本科研业务费专项基金资助项目(2017MS096)
Single-terminal line protection for UHVDC power transmission based on voltage backward traveling wave
DAI Zhihui1,2, LIU Ningning1, LIU Yuan1, LU Hao1, CAO Hong2
1.School of Electrical and Electronic Engineering, North China Electric Power University, Baoding 071003, China;2.State Key Laboratory of Power Grid Safety and Energy Conservation, China Electric Power Research Institute, Beijing 100192, China
Abstract:
In view of the shortages of traditional current differential protections for UHVDC(Ultra High Vol-tage Direct Current) transmission lines, such as poor tripping speed and limited adaptability to high-resistance faults, a single-terminal line protection based on voltage backward traveling wave is proposed. Consi-dering the attenuation impacts of both line boundary and UHVDC lines on high-frequency voltage trave-ling wave, the transmission characteristics of traveling wave with respect to internal and external faults on UHVDC lines are performed. It shows that the high-frequency voltage backward traveling wave at the rectifier side is relatively large in the case of internal faults. However, the backward traveling wave is approximately to be 0 in the case of external faults. Thus, it can be utilized to discriminate internal faults from external ones. The improved voltage gradient method is used to realize the quick and reliable pickup criterion. Numerous simulative results show that the proposed protection scheme can identify the internal and external faults quickly without communication, and can protect the entire line reliably. Besides, it can identify high-impedance faults and is not subject to the distributed capacitor of DC lines.
Key words:  UHVDC power transmission  single-terminal protection  line protection  voltage backward traveling wave  line boundary  high-impedance grounding fault

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