基于首行波曲率的柔性直流输电线路单端量保护  

Single-Ended Protection for Flexible DC Transmission Line Based on Curvature of Initial Traveling Wave

作　　者：戴志辉[1] 刘自强 刘雪燕 严思齐 姜妍 Dai Zhihui;Liu Ziqiang;Liu Xueyan;Yan Siqi;Jiang Yan(School of Electric and Electronic Engineering North China Electric Power University,Baoding 071003 China;State Grid Yangzhou Power Supply Company,Yangzhou 225100 China)

机构地区：[1]华北电力大学电气与电子工程学院,保定071003 [2]国网扬州供电公司,扬州225100

出　　处：《电工技术学报》2021年第9期1831-1841,共11页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金(51877084);河北省自然科学基金(E2018502063)资助项目。

摘　　要：传统柔性直流输电线路行波保护存在高阻故障时灵敏度不足及拒动的问题。该文首先通过定量分析双极柔性直流输电线路故障时首行波在线路上的色散效应及在边界处的传播特性,推导了区内外故障首行波表达式,得到首行波弯曲程度与故障位置及过渡电阻的关系;其次,利用区内、外故障首行波曲率的显著差异构造故障识别判据,首行波解析式也为定值整定提供了理论依据;然后基于故障极与健全极电流故障分量积分比值实现故障选极,并结合雷击干扰识别判据,形成了完整的柔性直流输电线路单端量保护方案。最后,基于PSCAD/EMTDC进行了仿真分析。结果表明,所提方案能够快速、可靠地识别线路区内外故障,具有较强的抗过渡电阻能力。Legacy traveling-wave protections are susceptible to low sensitivity and failure under high-impedance faults.First,based on quantitative analysis on the dispersion effect of the initial traveling wave on bipolar flexible DC transmission lines and its propagation characteristics at the line boundary,the expression of initial traveling wave was derived.The relationship between the bending degree of the initial traveling wave and the fault distance,as well as the fault resistance,was obtained.Second,the notable difference between the curvature of internal and external faults was utilized to construct the fault identification criterion,and the analytical expression of the initial traveling wave provides the theoretical basis for the threshold setting.Then,the integral ratio of fault and healthy-pole superimposed-currents was used to realize fault-pole selection.Combined with the identification criterion of lightning strikes,a complete single-ended protection scheme for flexible DC transmission lines was formed.Finally,simulation in PSCAD/EMTDC was carried out to verify the scheme.The results show that the proposed scheme with enhanced tolerance to transition resistance can distinguish internal and external faults quickly and reliably.

关 键 词：柔性直流系统 直流输电线路 曲率 行波色散 单端保护 

分 类 号：TM774[电气工程—电力系统及自动化]