摘要
为提高直流线路后备保护动作性能,提出一种基于行波调谐能量的高压直流线路纵联保护。利用S变换提取直流滤波器调谐频率下的故障电压、电流分量,计算前行波与反行波,分析证明调谐频率下的前、反行波在线路边界处满足全反射的关系。区内故障时,线路两端的前、反行波暂态调谐能量比值均接近于1;区外故障时,远离故障的一侧前、反行波暂态调谐能量接近1,而另一侧的比值非常大。区内、外故障时线路两端暂态调谐能量比值差异明显,可用来识别线路故障。该方法原理简单,门槛值便于整定,对通信的要求较低,适合作为高压直流线路的后备保护。PSCAD/EMTDC仿真结果证明,该保护在不同故障位置、故障类型的条件下均能准确判别区内、外故障,并具有良好的耐受高阻故障能力。
To improve the performance of back-up protection for DC lines,a pilot protection scheme utilizing traveling wave tuning energy was proposed.Firstly,S transform was used to extract the fault voltage and current components under the tuning frequency of DC filter.Then forward and backward waves were calculated,verifying that they met the relationship of total reflection.When an internal fault occurs,the transient tuning energy ratios of the forward and backward waves at both ends of line were close to 1.For external fault,one transient tuning energy ratio was close to 1 and the other was very large.Thus,the external and internal faults could be distinguished with the amplitude difference between measured ratios.The proposed method is simple and its threshold value is easy to set.Besides,it is less demanding for communication and suitable for back-up protection.Simulation results based on PSCAD/EMTDC show that the protection can accurately identify internal faults from external under various fault conditions,and also has a better tolerance to high-resistance faults.
作者
戴志辉
张程
何永兴
刘自强
DAI Zhihui;ZHANG Cheng;HE Yongxing;LIU Ziqiang(School of Electrical and Electronic Engineering,North China Electric Power University,Baoding 071003,Hebei Province,China)
出处
《电网技术》
EI
CSCD
北大核心
2020年第7期2710-2721,共12页
Power System Technology
基金
国家自然科学基金项目(51877084)
河北省自然科学基金项目(E2018502063)
中央高校基本科研业务费专项资金项目(2017MS096)。
关键词
高压直流线路
S变换
全反射
暂态调谐能量比值
纵联保护
HVDC transmission lines
S transform
total reflection
transient tuning energy ratios
pilot protection
