一种基于行波固有频率的特高压直流输电线路保护方法.docVIP

 一种基于行波固有频率的特高压直流输电 线路保护方法# 廖凯，何正友，李小鹏，林圣** 5 10 15 20 25 30 35 40 （西南交通大学电气工程学院，成都 610031） 摘要：特高压直流输电 UHVDC 在远距离大容量输电中有着突出的优势，近年来得到了快速 的发展，本文提出了一种仅利用单端暂态量频谱信息进行 UHVDC 线路全线保护的新方法。 与传统的基于电报方程的行波分析方法不同，本文采用的基于行波固有频率主成份的方法不 受行波波头识别等的限制，只需要故障后的一段暂态电压信息，通过对暂态电压信息的频谱 分析，得到行波固有频率的主成份，由于该自然频率的形成仅与故障距离和系统端行波反射 系数有关，故可利用该频率并结合故障线路边界条件计算出故障距离。通过固有频率及其幅 值，构造保护判据，能达到保护线路全长的目的。在 PSCAD/EMTDC 中建立特高压直流输 电系统模型，在此基础上针对不同过渡电阻下的单极接地故障对该算法进行了不同运行方式 下的仿真验证，结果表明该保护方法在高压直流输电线路上能实现直流线路区外故障时可靠 不动作，区内故障时可靠动作。 关键词：特高压直流输电； PSCAD/EMTDC； 行波固有频率； 线路保护 中图分类号：TM74 A Natural Traveling wave propagation paths and its natural Frequency Based Protection Method for UHVDC Transimission Line LIAO Kai, HE Zhengyou, LI Xiaopeng, LIN Sheng (College of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031) Abstract: In recent years, UHVDC (ultra high voltage direct current) has developed rapidly due to its excellent advantages in long distance and high capacity power transmission. This paper presents a protection and fault location method for UHVDC transmission lines using one terminal voltage data. Being different from the traditional telegrapher’s equations based analyzing methods, the proposed method is based on the traveling wave natural frequency. The transient signals are analyzed to extract the natural frequencies using MUSIC after the fault occurred at the line. Then the fault distance can be calculated with the relationship among the fault distance, the dominant natural frequency and the terminal conditions of transmission line. A simulation model of 800 kV ultra high voltage direct current (UHVDC) transmission system is built in PSCAD/EMTDC. Various transmission line fault situations are considered to locate the fault point with different opretion type. The results confirm that the proposed method is feasible and accurate. Key words: UHVDC; PSCAD/EMTDC; Natural frequency; Transmission line protection 0 引言 特高压直流输电在远距离、大容量送电以及电网互联等方面有着独特的优势。随着西部 水电的快速建设，高压直流输电系统在我国电网中发挥着越来越重要的作用，线路