基于小波分析的特高压直流输电线路双端电压暂态保护  

Wavelet Analysis Based Two-Terminal Transient Voltage Protection for UHVDC Transmission Lines

作　　者：陈仕龙[1] 张杰[1] 毕贵红[1] 谢佳伟[1] 束洪春[1] 

机构地区：[1]昆明理工大学电力工程学院,云南省昆明市650500

出　　处：《电网技术》2013年第10期2719-2725,共7页Power System Technology

基　　金：国家自然科学基金项目(51267008)~~

摘　　要：分析云广直流输电线路和边界的频率特性,结果表明当故障发生点与保护安装点的距离大于一定值时,线路对某频率的高频信号衰减作用将大于本侧边界对该频率高频信号的衰减作用,据此提出用保护元件区分对端区内外故障的特高压直流线路暂态保护原理。分析和仿真试验表明该暂态保护原理能够保护线路的全长。通过比较两端检测到的故障暂态信号,判断故障位置更靠近整流侧还是逆变侧;对检测到的对端故障电压暂态信号进行多尺度小波变换,利用高频段小波能量与低频段小波能量不同构造区内外故障判据;根据故障后两极线上暂态电压之间的差异构造故障选极判据。仿真结果表明所提方法具有良好的反映过渡电阻的能力。The frequency characteristics of UHVDC transmission line from Yunnan to Guangdong as well as those at the boundaries of the project are analyzed, and analysis results show that when the distance between the fault point and the position where the protection device is installed exceeds a certain length, the signal of a certain high frequency will be more attenuated by transmission line than by local boundary where the protection device is installed, on this basis, a transient protection principle for UHVDC transmission line, in which the fault that occurs inside or outside the protection zone at the opposite terminal is distinguished by protective element, is proposed. Results of analysis and simulation show that using the proposed protection principle the full length of the transmission line can be protected. By means of comparing the transient fault signal detected at both terminals, it can be judged that the fault point is closer to rectifier side or to inverter side; applying multi-scale wavelet transform to the detected fault transient voltage signal at opposite terminal, using the difference between wavelet energy in high-frequency section and that in low-frequency section the criterion to distinguish the fault occurred inside protection zone from the fault occurred outside protection zone can be constructed; according to the difference between post-fault transient voltages of both DC polar lines, a criterion for fault pole selection can be constructed. PSCAD based simulation results show that the proposed method can reflect transition resistance well.

关 键 词：双端电压暂态保护 特高压直流 高频衰减 小波分析 故障选极 

分 类 号：TM721[电气工程—电力系统及自动化]