利用电压辅助电流选相的同杆双回线单端电气量选相原理  

A Fault Phase Selection Scheme of Currents With Assistant Voltages for Common-tower Double-circuit Transmission Lines Using One-terminal Electrical Quantities

作　　者：张海[1] 黄少锋[1] 

机构地区：[1]华北电力大学电气与电子工程学院,北京市昌平区102206

出　　处：《中国电机工程学报》2013年第7期139-148,8,共10页Proceedings of the CSEE

摘　　要：目前同杆双回线后备保护I段的电流选相算法复杂或选相不够准确,而且近端故障时有时因电流互感器(currenttranformer,CT)饱和而导致电流选相不准确或漏选相,针对此问题提出一种利用电压辅助电流选相的同杆双回线单端电气量选相原理,并给出了辅助选相判据。先利用故障初始阶段3相电压和3个同名相电流和的工频分量的变化量分别选相,共同确定故障相别,保证了近端单回线和跨线故障时选相元件不会因电流互感器饱和而无法正确选相,也避免了单纯使用电压选相在线路中远端发生故障时可能出现的选相困难;然后再比较各故障相的同名相电流故障分量的相位和幅值关系来判断出具体的故障相序,并在CT饱和时取故障稳态时的电流分量进行比较。该方法可对同杆双回线的各种单回线和跨线短路故障进行选相,原理简单,可靠性高。ATP-EMTP仿真结果表明,该方法能够实现双回线80%范围的单回线及跨线故障的可靠选相,可作为保护I段的选相判据。For common-tower double-transmission lines,the algorithms of phase selection schemes based on currents for back-up relay protection’s first section are complicated or the selection results are not accurate enough.Furthermore,the saturation of current transformers（CTs） caused by near-terminal faults may result in inaccurate phase selection or missing some fault phases.To solve these problems,a fault phase selection scheme based on currents,in which the voltages are assistant electrical quantities,was proposed for common-tower double-transmission line using one-terminal electrical quantities.At the beginning stage of faults,the power-frequency fault components of 3 one-terminal voltages and the 3 one-terminal same-name-phases’ sum-currents were applied respectively for selecting the fault phases and the results were integrated to discriminate the fault phases.This way can avoid the negative effects of CT saturation when the fault is at lines’ near terminal and the disadvantages of phase selection only using voltages when the fault is at the middle of the lines or far terminal.Then,by comparing the fault component values and phases of same-name-phase currents,the fault phase-lines can be identified.And if CT saturation occurs,the steady state fault currents will be used for selecting the fault phase-line.The proposed scheme is simple,reliable,and can deal with all kinds of short circuit faults on same-tower double circuit lines.The result of ATP-EMTP simulation shows that the proposed scheme can reliably select fault phase-lines when the fault occurs at the near side of parallel lines with a length range of 80%,which means it can serve for the relay protection’s first section.

关 键 词：同杆双回线 选相 电流故障量 电压变化量 单端电气量 跨线故障 

分 类 号：TM77[电气工程—电力系统及自动化]