中文摘要：

为避免距离III段保护可能由潮流转移引起误动,运用WAMS的优势提出一种计及振荡过程的电力系统潮流转移识别方案。根据非振荡下潮流转移与区内故障中线路三相电流不对称程度、零序电流相对大小、正序电压最小值的明显差别,引入能区分二者的潮流转移特征值（transfer power flow characteristic,TPFC）概念,基于TPFC提出识别判据;考虑到振荡时电压、电流大小随系统功角变化可能影响判据的满足情况,详细推导出功角从0？到180？变化过程中分别发生潮流转移与各类故障时TPFC的不同范围,依此整定判据阈值和识别延时,阐述了方案的具体实施流程。对IEEE10机系统的仿真结果表明,所提方案能准确判别潮流转移和各类故障,不受系统运行方式、潮流分布与过渡电阻的影响;不改变现行保护的延时跳闸功能,计算和通信负担小,利于适应节点数较多的大电网,对有效预防级联跳闸事故提供了参考。

英文摘要：

To avoid possible malfunction of zone 3 distance protection caused by power flow transfer, taking advantage of wide area measurement system, a scheme for power flow transfer identification concerning power swing is proposed. In terms of differences between power flow transfer and internal short-circuit fault without power swing in three-phase currentasymmetry, relative zero-sequence current and minimum positive-sequence voltage, a new concept of transfer power flow characteristic（TPFC） is introduced to distinguish the 2 cases, based on which identification criteria are put forward. Considering that voltage and current variationduring power swings may affect criterion satisfaction, different ranges of TPFC under conditions of power flow transfer and internal faults with power angle changing from 0° to 180° are derived in detail. Then criterionthresholds and identification delay time are set according to derived conclusion, and concrete flowchart of the scheme is provided. Simulation results with IEEE 10-machine test system show that the scheme can discriminate power flow transfer and all types of faults accurately,regardless of system operating mode, flow distribution or transition resistance. Besides, it doesn＇t change original property of existing protection or increase much burden on computation and communication,suitable for smart grid with a large number of nodes. It provides reference for effective prevention of cascading trips.