统一潮流控制器对线路纵联保护的影响分析

外部交流系统故障时，统一潮流控制器的保护可能动作于使统一潮流控制器退出运行。这将引起交流系统中电气量的再一次快速变化，与交流故障造成的扰动形成“电气竞争”，可能给线路纵联保护带来不利的影响。对南京西环网统一潮流控制器示范工程进行了介绍。并在分析统一潮流控制器保护系统设计原则的基础上，通过理论分析和数字仿真研究了统一潮流控制器对纵联零序保护、纵联距离保护和工频变化量方向保护的影响。研究表明统一潮流控制器的接入可能导致工频变化量方向保护区内故障拒动或区外故障误动，有必要对相关线路的保护进行改造。

Impact analysis of unified power flow controller on transmission line pilot protection

When the AC fault occurs in the power grid, the protection of unified power flow controller (UPFC) would trip to make the UPFC out of operation. It would cause the electrical quantities in the power grid change suddenly once again. Subsequently, the competition between the disturbance caused by AC fault and that caused by the trip of UPFC protection would have adverse influence on the transmission line pilot protection. The demonstrative project of UPFC in the western Nanjing grid is introduced. Moreover, based on the discussion about the UPFC protection system, the impacts of UPFC on the performances of pilot zero-sequence protection, pilot distance protection and superimposed component direction protection are studied with theoretical analysis and simulation study. It points out that the mal-operation or fail-to-trip of the superimposed component direction protection would occur due to the impact of UPFC, and it is necessary to improve the relevant protection schemes.