基于电流斜率的多端柔性直流输电线路保护方法

A Protection Method for Multi-terminal Flexible DC Transmission Line Based on Current Slope

摘要:

文中研究了多端柔性直流输电系统在各种故障情况下的故障特征，根据理论分析得出当发生内部故障时，故障线路两端的故障电流方向是相同的，非故障线路两端的故障电流方向相反。提出了一种基于电流斜率的选线方法。通过比较线路两端故障电流的斜率，可以有效地识别出故障线路，可用于柔性直流输电系统的后备保护。最后，利用PSCAD/EMTDC软件建立了张北四端柔性直流电网的仿真模型，并对所提出的保护原理进行了仿真验证。

Abstract:

The fault characteristics of multiterminal flexible DC transmission system under various fault scenarios are studied. According to theoretical analysis, when an internal fault occurs, the fault current direction on both ends of the fault line is the same; however, the direction of the fault current on both ends of the healthy line is opposite. Then a fault line selection method[JP+2] based on current slope is proposed. By comparing the slope of fault current at both ends of the line, the fault line can be effectively identified, which can be used in the flexible DC transmission systems as a backup protection. Finally, the simulation[JP+2] model of Zhangbei four terminal flexible DC grid is established by using PSCAD/EMTDC software, and the simulation[JP] is carried out to verify the effectiveness of the proposed protection principle.