中文摘要：

当光伏电站、风机等逆变型分布式电源（inverter interfaced distributed generation,IIDG）T接入高压配电线路后,对纵联差动保护的可靠性与选择性带来了影响,保护范围内经过渡电阻发生短路故障时,易发生拒动现象。针对此问题,根据IIDG的故障特性,推导了T接IIDG后双端电源系统经过渡电阻发生不对称短路故障时的复合序网,进而推导了纵联差动保护中差动电流的计算公式。然后利用Matlab仿真软件重点分析了IIDG并网位置固定时,故障位置、故障类型、过渡电阻、IIDG容量以及两侧系统等值电势相角差对差动电流的影响,并在此基础上提出纵联差动保护影响下IIDG准入容量的计算方法。最后,利用PSCAD/EMTDC仿真平台,对提出的IIDG准入容量计算方法的正确性进行了仿真验证。

英文摘要：

When inverter interfaced distributed generation（IIDG） is connected to HV distribution network as a teed line,reliability and selectivity of longitudinal differential protection will be affected.Longitudinal differential protection may fail to operate when fault occurs in protection range through transition resistance.Based on IIDG fault characteristics,composite sequence circuit was derived for unbalanced fault through transition resistance in double-power supply system connecting IIDG.Computational formula of differential current was proposed.Then,relationships between fault position,fault type,transition resistance,IIDG capacity,angular phase difference of system potential and differential current were analyzed with simulation software MATLAB.On this basis,a method was proposed to calculate allowed IIDG penetration level under influence of longitudinal differential protection.At last,based on PSCAD/EMTDC simulation platform,validity of maximum IIDG penetration capacity was verified.