面向含不可测分支配电线路不对称故障可靠辨识的负序电流比相保护判据  

Phase Comparison Protection of Negative Sequence Current for Distribution Lines with Unmeasurable Branches

作　　者：肖澍昱 林湘宁[1] 魏繁荣[1] 吴宇奇 李正天[1] Xiao Shuyu;Lin Xiangning;Wei Fanrong;Wu Yuqi;Li Zhengtian(State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology,Wuhan,430074,China)

机构地区：[1]强电磁工程与新技术国家重点实验室(华中科技大学),武汉430074

出　　处：《电工技术学报》2023年第9期2435-2447,共13页Transactions of China Electrotechnical Society

基　　金：国家电网公司总部科技项目资助(5100-202140339A-0-0-00)。

摘　　要：城市配电网的主动配电网特征日趋显著,含不可测分支结构的馈电线路大量增加。受上述特点影响,单端量保护性能显著降低。因此,对于特别重要的线路,亟待双端量保护来保证故障切除的可靠性和灵敏性。但是,分支电流的差动特性导致相量差动保护从原理上即不适用,而纵联距离保护和方向比较式纵联保护由于需要电压信息,在仅配置电流互感器的线路不具备实施条件。此外,电压和分支两因素的叠加使得上述保护的动作行为分析尤为困难。因此,有必要寻找新型纵联保护判据。该文充分考虑不可测分支的影响,提出了仅利用负序电流相位差这一不对称故障期间始终存在的故障分量来反映故障的思路,并构建了一种适用于这类配电网线路的负序电流比相判据。与现有含分支的幅值差动类保护相比,所提判据在安全性方面具有优势。在PSCAD/EMTDC中搭建10 kV配电网模型,设计多组仿真算例,对比验证了所提判据的有效性。The remarkable evolution in the urban distribution networks highlights its active-distribution-characteristic.And the number of distribution feeders with unmeasurable branch structures increases greatly.To adapt to this feature,the performance of non-unit protection degrades to a great extent.For particularly important feeders,pilot protection is urgently needed to ensure the reliability and sensitivity of fault removal.Due to the differential characteristics of branch current,phasor differential protection is not applicable in principle.The pilot distance protection and directional comparison pilot protection both require voltage information while Potential Transformers(PTs)are not available for the protection of distribution network.In addition,both factors mentioned above make it difficult to analyze the action behavior of protection.Therefore,it is of great significance to design a new pilot protection criterion.Firstly,the influence of unmeasurable branches is fully considered,and the idea of using only the phase difference of negative sequence current,the fault component that always exists during the asymmetric fault,to reflect the fault is proposed.Next,considering the passive property equivalence of motor type distributed generation(DG)and inverter type DG in negative sequence network,the phase comparison range of negative sequence current on both sides of the line in case of internal fault and external fault is analyzed respectively,and the difference between them is plotted in the phase comparison plane.Finally,based on this difference,the negative sequence phase comparison criterion of each level of line is set,and combined with the auxiliary criterion of negative sequence current check,a negative sequence current phase comparison protection suitable for branched distribution network line is constructed.Simulation results of a 10 kV distribution network model in PSCAD/EMTDC show that the data processing time required for protection is about 20 ms.This meets the requirements of distribution network diff

关 键 词：负序电流比相判据 不可测分支 不对称故障 负序电流校核判据 有源配电网 

分 类 号：TM773[电气工程—电力系统及自动化]