HVDC馈入及其换相失败对交流电网选相元件的影响分析  

Influence Analysis of HVDC and Commutation Failure on AC Phase Selector

作　　者：李永丽[1] 杨子荷 宋金钊 陈晓龙[1] LI Yongli;YANG Zihe;SONG Jinzhao;CHEN Xiaolong(Key Laboratory of Smart Grid(Tianjin University),Ministry of Education,Nankai District,Tianjin 300072,China)

机构地区：[1]智能电网教育部重点实验室(天津大学),天津市南开区300072

出　　处：《电网技术》2020年第5期1825-1833,共9页Power System Technology

基　　金：国家重点研发计划资助项目(2016YFB0900603);国家电网公司科技项目(52094017000W)。

摘　　要：在交直流互联电网中,交、直流系统之间的相互作用以及直流换相失败将导致逆变侧交流电流呈现新的故障特征,进而对交流电网保护造成不利影响。从开关函数调制理论的角度出发,研究了交流系统故障时刻对于发生换相失败的换流阀组所属相别的影响,计算了故障暂态及稳态阶段逆变器三相开关函数工频量,进而分析了注入逆变侧交流系统等值工频电流的暂态及稳态故障特征。基于上述内容,分析指出当现有突变量选相元件以及稳态序分量选相元件应用于交直流互联电网时,由于交流系统故障时刻以及直流系统换相失败程度的影响,选相元件将出现误判故障类型甚至误选相的情况。通过PSCAD/EMTDC仿真验证了理论分析的正确性。In AC/DC interconnected system, the interaction between AC and DC systems and the commutation failure caused by AC system fault at inverter side will bring complicated fault features on inverter side AC system, influencing AC protection. The influence of AC fault time and commutation failure extent on three phase switching function was discussed in this paper. Combined with switching function theory, the transient and steady fault features of AC system current at the inverter side were studied. On this basis, adaptations of phase selector based on fault component and sequence component in AC system with DC system interconnected were respectively analyzed. Results show that both phase selector theories are no more adaptive in AC/DC interconnected system because of the influence of AC system fault time and commutation failure extent, possibly leading to misjudgment on both fault type and fault phase. PSCAD/EMTDC simulations verify correctness of the theoretical analysis.

关 键 词：换相失败 选相元件 突变量 稳态序分量 开关函数 

分 类 号：TM721[电气工程—电力系统及自动化]