基于虚拟阻抗的多落点混合级联直流系统故障电流抑制方法  

Fault current suppression method of multi-point hybrid cascaded DC system based on virtual impedance

作　　者：吴海艳 江琴 李保宏[1] 刘天琪[1] 张敏 王腾鑫 WU Haiyan;JIANG Qin;LI Baohong;LIU Tianqi;ZHANG Min;WANG Tengxin(College of Electrical Engineering,Sichuan University,Chengdu 610065,China;Electric Power Research Institute of State Grid Shanxi Electric Power Co.,Ltd.,Taiyuan 030012,China)

机构地区：[1]四川大学电气工程学院,四川成都610065 [2]国网山西省电力有限公司电力科学研究院,山西太原030012

出　　处：《电力自动化设备》2023年第2期191-196,202,共7页Electric Power Automation Equipment

基　　金：国家电网公司科技项目(5100-202199274A-0-0-00)。

摘　　要：多落点混合级联直流系统存在特有的模块化多电平换流器(MMC)功率盈余问题。当受端交流系统发生短路故障时,MMC过流、过压将引起MMC阀组闭锁,进一步可能导致系统功率中断。多落点混合级联直流系统整流侧采用电网换相型换流器(LCC)、逆变侧采用LCC与多台MMC级联。针对该系统提出一种适用于受端交流系统故障的故障电流限制方法,在逆变侧MMC控制中引入虚拟阻抗降低故障电流,无需额外添加设备。对虚拟阻抗的控制引入、计算以及投入实现过程进行了详细阐述,并在PSCAD/EMTDC中搭建模型进行仿真分析。结果表明,所设计的虚拟阻抗控制器可以实现故障电流的有效抑制,并防止功率倒送,从而实现混合级联直流系统的交流故障成功穿越和功率可靠传输。There is a unique power surplus problem of modular multilevel converter(MMC) in multi-point hybrid cascaded DC system. When a short circuit fault occurs in the receiving end AC system,the MMC overcurrent and overvoltage will cause the MMC valve blocked,which may further cause system power interrupted. The rectifier-side of multi-point hybrid cascaded DC system adopts the line commutated converter(LCC),and the inverter-side adopts the cascade connection of LCC and multiple MMCs. A fault current suppression method suitable for fail occurred at receiving end AC system is proposed. The fault current is reduced by introducing a virtual impedance in the MMC control at inverter side without additional equipment. The control introduction,calculation and input realization process of virtual impedance are elaborated in detail,and a model is built in PSCAD/EMTDC for simulation analysis. The results show that the designed virtual impedance controller can realize the fault current suppression effectively and prevent power reversal,so as to achieve the successful ride-through of AC faults and reliable power transmission of hybrid cascaded DC system.

关 键 词：多落点混合级联直流系统 协调控制策略 故障穿越 限流措施 虚拟阻抗 

分 类 号：TM721.1[电气工程—电力系统及自动化]