电网不对称故障下混合型MMC不间断运行技术  

Uninterrupted Operation Technology of Hybrid MMC Under Unbalanced Grid Fault

作　　者：孙仕达 向往[1] 饶宏 许树楷 黄润鸿 林卫星 文劲宇[1] SUN Shida1, XIANG Wang1 , RAO Hong2, XU Shukai2 , HUANG Runhong2, LIN Weixing3 , WEN Jinyu1(1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China; 2. State Key Laboratory of HVDC, Electric Power Research Institute, CSG, Guangzhou 510663, China; 3. TBEA China Xinjiang Sunoasis Co. , Ltd. , Urumchi 830011, Chin)

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 [2]直流输电技术国家重点实验室(南方电网科学研究院),广州510663 [3]特变电工新疆新能源股份有限公司,乌鲁木齐830011

出　　处：《南方电网技术》2018年第2期12-19,共8页Southern Power System Technology

基　　金：国家重点研发计划项目(2016YFB0901002);中国博士后创新人才支持计划项目(BX201700088)~~

摘　　要：为提高混合型MMC的不间断运行能力,提出了一种混合型MMC在电网不对称故障下的控制策略。该控制器在交、直流解耦控制的架构上,引入dq坐标系下的正负序分离锁相环、准谐振控制环节、低压限流环节和零序环流抑制环节,实现了负序电流抑制,限制了桥臂的过电流,消除了零序二倍频环流。首先介绍了电网不对称下换流器的模型,基于功率和桥臂电流的表达式,分析了换流器受到的影响。然后针对不对称故障,设计了负序电流抑制策略、有功功率控制策略和桥臂环流抑制策略,以保证混合型MMC的安全稳定运行。最后在PSCAD/EMTDC中搭建了双端MMC-HVDC模型,验证了所设计策略在电网不对称故障下的有效性,实现了混合型MMC的不间断运行。To improve the uninterrupted operation capability of hybrid modular multilevel converter（ MMC）,the control strategy considering unbalanced grid fault is proposed in this paper. A control loop including ANF-PLL,quasi resonant part,low voltage current limiting and zero-sequence circulating current suppressing is added based on AC/DC decoupling control. The negative-sequence current is suppressed,the overcurrent of the arm is limited and the zero-sequence double frequency current is eliminated. Firstly,the converter model under unbalanced condition is introduced. The impact is analyzed based on the expression of power and arm current.Then the negative-sequence current suppression strategy,active power control strategy and circulating current suppression strategy are designed to ensure the safe and stable operation of hybrid MMC. Finally,a two-terminal MMC-HVDC model is built with PSCAD/EMTDC. The proposed control strategy is verified by simulations under an unbalanced grid fault. The uninterrupted operation of hybrid MMC is achieved.

关 键 词：混合型MMC 电网不对称故障 负序电流抑制 低压限流 环流抑制 

分 类 号：TM715[电气工程—电力系统及自动化]