混合型MMC非闭锁型直流故障穿越的故障等效模型  

Fault equivalent model for non-blocking DC fault ride-through of hybrid MMC

作　　者：王泽青 夏成军[1,2] 赖胜杰 纪焕聪 周月宾 蔡海青 WANG Zeqing;XIA Chengjun;LAI Shengjie;JI Huancong;ZHOU Yuebin;CAI Haiqing(School of Electric Power Engineering,South China University of Technology,Guangzhou 510641,China;Guangdong Province Key Laboratory of Intelligent Operation and Control for New Energy Power System,Guangzhou 510663,China;State Key Laboratory of HVDC(Electric Power Research Institute of China Southern Power Gird),Guangzhou 510663,China)

机构地区：[1]华南理工大学电力学院,广东广州510641 [2]广东省新能源电力系统智能运行与控制企业重点实验室,广东广州510663 [3]直流输电技术国家重点实验室(南方电网科学研究院有限责任公司),广东广州510663

出　　处：《电力工程技术》2023年第2期103-111,共9页Electric Power Engineering Technology

基　　金：广东省重点领域研发计划资助项目“粤港澳大湾区智慧电力柔性互联关键技术研究”(2019B111109001)。

摘　　要：由半桥子模块和全桥子模块构成的混合型模块化多电平换流器(modular multilevel converter,MMC)相比于全桥型MMC能够在降低成本的同时具备直流故障穿越能力,直流故障暂态分析是混合型MMC器件选型和配比设计的基础。为分析混合型MMC直流侧故障的暂态特性,文中建立额定运行状态和降压运行状态下发生极间短路的混合型MMC非闭锁型直流故障穿越过程的故障等效模型;分析了直流故障穿越期间混合型MMC各桥臂子模块的动态投切过程,将非闭锁型直流故障穿越控制策略切换前的暂态过程等效为不可控的子模块电容放电过程,将控制策略切换后的暂态过程等效为带有电感初始储能和反向电压源的限流过程;给出了直流侧短路电流的解析计算方法。最后,基于PSCAD/EMTDC搭建仿真模型,验证了文中模型和计算方法的有效性,能够为混合型MMC的优化设计提供参考。Compared with full-bridge modular multilevel converter(MMC),the hybrid MMC composed of half bridge sub-module and full bridge sub-module has the low cost and high DC fault ride-through capability.The DC fault transient analysis is the basis of device selection and proportioning design of hybrid MMC.In order to analyze the transient characteristics of hybrid MMC after DC side fault,the equivalent fault models of DC pole-pole short circuit during the non-blocking DC fault ride-through in rated operation and step-down operation are established.The dynamic switching process of each bridge arm sub-module of hybrid MMC during DC fault ride-through is analyzed.The transient process before the switching of the non-blocking DC fault ride-through control strategy is equivalent to the uncontrollable sub-module capacitor discharge process,while the transient process after switching the control strategy is equivalent to the current limiting process with the initial energy storage of the inductor and the reverse voltage source.The analytical calculation method of the short-circuit current on the DC side of hybrid MMC is also given in this paper.Finally,the effectiveness of the model and calculation method proposed in this paper is verified by the PSCAD/EMTDC simulation platform,which can provide a reference for the optimal design of hybrid MMC.

关 键 词：混合型模块化多电平换流器 直流侧故障 非闭锁型故障穿越 暂态分析 故障等效模型 短路电流计算 

分 类 号：TM721.1[电气工程—电力系统及自动化]