混合式MMC及其直流故障穿越策略优化  

Optimal Design for Hybrid MMC and Its DC Fault Ride-through Strategy

作　　者：李少华[1] 王秀丽[1] 李泰 彭忠 

机构地区：[1]西安交通大学电气工程学院,陕西省西安市710049 [2]许继电气股份有限公司,河南省许昌市461000

出　　处：《中国电机工程学报》2016年第7期1849-1858,共10页Proceedings of the CSEE

基　　金：国家863高技术基金项目(2015AA050101)~~

摘　　要：模块化多电平换流器(modular multilevel converter,MMC)应用于大容量架空线输电系统是柔性直流输电技术的研究热点,直流故障的处理是研究的难点。针对一种整流侧采用电网换相换流器(line commutated converter,LCC)、逆变侧采用混合式模块化多电平换流器的混合直流输电系统,重点研究混合式MMC的优化设计、过调制及直流故障穿越问题。推导在满足低直流电压过调制运行、直流故障穿越和子模块电容电压平衡条件下其全桥子模块(full bridge sub-module,FBSM)和半桥子模块(half bridge sub-module,HBSM)的数目配置要求。并提出混合式MMC直流故障穿越的优化控制策略,可以更好地平衡子模块电容电压,且在直流故障期间仍可保持对交流系统的无功功率补偿。最后在PSCAD/EMTDC仿真环境中建立该混合直流输电系统模型,对直流故障穿越和过调制运行进行仿真研究,结果证明优化策略的有效性。Modular multilevel converter（MMC） for bulk power overhead line transmission is a hot issue of flexible DC transmission study in China. Difficultly and costly to handle DC fault is the main challenge. This paper investigated a hybrid high voltage direct current（HVDC） system, in which the rectifier adopts line commutated converter（LCC） and the inverter adopts hybrid MMC composed of half bridge sub-module（HBSM） and full bridge sub-module（FBSM）. On the premise of being capable of operating at low DC voltage with over modulation, clearing DC fault and successful voltage balancing of HBSMs, the required number of sub-modules and the more costly FBSMs were calculated. Moreover, an improved DC fault ride-through strategy was proposed which balanced the capacity voltage of FBSMs better and maintained the reactive power compensation during the DC fault period. Finally, the capability of DC fault ride-through, over modulation and the operation under low DC voltage with optimal sub-module count for the hybrid MMC were verified using PSCAD/EMTDC simulations.

关 键 词：混合直流输电系统 电网换相换流器 混合式模块化多电平换流器 直流故障穿越 

分 类 号：TM72[电气工程—电力系统及自动化]