LCC-FHMMC混合直流输电系统阀侧故障特性及保护策略  

Grounding fault characteristics of converter valve-side and protection strategy in LCC-FHMMC hybrid DC transmission system

作　　者：陆书豪 贾秀芳[1] LU Shuhao;JIA Xiufang(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,北京102206

出　　处：《电力自动化设备》2021年第11期211-216,224,共7页Electric Power Automation Equipment

基　　金：国家自然科学基金资助项目(51777072)。

摘　　要：送端采用电网换相换流器(LCC)、受端采用半桥与全桥混合型模块化多电平换流器(FHMMC)的LCCFHMMC混合直流输电系统,在受端发生阀侧单相接地故障时,具有与半桥或全桥型MMC不同的故障特性。分别从交流电源贡献、直流电源贡献以及高低端阀组差异3个角度对阀侧单相接地故障下子模块过电压机理进行了分析。随后,针对FHMMC混合直流输电系统直流侧无直流断路器的特点,提出了一种基于选相型单向晶闸管旁路支路的故障隔离策略,以及适用于LCC-FHMMC混合直流输电系统阀侧单相接地故障的保护策略。最后,基于PSCAD/EMTDC仿真平台搭建了相关模型,通过仿真验证了理论分析的正确性以及所提保护策略的有效性。LCC-FHMMC hybrid DC transmission system,in which the sending end adopts LCC(Line Commutated Converter)and the receiving end adopts FHMMC(Full-bridge and Half-bridge Modular Multi-level Converter),has different characteristics from half bridge MMC or full bridge MMC when a single-phase grounding fault occurs on the converter valve-side at the receiving end.The overvoltage mechanism of the sub-module under the grounding fault on converter valve-side is analyzed from three perspectives of AC power contribution,DC power contribution and the difference between high-and low-valve groups.According to the characteristics of non-DC circuit breaker on the DC side of LCC-FHMMC hybrid DC transmission system,a fault isolation method based on phase selection type unidirectional thyristor bypass branch and a protection strategy suitable for single-phase grounding fault occurs on the converter valve-side in LCCFHMMC hybrid DC transmission system are proposed.Finally,a related model is built based on the PSCAD/EMTDC simulation platform,and the correctness of the theoretical analysis and the effectiveness of the proposed protection strategy are verified by simulation.

关 键 词：LCC-FHMMC混合直流输电 换流器 阀侧接地故障 晶闸管旁路支路 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM771