降低直流输电换相失败概率的改进拓扑及其控制策略  

An Improved Topology to Decrease the Commutation Failure in LCC-HVDC and Its Control Strategy

作　　者：倪晓军 赵成勇 许韦华 刘羽超 郭春义 阳岳希 

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市昌平区102206 [2]国网智能电网研究院,北京市昌平区102200

出　　处：《中国电机工程学报》2015年第4期811-820,共10页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51177042);国家电网公司大电网重大专项资助项目(SGCC-MPLG004-2012);国家863高技术基金项目(2012AA052701)~~

摘　　要：为了降低电网换相高压直流输电(line-commutatedconverter high voltage direct current,LCC-HVDC)的换相失败概率,提出一种LCC-HVDC改进拓扑。该拓扑从增大换流阀换相电压的角度出发,在原阀臂中串联接入新型可控子模块,以辅助换相。首先介绍该拓扑中子模块的3种工作状态,并分析子模块开关管的电压和电流。然后设计改进拓扑的控制策略,提出"最优充电初始电压"这一概念,并对其进行优化计算。PSCAD/EMTDC仿真结果表明,该拓扑能灵活切换子模块的工作状态,提高了LCC-HVDC防御换相失败的能力;所提出"最优充电初始电压"的优化计算方法效果良好,对该拓扑的换相失败防御能力有进一步的提升作用。An improved topology was proposed to decrease the commutation failure in Line-Commutated-Converter High Voltage Direct Current（LCC-HVDC）. With novel controllable sub-modules inserted into the bridge, the topology assists in commutating from the viewpoint of increasing the commutating voltage. Firstly, the operating modes of sub-module were analyzed, and the operation voltage and current of the sub-module switches were given by theoretical derivation. Additionally, the control strategy was designed, then the concept of optimal initial charging voltage was presented and its calculation method was investigated. The simulation results in PSCAD/EMTDC show that it is flexible to change the sub-module operation modes, and commutation failure is decreased in LCC-HVDC. The proposed calculation method of optimal initial charging voltage proved to be accurate and it can further reduce the possibility of commutation failure.

关 键 词：电网换相高压直流输电 换相失败 新型可控子模块 子模块控制 最优充电初始电压 

分 类 号：TM85[电气工程—高电压与绝缘技术]