摘要
模块化多电平换流器(MMC)的各个子模块间的电压均衡问题,是MMC拓扑的难点之一。本文在采用最近电平调制方式的基础上,对按子模块电容电压排序后,根据桥臂电流方向直接选择相应子模块触发的传统电压均衡方法进行了改进,引入子模块间最大电压偏差量,有效避免了因排序算法导致的同一IGBT不必要的反复投切现象,从而在保证各子模块电容电压基本一致的前提下,大大降低了因排序算法导致的过多的IGBT开关次数,明显减小了换流器的开关损耗。最后通过PSCAD/EMTDC搭建了20子模块的MMC仿真模型,对优化前后的电压均衡控制方法进行了比较,仿真结果表明该改进算法可以在保证系统稳态特性的前提下,明显减小IGBT开关次数,降低开关损耗。
Modular multilevel converter based HVDC（MMC-HVDC） is a new generation VSC-HVDC topology invented by Siemens.The problem of voltage balancing among the submodules（SM） is difficult to solve.The traditional method,which uses the sorting results of the SM capacitor voltages and fires the IGBTs directly,leads to relatively higher power losses.This paper proposes an improved voltage balancing control method,which reduces the switching operation significantly and the switching losses of the converter decreases consequently.The model of MMC-HVDC with 20 SMs is realized by PSCAD/EMTDC,and the traditional and improved voltage balancing control methods are compared.The simulation results demonstrate that the model is reasonable and the improved method is effective.
出处
《电工技术学报》
EI
CSCD
北大核心
2011年第5期15-20,共6页
Transactions of China Electrotechnical Society
关键词
模块化多电平换流器
子模块
电压均衡
开关频率
开关损耗
Modular multilevel converter
sub modules
voltage balancing
switching frequency
switching losses
