基于T型三电平变换器的优化损耗分布控制策略  

Optimal loss distribution control strategy based on a T-type three-level converter

作　　者：周思邈 马伏军[2] 许明春 丁红旗 黄格林 章程 王俊攀 ZHOU Simiao;MA Fujun;XU Mingchun;DING Hongqi;HUANG Gein;ZHANG Cheng;WANG Junpan(Zhenjiang Power Supply Branch of State Grid Jiangsu Electric Power Co.,Ltd.,Zhenjiang 212001,China;College of Electrical and Information Engineering,Hunan University,Changsha 410082,China;CHINA HUANENG Hunan Branch,Changsha 410082,China)

机构地区：[1]国网江苏省电力有限公司镇江供电分公司,江苏镇江212001 [2]湖南大学电气与信息工程学院,湖南长沙410082 [3]华能集团湖南分公司,湖南长沙410082

出　　处：《电力系统保护与控制》2023年第24期66-76,共11页Power System Protection and Control

基　　金：国家自然科学基金项目资助(51977067);湖南省研究生科研创新项目资助(CX20220393);湖南省自然科学基金优青项目资助(2020JJ3010)。

摘　　要：T型三电平变换器在常规调制策略下,存在着严重的内管外管损耗不均的问题。当变换器的调制比低于0.57时,T型三电平变换器的内管温升明显高于外管温升,这个问题在低电压穿越(low voltage ride through, LVRT)运行时更为严峻,将威胁变换器的长期可靠运行。为此,提出了一种基于损耗优化分布的不连续脉宽调制策略,在空间矢量图的对应区域采用新的开关序列,每相采用钳位到直流侧正极或直流侧负极的钳位方式,进而实现外管内管电流的重新分配。新调制策略采用五段式发波,不仅有效改善了内外管损耗的分布,还能提高变换器整体效率;通过冗余小矢量互补的序列,维持中点电压的平衡;新调制策略具有统一的载波调制实现方式。最后,通过电气-热联合仿真,验证了所提损耗优化分布调制策略的有效性。In conventional modulation strategy,there is a serious problem of uneven loss between inner and outer switches of a T-type three-level converter.When the converter’s modulation ratio is below 0.57,the inner switch temperature rise is significantly higher than that of the outer switch,and this issue is even worse during a low voltage ride through(LVRT)operation.It will threaten the long-term reliable operation of the converter.Therefore,a discontinuous pulse width modulation strategy based on optimal loss distribution is proposed.This adopts new switching sequences in corresponding regions of the space vector diagram.The clamping mode of each phase is to be clamped to the positive or negative pole so as to redistribute the current in outer and inner switches.This new modulation strategy adopts a five-stage wave mode.This can not only effectively improve the loss distribution of the inner and outer switches,but also enhance the efficiency of the converter.The balance of midpoint voltage is maintained through redundant small vector complementary sequences.The new modulation strategy has a unified carrier-modulation method.Finally,the effectiveness of the proposed loss distribution modulation strategy is verified by electrical-thermal co-simulation.This work is supported by the National Natural Science Foundation of China(No.51977067).

关 键 词：T型三电平变换器 损耗均衡 不连续调制 中点电压控制 

分 类 号：TM46[电气工程—电器]