标题：A control strategy for suppressing zero-sequence circulating current in paralleled three-phase voltage-source PWM converters
作者：Han Z.; Wang X.; Jiang B.; Chen J.
作者机构：[Han, Z] School of Mechanical, Electrical and Information Engineering, Shandong University, Weihai, 264209, China;[ Wang, X] School of Mechanical, Ele 更多
通讯作者地址：[Wang, X] School of Mechanical, Electrical and Information Engineering, Shandong UniversityChina;
来源：Applied Sciences (Switzerland)
关键词：Feedforward compensation; Paralleled converters; Proportional-integral quasi-resonant (PIQR) control; Three-phase voltage-source PWM converter; Zero-sequence circulating current (ZSCC) suppression; Zero-vector duty ratio
摘要：In microgrids, paralleled converters can increase the system capacity and conversion efficiency but also generate zero-sequence circulating current, which will distort the AC-side current and increase power losses. Studies have shown that, for two paralleled three-phase voltage-source pulse width modulation (PWM) converters with common DC bus controlled by space vector PWM, the zero-sequence circulating current is mainly related to the difference of the zero-sequence duty ratio between the converters. Therefore, based on the traditional control ideal of zero-vector action time adjustment, this paper proposes a zero-sequence circulating current suppression strategy using proportional-integral quasi-resonant control and feedforward compensation control. Firstly, the dual-loop decoupled control was utilized in a single converter. Then, in order to reduce the amplitude and main harmonic components of the circulating current, a zero-vector duty ratio adjusting factor was initially generated by a proportional-integral quasi-resonant controller. Finally, to eliminate the difference of zero-sequence duty ratio between the converters, the adjusting factor was corrected by a feedforward compensation link. The simulation mode of Matlab/Simulink was constructed for the paralleled converters based on the proposed control strategy. The results verify that this strategy can effectively suppress the zero-sequence circulating current and improve power quality. © 2020 by the authors.