Analysis of the performance characteristics and arm current control for modular multilevel converter with asymmetric arm parameters. (September 2019)

• Record Type: Journal Article
• Authors: Liu, Ziwen; Miao, Shihong; Fan, Zhihua; Kang, Yilong; Tu, Qingyu
• Is Part Of: International journal of electrical power & energy systems. Volume 110(2019)
• Page Start: 258
• Page End: 270
• Publication Date: 2019-09
• Subjects: Modular multilevel converter -- Asymmetric arm parameters -- Performance characteristics analysis -- Circulating current -- Dynamic response; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2019.03.010
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: The performance characteristics of MMC with asymmetric arm parameters is conducted based on average switching function current model. It is demonstrated that fundamental and double frequency ripples exist in arm circulating current under asymmetric arm parameter conditions. It is also demonstrated that there will be dc and double frequency components in the ac side current, while fundamental and double frequency ripples also appear in the dc side current. The arm current control based on an improved PIR controller via the FAC method is proposed to suppress the asymmetric components with significantly enhanced dynamic response. Abstract: In this paper, the performance characteristics analysis and an improved arm current control of modular multilevel converter (MMC) with asymmetric arm parameters are presented. The performance characteristics analysis of MMC is conducted based on the average switching function current model, which demonstrates that fundamental and double frequency ripples exist in the arm circulating current under asymmetric arm parameter conditions. Besides, there will be dc and double frequency components in the ac side current, while fundamental and double frequency ripples also appear in the dc side current. According to the analysis results, the arm current control based on an improved PIR (Proportional Integral-Resonant) controller via the FAC (feedback adjustment control) method is proposed to suppress the asymmetric components with significantly enhanced dynamic response. Theoretical analysis shows that by introducing the integration and feedback loops of the FAC method to the conventional PIR controller, the inertia and damping effects are emerged in the system, which can help to enhance the system dynamic response during transient and achieve better suppression performance of the asymmetric components. Simulation cases verify the correctness of the theoretical analysis and the validity of the proposed control.