A Modular multilevel converter with hybrid redundant strategy for HVDC system

Wanli Jing; Lixin Jia; Lixia Yang; Mengyi Li; Yuxin Ma; Wenyao Sun

Energy Reports (Nov 2021)

A Modular multilevel converter with hybrid redundant strategy for HVDC system

Wanli Jing,
Lixin Jia,
Lixia Yang,
Mengyi Li,
Yuxin Ma,
Wenyao Sun

Affiliations

Wanli Jing: School of Electrical Engineering, Xi’an Jiaotong University, No. 28 , West Xianning Road, Xi’an, Shaanxi, 710049, China
Lixin Jia: Corresponding author.; School of Electrical Engineering, Xi’an Jiaotong University, No. 28 , West Xianning Road, Xi’an, Shaanxi, 710049, China
Lixia Yang: School of Electrical Engineering, Xi’an Jiaotong University, No. 28 , West Xianning Road, Xi’an, Shaanxi, 710049, China
Mengyi Li: School of Electrical Engineering, Xi’an Jiaotong University, No. 28 , West Xianning Road, Xi’an, Shaanxi, 710049, China
Yuxin Ma: School of Electrical Engineering, Xi’an Jiaotong University, No. 28 , West Xianning Road, Xi’an, Shaanxi, 710049, China
Wenyao Sun: School of Electrical Engineering, Xi’an Jiaotong University, No. 28 , West Xianning Road, Xi’an, Shaanxi, 710049, China

Journal volume & issue: Vol. 7
pp. 605 – 612

Abstract

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As a typical voltage source converter topology, Modular multilevel converter (MMC) widespread used in high voltage direct current (MMC-HVDC) power systems due to its modularization, low harmonic, easy expansion, and high efficiency. The failure of SMs will cause inhibit circulating current growth and unbalanced system voltage. Therefore, the handling of faulty SM has an utmost significance for MMC-HVDC. This paper proposes a hybrid control method of redundant SMs with semi-hot and cold standby redundant SM control methods. In normal operation, some redundant SMs are pre-charged to become semi-hot standby SMs. When the SM fails, one semi-hot standby SM is charged to become a working SM, and one cold standby SM is charged to become a semi-hot standby SM. In this paper, the proposed method is verified by simulation. The simulation shows two working states of MMC-HVDC, one is the voltage balance control of semi-hot standby SM in the normal working condition, another is the SM failure and redundant SM insertion control. Compared to using only one SM strategy, the implementation of the hybrid redundant strategy is easier and the loss is also lower.

Published in Energy Reports

ISSN: 2352-4847 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering
Website: http://www.journals.elsevier.com/energy-reports/

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