Analysis of the Influence of Overmodulation Conditions on the Operational Stability of the Hybrid Modular Multilevel Converter in the Medium-Voltage DC Distribution Network Scenario

被引：0
|
作者：
Xiao Q. [1 ]
Xu J. [1 ]
Jia H. [1 ]
Mu Y. [1 ]
Jin Y. [1 ]
Lu W. [1 ]
机构：
[1] Key Laboratory of Smart Grid of Ministry of Education, Tianjin University, Tianjin
来源：
Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology | 2024年 / 57卷 / 02期
基金：
中国国家自然科学基金; 英国工程与自然科学研究理事会;
关键词：
hybrid modular multilevel converter(hybrid MMC); medium-voltage DC(MVDC)distribution network; root-locus curve; small-signal modeling; stability analysis;
D O I：
10.11784/tdxbz202211030
中图分类号：
学科分类号：
摘要：
The hybrid modular multilevel converter(hybrid MMC)can realize DC fault ride-through of the medium-voltage DC(MVDC)distribution network through overmodulation operation. The existing research has not completely analyzed the operational stability of the hybrid MMC under overmodulation conditions，which cannot meet the operational requirements of the MVDC distribution network. Therefore，this study analyzes the influence of overmodulation conditions on the operational stability of the hybrid MMC by comparison with normal conditions. Firstly，under the unified dq coordinate system of electrical and control components，a small-signal model considering the DC modulation ratio of the hybrid MMC is constructed，and the accuracy of the established model is verified by comparison with the detailed electro-magnetic transient(EMT)simulation results. Secondly，the root-locus curves under normal and overmodulation conditions are compared，and the influence of overmodulation conditions on the operational stability of the system is analyzed from the perspective of the feasible regions of the control parameters. Thirdly，based on the imaginary component of the characteristic root of the dominant mode，the oscillation frequency is calculated when the system is unstable and compared with the result obtained from the EMT simulation with the same control parameters，and the accuracy of the above stability analysis results is verified. Finally，the participation degree of each state variable in the dominant mode is calculated based on the participation factor method，and the key state variables significantly affecting the stability of the system are revealed. Theoretical analysis and simulation results show that the internal modes of the hybrid MMC are unstable with increasing AC/DC controller parameters. Compared with those under normal conditions，the feasible ranges of the hybrid MMC control parameters are expanded，and the small-signal stability is improved under overmodulation conditions. © 2024 Tianjin University. All rights reserved.
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页码：123 / 136
页数：13
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