MMC-based cascaded converter impedance model and stability analysis

被引：0
|
作者：
Sun W. [1 ]
Xia X. [1 ]
Liu G. [1 ]
Lu X. [1 ]
Yang R. [1 ]
Ma H. [1 ]
Wang Z. [2 ]
机构：
[1] State Grid Xiaogan Power Supply Company, Xiaogan
[2] Electric Power Security and High Efficiency Key Lab, Huazhong University of Science and Technology, Wuhan
来源：
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | 2023年 / 51卷 / 05期
关键词：
cascaded system; impedance model; MMC; stability analysis;
D O I：
10.19783/j.cnki.pspc.220990
中图分类号：
学科分类号：
摘要：
In engineering, different types of converters are often flexibly cascaded to achieve different functions. However, the interaction between the front and rear converters in the converter cascade system may lead to insufficient stability margin or even instability of the system. Different types of modular multilevel converter (MMC) based cascaded converters will face different stability problems. In this paper, a stability analysis model of an MMC cascaded converter is established, and a series resistance-based stability improvement strategy is proposed. First, the impedance models of an MMC-based AC/DC converter and a DC/DC converter are established. The small signal models of the two MMC-based converters are deduced near the steady-state operating point. From these the output impedance of the source converter and the input impedance of the load converter are obtained. Second, the stability of the MMC cascaded converter is analyzed. The results show that when the output impedance of the source converter does not match the input impedance of the load converter the stability margin of the cascade system may be insufficient, resulting in system instability. Then, is analyzes the influence of primary parameters such as smoothing and arm inductances and sub-module capacitance of the MMC cascaded converter on the stability of the cascaded system. Finally, a stability improvement method based on series resistance is proposed, and selection suggestions for series resistance are given. Simulation results show that the proposed stability control method can effectively improve the stability of an MMC converter cascade system. © 2023 Power System Protection and Control Press. All rights reserved.
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页码：117 / 127
页数：10
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