控制理论(社会学)
网格
模块化设计
高压直流电
电压
工程类
电流(流体)
传动系统
电压源
拓扑(电路)
转换器
计算机科学
电子工程
传输(电信)
控制(管理)
直流电
电气工程
数学
操作系统
人工智能
几何学
作者
Shaohua Li,Xiuli Wang,Zhiqing Yao,Tai Li,Zhong Peng
出处
期刊:IEEE Transactions on Power Electronics
[Institute of Electrical and Electronics Engineers]
日期:2015-01-01
卷期号:30 (1): 387-397
被引量:277
标识
DOI:10.1109/tpel.2014.2329059
摘要
Modular multilevel converter (MMC) is considered as a promising topology for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. This paper presents a new control strategy for MMC-HVDC under unbalanced grid conditions. First, a new inner loop current control strategy based on nonideal proportional resonant (PR) controllers in stationary αβ frame is designed, which is more concise compared to the existing dual sequence current control scheme. Second, an analytical expression for circulating current is obtained which shows that the circulating currents will be asymmetric under unbalanced grid conditions and can be decomposed into positive-, negative-, and zero-sequence component. In order to suppress all these components, a new circulating current suppressing strategy is analyzed and designed also based on nonideal PR controllers. Application of nonideal PR controllers makes the control system well adapt to the fluctuation of grid frequency. The effectiveness of the proposed control strategy is verified through a simulation case of a 251-level MMC-HVDC transmission system using real-time digital simulator.
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