Abstract：In order to improve the fault tolerance under the sub-module fault of the modular multilevel DC transformer(MMDCT), this paper proposes a fault-tolerant control strategy for the MMDCT based on single-side-dual-phase-shift control. First, this paper analyzed the working principle and power model under dual-phase-shift control of MMDCT, and the system operating characteristic under the sub-module faults was investigated. The mechanisms of the arm voltage asymmetry, submodule voltage instability and circulating current fluctuation causing by the bypass fault sub-module were revealed. Then based on the single-side-dual-phase-shift control, a fault-tolerant control strategy of MMDCT was proposed, which used the single-side-phase-shift angle in and between the primary side arm as the control variable. By balancing the average sub-module voltage of the fault arm, the system instability caused by the asymmetric arm was solved, and the arm circulation fluctuation was also suppressed. Finally, a MMC DC transformer with 10 sub-modules per arm was built in the Matlab/Simulink platform. The effectiveness of the proposed fault tolerant control strategy was verified by both the steady-state and submodule fault operation conditions.
孙冠群, 尹项根, 赖锦木, 王祯, 杜云飞. 模块化多电平直流变压器容错控制策略[J]. 电工技术学报, 2022, 37(zk1): 246-256.
Sun Guanqun, Yin Xianggen, Lai Jinmu, Wang Zhen, Du Yunfei. Fault-Tolerant Control Strategy of Modular Multilevel DC Transformer. Transactions of China Electrotechnical Society, 2022, 37(zk1): 246-256.
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