Short-Circuit Current Estimation of Modular Multilevel Converter Using Discrete-Time Modeling

Yushuang Liu, Meng Huang, Xiaoming Zha, Herbert Ho Ching Iu

Research output: Contribution to journalArticle

6 Citations (Scopus)


Short-circuit faults are hazardous for high-power modular multilevel converters (MMCs). Hence, an accurate current calculation will be helpful to the system protection design. In this paper, a new method of short circuit current calculation based on a discrete-time modeling is proposed. With a commonly adopted nearest level modulation, the operating state during one period can be divided into several stages, according to the number of inserted sub-modules in a bridge arm. Then, a piecewise analysis allows to construct a new discrete-time model by recursion in the state variables stage-by-stage. From this model, the current evolution during short-circuit fault can be accurately calculated when given an initial state. The effects of different fault occurrence times in one period are also calculated and discussed. Finally, PSCAD/EMTDC simulations and a circuit experiment on a single-phase five-level MMC verify the effectiveness of the proposed calculation method.

Original languageEnglish
Article number8364615
Pages (from-to)40-45
JournalIEEE Transactions on Power Electronics
Issue number1
Publication statusPublished - Jan 2019

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