A Copula-Based k-out-of-n Reliability Modeling for MMC with Considering the Submodule Correlation

The reliability of modular multilevel converter (MMC) is related to the reliable operation of the flexible HVDC system. Firstly, based on the analysis of MMC single submodule(SM) reliability model, a SM correlation scenario is constructed by using Latin Hypercube Sampling (LHS). Secondly, on the basis of the SM correlation scenario, the optimal Copula function type is selected by the minimum Euclidean distance, and the correlation coefficient of the Copula function are obtained by the maximum likelihood estimation theory. Thirdly, considering the SM correlations in the same arm, MMC reliability model based on k-out-of-n modeling is established. Finally, a flexible DC transmission demonstration project in China is taken as an example to verify that the proposed method can meet the MMC reliability analysis requirements.