Reliability analysis of half-/full-bridge hybrid MMCs based on submodule correlation

The traditional reliability analysis methods for Modular Multilevel Converters (MMC) usually neglect the correlations between submodules within the bridge arm, leading to inadequate fault risk assessments and maintenance strategies. As hybrid MMCs, which consist of both half-bridge and full-bridge submodules, are widely used in engineering, focusing solely on the reliability of single half-bridge submodules is insufficient. This paper proposes a reliability analysis method based on Mixed Copula that takes the correlation of the bridge arm into account. First, a Mixed Copula is constructed using correlation scenarios and the quasi-Newton method to address the limitations of fitting a single copula function to correlation data. Next, a comprehensive reliability analysis model specifically designed for hybrid MMCs is developed in line with MMC topology. Finally, the model is implemented and analysed using MATLAB to validate its effectiveness.