A Thevenin Model for Internal Electromagnetic Transient Characteristics Study of the MMCs

Modular multilevel converters (MMCs) are essential parts of power transmission systems. Studying internal transient processes in the case of system transient faults is required to enhance the insulating protection of the internal MMC devices, which necessitates modeling the detailed internal MMC structure. This study proposes a Thevenin equivalent model based on the associated discrete circuit (ADC) switching model (ADC-Thevenin) and then generates a parameter configuration method for the recommended model based on the principle of minimum energy. The suggested model addresses the shortcoming of the current Thevenin models, which ignore internal electromagnetic transient processes to speed up the calculation and is verified by the simulations of the single-terminal MMC system. Finally, the effect of stray parameters on the MMC impulse characteristics is examined using the ADC-Thevenin model.