Modular multilevel converter electrical circuit model for HVdc applications

Abstract

Several MMC models are present in the literature. The suitable converter model used depends on the studies that must be performed. The work presents a simplified electrical equivalent model for the Modular Multilevel Converter (MMC) which can be used for ac power flow and fault studies. The total energy that is stored in the MMC submodules is modelled as an equivalent capacitor. Also, decouples the converter DC link from the equivalent arm capacitors voltages and allows the MMC arm's energy balance. The proposed electrical model was tested and compared with the existent literature data equivalent model (DEM) under different operating conditions. The mean percentage deviations between the signals retrieved by both models shows the higher deviation less than 1.1%. Besides very accurate, the presented model reveals to save around 72% of computational time leading to a faster model.