On modelling of MMC in EMT-type program

Modular Multilevel Converter (MMC) modelling for electromagnetic transient type (EMT-type) simulations is challenging due to numerous IGBTs/diode devices. Detailed models of HVDC-MMC transmission systems require long computation times. Simplified and averaged models have been proposed in the past to overcome this problem. However, some of these types of model require a hard-coding development which depends on the EMT software used. This article presents a simple approach for modelling these types of MMC using only generic EMT blocks (i.e. power circuits and control components) that can be found in most EMT software libraries. In addition, the article describes, step-by-step, the intermediate circuits and the mathematical assumptions made that lead from one type of model to another. The INELFE link is used as a real test case for validating the proposed MMC models.