A universal arm-averaged model for accelerated EMT simulation of MMCs based on various submodule circuits

In this paper, a universal arm-averaged model (UAAM) is proposed for accelerated electromagnetic transient (EMT) simulation of modular multilevel converters (MMCs) based on various submodule (SM) circuits. In the UAAM, each arm of the MMC is averaged as a controlled voltage source (CVS) series connected with a controlled resistor (CR). The nonlinear characteristics of diodes are taken into consideration to control the CVS and CR properly, and thus the UAAM is able to represent the MMC under both normal and blocking conditions without adopting additional diodes or switches. The control functions of the CVS and CS are related to some parameters of the SM circuit adopted in the arm. By modifying the value of these parameters, the UAAM can be easily extended to MMCs based on different types of SM circuits. The accuracy and efficiency of the proposed UAAM are verified by the simulation results conducted in the PSCAD/EMTDC.