Simplified Average-Dynamical Models of a New Family of Modular Multilevel Converters

Multilevel converters are a valid solution for improving efficiency and harmonic content in many applications, from low to high power scenarios. Moreover, the number of available switches allows the integration of advanced functionalities in the systems, safety operations included. Thus, a new family of modular multilevel converters for rectifying, inversion and DC/DC operations has been studied in the last years and patented by the Italian Transmission System Operator for possible applications in HVDC conversion stations. Their working principles were validated as well as the expected real behavior was predicted thanks to switching models. A low-voltage prototype has been designed based on their simulations. However, the switching approach is heavy from a computational point of view and time consuming to run. Thus, this work proposes simplified average equivalent circuits for this kind of devices that have been validated versus the switching model. This approach should lead to easier and faster studies of the converter as well as the control design of new power stations.