Multi-level converter dimensioning with structure and losses consideration for DFACTS applications

Due to electrical system´s deregulation and subventions given by authorities for renewable energy, there is a multiplication of Distributed Generation (DG) connected to low and medium voltage grids. This increases the number of intermittent power exchanges. To maximize the penetration of DG it is necessary to use new grid´s exploitation schemes. Series connected power electronics devices connected to looped or meshed distribution grids called distributed flexible alternating current transmission systems (DFACTS) could bring optimal functioning by dynamic Ohm´s law to realize optimal share of power flows and also to limit short-circuit currents. So far uses of FACTS and DFACTS have been limited because they were suffering from reliability, high maintenance costs and losses. Losses are mainly due to switches commutations and make them not very attractive, especially for FACTS based on the Voltage Source Converter (VSC). This paper proposes a method to find the most adapted multi-level converter structure configuration and switch by considering the IGBT parameters and the commutation conditions.