Blackbox Small-signal Modeling of Grid-Connected Inverters under Unbalanced Conditions

Modern electric power distribution systems are characterized by high penetration of Power Electronic Converters (PECs). Grid-connected three-phase inverters are widely used for the integration of renewable sources and in specialized applications such as FACTS or storage systems in Smart Grids and microgrids but also standard grids. Although the electrical model of each element of these systems is important for their system-level analysis, they are not always available. Blackbox modeling strategies are a useful tool to obtain behavioral models of commercial electronic converters. Most blackbox modeling strategies are focused on dc-dc electronic converters, however, some works have extended these concepts to three-phase converters by means of the d-q framework, under the assumption of balanced conditions. This work proposes a new structure to represent the behavior of grid-connected commercial converters under unbalanced conditions. Experimental tests have been performed on a power converter to identify its blackbox model and its performance has been validated in unbalanced scenarios.