Seamless Transition of Synchronous Inverters Using Synchronizing Virtual Torque and Flux Linkage

The introduction of virtual-synchronous machine and generator as well as synchronous inverter (synchronverter), in recent years, has facilitated the integration of inverter-interfaced distributed energy resources (IIDERs) into the synchronous generator (SG) dominant microgrids and power grid. In this concept, the voltage source inverter (VSI) is controlled in such a way that it mimics the behavior of SG. To provide a reliable utilization of the IIDERs, a seamless transition of the VSIs between islanded and grid-connected operation modes is required. This paper integrates a novel virtual torque and virtual flux linkage-based synchronizing technique into the synchronverter controller to provide a plug `n' play capability of the VSIs and their smooth transition between these two operating modes. Comprehensive mathematical modeling, design, and dynamic stability analysis as well as dSPACE-based real-time simulation are provided to validate the effectiveness of the proposed technique.