Converter Interactions in Medium-Voltage Distribution Grids with Multiport Converters

The integration of power electronic converters in power distribution systems is introducing new dynamic interactions that could lead to instabilities. This paper analyzes the impact of Multiport Converters (MPCs) on grid stability based on small-signal analysis, in particular, modal analysis methods. Four scenarios are tested on the IEEE 33-bus system, including radial topology, meshed topology, grid-following MPCs, and islanded grid-forming operation. Results show that converter interactions, particularly reactive power control and converters operating points, significantly influence system dynamics. Small-signal linear models and results are validated using non-linear simulations.