2nd China International Youth Conference on Electrical Engineering (CIYCEE 2021)

The traditional power system is undergoing the paradigm shift towards a more power-electrolyzed system, where substantial inverters have been deployed and utilized as the grid interfaces for renewable energies. However, in such high inverter-penetrated systems, small-signal instability issues typically occurring in the form of oscillations are frequently reported. The impedance-based method is among the most popularly applied approach for such analyses. This presentation will introduce the LTI and LTP framework-based impedance modeling techniques for grid-tied inverters. In which, the impedance transformation techniques that are useful for stability analysis will be introduced, e.g., DQ-domain to sequence-domain and MIMO to SISO transformations. A practical method for automating the parametric stability analysis in the LTP framework will be introduced. Technical issues related to the stability analysis of an impedance network will be mentioned and discussed.