Immittance-Based Stability and Instability Participation Analysis for DC Microgrids

The existing immittance-based stability analysis approaches for dc microgrids rarely account for the line network, and they are always troubled by the non-minimum phase issues. In this article, we introduce a novel method for stability analysis based on the determinant of the constructed immittance matrix. Since the determinant's right-half-plane poles are explicitly proven absent, it is only necessary to ascertain the net number of times that the phase trajectory crosses the ±180° line in system stability analysis. Subsequently, based on the immittance matrix decomposition and sensitivity calculation, a participation analysis method is further presented to identify the critical converter that dominates system instability. Finally, the simulation case of a 750 V 30 kW dc microgrid and the experiment case of a 24 V 180 W dc microgrid are established to validate these methods.