Dynamic Analysis of AC Microgrids with Constant Power Loads or Sources

This paper investigates the dynamic characteristics of AC microgrids in the presence of Constant Power Loads or Constant Power Sources (CPL/CPS). This dynamic characteristic is useful for understanding how AC microgrids behave in different operating points. If the dynamic characteristic is not desired, microgrids’ components can be tuned or proper approaches can be adopted to improve it. In this paper, the input impedances of a non-ideal CPL/CPS is mathematically derived through vigorous modeling. Moreover, the closed-loop output impedance of a distributed energy resource regulating the microgrid voltage is modelled. A unifying approach is adopted to transfer impedances of AC microgrid components to the same coordinate in order to utilize impedance-based stability analysis to assess the dynamic characteristics of AC microgrids in different operating points. Finally, simulation results are provided to validate findings.