Stability Analysis of AC Microgrids With Constant Power Loads Based on Popov's Absolute Stability Criterion

This brief considers nonlinear stability analysis of ac microgrids with constant power loads (CPLs). A microgrid is a subsystem consisting of small electrical resources, local loads, and power electronic devices. It should be noted that the presence of a CPL as a sink in a microgrid results in nonlinear behavior of the microgrid. CPLs are generally connected to an ac microgrid through a controlled rectifier and/or dc-dc converters. We model an ac microgrid with local RLC load and a CPL with power converter subsystem, which results in a set of nonlinear state-space equations. Then, Popov's absolute stability theorem is utilized to analyze stability conditions for an ac microgrid in the presence of CPL. Simulation results are presented, which are in agreement with the analytical approach.