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.