Stability Analysis Method for Interconnected AC Islanded Microgrids

Stability analysis is the primary task for ac microgrids operation. For a Single-Bus MicroGrid (SBMG) including voltage-and current-controlled inverters, the existing impedance analysis methods divide the microgrid into two parts and judge the stability by whether the impedance ratio of the two parts satisfies the Nyquist stability criterion. However, it would be complicated for the SBMG interconnection system. This paper proposes a single-bus based stability analysis method for interconnected ac islanded microgrids. The main idea starts from each SBMG stability analysis, and then according to the power line topologies among buses and the distribution of loads to derive the reference node voltage for the stability analysis of the entire system. The influence of controller parameters on system stability is analyzed by using the proposed method. Simulation results for interconnected ac islanded microgrids are given and indicate that the stability of the SBMG interconnection system shows different sensitivities to the controller parameters of different controlled inverters.