Hybrid impedance-based modelling and stability analysis of IMG-PICDPS

A hybrid impedance model of Islanded MicroGrid with Paralleled Inverters Controlled by Droop and PQ Strategies (IMG-PICDPS) is derived, in which the PQ-controlled Inverters (PQ-Invs) are equivalent to Norton's circuits, while the DRoop-controlled Inverters (DR-Inv) to Thevenin's circuits in this paper. An impedance-based stability analysis method is further proposed according to the Nyquist criterion for multiloop system because the derived impedance model of the IMG-PICDPS can be expressed as a double close-loop system. The impact of line impedance and the penetration of PQ-Invs on the system stability are analyzed through the characteristics of equivalent impedance of IMG-PICDPS and the proposed stability analysis method. To test the proposed method, an IMG-PICDPS model is established in Matlab/Simulink. And the simulation results prove the correctness of the proposed model and stability analysis method for IMG-PICDPS.