Small-signal stability analysis of a microgrid operating in droop control mode

Microgrid consists of various micro sources, power electronic devices, and constant power loads (CPLs), because of which, there is a stability problem in such system. Therefore, stability analysis must be taken into consideration regardless of in the design or in the operation of microgrid. In this paper, the method modeling the CPLs in AC system is analyzed. A small signal state-space model of microgrid is developed, which consists of a sub-model of power controller, a sub-model of CPLs, and a sub-model of network and loads. The relationship between the small-signal stability of microgrid and such affecting factors as droop gain, CPLs, and equivalent line impedance is studied. A simulation model of a microgrid operating in islanding mode is developed in PSCAD, to demonstrate the conclusion of eigenvalue analysis.