Bulk power system frequency stability assessment in presence of microgrids

An attempt is made in this paper to propose an analytical approach to mathematically assess the impact of MGs penetration level on power system frequency stability. Firstly, experimental-based model of constitute DGs of the University of Kurdistan-MG (UOK-MG) in islanded mode may be derived. Afterwards, realistic model of the MG in grid connected mode may be derived to realize penetrated system for future studies. Finally, some simple algebraic equations are derived to predict frequency dynamics of interest in penetrated system. The method interprets the frequency dynamic behavior of the penetrated system based on the conventional system in terms of frequency nadir, Rate of Change of Frequency (RoCoF), steady state deviation and a rolling window. Simulation results demonstrate high efficiency of the proposed approach for dynamical modeling and stability analysis of penetrated power systems.