Generic Simplified Small-Signal Modeling Framework for Islanded Microgrid System with Distributed Secondary Control

Accurate and simplified modelling for analyzing islanded microgrid (MG) small-signal stability is of significance. This paper proposes a generic islanded MG modeling framework consisting of the dynamics of primary control and Distributed Secondary Control. The modeling process in the electrical layer is generalized and simplified by utilizing nodal graph theory to represent the location of loads and the connection of lines in algebraic expressions. The modeling process in the communicational layer adopts undirected graph theory to represent the communication link between Distributed Generators (DGs). Compared to existing works, the proposed framework balances the modeling's complexity and accuracy, adapts to different systems, and achieves fast stability assessment. Its applicability is validated through time-domain simulation and eigenvalue plot with the full-order method, and its accuracy is further confirmed by comparing with a model obtained from MATLAB linearization toolbox. Finally, the proposed framework has been tested using a modified IEEE 37 bus test system with 6 DGs.