An aggregated linearised model of a grid-tied microgrid for stability studies

Microgrids comprising multiple distributed energy resources are being increasingly integrated into electricity networks. Considering the multiplicity of the distributed energy resources, it is impractical to represent them as detailed models in power system simulations. Hence, it will be attractive for electricity utilities to employ simplified models of microgrids in dynamic studies. This paper proposes a method for representing grid-tied microgrids as simplified models in such studies. The proposed aggregated modelling approach investigates the applicability of modal analysis as a tool for model aggregating of grid-tied microgrids. A new step to automate the selection of dominant modes is introduced in the model aggregating procedure. Validity of the reduced order dynamic equivalents is tested under different operating conditions. The paper demonstrates that the enhanced modal analysis reduces the model order and enables the representation of a hybrid microgrid in terms of the states of the microgrid PCC, while preserving the important dynamics.