A Method for Practical Stability Region Evaluation and a Preventive Control Strategy for MicroGrids

This paper presents an innovative method for practical Static Security Assessment (SSA) of a Smart MicroGrid (MG). The proposed methodology defines a feasibility region where the MG exhibits stable behavior according to voltage-related relay settings. This offline approach facilitates the proactive feasibility assessment of any assumed operating condition expressed in terms of active and reactive injected powers. The feasibility region is defined through an ellipsoid that, with a minimum volume, encloses feasible points randomly generated and tested by load flow analyses. If an infeasible operating point is detected, the method is able to reschedule generators, storages and loads by proposing a new condition having a minimal Euclidean distance from the infeasible one. The method's simplicity, its ability to rapidly assess the feasibility of any assumed operating point and the possibility to implement fast preventive control strategies, give rise to a practical and useful tool in small enterprises owning MGs where sophisticated algorithms are not usually available, even if it can be adopted also in more large and complex systems. The proposed strategy was subsequently applied to the static model of a subset of the experimental MG in the PrInCE laboratory, located at the Polytechnic University of Bari.