Interconnection of two neighboring autonomous microgrids based on small signal analysis

Abstract

Load-shedding is a mechanism to prevent overloading of an islanded microgrid (MG). To minimize load-shedding, extra support can be provided by interconnecting the overloaded MG to another islanded neighboring MG to support each other. For this, extra generation capacity needs to be available in the distributed energy resources of the neighboring MG. This paper proposes a decision making criterion for interconnection of two neighboring islanded MGs based on small signal stability analysis. The closed-loop control system of an MG is expressed in statespace domain and used for the stability analysis of the individual MGs as well as the system of coupled MGs. The results of this analysis are applied as a stability criterion to allow interconnection of two islanded MGs. Additionally, if it is revealed that interconnection of MGs will cause instability, the analysis yields the proper range for the droop control coefficients which need to be updated in the DERs, before they MGs are interconnected. MATLAB-based simulation studies are provided to evaluate the developed small signal stability analysis.