A case study for controlled islanding based on line contingency ranking in autonomous micro-grids

Micro-grids are formed on introduction of Distributed Generator(DG) units in conventional distribution systems. These micro-grids operate in either autonomous mode or non-autonomous mode. When line contingencies occur in micro-grids, there are chances for formation of accidental islands. This paper proposes an algorithm for forming controlled islands on occurrence of line contingencies in micro-grids, using the information about accidentally formed islands and line contingency ranking. Identification of such accidental islands has been attempted in this work, by tracing the change in the configuration of the autonomous micro-grids. Ranking of line contingencies is done with the database of the detected accidental islands. The proposed algorithm is also attempted for radial and weakly meshed structures based on the voltage profile, performance indices, line losses and transient stability of the DGs. MATLAB coding is developed to validate the proposed algorithm & the standard 33-node radial distribution system is used for validation of the proposed algorithm.