  With the emergence of smart grids as the primary means of distribution across
wide areas, the importance of improving its resilience to faults and mishaps is
increasing. The reliability of a distribution system depends upon its tolerance
to attacks and the efficiency of restoration after an attack occurs. This paper
proposes a unique approach to the restoration of smart grids under attack by
impostors or due to natural calamities via optimal islanding of the grid with
primary generators and distributed generators(DGs) into sub-grids minimizing
the amount of load shed which needs to be incurred and at the same time
minimizing the number of switching operations via graph theory. The minimum
load which needs to be shed is computed in the first stage followed by
selecting the nodes whose load needs to be shed to achieve such a configuration
and then finally deriving the sequence of switching operations required to
achieve the configuration. The proposed method is tested against standard IEEE
37-bus and a 1069-bus grid system and the minimum load shed along with the
sequencing steps to optimal configuration and time to achieve such a
configuration are presented which demonstrates the effectiveness of the method
when compared to the existing methods in the field. Moreover, the proposed
algorithm can be easily modified to incorporate any other constraints which
might arise due to any operational configuration of the grid.
