  Controlled islanding, which splits the whole power system into islands, is an
effective strategy against rolling blackout during severe disturbances. Finding
the islanding solutions in a real-time manner is complicated because of the
combinatorial explosion of the solution space occurs for a large power network.
In this work, a computationally efficient controlled islanding algorithm is
proposed that uses constrained spectral clustering while addressing the
generator coherency problem. The objective function used in this controlled
islanding algorithm is the minimal power-flow disruption. The sole constraint
applied to this solution is related to generator coherency. An undirected
edge-weighted graph is created based on absolute values of apparent power flow
and constraints related to transmission line availability and coherent
generator groups are included by altering the edge weights of the graph and
using a subspace projection. Spectral clustering is then applied to the
constrained solution subspace to find the islanding solution. The methodology
is tested on an IEEE-39 test system with a fully dynamic model. Simulation
results demonstrate the efficacy of our approach.
