  Electrical networks contain thousands of interconnected nodes and edges,
which leads to computational challenges in some power system studies. To
address these challenges, we contend that network reductions can serve as a
framework to enable scalable computing in power systems. By building upon a
prior AC "Opti-KRON" formulation, this paper presents a DC power flow
formulation for finding network reductions that are optimal within the context
of large transmission analysis. Opti-KRON previously formulated optimal
Kron-based network reductions as a mixed integer linear program (MILP), where
the number of binary variables scaled with the number of nodes. To improve the
scalability of the Opti-KRON approach, we augment the MILP formulation with a
community detection (CD) technique that segments a large network into smaller,
disjoint, but contiguous sub-graphs (i.e., communities). For each sub-graph, we
then (in parallel) apply MILP-based along with a new cutting plane constraint,
thus, enhancing scalability. Ultimately, the new DC-based Opti-KRON method can
achieve a 80-95\% reduction of networks (in terms of nodes) while statistically
outperforming other CD- and Kron-based methods. We present simulation results
for the IEEE RTS-96 and the 2383-bus Polish networks.
