  Coordinating multiple local power sources can restore critical loads after
the major outages caused by extreme events. A radial topology is needed for
distribution system restoration, while determining a good topology in real-time
for online use is a challenge. In this paper, a graph theory-based heuristic
considering power flow state is proposed to fast determine the radial topology.
The loops of distribution network are eliminated by iteration. The proposed
method is validated by one snapshot and multi-period critical load restoration
models on different cases. The case studies indicate that the proposed method
can determine radial topology in a few seconds and ensure the restoration
capacity.
