A Graph Theory Based Post-Event Degraded State Resiliency Index for Power Systems

In this paper, a new Post-Event Degraded State Resilience Index is proposed. This is developed based on graph theory concepts incorporating the use of eigenvector centrality as a factor in determining the criticality of nodes. The index can be evaluated for the post-event degraded state after a ‘High Impact Low Frequency (HILF)’ event occurs that affects a given system. The index developed is then used in determining the resiliency of IEEE 5 and 33 Bus System when the buses of that network are targeted by cyber-attacks and are islanded entirely from the rest of the network. Two types of attack are considered and evaluated - simultaneous attack of multiple nodes in a system and sequential attack of nodes one after another with a finite time interval between each attack. The above mentioned attacks are considered for the worst-case scenario in which the critical nodes are identified based on their eigenvector centrality in a given configuration.