Impact of Functional Models in a Decision Context of Critical Infrastructure Vulnerability Reduction

Critical infrastructures provide essential services for the functioning of the society, and vulnerability analysis is an important basis for decisions concerning increasing their robustness against strains. Since critical infrastructures can be regarded as complex systems, such analyses can prove challenging. To analyze the system response to strains, several different functional models have been suggested in the scientific literature, ranging from simple topological to more advanced engineering models. The simple models are computationally less burdensome which enables more comprehensive vulnerability analyses. The downside, however, is that they may not accurately describe system performance. The advanced engineering models, on the other hand, capture the system performance more accurately, but are computationally burdensome which leads to less comprehensive analyses.In the present paper, nine different functional models are used to assess the vulnerability of the IEEE RTS96 transmission power test system The results from these analyses are then used in two decision contexts, 1) identification of critical components and 2) ranking of structural improvements, to study to what extent the models provide a good decision support. Preliminary results suggest that the use of functional model impacts the decision, and hence care should be taken when choosing which functional model to use as a basis for decisions of critical infrastructure improvements.