Biblio

Modern electric power systems are complex cyber-physical systems. The integration of traditional power and digital technologies result in interdependencies that need to be considered in risk analysis. In this paper we argue the need for analysis methods that can combine the competencies of various experts in a common analysis focusing on the overall system perspective. We report on our experiences on using the Vulnerability Analysis Framework (VAF) and bow-tie diagrams in a combined analysis of the power and cyber security aspects in a realistic case. Our experiences show that an extended version of VAF with increased support for interdependencies is promising for this type of analysis.

This paper studies the modeling of cyber-physical dependencies observed within power grids and the effects of these intra-dependencies, on power grid resilience, which is evaluated quantitatively. A fundamental contribution of this paper is the description of the critically important role played by cyber-physical buffers as key components to limit the negative effect of intra-dependencies on power grids resilience. Although resilience issues in the electric power provision service could be limited thanks to the use of local energy storage devices as the realization of service buffers, minimal to no autonomy in data connectivity buffers make cyber vulnerabilities specially critical in terms of resilience. This paper also explains how these models can be used for improved power grids resilience planning considering internal cyber-physical interactions.

Resilience and security of infrastructures depend not only on their constituent systems but also on interdependencies among them. This paper studies how these interdependencies in infrastructures affect the defense effort needed to counter external attacks, by formulating a simultaneous game between a service provider (i.e., defender) and an attacker. Effects of interdependencies in three basic topological structures, namely, bus, star and ring, are considered and compared in terms of the game-theoretic defense strategy. Results show that in a star topology, the attacker's and defender's pure strategies at Nash Equilibrium (NE) are sensitive to interdependency levels whereas in a bus structure, the interdependencies show little impact on both defender's and attacker's pure strategies. The sensitivity estimates of defense and attack strategies at NE with respect to target valuation and unit cost are also presented. The results provide insights into infrastructure design and resource allocation for reinforcement of constituent systems.

The evolution of electrical grids, both in terms of enhanced ICT functionalities to improve efficiency, reliability and economics, as well as the increasing penetration of renewable redistributed energy resources, results in a more sophisticated electrical infrastructure which poses new challenges from several perspectives, including resilience and quality of service analysis. In addition, the presence of interdependencies, which more and more characterize critical infrastructures (including the power sector), exacerbates the need for advanced analysis approaches, to be possibly employed since the early phases of the system design, to identify vulnerabilities and appropriate countermeasures. In this paper, we outline an approach to model and analyze smart grids and discuss the major challenges to be addressed in stochastic model-based analysis to account for the peculiarities of the involved system elements. Representation of dynamic and flexible behavior of generators and loads, as well as representation of the complex ICT control functions required to preserve and/or re-establish electrical equilibrium in presence of changes need to be faced to assess suitable indicators of the resilience and quality of service of the smart grid.