Simulation Models and Implementation of a Simulator for the Performability Analysis of Electric Power Systems Considering Interdependencies

Electric Power Systems (EPS) become more and more critical for our society, since they provide vital services for the human activities. At the same time, obtaining dependable behaviour of EPS is an highly challenging task, both in terms of defining effective business management and in terms of analysis of dependability and performability attributes. A major concern when dealing with EPS is the understanding and the evaluation of the interdependencies between Electric Infrastructures (EI) and the Computer-based Control System (CCS), which controls the status and the activities of EI. Studies on these interdependencies are only at early stage of development. Major difficulties are the complexity of the infrastructures under analysis and the lack of well-established models and tools for dealing with them. This paper presents an ad-hoc simulator for the evaluation of dependability and performability measures in EPS. The system model the simulator is based on focuses on interdependencies between EI and CCS. Most existing modeling approaches in EPS do not provide explicit modeling of interdependencies among the composing subsystems, so that the cascading or escalating phenomena can not be deeply analysed. Our stochastic model is composed by separated and simple, but representative, submodels representing the dynamics of EI and different policies of reactions to disruptions and reconfigurations triggered by CCS. In this way, the simulator aims to provide explicit modeling of the interdependencies between the main subsystems, so the impact on the dependability and performability of the cascading or escalating failures can be analyzed. In this paper, we describe the simulator and highlight the design choices.