Modeling and Analysis of Dependability and Interdependency Failures in Smart Grids: Study on how the wide usage of ICT changes the Dependability in the future Power Grid

摘要

The transition from the current electrical power grid towards a smart grid is drivenudby new technologies and services. Traditional dedicated power grid componentsudare exchanged with more powerful and highly configurable devices that are interconnectedudand help monitoring and controlling the power grid. The power grid isuda critical infrastructure with high dependability requirements. The pervasive useudof information and communication technology (ICT) to support the operation inudthe smart grid creates a complex interdependent system in which the dependabilityudof the ICT systems plays an important role for the overall dependability. Additionally,udinterdependent system-of-systems feature new failure modes not found inudsimple systems. Therefore, it becomes crucial to understand and address the dependabilityudissues in the smart grid in order not to risk a decreasing dependabilityudwith the introduction of new technology.udThe objective of this thesis has been to analyze how the dependability of theudpower grid changes with the introduction of smart grid technologies, to proposeudnew dependability models and propose operational support mechanisms for theudcontrol center to detect and master the expected dependability issues in the smartudgrid. The first step of the research was to conduct literature studies to find new dependabilityudchallenges in the smart grid. Based on that, the consequences of theseudnew challenges are assessed with the help of analytical models and simulations.udMy findings show that there are several challenges such as cascading and escalatingudfailures, latent errors and a risk of automation waiting when transitioningudtowards a smart grid. The qualitative and quantitative analysis show that theseudeffects can have a strong impact on the total dependability of the smart grid andudneed to be considered. The analysis also shows that smart services like demandudresponse or automatic detection and isolation of failures can help improving theuddependability if implemented with the right supporting measures. As a conclusionudfrom the analysis, I give a list of guidelines for the control center on how toudaddress the future challenges. One of the central advices from this thesis to theudelectrical utilities is, that they should try to thoroughly understand their specific interdependencies by analyzing their systems, processes and organizational structure.udThe next step is then to create awareness inside the company and invest inudpreparedness and mitigation strategies.udOverall, this thesis contributes to the discussion on new dependability challengesudin the smart grid, the definition of realistic use cases illustrating how theyudmight affect the system, the quantification of their consequences, and the discussionudon how the utilities might address these new challenges.