1,077 research outputs found
Quantitative dependability and interdependency models for large-scale cyber-physical systems
Cyber-physical systems link cyber infrastructure with physical processes through an integrated network of physical components, sensors, actuators, and computers that are interconnected by communication links. Modern critical infrastructures such as smart grids, intelligent water distribution networks, and intelligent transportation systems are prominent examples of cyber-physical systems. Developed countries are entirely reliant on these critical infrastructures, hence the need for rigorous assessment of the trustworthiness of these systems. The objective of this research is quantitative modeling of dependability attributes -- including reliability and survivability -- of cyber-physical systems, with domain-specific case studies on smart grids and intelligent water distribution networks. To this end, we make the following research contributions: i) quantifying, in terms of loss of reliability and survivability, the effect of introducing computing and communication technologies; and ii) identifying and quantifying interdependencies in cyber-physical systems and investigating their effect on fault propagation paths and degradation of dependability attributes.
Our proposed approach relies on observation of system behavior in response to disruptive events. We utilize a Markovian technique to formalize a unified reliability model. For survivability evaluation, we capture temporal changes to a service index chosen to represent the extent of functionality retained. In modeling of interdependency, we apply correlation and causation analyses to identify links and use graph-theoretical metrics for quantifying them. The metrics and models we propose can be instrumental in guiding investments in fortification of and failure mitigation for critical infrastructures. To verify the success of our proposed approach in meeting these goals, we introduce a failure prediction tool capable of identifying system components that are prone to failure as a result of a specific disruptive event. Our prediction tool can enable timely preventative actions and mitigate the consequences of accidental failures and malicious attacks --Abstract, page iii
Cyber-Physical Power System (CPPS): A Review on Modelling, Simulation, and Analysis with Cyber Security Applications
Cyber-Physical System (CPS) is a new kind of digital technology that increases its attention across academia, government, and industry sectors and covers a wide range of applications like agriculture, energy, medical, transportation, etc. The traditional power systems with physical equipment as a core element are more integrated with information and communication technology, which evolves into the Cyber-Physical Power System (CPPS). The CPPS consists of a physical system tightly integrated with cyber systems (control, computing, and communication functions) and allows the two-way flows of electricity and information for enabling smart grid technologies. Even though the digital technologies monitoring and controlling the electric power grid more efficiently and reliably, the power grid is vulnerable to cybersecurity risk and involves the complex interdependency between cyber and physical systems. Analyzing and resolving the problems in CPPS needs the modelling methods and systematic investigation of a complex interaction between cyber and physical systems. The conventional way of modelling, simulation, and analysis involves the separation of physical domain and cyber domain, which is not suitable for the modern CPPS. Therefore, an integrated framework needed to analyze the practical scenario of the unification of physical and cyber systems. A comprehensive review of different modelling, simulation, and analysis methods and different types of cyber-attacks, cybersecurity measures for modern CPPS is explored in this paper. A review of different types of cyber-attack detection and mitigation control schemes for the practical power system is presented in this paper. The status of the research in CPPS around the world and a new path for recommendations and research directions for the researchers working in the CPPS are finally presented.publishedVersio
Resilience assessment and planning in power distribution systems:Past and future considerations
Over the past decade, extreme weather events have significantly increased
worldwide, leading to widespread power outages and blackouts. As these threats
continue to challenge power distribution systems, the importance of mitigating
the impacts of extreme weather events has become paramount. Consequently,
resilience has become crucial for designing and operating power distribution
systems. This work comprehensively explores the current landscape of resilience
evaluation and metrics within the power distribution system domain, reviewing
existing methods and identifying key attributes that define effective
resilience metrics. The challenges encountered during the formulation,
development, and calculation of these metrics are also addressed. Additionally,
this review acknowledges the intricate interdependencies between power
distribution systems and critical infrastructures, including information and
communication technology, transportation, water distribution, and natural gas
networks. It is important to understand these interdependencies and their
impact on power distribution system resilience. Moreover, this work provides an
in-depth analysis of existing research on planning solutions to enhance
distribution system resilience and support power distribution system operators
and planners in developing effective mitigation strategies. These strategies
are crucial for minimizing the adverse impacts of extreme weather events and
fostering overall resilience within power distribution systems.Comment: 27 pages, 7 figures, submitted for review to Renewable and
Sustainable Energy Review
Cyber-Physical Power System Layers: Classification, Characterization, and Interactions
This paper provides a strategy to identify layers and sub-layers of
cyber-physical power systems (CPPS) and characterize their inter- and
intra-actions. The physical layer usually consists of the power grid and
protection devices whereas the cyber layer consists of communication, and
computation and control components. Combining components of the cyber layer in
one layer complicates the process of modeling intra-actions because each
component has different failure modes. On the other hand, dividing the cyber
layers into a large number of sub-layers may unnecessarily increase the number
of system states and increase the computational burden. In this paper, we
classify system layers based on their common, coupled, and shared functions.
Also, interactions between the classified layers are identified, characterized,
and clustered based on their impact on the system. Furthermore, based on the
overall function of each layer and types of its components, intra-actions
within layers are characterized. The strategies developed in this paper for
comprehensive classification of system layers and characterization of their
inter- and intra-actions contribute toward the goal of accurate and detailed
modeling of state transition and failure and attack propagation in CPPS, which
can be used for various reliability assessment studies.Comment: Accepted in Texas Power and Energy Conference (TPEC) 202
Multi-Layer Cyber-Physical Security and Resilience for Smart Grid
The smart grid is a large-scale complex system that integrates communication
technologies with the physical layer operation of the energy systems. Security
and resilience mechanisms by design are important to provide guarantee
operations for the system. This chapter provides a layered perspective of the
smart grid security and discusses game and decision theory as a tool to model
the interactions among system components and the interaction between attackers
and the system. We discuss game-theoretic applications and challenges in the
design of cross-layer robust and resilient controller, secure network routing
protocol at the data communication and networking layers, and the challenges of
the information security at the management layer of the grid. The chapter will
discuss the future directions of using game-theoretic tools in addressing
multi-layer security issues in the smart grid.Comment: 16 page
Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems
The first-ever Ukraine cyberattack on power grid has proven its devastation
by hacking into their critical cyber assets. With administrative privileges
accessing substation networks/local control centers, one intelligent way of
coordinated cyberattacks is to execute a series of disruptive switching
executions on multiple substations using compromised supervisory control and
data acquisition (SCADA) systems. These actions can cause significant impacts
to an interconnected power grid. Unlike the previous power blackouts, such
high-impact initiating events can aggravate operating conditions, initiating
instability that may lead to system-wide cascading failure. A systemic
evaluation of "nightmare" scenarios is highly desirable for asset owners to
manage and prioritize the maintenance and investment in protecting their
cyberinfrastructure. This survey paper is a conceptual expansion of real-time
monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework
that emphasizes on the resulting impacts, both on steady-state and dynamic
aspects of power system stability. Hypothetically, we associate the
combinatorial analyses of steady state on substations/components outages and
dynamics of the sequential switching orders as part of the permutation. The
expanded framework includes (1) critical/noncritical combination verification,
(2) cascade confirmation, and (3) combination re-evaluation. This paper ends
with a discussion of the open issues for metrics and future design pertaining
the impact quantification of cyber-related contingencies
On the identification and analysis of ICT-induced stability risks in cyber-physical energy systems
This thesis addresses emerging ICT-based stability risks for cyber-physical energy systems (CPESs) in light of the increasingly complex task of coordinating modern generation and consumption assets in power grids. It does so by identifying cyber-physical services as the main drivers of interdependence first. It then provides a general approach on how to assess such a service's dependence on data in general and its sensitivity towards the high-level ICT error categories "latency", "data loss" and "data corruption" in particular. Based on these results, the service states "normal", "limited", and "failed" are introduced in order to summarise the findings in an abstract and more widely applicable as well as comparable manner. These aggregated service states are required as additional inputs for the main method which determines how disturbances propagate through modern CPESs. This method is first presented with a focus on static stability and is later extended to also incorporate dynamic stability phenomena. The resulting disturbance propagation, combined with the service states and the ENTSO-E state description for power systems, can be used to derive a summarising state trajectory which helps compare different CPES layouts and control designs concerning their stability.Diese Arbeit befasst sich mit neuartigen, IKT-basierten StabilitĂ€tsrisiken fĂŒr cyber-physikalische Energiesysteme (CPES) vor dem Hintergrund zunehmend komplexer Koordination neuartiger Verbraucher und Erzeugungsanlagen in modernen Energiesystemen. Dazu werden zunĂ€chst IKT-basierte Dienste als Haupttreiber wechselseitiger AbhĂ€ngigkeiten zwischen der Energie- und IKT-DomĂ€ne im CPES identifiziert. AnschlieĂend wird ein Ansatz zur Bewertung der DatenabhĂ€ngigkeit solcher Dienste im Allgemeinen sowie ihrer Empfindlichkeit gegenĂŒber erhöhter Kommunikationslatenz, Datenverlust und Datenkorruption im Speziellen vorgestellt. Basierend auf diesen Ergebnisse werden drei BetriebszustĂ€nde fĂŒr Dienste eingefĂŒhrt. Diese lauten "normal", "eingeschrĂ€nkt" und "fehlerhaft" und dienen der Abstraktion und Vergleichbarkeit der IKT-AbhĂ€ngigkeit verschiedener Dienste. Im Anschluss wird eine Methode vorgestellt, die der Bestimmung der Ausbreitung von Störungen innerhalb des CPES dient. Die Methode wird zunĂ€chst mit einem Fokus auf statischer StabilitĂ€t erlĂ€utert und anschlieĂend so erweitert, dass auch dynamische StabilitĂ€tsphĂ€nomene berĂŒcksichtigt werden können. Die sich daraus ergebende Ausbreitung von Störungen kann in Verbindung mit den BetriebszustĂ€nden und der ENTSO-E-Zustandsbeschreibung fĂŒr Stromversorgungssysteme zur Ableitung eines zusammenfassenden Zustandsverlaufs verwendet werden. Mit den so ermittelten ZustandsverlĂ€ufen wird wiederum ein qualitativer StabilitĂ€tsvergleich verschiedener CPES-Layouts und Regelungskonzepte ermöglicht
Survivability modeling for cyber-physical systems subject to data corruption
Cyber-physical critical infrastructures are created when traditional physical infrastructure is supplemented with advanced monitoring, control, computing, and communication capability. More intelligent decision support and improved efficacy, dependability, and security are expected. Quantitative models and evaluation methods are required for determining the extent to which a cyber-physical infrastructure improves on its physical predecessors. It is essential that these models reflect both cyber and physical aspects of operation and failure. In this dissertation, we propose quantitative models for dependability attributes, in particular, survivability, of cyber-physical systems. Any malfunction or security breach, whether cyber or physical, that causes the system operation to depart from specifications will affect these dependability attributes. Our focus is on data corruption, which compromises decision support -- the fundamental role played by cyber infrastructure. The first research contribution of this work is a Petri net model for information exchange in cyber-physical systems, which facilitates i) evaluation of the extent of data corruption at a given time, and ii) illuminates the service degradation caused by propagation of corrupt data through the cyber infrastructure. In the second research contribution, we propose metrics and an evaluation method for survivability, which captures the extent of functionality retained by a system after a disruptive event. We illustrate the application of our methods through case studies on smart grids, intelligent water distribution networks, and intelligent transportation systems. Data, cyber infrastructure, and intelligent control are part and parcel of nearly every critical infrastructure that underpins daily life in developed countries. Our work provides means for quantifying and predicting the service degradation caused when cyber infrastructure fails to serve its intended purpose. It can also serve as the foundation for efforts to fortify critical systems and mitigate inevitable failures --Abstract, page iii
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