Takis Zourntos

Towards a Framework for Cyber Attack Impact Analysis of the Electric Smart Grid

This paper presents a framework for cyber attack impact analysis of a smart grid. We focus on the model synthesis stage in which both cyber and physical grid entity relationships are modeled as directed graphs. Each node of the graph has associated state information that is governed by dynamical system equations that model the physics of the interaction (for electrical grid components) or functionality (for cyber grid elements). We illustrate how cause-effect relationships can be conveniently expressed for both analysis and extension to large-scale smart grid systems.

Digital Video Steganalysis Exploiting Statistical Visibility in the Temporal Domain

In this paper, we present effective steganalysis techniques for digital video sequences based on interframe collusion that exploits the temporal statistical visibility of a hidden message. Steganalysis is the process of detecting, with high probability, the presence of covert data in multimedia. Present image steganalysis algorithms when applied directly to video sequences on a frame-by-frame basis are suboptimal; we present methods that overcome this limitation by using redundant information present in the temporal domain to detect covert messages embedded via spread-spectrum steganography. Our performance gains are achieved by exploiting the collusion attack that has recently been studied in the field of digital video watermarking and pattern recognition tools. Through analysis and simulations, we evaluate the effectiveness of the video steganalysis based on linear collusion approaches. The proposed steganalysis methods are successful in detecting hidden watermarks bearing low energy with high accuracy. The simulation results also show the improved performance of the proposed temporal-based methods over purely spatial methods

Towards modelling the impact of cyber attacks on a smart grid

This paper provides an introduction to cyber attack impact analysis in the smart grid and highlights existing research in the field. We present an impact analysis framework where we focus on the model synthesis stage where both cyber and physical grid entity relationships are modelled as directed graphs. Each node of the graph has associated state information that is governed by dynamical system equations that model the physics of the interaction (for electrical grid components) or functionality (for cyber grid elements). We illustrate how cause-effect relationships can be conveniently expressed for both analysis and extension to large-scale smart grid systems.

Security and Privacy for Distributed Multimedia Sensor Networks

There is a critical need to provide privacy and security assurances for distributed multimedia sensor networking in applications including military surveillance and healthcare monitoring. Such guarantees enable the widespread adoption of such information systems, leading to large-scale societal benefit. To effectively address protection and reliability issues, secure communications and processing must be considered from system inception. Due to the emerging nature of broadband sensor systems, this provides fertile research ground for proposing more paradigm-shifting approaches. This paper discusses issues in designing for security and privacy in distributed multimedia sensor networks. We introduce the heterogeneous lightweight sensornets for trusted visual computing framework for distributed multimedia sensor networks. Protection issues within this architecture are analyzed, leading to the development of open research problems including secure routing in emerging free-space optical sensor networks and distributed privacy for vision-rich sensor networking. Proposed solutions to these problems are presented, demonstrating the necessary interaction among signal processing, networking, and cryptography.

A Framework for Modeling Cyber-Physical Switching Attacks in Smart Grid

Security issues in cyber-physical systems are of paramount importance due to the often safety-critical nature of its associated applications. A first step in understanding how to protect such systems requires an understanding of emergent weaknesses, in part, due to the cyber-physical coupling. In this paper, we present a framework that models a class of cyber-physical switching vulnerabilities in smart grid systems. Variable structure system theory is employed to effectively characterize the cyber-physical interaction of the smart grid and demonstrate how existence of the switching vulnerability is dependent on the local structure of the power grid. We identify and demonstrate how through successful cyber intrusion and local knowledge of the grid an opponent can compute and apply a coordinated switching sequence to a circuit breaker to disrupt operation within a short interval of time. We illustrate the utility of the attack approach empirically on the Western Electricity Coordinating Council three-machine, nine-bus system under both model error and partial state information.

Multi-Agent System-Based Real-Time Load Management for All-Electric Ship Power Systems in DC Zone Level

All-electric ship power systems have finite generation and include a large portion of dynamic loads and nonlinear loads relative to the total power capacity. Therefore, the load demand and power generation of the system should be matched in real-time. In this paper, a novel multi-agent system-based real-time load management technique is proposed to optimally determine the switch status of loads in DC zones while satisfying the operating constraints of the system in real-time. The multi-agent system cooperative control protocol is developed based on a proposed reduced-order agent model and artificial potential function of the multi-agent system, which aims to maximize the energized loads in the all-electric ship power system. The cooperative controller aims to cooperatively achieve the group objectives that are difficult to reach by centralized controller. Further, simulation results verify the viability and performance of the proposed technique in PSCAD/EMTDC software.

A flocking-based dynamical systems paradigm for smart power system analysis

We propose a paradigm to model the cyber-physical interactions related to transient stability in a smart grid. In our multi-agent framework each node, representing both electrical and information system components, is modeled as having dynamics that synergistically describe physical and information couplings with neighboring agents. Physical behaviors are described through the application of swing equations to a reduced model of the electrical grid. Cyber-physical integrated action is formulated as a flocking control problem to achieve transient stability. Analysis and simulation demonstrate the potential of the paradigm to model cyber-physical smart grid dynamics as well as highlight strategies for effective distributed control.

A Coordinated Multi-Switch Attack for Cascading Failures in Smart Grid

This paper explores distributed smart grid attack strategies to destabilize power system components using variable structure system theory. Here, an opponent is able to remotely control multiple circuit breakers within a power system, say through data corruption or communication network attack, to destabilize target synchronous generators through application of state-dependent breaker switching. In contrast to attack via a single breaker, the multi-switch case provides additional degrees of freedom that can lead to stealthier and wide-scale cascading failures. We provide a dynamical systems context for formulating distributed multi-switch strategies and execute such attacks on the New England 10-generator 39-bus test system.

A Flocking-Based Paradigm for Hierarchical Cyber-Physical Smart Grid Modeling and Control

It is well known that information will play an important role in enhancing emerging smart grid system operation. Therefore, questions naturally arise as to when the increased data-dependence may be considered excessive. Two practical considerations emerge: 1) communications and computational overhead, in which redundant and irrelevant information acquisition and use results in heavy computational burden with limited performance return; and 2) increasing risks of power system disruption due to information delay from communication congestion or cyber attack. One strategy to improve smart grid resilience is to determine the appropriate degree of dependence on cyber information to balance performance with overhead and risk. In this paper, we present a hierarchical cyber-physical multiagent model of smart grid system operation based on flocking theory in the context of the transient stability problem. Through this model, we study strategies that harness a selective degree of cyber technology by leveraging physical couplings. Our formulation enables the identification of large-scale distributed control strategies for robust and resilient power grid operation. We demonstrate the potential performance improvements of our findings on the New England 39-bus power system for case studies involving a variety of system faults and communication delays.

A smart grid vulnerability analysis framework for coordinated variable structure switching attacks

In this paper we have proposed an approach for vulnerability analysis of a class of cyber-physical reconfiguration attacks called coordinated variable structure switching. In such an attack, an opponent who gains control over a target circuit breaker, relay or switch can apply a given switching sequence to destabilize the system even if the system is stable in static switch positions. Our analysis approach is illustrated through a case study of the Western Electricity Coordinating Council 3-machine, 9-bus system. MATLAB and PSCAD® simulations are employed to validate the approach. Moreover the insights gained from the vulnerability analysis of the WECC system are consistent with intuition.