Search

We study the application of cyber-physical hierarchy on a class of smart grid systems to improve scalability. Our framework employs a multi-agent flocking-based approach to study the transient stability problem in emerging power systems. An agent in this context embodies a coherent group of system generators. We demonstrate how our paradigm conveniently facilitates the identification of coherent machine clusters through spectral bisection of the associated Kron-reduced power system graph. This enables a state-dependent system hierarchy whereby inter-agent interactions are cyber-physical (tier-1) and intra-agent synergies are physical (tier-2). By leveraging this layered perspective, active control can be employed only at a select “lead” generator of each agent; secondary generators that are necessarily coherent to a lead generator will naturally follow suit. Thus this cyber-physical hierarchy improves communications and energy overhead by introducing cyber couplings only within components of the smart grid where physical relationships are insufficient for transient stability in the face of a incidental fault or intentional attack. We demonstrate the performance of our approach on the 9-bus WECC system demonstrating its lower overhead and greater robustness to cyber attacks resulting in information delay. [ABSTRACT FROM PUBLISHER]

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. This paper presents a dynamic pricing concept that can be applied to hybrid electric power mini-grid systems to enable affordability of energy in these systems setup for the supply of energy to rural consumers. A location was identified in Eastern Uganda, resource assessment done, and a proposed hybrid electric power mini-grid system designed to supply electricity to this rural location. A theoretical deterministic demand profile was generated, and with it different supply configurations of the system were simulated to meet the daily load. The fluctuations in the demand and supply triggered a change in the cost of generating energy, due to the variations in the contributing electricity generating sources. Through communication, an intelligently designed and operated time-varying pricing scheme can be an effective tool for influencing the actions of price-responsive end-users such as rural consumers. A software program was used to simulate the hourly demand, supply, and corresponding cost of energy variations. This pricing model could potentially contribute to the ongoing search for the provision of affordable rural energy services. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

This paper describes the Survivor Buddy human-robot interaction project and how it was used by four middle-school girls to illustrate the scientific process for an episode of "SciGirls", a Public Broadcast System science reality show. Survivor Buddy is a four degree of freedom robot head, with the face being a MIMO 740 multi-media touch screen monitor. It is being used to explore consistency and trust in the use of robots as social mediums, where robots serve as intermediaries between dependents (e.g., trapped survivors) and the outside world (doctors, rescuers, family members). While the SciGirl experimentation was neither statistically significant nor rigorously controlled, the experience makes three contributions. It introduces the Survivor Buddy project and social medium role, it illustrates that human-robot interaction is an appealing way to make robotics more accessible to the general public, and raises interesting questions about the existence of a minimum set of degrees of freedom for sufficient expressiveness, the relative importance of voice versus non-verbal affect, and the range and intensity of robot motions. [ABSTRACT FROM AUTHOR]