Showing papers by "Shahin Nazarian published in 2013"

A game-theoretic price determination algorithm for utility companies serving a community in smart grid

Abstract: Distributed power network is the major trend of future smart grid, which contains multiple non-cooperative utility companies who have incentives to maximize their own profits. The energy price competition forms an n-person game among utility companies where one's price strategy will affect the payoffs of others. More interestingly, the use of dynamic energy pricing schemes incentivizes homeowners to consume electricity more prudently in order to minimize their electric bill. In this paper, two models of price determination are introduced for utility companies under different assumptions. In the first model, a Nash equilibrium solution is presented and the uniqueness of Nash equilibrium point is proved. The second model accounts for more sophisticated factors such as the cost of energy generation and the homeowner's reaction to the change of energy usage as a factor of energy price. Although it is no longer possible to prove the uniqueness of Nash equilibrium for the second model, we present a practical solution in which no utility company can increase its expected profit by adjusting the price function. Experimental results show the effectiveness of our two models both in reliability of solution and in runtime.

An efficient current-based logic cell model for crosstalk delay analysis

Abstract: Logic cell modelling is an important component in the analysis and design of CMOS integrated circuits, mostly due to nonlinear behaviour of CMOS cells with respect to the voltage signal at their input and output pins. A current-based model for CMOS logic cells is presented, which can be used for effective crosstalk noise and delta delay analysis in CMOS VLSI circuits. Existing current source models are expensive and need a new set of Spice-based characterisation, which is not compatible with typical EDA tools. In this article we present Imodel, a simple nonlinear logic cell model that can be derived from the typical cell libraries such as NLDM, with accuracy much higher than NLDM-based cell delay models. In fact, our experiments show an average error of 3% compared to Spice. This level of accuracy comes with a maximum runtime penalty of 19% compared to NLDM-based cell delay models on medium-sized industrial designs.

A nested game-based optimization framework for electricity retailers in the smart grid with residential users and PEVs

Abstract: In the smart grid, real-time pricing policy is an important mechanism for incentivizing the consumers to dynamically change or shift their electricity consumption, thereby improving the reliability of the grid. Retailers are incorporated to the smart grid with distributed control mechanism in order to reduce the amount of communication overhead associated with the direction interaction between utility companies and consumers. The retailer procures electricity from both traditional and renewable energy sources, and sells it to its consumers. The consumers include residential users that can only consume power, and plug-in electric vehicles (PEVs) that can either consume power or supply power stored in its battery to the grid. In this work, a novel four-stage nested game model is proposed to model the interaction of the electricity retailer, utility companies, and consumers. The objective of the retailer is to maximize its overall profit as well as perform frequency regulation, whereas the goal of each consumer is to maximize a predefined utility function. In the game theoretic framework, the retailer should decide the amounts of electricity purchased from the renewable and traditional energy sources, respectively, as well as the real-time pricing scheme for its consumers. The consumers will react to the pricing mechanism and maximize their utility functions by adjusting the electricity demand. The optimal solution of the nested game is provided through: (i) finding the subgame perfect equilibrium (SPE) of all the consumers, and (ii) optimizing the retailer's action using the backward induction method. Experimental results demonstrate the effectiveness of the proposed game theoretic modeling and optimization framework.

Semi-analytical current source modeling of near-threshold operating logic cells considering process variations

Abstract: Operating circuits in the ultra-low voltage regime results in significantly lower power consumption but can also degrade the circuit performance. In addition, it leads to higher sensitivity to various sources of variability in VLSI circuits. This paper extends the current source modeling (CSM) technique, which has successfully been applied to VLSI circuits to achieve very high accuracy in timing analysis, to the near-threshold voltage regime. In particular, it shows how to combine non-linear analytical models and low-dimensionality CSM lookup tables to simultaneously achieve modeling accuracy, space and time efficiency, when performing CSM-based timing analysis of VLSI circuits operating in near-threshold regime and subject to process variability effects.