A Survey on Communication Networks for Electric System Automation

Published in Computer Networks 50 (2006) 877–897, an Elsevier journal. The definitive version of this publication is available from Science Direct. Digital Object Identifier:10.1016/j.comnet.2006.01.005In today’s competitive electric utility marketplace, reliable and real-time information become the key factor for reliable delivery of power to the end-users, profitability of the electric utility and customer satisfaction. The operational and commercial demands of electric utilities require a high-performance data communication network that supports both existing functionalities and future operational requirements. In this respect, since such a communication network constitutes the core of the electric system automation applications, the design of a cost-effective and reliable network architecture is crucial. In this paper, the opportunities and challenges of a hybrid network architecture are discussed for electric system automation. More specifically, Internet based Virtual Private Networks, power line communications, satellite communications and wireless communications (wireless sensor networks, WiMAX and wireless mesh networks) are described in detail. The motivation of this paper is to provide a better understanding of the hybrid network architecture that can provide heterogeneous electric system automation application requirements. In this regard, our aim is to present a structured framework for electric utilities who plan to utilize new communication technologies for automation and hence, to make the decision making process more effective and direct.This work was supported by NEETRAC under Project #04-157

On Equilibrium Prices in Continuous Time

We combine general equilibrium theory and theorie generale of stochastic processes to derive structural results about equilibrium state prices

Comparing visible and less visible costs of the Habitats Directive: The case of hamster conservation in Germany

The EU Habitats Directive provides in Annexes II and IV a list of species needing to be conserved. Member States have implemented a variety of conservation measures in response to this obligation. These measures include the rejection, modification or delay of land development plans, payments for landowners to perform conservation measures and management actions such as breeding programmes. The costs of the various conservation measures are not always apparent. There may be an underestimation of the resulting costs when land development plans are altered, because there is no visible flow of financial resources. Such a biased perception may result in selecting conservation measures with high but less visible costs, whereas conservation measures with low but more visible costs are neglected. The purpose of this paper is to contribute to avoiding a biased selection of conservation measures by presenting a framework which captures a broad variety of costs relevant to the conservation of species protected by the Habitats Directive. We also demonstrate the relevance of a biased selection of conservation measures by using the framework to empirically estimate the costs of protecting the common hamster (Cricetus cricetus) in the region of Mannheim, Germany. We find that the less visible costs of changes in development plans are significantly higher than the more visible costs of payments to landowners and management actions. This result suggests that measures with visible costs should be given more attention in the future. --Common hamster,Cost assessment,Cost-effectiveness,EU Habitats Directive,Land use,Spatial planning,Species conservation