1,721,115 research outputs found
Robust optimal demand-side management in smart grids
Full text linkSmart grids (SGs) are experiencing an increasing growth due to their economic, social and environmental benefits. The concept of SG has recently gained significant attention from the research community due to its ability to effectively integrate distributed energy resources (DER) including renewable energy sources (RES), energy storage systems (ESS) and the demand side management (DSM) programs. A SG can change the operation paradigm of the electric grid to ensure an efficient and sustainable electricity supply with lower losses and greater reliability and security. Despite these potential benefits, the massive penetration of DERs in SGs may impose new challenges to the system design and functioning. A substantial challenge arises from system uncertainties due to forecast errors. For instance, the inherent intermittency of RESs, the unpredictable changes in users’ electricity demand, and the volatility of the dynamic electricity price in electricity markets can inject considerable amounts of uncertainty into the electric grid.
Facing these challenges, this thesis investigates the integration of DERs and DSM programs as great sources of flexibility and essential elements for effective supply-demand balancing into SGs in the presence of uncertainty. Firstly, we present a comprehensive classification, review and analysis of existing approaches and findings for DSM to highlight key features and components of energy management systems for more flexible and intelligent grids. We provide a definition of DSM and introduce the reader to the functionalities and achievements of DSM applications in SGs. We then focus on the state-of-the-art decision-making and control approaches for DSM, followed by a comprehensive description of demand side applications detailed for smart users, distribution networks and transmission networks.
Afterwards, we characterize our novel methodologies presented in this thesis in two main parts including centralized and decentralized/distributed approaches.
In the first part, we present five novel robust centralized DSM approaches for the optimal scheduling of residential microgrids (MGs) comprising a number of interconnected end-use consumers with various types of electrical loads, RESs, ESSs, and plug-in electric vehicles (PEVs). The general objective of the optimal scheduling is minimizing the expected electricity cost while satisfying device/comfort/contractual constraints of the system under the uncertainties on RES generation and users’ electricity demand. In addition, we deal with the conservativeness of the proposed approaches for different scenarios in terms of the cost saving, the peak-to-average ratio (PAR), and the constraints’ violation rate. The proposed robust DSM approaches allow the decision maker (i.e., the energy manager of the system) to make a satisfactory trade-off between the electricity cost and constraints’ violation rate considering the system technical limits and the users’ comfort. We validate the effectiveness of the proposed approaches on several simulated case studies and provide comparisons and discussions on the results.
In the second part, we explore decentralized and distributed DSM approaches for the coordinated optimal charge control of PEVs in SGs. In particular, we develop a novel fully distributed control strategy for the optimal charging of large-scale PEV fleets aiming at the minimization of the aggregated charging cost and battery degradation, while satisfying the PEVs’ individual load requirements and the overall grid congestion limits. The proposed resolution algorithm requires a minimal shared information between PEVs that communicate only with their neighbors without relying on a central aggregator. Thus, it guarantees the PEV users’ privacy. We validate the proposed approach on numerical experiments with a large number of PEVs to demonstrate the ability of the approach in finding a global optimum solution with a favorable computational efficiency. Moreover, we present a new robust decentralized framework for day-ahead charge control of PEV fleets under uncertainties on the dynamic electricity price and the inelastic loads demand. The main objective of this work is minimizing both the overall charging cost and the aggregated battery degradation cost of PEVs while preserving the robustness of the solution against perturbations in the uncertain parameters. In addition, power congestion limits of the overall capacity of the distribution network and the PEVs’ individual needs such as charge level requirements and battery degradation cost are taken into account
Game-theoretic Control of Autonomous Power Grids
Full text linkPower systems are currently undergoing a period of unprecedented transformations. Environmental and sustainability concerns lead to the replacement of centralized generation, based on conventional fossil fuel-based power plants, with distributed generation from renewable energy sources. In addition, a variety of new autonomous entities able to adjust their load demand or provide ancillary services to the grid are increasing the complexity of energy systems, requiring a decentralization of the control structures.
In this context, autonomous power grids have been proposed as a necessary paradigm to capture the need for distributed operation of power grids.
Nevertheless, the existing control and optimization techniques are inadequate to reach this goal while ensuring the efficiency and security of power systems.
Due to its capacity to capture interactions among interdependent decision-making entities, game theory offers a promising way to implement and control autonomous power grids. Nonetheless, several technical issues must be solved in order to fully implement this new paradigm. As a result, this thesis is dedicated to solving two of the most important research challenges in designing and operating game-theoretical control for autonomous power grids.
In the first part, this thesis deals with the development of optimization tools devoted to closing the gap between variable generation and adjustable load demand. The increasing penetration of renewable energy sources poses significant challenges to the existing power systems due to the difficulty in coping with their inherent time-varying nature. To this aim, a series of stochastic techniques for energy system optimization are proposed to accommodate uncertainty in autonomous power grids operation. Consequently, game-theoretical frameworks are defined with the aim of increasing the flexibility of the grid through the active participation of autonomous entities.
The second part of this thesis is further focused on coordinating autonomous entities in game-theoretical frameworks. The coordination of these entities is not straightforward due to the fact that they are interconnected through power lines and therefore must respect the so-called power flow constraints. The nonconvexity of the resulting control problem thus makes difficult to use traditional mathematical tools.
To solve this problem, a novel mathematical theory for game-theoretical frameworks with nonconvex coupling constraints is developed and applied to ensure the quality and feasibility of autonomous power grid operation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Preparation of 2,3-dihydro(1,5)benzothiazepines and 2,3-dihydro(1,5)benzodiazepines
No full text2,3-dihydro[1,5] benzothiazepines and diazepines can be prepared by condensation of o-aminothiophenol or o-phenylenediamines with a variety of 3-chlorothieno- or benzothienopropanones
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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