1,721,038 research outputs found
Multicarrier energy systems
No full textIn recent years, the power system studies changed dramatically, shifting their focus from power system expansion planning as well as operation quality enhancement to other issues such as the integration of large amounts of renewable resources, the definition of new roles for the Transmission System Operator and Distribution System Operator since more and more generation is moving on the distribution side, resiliency of grids and economic sustainability of the on-going revolution in the energy field.
Most energy infrastructures in the world were developed in the second half of the 20th century. The main question in energy system planning and development is whether these old systems can meet future growing needs for different types of energy carriers or not. Along with composite energy transfer systems, many of the installed equipment and tools are getting close to their useful lifetime or their relevant operational limitations. In addition, challenges such as the continuous growth of energy demand, still a strong dependence on fossil fuels, the need for power system reinforcement and the deep penetration of clean and sustainable energy resources raise the need for a new vision of energy systems along with some basic changes in existing systems.
Adopting the distributed generation units as well as gas-fired power generation technologies such as combined heat and power units or combined cooling, heat and power units, gas furnaces, gas converters, etc., in an energy hub has motivated applied research to investigate how to integrate different infrastructures such as electricity, natural gas and heat. The resulting system, called multienergy carriers, hybrid systems or combined energy systems, requires the application of new and integrated modelling as well as operation tools.
Possible scenarios for the future of the energy systems have been developed to overcome limitations of current structure due to a stronger interaction among different infrastructures (for example, gas and electricity). Many studies were oriented to guarantee standard levels of voltage and frequency in electrical systems or standard gas pressure in pipes in presence of increasing gas and electrical loads. Although these studies provided important details for the systems under investigation, they often propose solutions in line with existing reality and limit the analysis in finding an optimisation of the existing system without considering the possibilities deriving from different architectures. Modern energy systems, nowadays, must consider the coexistence of multiple carriers of energy, and, in the future, the concurrent planning and operational optimisation of them can provide an effective approach for improving economical performances, increasing sustainability and ensuring a secure and resilient operation.
This chapter will present some modelling and optimisation issues of strongly interacting energy systems and explore the possibility offered by multicarrier energy systems to improve the overall efficiency of coupled systems
Unbalanced Three-Phase Optimal Power Flow for the Optimization of MV and LV Distribution Grids
No full textOptimal power flow (OPF) techniques are a basic function of advanced distribution management systems (ADMS) and can be applied effectively for controlling distribution grids at both medium voltage (MV) and low voltage (LV) voltage levels. This chapter shows a basic methodology for the control of smart distribution grids together with some realistic applications aimed to solve operative problems that might be encountered in distribution systems, at both MV and LV levels. Three-phase distribution OPF (TDOPF) mathematical formulations and solutions are similar to the ones adopted for classical single-phase OPF routines. Both three-phase and single-phase approaches must employ nonlinear optimization techniques. The network model used for tests is based on actual data concerning the MV and LV circuits adopted for primary and secondary distribution in a real urban distribution network in the city of Bari. The network model developed for tests comprises three whole MV feeders and secondary substation
Optimization of Multi-energy Carrier Systems in Urban Areas
No full textA desirable approach to achieve integration and coordination of energy infrastructures in a Smart City is to develop multi-energy carrier systems where different energy resources are optimized following a holistic approach. This chapter presents two optimization methodologies: the first aiming to solve an operating problem; and the second to solve a planning problem. The optimal control of multi-carrier energy resources is obtained through the solution of a nonlinear optimization problem aimed at minimizing the overall cost of production, equipment wear (BESS) and interruption costs. The chapter collects some results of the "San Paolo Power Park" research project. The project was aimed substantially at the design of an energy district, in which combining low environmental impact methods is possible to fulfill urban regeneration objectives, improving the quality of life of citizens. The project is part of the Strategic Plan for the development of the metropolitan area of the city of Bari
Optimal Gas Flow Algorithm for Natural Gas Distribution Systems in Urban Environment
No full textThis chapter deals with crucial issues on the evolution of natural gas distribution grids, starting from research and field tests activities conducted as part of a research project named "Smart Grid Project". One of the goals of the Smart Grid Project was the design, set up and installation of a prototype of a Supervisory Control and Data Acquisition (SCADA) system equipped with the remote control of three of the 180 Final Reduction Units (FRUs) that supply the urban gas distribution grid of the Bari municipality, a medium-sized town in Italy. Modern natural gas distributions networks should be operated under real-time monitoring and control with an aim of achieving the optimization of various parameters. The general Optimal Gas Flow (OGF) problem can be formulated as a general nonlinear optimization problem, where inequality constraints are treated with penalty functions since the inequality limits in the current problem can be considered as soft constraints
Multicarrier Energy System Optimal Power Flow
No full textThis chapter presents a new modified optimization algorithm based on a powerful heuristic method, namely Time Varying Acceleration Coefficient Gravitational Search Algorithm (TVAC-GSA), to solve optimal power flow (OPF) problems in multi-carrier energy systems focusing the interactions between the power grid and the gas network. The proposed algorithm is based on the Newtonian laws of gravitation and motion. Multi-carrier networks are simultaneously optimized to meet demands more efficiently. In general, they include several energy systems, such as electrical and gas infrastructures. The chapter addresses the main complexities associated with the multi-carrier system structure and several dispatched hubs equipped with Combined Heat and Power (CHP) units/furnaces/transformers. In order to understand how TVAC-GSA works, it is interesting to compare the main differences between its main structure and well-known heuristic algorithm such as particle swarm optimization (PSO). In both PSO and TVAC-GSA, the optimization is obtained by the agent's movement in the search space
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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