1,720,992 research outputs found
Optimal planning of battery systems for power losses reduction in distribution grids
No full textThe minimization of the power losses in the distribution grid is one of the main issue for the Distribution System Operator in order to reduce the management costs of the grid. The recent development of the battery technologies has introduced new possible applications for these systems within the radial distribution grid. In fact, batteries can be opportunely integrated in the grid and managed in order to reduce the power losses, and consequently increasing, for instance, the penetration of the renewable distributed generation and contributing to voltage regulation through reactive power production from battery inverter. In this context, one of the main research interest is the definition of the optimal siting and sizing of the energy storage solutions, considering a battery management capable to reduce network power losses and taking into account battery installation costs.
Since network losses are expressed by means of quadratic function, an approach based on Mixed Integer Quadratically Constrained Quadratic Programming is proposed here to identify possible batteries optimal management strategies capable to minimize the power losses. Evaluation of the grid variables is obtained by the iterative Backward/Forward Sweep method implemented within the formulation of the optimization problem. The reactive power generated by the battery inverter is modeled as well by introducing quadratic constraints in order to further contribute in the network power losses reduction, taking into account the power factor limitation due to the inverter capability curve.
An optimization procedure, called D-XEMS13, based on the formulation of the optimization problem, is implemented within a single loop optimization algorithm in order to identify the best size of the connected BESSs units, capable to maximize the reduction of the power losses in test grids. BESS optimal placement is also identified through a proposed approach based on a nodal sensitivity analysis of the network power losses. Validation of the proposed approach is then obtained by means of a cost/benefit comparison from energy point of view.
Finally, the single loop optimization algorithm is further implemented on two test grids with optimal BESSs sizes and siting, assuming different capability curves for the BESS inverters. The results of simulations with the corresponding benefits are then presented and discussed
Uncertainty quantification in energy management procedures
Full text linkComplex energy systems are made up of a number of components interacting together via different energy vectors. The assessment of their performance under dynamic working conditions, where user demand and energy prices vary over time, requires a simulation tool. Regardless of the accuracy of this procedure, the uncertainty in data, obtained both by measurements or by forecasting, is usually non-negligible and requires the study of the sensitivity of results versus input data. In this work, polynomial chaos expansion technique is used to evaluate the variation of cogeneration plant performance with respect to the uncertainty of energy prices and user requests. The procedure allows to obtain this information with a much lower computational cost than that of usual Monte-Carlo approaches. Furthermore, all the tools used in this paper, which were developed in Python, are published as free and open source software
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
Economic, energy, and environmental analysis of PV with battery storage for Italian households
No full textThe use of renewable energy sources is one way to decarbonize current energy consumption. In this context, photovoltaic (PV) technology plays a direct fundamental role since it can convert sun irradiance into electricity to be used for supplying electric loads for households. Despite the huge availability of the solar resource, the intermittence of PV production may reduce its exploitation. This problem can be solved by the introduction of storage systems, such as batteries, storing electricity when PV overproduction occurs and acting as a source when PV generation is absent. Consequently, increase in self-sufficiency and self-consumption can be expected in residential end users, paving the way for more sustainable energy systems. In this paper, an economic, energy, and environmental analysis of PV systems (without and with batteries) for the household is performed for the whole of Italy, by means of a Geographical Information Systems (GIS) approach. A model to simulate energy balance and to manage batteries is defined for households to assess the profitability of such systems under an Italian regulation framework. Concerning results, indicators are provided at a national scale using GIS tools to highlight areas where investments are more profitable, boosting the CO2 emission reduction
Renewable Energy Communities business models under the 2020 Italian regulation
No full textRecently in Italy several regulation actions have been setup defining the Renewable Energy Communities implementation. Beyond the regulatory aspects of the legislation, the definition of economic incentives has open the possibility for the evaluation of the business models of the Renewable Energy Community initiative. The present work is focused on a methodology aimed at the sizing of the active part of an energy community: a solar photovoltaic system with electrochemical energy storage. It develops a multicriteria optimisation procedure by evaluating two independent and normalised key performance indices: self consumption and self sufficiency of the energy community. These two KPIs are evaluated on a hourly based energy balance by minimising the power flow to/from the electrical grid through a Mixed Integer Linear Programming scheme. Results obtained by changing the PV and the energy storage sizes are mapped in a Pareto plane and their distance from “utopia point” are evaluated. Economic indicators are then used to pick up the most performing configuration. Three different options of business model are considered on the optimal point: one where the Renewable Energy Community is taking on itself all the capital expenditure for photovoltaic and battery, a second one where an independent company is acting as a “technological partner” acquiring and managing the assets, sharing with the community the revenues and one intermediate case where costs and revenues are shared between community and developer. The procedure is applied to a real test case of an energy community located in the north-western region of Italy. Results show both positive economic and environmental performances, where the internal rate of return is greater than 11% and CO2 emission reduction is close to 45% for all the configurations, making attractive the exploitation of REC in the Italian context
The Role of MicroRNAs in Influencing Body Growth and Development
Full text linkBody growth and development are regulated among others by genetic and epigenetic factors. MicroRNAs (miRNAs) are epigenetic regulators of gene expression that act at the post-transcriptional level, thereby exerting a strong influence on regulatory gene networks. Increasing studies suggest the importance of miRNAs in the regulation of the growth plate and growth hormone (GH)-insulin-like growth factor (IGF) axis during the life course in a broad spectrum of animal species, contributing to longitudinal growth. This review summarizes the role of miRNAs in regulating growth in different in vitro and in vivo models acting on GH, GH receptor (GHR), IGFs, and IGF1R genes besides current knowledge in humans, and highlights that this regulatory system is of importance for growth
- …
