1,721,005 research outputs found
Analisi comparativa di linee di trasmissione innovative tetrafase e tradizionali trifase nel nuovo scenario del mercato liberalizzato dell’energia elettrica
No full textNel lavoro si confrontano linee di trasmissione aeree tetrafase e tradizionali trifase. In particolare si mostra come le linee tetrafase, che presentano caratteristiche tecnico-economiche interessanti per la trasmissione di potenze e su distanze elevate, possono comportare in alcuni casi un minor impatto ambientale rispetto a soluzioni trifase equivalenti
The Loadability of Overhead Transmission Lines. Part I: Analysis of Single-Circuits
No full textThis paper provides a methodology for a thorough technical comparison between traditional three-phase ac lines, on the one hand, and possible (in some cases non-conventional) alternative solutions that include HVDC lines, four-phase ac lines and combined ac-dc lines, on the other. The comparison is based on the loadability curves, which are calculated here for all the considered lines taking into account thermal limits, voltage drop, power losses and – when feasible – steady-state and transient stability. The focus is on four-phase ac and combined ac-dc lines, for which the loadability curves are derived for the first time, whereas the loadability curves of three-phase ac lines - well-known in the literature - are derived and used here just as the natural reference for the comparison. Due to the great deal of theoretical and numerical developments, the study is split in two. Part I analyzes single-circuit lines of comparable loadability at the thermal limit (three-phase, four-phase and monopolar HVDC). Part II broadens the analysis to double-circuit lines of comparable loadability at the thermal limit (three-phase, bipolar HVDC and combined ac-dc) and performs an overall comparison among the different systems in single-circuit and double-circuit configuration
4-Phase AC Connections: an Alternative Possibility for the Expansion of Transmission Grids
No full textThis paper investigates the economical feasibility of four-phase (4P) overhead transmission lines, considered as a possible alternative to the traditional three-phase (3P) connections. The paper performs an economical comparison between innovative 4P transmission lines and traditional 3P lines, with the goal of evaluating the contests where a 4P connection could become convenient, accounting for different reliability, land occupation, visual impact, energy losses and investment costs
Can Four-Phase Transmission Lines be Considered as a Practical Alternative to Traditional Three-Phase Lines in the European electricity market?
No full textThis paper aims at investigating the feasibility of four-phase (4P) overhead transmission lines, that could be viewed as a possible alternative to the traditional three-phase (3P) solutions for the construction of new transmission lines. This subject is important especially in the European framework, where expansion and reinforcement of existing transmission systems are increasingly required. This paper performs an economical comparison between innovative 4P transmission lines and traditional 3P lines, with the specific goal of evaluating the contests where a 4P transmission might compete with traditional 3P systems with single or double circuit lines
Analisi economica per l’individuazione degli ambiti di convenienza di linee di trasmissione innovative tetrafase
No full textIl lavoro esamina la fattibilità economica di linee di
trasmissione aeree tetrafase (4P) in alternativa a quelle
tradizionali trifase (3P). Mediante un confronto economico
tra linee innovative 4P e linee tradizionali 3P - che tiene
conto dei costi di investimento, perdite di energia,
affidabilità, occupazione del territorio e impatto visivo -
vengono individuati i possibili ambiti di convenienza di
una connessione 4P
Sistemi privi di accumulo di energia per il contenimento degli effetti dei buchi di tensione sugli impianti utilizzatori
No full text
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
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