A simplified analytical approach for optimal planning of distributed generation in electrical distribution networks

DG-integrated distribution system planning is an imperative issue since the installing of distributed generations (DGs) has many effects on the network operation characteristics, which might cause significant impacts on the system performance. One of the most important characteristics that mostly varies because of the installation of DG units is the power losses. The parameters affecting the value of the power losses are number, location, capacity, and power factor of the DG units. In this paper, a new analytical approach is proposed for optimally installing DGs to minimize power loss in distribution networks. Different parameters of DG are considered and evaluated in order to achieve a high loss reduction in the electrical distribution networks. The algorithm of the proposed approach has been implemented using MATLAB software and has been tested and investigated on 12-bus, 33-bus, and 69-bus IEEE distribution test systems. The results show that the proposed approach can provide an accurate solution via simple algorithm without using exhaustive process of power flow computations

Comparison between the performances of daylight linked control system at two different latitudes

The aim of this work is to compare the performance of a daylight-linked control system installed and tested in two different case studies by means of a set of indices. The two case studies are characterized by different geometry, location and windows orientation. The first one is located at the ENEA premises in Lampedusa (IT, 35° 30' N); the second one is located in Palermo (IT, 38°6' N) on the third floor of the building 9 of the Department of Engineering if the University of Palermo. In both cases, the indices were calculated by using the same daylight-linked control system and the same end-use (office). The results were reported and analysed in order to demonstrate as the performances of the control system can be different from the ideal performance and that they can be different according to the installation. Furthermore, according to the first outcomes, it results that a detailed analysis of the space before the installation of the control system is a necessary practice

Analysis and simulations of the primary frequency control during a system split in continental europe power system

The occurrence of system separations in the power system of Continental Europe has been observed in recent decades as a critical event which might cause power imbalances higher than the reference incident specified per system design, representing an actual challenge for the stability and safe operation of the system. This work presents an analysis and simulations of the primary frequency control in the Continental Europe synchronous area in conditions of system separation. The adopted approach is based on fundamental aspects of the frequency-containment reserve process. The analysis takes an actual event into consideration, which determined the separation of the system in January 2021. The main purpose of the work is the development of specific models and simulations able to reproduce the actual split event. Due to specific arrangements discussed in detail, it is possible to obtain a substantial match between the simulations and the frequencies registered after the system split. The work also provides insight into the importance of the temporal sequence of power imbalances and defensive actions in the primary frequency control process. The models developed in the work are finally used to investigate the separation event under different operating conditions, such as missing defensive actions and low inertia scenarios

Sviluppo, messa a punto e sperimentazione di un sistema combinato batterie al litio-ferro-fosfato/FER per applicazioni in bassa tensione. Report 2 -Test e prove di funzionamento, anche in connessione con la rete elettrica di distribuzione.

Il presente documento costituisce il report dell’attività svolta nel periodo aprile - settembre 2013 avente per oggetto: “Sviluppo, messa a punto e sperimentazione di un sistema combinato batterie al litio-ferrofosfato/FER per applicazioni in bassa tensione”. Nel corso di tale attività, sono state eseguite molteplici prove in condizioni reali di funzionamento, integrando il sistema sviluppato (comprendente il pacco-batterie al litio-ferro-fosfato per una capacità complessiva di 16 kWh e l’insieme degli apparati di interfaccia - di potenza e di segnale - di controllo e di protezione), in una rete elettrica di distribuzione di bassa tensione attualmente in esercizio, al fine di verificare sperimentalmente sul campo l’operatività delle funzioni di protezione e comunicazione implementate. Nel presente Report: - è descritta la rete alla quale è stato collegato il dispositivo per l’esecuzione dei test e delle prove sperimentali; - sono elencati i test e le prove eseguite; - sono riportate le modalità di esecuzione dei test e delle prove; - è descritto e testato un nuovo algoritmo di gestione del sistema di controllo del dispositivo di accumulo; - sono riportati i risultati dei test e delle prove. Le attività sono state condotte in sinergia con il personale tecnico di ENEA e con la collaborazione dell’azienda Layer Electronics s.r.l. di Erice (TP)

Sviluppo, messa a punto e sperimentazione di un sistema combinato batterie al litio-ferro-fosfato/FER per applicazioni in bassa tensione. Report 1 –Sviluppo sperimentale e perfezionamento degli apparati di controllo e comunicazione.

Il presente documento costituisce il report dell’attività svolta nel periodo ottobre 2012 – marzo 2013 avente per oggetto: “Sviluppo, messa a punto e sperimentazione di un sistema combinato batterie al litioferro-fosfato/FER per applicazioni in bassa tensione”. L’attività s’inquadra come avanzamento delle ricerche svolte nel corso di collaborazioni precedenti con lo sviluppo sperimentale e la realizzazione prototipale di un sistema di controllo ed interfaccia verso la rete di un sistema combinato di accumulo elettrico-generazione FER, della taglia di 20 kW, progettato per applicazioni in bassa tensione tali da consentire l’implementazione di funzionalità innovative improntate al modello “smart” (di tipo Virtual PowerPlant, Demand Response, ect.). Il sistema, progettato e realizzato per operare sia in base a logiche di controllo locale, sia in risposta a segnali di controllo da remoto provenienti dal gestore della rete di distribuzione e/o dal mercato, è dotato di una doppia interfaccia, verso il sistema di potenza e verso i sistemi di telecomunicazione, in entrambi i casi con caratteristiche di bidirezionalità dei flussi (di potenza e di dati). Nel corso della precedente annualità (PAR 2011), sul sistema sviluppato è stata già svolta una campagna di test condotti in laboratorio utilizzando un sistema di accumulo elettrochimico di tipo tradizionale (batterie al piombo). L’attività svolta nella presente annualità ha avuto come obiettivo precipuo l’integrazione nell’apparato di un sistema di accumulo al litio (in sostituzione delle batterie al piombo) con il perfezionamento e la messa a punto, attraverso una campagna di test sperimentali, dell’intero sistema (logico e fisico) di controllo dell’apparato secondo il modello MASs (Multi Agent Systems), integrando i controllori delle unità costituenti il sistema di power conditioning, l’unità di controllo del sistema di protezione d’interfaccia e di comunicazione verso la rete e il BMS (Battery Management System) del pacco batterie. Più in particolare, l’attività di ricerca del DEIM si è articolata in due fasi successive. Nel corso della prima fase, l’attività ha riguardato l’integrazione fisica e funzionale, nel sistema ibrido accumulo-FER, di un pacco batterie costituito da 250 celle al litio-ferro-fosfato (per una capacità complessiva di 16 kWh). A tal fine è stato necessario procedere allo sviluppo hardware e software degli apparati di interfaccia e comunicazione tra i controllori delle unità costituenti il sistema di power conditioning, l’unità di controllo del sistema di protezione d’interfaccia e di comunicazione verso la rete e il BMS (Battery Management System) delle batterie al litio. Il presente documento riporta i risultati di tale attività. Nel corso della seconda fase, oggetto di un successivo report, si relazionerà sui test e le prove a cui il sistema sviluppato sarà soggetto. Le attività di cui al presente report sono state condotte in sinergia con il personale tecnico di ENEA e con la collaborazione dell’azienda Layer Electronics s.r.l. di Erice (TP)

Adenosine negatively regulates duodenal motility in mice: role of A1 and A2a receptors .

BACKGROUND AND PURPOSE: Adenosine is considered to be an important modulator of intestinal motility. This study was undertaken to investigate the role of adenosine in the modulation of contractility in the mouse duodenum and to characterize the adenosine receptor subtypes involved. EXPERIMENTAL APPROACH: RT-PCR was used to investigate the expression of mRNA encoding for A(1), A(2A), A(2B) and A(3) receptors. Contractile activity was examined in vitro as changes in isometric tension. KEY RESULTS: In mouse duodenum, all four classes of adenosine receptors were expressed, with the A(2B) receptor subtype being confined to the mucosal layer. Adenosine caused relaxation of mouse longitudinal duodenal muscle; this was antagonized by the A(1) receptor antagonist and mimicked by N(6)-cyclopentyladenosine (CPA), selective A(1) agonist. The relaxation induced by A(1) receptor activation was insensitive to tetrodotoxin (TTX) or N(ω)-nitro-l-arginine methyl ester (l-NAME). Adenosine also inhibited cholinergic contractions evoked by neural stimulation, effect reversed by the A(1) receptor antagonist, but not myogenic contractions induced by carbachol. CPA and 2-p-(2-carboxyethyl) phenethylamino-5′-N-ethylcarboxamidoadenosine hydrochloride hydrate (CGS-21680), A(2A) receptor agonist, both inhibited the nerve-evoked cholinergic contractions. l-NAME prevented only the CGS-21680-induced effects. S-(4-Nitrobenzyl)-6-thioinosine, a nucleoside uptake inhibitor, reduced the amplitude of nerve-evoked cholinergic contractions, an effect reversed by an A(2A) receptor antagonist or l-NAME. CONCLUSIONS AND IMPLICATIONS: Adenosine can negatively regulate mouse duodenal motility either by activating A(1) inhibitory receptors located post-junctionally or controlling neurotransmitter release via A(1) or A(2A) receptors. Both receptors are available for pharmacological recruitment, even if only A(2A) receptors appear to be preferentially stimulated by endogenous adenosine. LINKED ARTICLE: This article is commented on by Antonioli et al., pp. 1577–1579 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2011.01529.

POSTNATAL DEVELOPMENTAL CHANGES IN ENTERIC DOPAMINERGIC SYSTEM

The postnatal period is a key period of life, characterized by the maturation of various organs and in particular of the gut. Currently, we have a poor understanding of the development of neurological and endocrine factors that control intestinal motility. Such knowledge can provide indications about the potency, efficacy, or therapeutic range of a drug in premature infants. Dopaminegic antagonists are often used as prokinetic drugs to treat impaired GI propulsion, although the role of the enteric dopaminergic system in the control of intestinal motility in neonatal vs adult has not been adequately addressed. In this view the aim of this study, was to examine, the functionality of the dopaminergic systems in the regulation of duodenal contractility in neonatal vs adult, using a murine animal model. Transcripts for all dopaminergic receptors (D1-like family, D1 and D5 receptors, and D2-like family, D2, D3, and D4 receptors) can be detected in mouse gut at each age. Mechanical responses to dopamine (DA) were examined in vitro in duodenal longitudinal muscle from postnatal and adult mice as changes in isometric tension. In neonatal duodenum, DA evoked a TTX-insensitive muscular contraction, reduced by SCH 23390, D1-like receptor antagonist, but not by domperidone, D2-like receptor antagonist, and mimicked by a D1 receptor agonist. The contractile response to DA decreased in intensity with age and in adults, in its place, a distinct TTX-insensitive muscular relaxation was detected. Inhibitory response to DA was mimicked by D1 or D2 receptor agonists and reduced by domperidone, and, to a lesser extent, by SCH 23390. In neonatal mice the excitatory responses mediated by D1 receptor activation were antagonized by U-73122, phospholipase C (PLC) inhibitor, whilst in adults the inhibitory effects were blocked by DDA, adenylyl cyclase inhibitor. In mouse gut, dopaminergic transmission undergoes to postnatal change in the pattern of receptor functionality. In postnatal period, DA leads to muscular contraction exclusively via D1-like receptors, likely D5 receptors, linked to activation of PLC. In adults, DA is able to relax duodenum recruiting D2 receptors and shifting the effects mediated by D1-like receptors, likely D1 receptors, activating cAMP pathway

An original control strategy of storage systems for the frequency stability of autonomous grids with renewable power generation

This work examines the operation of the autonomous power system of a geographical island assuming the integration of significant generation shares from renewable energy sources and the installation of the required storage systems. The frequency stability of the system is investigated considering different operating conditions, in terms of load demand and renewable power generation. The main focus of the work is an original control strategy specifically designed for power converters interfacing storage units to the grid. The proposed strategy is based on an extended frequency droop control, which selects specific droop settings depending on the operating mode—charge or discharge—of the storage unit. A simulation model of the whole electrical system is developed for dynamic analysis. The model also implements the possibility of including specific auxiliary frequency controls for synthetic inertia and primary reserve. The results of the simulation and analysis indicate that the proposed control strategy has a significant positive effect, making the storage units able to provide a fundamental and more effective support to the frequency stability of the system. The application of the proposed control strategy to storage units also reduces the need for a contribution to the frequency control from intermittent and variable sources, making the whole system more robust, stable and reliable