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

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)

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.

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