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In this paper, an optimal power dispatch problem on a 24-h basis for distribution systems with distributed energy resources (DER) also including directly controlled shiftable loads is presented. In the literature, the optimal energy management problems in smart grids (SGs) where such types of loads exist are formulated using integer or mixed integer variables. In this paper, a new formulation of shiftable loads is employed. Such formulation allows reduction in the number of optimization variables and the adoption of real valued optimization methods such as the one proposed in this paper. The method applied is a novel nature-inspired multiobjective optimization algorithm based on an original extension of a glowworm swarm particles optimization algorithm, with algorithmic enhancements to treat multiple objective formulations. The performance of the algorithm is compared to the NSGA-II on the considered power systems application. © 2005-2012 IEEE.

In this chapter, the problem of energy management in smart-grids is outlined. Optimized energy management is here considered as the operation of energy and power flow control in the aim of attaining minimum cost or minimum power losses while meeting technical constraints. Of course, according to the type of energy system in which such operation is carried out, the meaningful variables and objectives in the problem may largely change. As the extension of the system increases, the influence of the physical behaviour of the electrical power lines takes a more important role. Power electronics takes instead an increasing influence, as the dimension of the power system decreases although Kirchhoff laws must always be verified. Energy management is also an interesting issue in multi-carrier energy hubs that implement a recent tendency in energy systems interfacing smart-grids. They include different energy resources that need to be managed differently, but in an integrated fashion. The chapter offers an overview of energy management in a smallsystem using a two levels centralized approach.

In this paper, a generalized double-shell framework for the optimal design of systems managed optimally according to different criteria is developed. Optimal design is traditionally carried out by means of minimum capital and management cost formulations and does not typically consider optimized operation. In this paper, the optimized multiobjective management is explicitly considered into the design formulation. The quality of each design solution is indeed defined by the evaluation of operational costs and capital costs. Besides, the assessment of the operational costs term is deduced by means of the solution of a multiobjective optimization problem. Each design solution is evaluated using the outcomes of a multiobjective optimization run: a Pareto hyper-surface in the n-dimensional space of the operational objectives. In the literature, commonly the evaluation of each design solution is carried out based on an approximate evaluation of the operational costs, not considering the real multiobjective optimized management. In this paper, such assessment is carried out using a suitable convergence indicator typically used for multiobjective optimization algorithms. The application is devoted to the problem of optimal sizing of distributed energy resources in medium voltage or low voltage microgrids. For this problem, the identification of the multiple operational impacts comes along with the solution of the optimal unit commitment of distributed generators. After the introductory section, the problem formulation is presented and an interesting application of the considered approach to the design of distributed energy sources in a microgrid is shown. © 2005-2012 IEEE.

This chapter outlines the concept of intelligent and multi-service infrastructures, addressing the interesting aspects of multi operability, potential of cogeneration and multi-carrier energy hubs, whose basic concepts were only recently described in [1]. The infrastructures that serve a community, such as energy distribution, water and waste piping, mobility and ICT networks are, in fact, the most important means for efficient operation of cities. The chapter, after outlining the contents of the document ISO TR 37150: 2014 concerning the Smart Community Infrastructures, highlights the different approaches needed to implement them within existing cities and newly built cities. At the end, the chapter presents the concept of Energy Hub and some cases study of urban districts (existing district and new built district) modelled as Energy Hubs.

This paper presents a combined optimal energy and power flow management for islanded microgrids. The highest control level in this case will provide a feasible and optimized operating point around the economic optimum. In order to account for both unbalanced and balanced loads, the optimal power flow is carried out using a Glow-worm Swarm Optimizer. The control level is organized into two different sub-levels, the highest of which accounts for minimum cost operation and the lowest one solving the optimal power flow and devising the set points of inverter interfaced generation units and rotating machines with a minimum power loss. A test has been carried out for 6 bus islanded microgrids to show the efficiency and feasibility of the proposed technique.

In this paper, a distributed intelligence algorithm is used to manage the optimal power flow problem in islanded microgrids. The methodology provides a suboptimal solution although the error is limited to a few percent as compared to a centralized approach. The solution algorithm is multi-agent based. According to the method, couples of agents communicate with each other only if the buses where they are located are electrically connected. The overall prizing system required for learning uses a feedback from an approximated model of the network. Based on the latter, a distributed reiforcement learning algorithm is implemented to minimize the joule losses while meeting operational constraints. Simulation studies with a small microgrids show that the method is computationally efficient and capable of providing sub-optimal solutions. Due to the limited computational complexity, the proposed method has great potential for online implementation.

PurposeThe purpose of this paper is to identify a new and simple two‐end algorithm for fault location identification and characterization, in electrical distribution systems.Design/methodology/approachThe developed diagnostic algorithm is based on a simple model of the network using a lumped parameters representation.FindingsTest results have proved the approach to be efficient, allowing a precise fault identification and location while not requiring synchronized measures from the two ends.Research limitations/implicationsThere is a need for measurement systems at all MV/LV substations.Practical implicationsApplicability with limited investments is not possible where metering systems are not so diffused, although smart grids and DG units require such infrastructures. Moreover, utilities are quite interested in such issues, since the new required quality standards put severe constraints on faults management and clearance.Originality/valueThe paper presents a new and easier diagnostic algorithm for faults diagnosis in distribution systems.

This paper proposes a numerical model of the soil ionization phenomena that can occur when earth electrodes are injected by high pulse transient currents, as the one associated with a direct lightning stroke. Based on finite difference time domain numerical scheme, this model ascribes the electrical breakdown in the soil to the process of discharge in the air. In fact, as soon as the local electric field overcomes the electrical strength, the air in the voids trapped among soil particles is ionized, and the current is conducted by ionized plasma paths locally grown. The dimension of these ionized air channels is strictly dependent upon the local temperature. Thus, a local heat balance is enforced in order to obtain the time variable conductivity profile of the medium. This model can be implemented both for concentrated and extended electrodes, since no hypothesis has to be enforced about the geometric shape of the ionized region. Validation of the proposed model is obtained by comparing simulation results with experimental data found in technical literature.

In this paper, the structure of the highest level of a hierarchical control architecture for micro-grids is proposed. Such structure includes two sub-levels: the Energy Management System, EMS, and the tertiary regulation. The first devoted to energy resources allocation in each time slot based on marginal production costs, the latter aiming at finding the match between production and consumption satisfying the constraints set by the EMS level about the energy production in each time slot. Neglecting the efficiency of the different energy generation systems as well as that of the infrastructure for electrical energy distribution, the problem dealt with by the EMS sub-level is linear and can be solved by well known Linear Programming optimization procedures. The tertiary sub-level, below the EMS, optimizes mainly technical objectives and requires the solution of the Optimal Power Flow problem. After a review of the state of the art on the topic, the higher control sub-levels are described and an application is proposed. The application shows the efficiency of Mixed Integer Linear Programming methods for cost minimization of the energy production systems for microgrids. Also the formulation of the OPF problem is briefly outlined to describe the interaction between the two sub-levels

In this paper, a wavelet-based efficient simulation of electromagnetic transients in a lightning protection systems (LPS) is presented. The analysis of electromagnetic transients is carried out by employing the thin-wire electric field integral equation in frequency domain. In order to easily handle the boundary conditions of the integral equation, semiorthogonal compactly supported spline wavelets, constructed for the bounded interval [0,1], have been taken into account in expanding the unknown longitudinal currents. The integral equation is then solved by means of the Galerkin method. As a preprocessing stage, a discrete wavelet transform is used in order to efficiently compress the Fourier spectrum of the waveform, used as the current source that directly strikes the LPS. Time profiles of electromagnetic quantities are then obtained by using an inverse discrete fast Fourier transform algorithm. The model has been validated by comparing the results with computed and measured data found in technical literature. A good agreement has been found with a significant computational reduction.

This paper presents an application of the Glowworm Swarm Optimization method (GSO) to solve the optimal power flow problem in three-phase islanded microgrids equipped with power electronics dc-ac inverter interfaced distributed generation units. In this system, the power injected by the distributed generation units and the droop control parameters are considered as variables to be adjusted by a superior level control. Two case studies with different optimized parameters have been carried out on a 6-bus test system. The obtained results showed the effectiveness of the proposed approach and overcomes the problem of OPF in islanded microgrids showing loads unbalance.

In this paper, an original scheduling approach for optimal dispatch of electrical Energy Storage Systems (ESS) in modern distribution networks is proposed. The control system is based on fuzzy rules and does not use forecasts since it repairs the past history according to the real time data on the electrical energy cost, renewable energy production and load. When the system detects a worsening of performances, the fuzzy logic rule-based control system self-adapts its membership functions using an economic indicator. The common use, in the relevant literature, of forecasted values in such systems can lead to large errors and economic losses. Moreover the speed of calculation guaranteed by the fuzzy control system allows the execution of new calculations even with high frequency. After the Introduction section, where the state of the art on the topic is outlined, the problem formulation is presented and an interesting application of the considered approach to the control on a medium size battery with real world data is proposed.

The purpose of the present work is to show the validation of a new model to simulate the physical phenomenon of partial discharge (PD) produced in air voids inside insulating epoxy resin. The model has been developed on the basis of a new approach that combines the known circuit model of three capacitors with a model used to describe the behavior of the ionized channel inside of the inclusion during the discharge phenomenon, short-circuiting the capacity that represents the void. The approach is based on time-variable conductance of the void, subjected to multistress conditions: voltage, temperature and pressure. The new approach has been developed from a time variable conductivity model used for the study of the discharge with dielectric barrier (DBD). The different parameters which influence the discharge phenomenon in the void are taken into account through an approach in which a lumped circuit is used to simulate the effects of global PD asset. The results of the multiple simulations have been compared with experimental and simulated behaviors found in the literature on the subject.

Il presente Rapporto descrive le attività svolte dal personale del DEIM dell’Università degli Studi Palermo nell’ambito della prima fase delle attività di ricerca dal titolo: “Implementazione di funzioni aggiuntive per la rappresentazione e la gestione ottimizzata di risorse energetiche distribuite in un distretto energetico. Simulazione di scenari in ambiente integrato”, oggetto dell’Accordo di Collaborazione tra ENEA e DEIM sottoscritto in data 25 marzo 2013. Scopo del presente accordo di collaborazione è la definizione di funzioni aggiuntive per i vari componenti del distretto energetico già descritti e modellati in un apposito software nella scorsa annualità. Le simulazioni sono state svolte su una piattaforma integrata che combina le caratteristiche termiche ed elettriche di carichi e generatori con le relative reti di distribuzione. E’ stata definita la interfaccia in Java costituita da due layer, elettrico e termico, e sono state implementate alcune funzionalità che rappresentano la gestione ottimizzata di alcune risorse energetiche del distretto secondo logiche di tipo tecnico ed economico in uno scenario di mercato liberalizzato. Poiché è stato necessario combinare la modellazione di componenti e sistemi elettrici all’interno di quanto sviluppato nella stessa annualità presso i laboratori ENEA, in fase di avvio delle attività di ricerca, si è convenuto che queste si sarebbero svolte in forte sinergia utilizzando lo strumento della videoconferenza via web, ma anche più incontri fra i partecipanti alle attività di ricerca. In questa attività, si sono utilizzati i risultati del lavoro degli scorsi anni sempre svolti in collaborazione con ENEA omogeneizzando i linguaggi di programmazione al fine di rendere la piattaforma di simulazione davvero un unico strumento. L’interfaccia è stata resa facilmente accessibile, consentendo la agevole modifica sia dei parametri elettrici che termici dei componenti del distretto energetico. La piattaforma è quindi un simulatore non solo di componenti ma anche delle loro logiche di gestione (scheduling). Ciascuno dei componenti del distretto energetico è un oggetto con proprietà e funzioni che ne caratterizzano il comportamento in relazione a scenari e obiettivi stabiliti per l’oggetto considerato. L’oggetto dell’accordo di collaborazione è quindi stato sviluppato in due fasi. Nella prima fase, che costituisce l’argomento del presente rapporto, si è fatta una descrizione delle dette funzionalità, individuando adeguate strategie di risoluzione dei problemi di scheduling che vengono affidate all’Energy Management System, EMS. Dopo aver fornito una descrizione della struttura gerarchica dei controllori per questi particolari sistemi elettrici a servizio di distretti energetici, ci si è soffermati sul livello così detto ‘terziario’ di gestione dell’energia a cui si riferiscono le dette logiche di gestione. Sono poi state descritte le strategie di gestione dei singoli componenti in modo autonomo o combinato, in relazione allo scenario esaminato. La seconda parte delle attività è invece dedicata alle diverse simulazioni che sono state svolte con la piattaforma realizzata. Si descrive la struttura definitiva della piattaforma integrata, la sua interfaccia verso l’esterno con i dati di input ed il flusso di dati all’interno della piattaforma. In questa fase dell’attività di ricerca, si sono svolte diverse simulazioni in alcuni scenari particolarmente significativi ed i risultati del modello vengono riportati e commentati in calce. Viene descritta anche l’interfaccia Java che consente una facile immissione dei dati caratteristici del sistema elettrico e termico. In appendice, è riportato il codice della semplice procedura di ottimizzazione utilizzata per la individuazione dello scheduling dei vari componenti del distretto. Futuri sviluppi del presente lavoro di ricerca prevedono: - la definizione di strategie di gestione dell’energia multilivello, che consentano, compatibilmente con i tempi del simulatore integrato messo a punto, il dispacciamento delle risorse energetiche in tempi diversi in relazione ai diversi tempi fisici di risposta di ciascuna risorsa; - la valutazione l’impatto degli errori previsionali sulla efficacia della strategia di dispacciamento del sistema di accumulo e dei carichi controllabili messo a punto; - la implementazione delle logiche di controllo del sistema di accumulo sperimentale messo a disposizione da ENEA.

In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies as the regulators parameters vary as well, thus showing that these are sensitive parameters that could have an important role in optimal management of such systems.

In micro-grids, due to their small scale, there is commonly only one power supplier. A competitive wholesale market hardly exists, so the question about how to consider market issues for small producers within micro-grids arises. On the other hand, the specific features of micro-grids where load and generated power hardly find a balance, require that customers take part to regulation issues, also using demand-response (DR) programs. In this paper, price responsive (PR) policies and their programs are discussed to answer this question. A case study of a micro-grid with one micro-turbine and two photovoltaic (PV) generators is analyzed to assess the overall production cost in order to build a PR program in different cases while changing the grid's characteristics.

This paper presents a novel nature-inspired multi-objective optimization algorithm. The method extends the glowworm swarm particles optimization algorithm with algorithmical enhancements which allow to identify optimal pareto front in the objectives space. In addition, the system allows to specify constraining functions which are needed in practical applications. The framework has been applied to the power dispatch problem of distribution systems including Distributed Energy Resources (DER). Results for the test cases are reported and discussed elucidating both numerical and complexity analysis.

Il presente Rapporto, strutturato in due parti (Parte Prima: “Modelli e strategie per la simulazione di distretti energetici” e Parte Seconda: Definizione e sviluppo di strumenti software per la simulazione integrata di distretti energetici in ambiente dedicato), descrive le attività svolte dal personale del DIEETCAM dell’Università degli Studi Palermo nell’ambito della prima fase delle attività di ricerca dal titolo: “MODELLI E STRATEGIE PER LA DEFINIZIONE DI STRUMENTI SOFTWARE PER LA SIMULAZIONE INTEGRATA DI DISTRETTI ENERGETICI IN AMBIENTE DEDICATO”, oggetto dell’Accordo di Collaborazione tra ENEA e DIEETCAM sottoscritto in data 27 gennaio 2012. Scopo del presente accordo di collaborazione è la definizione di un tool informatico per la modellazione della parte elettrica di una piattaforma integrata che rappresenta il comportamento elettrico e termico del sistema di approvvigionamento energetico di un sistema multi-edificio. Poiché si è reso necessario integrare elementi di modellazione dei sistemi elettrici nell’ambito di quanto sviluppato, nella stessa annualità, presso i laboratori ENEA, in fase di avvio delle attività, la fase operativa è stata caratterizzata da un azione di continua collaborazione tra il personale ENEA e DIEETCAM, utilizzando prevalentemente lo strumento della videoconferenza via web, ma anche incontri e riunioni fra quanti partecipavano alle attività. Il punto di partenza delle attività è stata la piattaforma ODESSE sviluppata presso i laboratori ENEA nelle passate annualità. Nel corso delle attività dell’annualità corrente, essa è stata opportunamente modificata al fine di rendere coerenti le scale di precisione del modello del sottosistema elettrico e del modello del sottosistema termico. Il lavoro è stato svolto con l’obiettivo di rendere lo strumento di simulazione un oggetto utilizzabile anche da un utente non esperto, nonché di sviluppare un modello integrato utile anche alla risoluzione di problemi più complessi di gestione ottimizzata di tipo integrato. Le attività sono state condotte in forte sinergia con il personale tecnico designato da ENEA e svolte prevalentemente all’interno dei locali e dei laboratori del DIEETCAM di Palermo. Nel corso delle attività, sono stati, infatti, svolti diversi incontri di confronto e coordinamento con il personale ENEA. L’oggetto dell’accordo di collaborazione è quindi stato sviluppato in due fasi. Nella prima fase si è sviluppata l’analisi di modelli elettrici e delle strategie per sistemi elettrici che alimentano distretti energetici. In particolare, sono stati analizzati i modelli di linee elettriche aeree ed in cavo esistenti in letteratura e le possibili semplificazioni idonee all’applicazione oggetto del presente contratto. E’ illustrata, anche, una rassegna degli algoritmi di calcolo dei flussi di potenza e viene analizzato il problema della modellazione di sorgenti e carichi. Successivamente viene esaminato in dettaglio uno strumento per la modellazione probabilistica dei carichi elettrici e per la rappresentazione della interazione con i carichi di tipo termico eventualmente presenti. Vengono, inoltre, rappresentate tecniche di demand-response che potrebbero condizionare la modellazione dei carichi ed in un successivo capitolo sono descritti i servizi ancillari che il distretto energetico potrebbe offrire alla rete. Infine, poiché le interazioni fra i vari nodi della rete sono per lo più di tipo economico, si è ritenuto interessante rappresentare un ulteriore strumento di analisi di tali sistemi complessi: un algoritmo per il tracciamento dei flussi di potenza. Tale strumento potrebbe infatti consentire di valutare il costo di trasporto dell’energia da un punto di alimentazione al carico consentendo così di imputare in modo preciso il costo di trasporto della stessa energia (Report Parte Prima). La seconda parte delle attività è invece dedicata all’implementazione del modello di rete di distribuzione dell’energia elettrica a servizio di un distretto energetico. In particolare, si descrive la realizzazione dei tool di supporto ed ampliamento della piattaforma derivata dal modello ODESSE, opportunamente modificata per ospitare la nuova filosofia integrata di gestione del distretto energetico (Report Parte Seconda).

In the next years, electric mobility will be one of the issues electric utilities will have to face. The detailed modeling of the electric load generated by the presence of Electric Vehicles, EV, parking lots will be essential to simulate the different working conditions of new distribution systems. Also the detailed modeling will allow to deduce technical and economical aspects, allowing Distribution Systems Operators to devise the right incentives for EV customers. Such as, or maybe more than, residential loading the EV loading is strongly variable because it is connected to the human behavior, the modeling thus has to include stochastic terms. Moreover, to get realistic load profile for electric mobility, it is essential to consider the social and economical aspects connected to the market penetration of the different models of EVs [1]. This implies the recourse to a Montecarlo approach for simulating the EV load profile. Costs of different types EVs will be a crucial aspect ruling this phenomenon. Habits of the typical customer of each of the considered models will in turn affect recharge start time. In this paper, based on realistic data available from studies carried out in the field, a load model for electrical vehicles parking lots is detailed. The parking lot can be composed by different types of vehicles and namely: FEV (Full Electric Vehicles,), PHEV (Partially Hybrid Electric Vehicle), EREV (Extended Range Electric Vehicles). The model of each type of vehicle is characterized by a driving range and a battery size. Moreover batteries are modeled using the Peukert’s law for lead acid batteries, which is typically not considered in statistical modeling. Moreover the use of the vehicle (domestic, professional) influences the distance covered each day and thus the State of Charge of the vehicle when it is connected to the recharge station. In the paper, the probabilistic model used to simulate a generic EV parking lot impact on a distribution grid is outlined; it considers also smart and unmanaged charging modes.

Aggregates of loads and generators working coordinated, called microgrids, are new entities appearing at distribution level. In this paper, an integrated platform for energy modeling of microgrids is proposed. The platform allows the evaluation of heat and electrical energy balance terms and of the steady state features of the distribution system supplying the grid. The interface is friendly and allows the positioning of different items, such as co-generators, photovoltaic and wind units, Electric Vehicles parking lots and buildings. The platform is built in Matlab while the interface in Java. Each component of the model can be placed using a CAD facility and each ‘node’ is characterized by different features and can be easily connected through suitable ‘links’. Links can either be lines (cables or aerial) or transformers and pipes over the heat layer. The load flow problem is solved using the Newton Raphson algorithm. All nodes can be either simulated as PQ or PV buses. EV parking lots are modeled using statistical methods ([1], [2], [3]) and considering the presence of different types of Electric Vehicles with different sizes and thus driving ranges and battery sizes. The platform also models micro-grids heating systems within a small area with few buildings (MFH, office, school). A simplified dynamic model has been studied and implemented to evaluate primary energy savings through the use of district heating instead of individual heating systems in buildings.

Il presente Rapporto descrive le attività svolte dal personale del DIEET dell’Università degli Studi Palermo nell’ambito della prima fase delle attività di ricerca dal titolo: “ARCHITETTURE E LOGICHE DI CONTROLLO OTTIMALE DI MICRORETI PER LA RAZIONALIZZAZIONE ENERGETICA’”, oggetto dell’Accordo di Collaborazione tra ENEA e DIEET sottoscritto in data 24 febbraio 2011. In fase di avvio delle attività, DIEET ed ENEA hanno concordato: che le reti sulle quali sviluppare le analisi e le successive simulazioni devono essere reti esistenti al fine di orientare il presente studio ad una successiva sperimentazione sul campo. Le attività sono state condotte in sinergia con il personale tecnico designato da ENEA e svolte sia all’interno dei locali e dei laboratori del DIEET di Palermo, sia presso i centri di ricerca ENEA di Portici (Napoli) e Casaccia (Roma). Nel corso delle attività, sono stati svolti diversi incontri di confronto e coordinamento con il personale ENEA. L’oggetto dell’accordo di collaborazione è sviluppato in due fasi. Nella prima fase, che costituisce l’argomento del presente rapporto, si è sviluppata una analisi della caratterizzazione delle architetture di microrete. In particolare, sono state analizzate e commentate le strutture di rete di distribuzione attualmente utilizzate e la loro specificità in relazione alla penetrazione delle tecnologie in uso nelle microreti. La prima fase delle attività riporta altresì una rassegna dei sistemi di poligenerazione che sono presenti in tali sistemi elettrici ed affronta il problema della modellazione di tali sorgenti all’interno delle microreti. Quest’ultimo tema è strettamente legato al livello al quale vengono sviluppate le logiche di controllo di cui si tratta nel presente accordo di collaborazione che riguardano per lo più la regolazione terziaria, cui maggiormente viene affidato il compito di mantenere una buona efficienza energetica del sistema. La descrizione dei vari livelli a cui può esplicarsi il controllo e la rappresentazione delle relative architetture è ancora oggetto della prima fase delle attività. La seconda parte delle attività è invece dedicata alla implementazione della logica di controllo con una particolare attenzione al software che dovrebbe sovrintendere alla gestione energeticamente efficiente dei sistemi individuati. Dopo una esaustiva rassegna che riporta lo stato dell’arte sull’argomento della gestione energeticamente efficiente delle microreti, sono rappresentati gli obiettivi che si vogliono conseguire e le variabili sulle quali si può intervenire. Successivamente, viene dato ampio spazio alle tecniche di soluzione di tali problemi in relazione alle soluzioni tecnologiche considerate. Le tecniche di soluzione tengono conto del problema della incertezza legato alla previsione tanto dei prelievi da parte degli utenti quanto delle grandezze metereologiche su un orizzonte temporale di diverse ore.

This work develops a new approach for optimal energy management of electrical distribution ‘smart-grids’. Optimality aims at improving sustainability through the minimization of carbon emissions and atreducing production costs and maximizing quality. Input data are the forecasted loads and productionsfrom renewable generation units, output data are a set of control actions for the actuators. Theconsidered electrical distribution system includes storage units that must be considered over a 24 h timeinterval, to consider an entire charge and discharge cycle. The objectives for the optimal management ofdistributed (renewables and not) generation are technical, economical and environmental. It is thusrequired to solve a multi-objective optimization problem over a 24 h time interval considering theuncertainty associated to weather conditions and loads profiles. The novelty of the proposed approachresides in considering the optimal scheduling of generation units an automatic planning process ina dynamic, non-deterministic and not fully observable environment, as it is, getting closer to actualconditions. The system proposed here is a planning and execution scheduler which allows the centralcontroller to monitor the execution of a scheduling plan, interrupt the monitoring to input new infor-mation and repair the plan under execution every time interval. 2011 Elsevier Ltd. All rights reserved.

Modern distribution systems are implemented through micro grids: small power networks where generation is close to consumption and ICT supports the coordinated management of the different energy resources. In such systems, the central control unit manages energy dispatch from the different sources according to different criteria (technical, economical and environmental) and takes care of tertiary regulation. Such optimization for the tertiary regulation is performed with a time interval that typically is of 24 hours. This is due to the fact that it is necessary to take into account the charge and discharge cycles of storage systems. On the other hand, such long time leads to large errors in the prediction of energy generation and consumption. In this paper an algorithmic approach allows to overcome this problem. It is indeed possible to integrate uncertainty within the problem formulation attaining a dispatch plan for all the energy sources that will not lead to constraints violations even if the objective function's variables and parameters are affected by uncertainty. The results on a medium size system show the ease and effectiveness of the proposed approach.

A high level of power quality in distribution networks is obtained by means of a diagnostic software, that on-line assesses the status of the network, by elaborating the measured data. An efficient telecommunication system is thus necessary. Upon occurrence of a fault the reliability of the distribution system depends on the security of the timely protective and restorative actions on the network. In this paper, after a brief examination of the diagnostic method, the telecommunication system is examined. For this purpose, the WiFi telecommunication system has been considered the most suitable due to its economy, although it is not adequately reliable for how it is managed by the IEEE 802.11 protocol. In this work, a new protocol derived by a modification of the IEEE 802.11 is described; the improvements which it introduces are highlighted and its capability for the diagnostic service is verified in the application section.

The paper presents a new methodology for fault identification and location in electrical distribution systems, based on the use of a lumped parameter representation of the faulted line and on a matrix approach. Utilities are quite interested in such items, since the new required quality standards put severe constraints on faults management and clearance.

La caratterizzazione elettromagnetica del comportamento dinamico di elettrodi interrati, disperdenti elevate correnti impulsive, costituisce uno degli aspetti primari nella progettazione di un sistema di protezione dalle fulminazioni atmosferiche (LPS). D’altra parte, elevate correnti impulsive possono causare l’insorgere di fenomeni di ionizzazione del terreno, nelle zone prossime agli elettrodi interrati, nei punti in cui il campo elettrico totale supera il valore critico. Modelli teorici e misure sperimentali correlano l’insorgere di variazioni di conducibilità del terreno in prossimità di elettrodi interrati interessati da elevate correnti impulsive al fenomeno della ionizzazione del terreno stesso. La modellizzazione portata avanti dai ricercatori dell’unità si inquadra nell’ambito dello studio della ionizzazione diffusa ed è basata sull’implementazione mediante il metodo delle differenze finite nel dominio del tempo (FDTD) di un modello del terreno a conducibilità variabile.

Simple compact models for combined overhead-cable lines supplying a substation are presented as an extension of a previous paper for grounding system analysis. The overhead line section can be equipped with uniform or combined ground wires, whereas the cable line section can consist of coated metal sheathed cables, with/without intermediate grounding, or uncoated metal sheathed cables in continuous contact with the earth. Besides the calculation of the earth current at the faulted substation, the proposed modeling method allows the evaluation of the leakage current at the transition station, where cables are connected to the overhead line, as well as at critical overhead line towers. In this manner, the effects of the so called ldquofault application transferrdquo phenomenon can be conveniently estimated at the design stage in order to assess the most appropriate safety conditions. Some numerical examples are given by applying a computer program based on the proposed methodology.

The paper introduces a methodology that through a probabilistic characterisation of load for MV network, and implementing a life model for combined electric and thermal stresses, simulates the process of ageing of the insulating materials evaluating the expected life time of the cable. Such evaluation is necessary to the possibility of assuming less restrictive thermal overloading limits on electrical cables, with the consequential increase on reserve that cables could offer. A numerical example is reported to better explain the methodology

The start of the electrical energy market has encouraged distributors to make new investments at distribution level so as to attain higher quality levels. The service continuity is one of the aspects of greater importance in the definition of the quality of the electrical energy. For this reason, the research in the field of fault diagnostic for distribution systems is spreading ever more. This paper presents a novel methodology to identify, locate and characterize the faulty events in the electrical distribution systems. The methodology can be extended to all types of faulty events and is applicable to reconfigurable systems. After having described the guidelines of the methodology, the Authors describe the architecture of the diagnostic control system implementing the analytic procedure. Finally the results of some relevant applications are reported.

PurposeIdentify a new methodology for fault characterization, identification and location in electrical distribution systems, based on the use of matrix algebra.Design/methodology/approachThe developed diagnostic methodology is based on a high precision analytical model of the network using a distributed parameters representation.FindingsTest results have proved the approach to be efficient and precise, while providing a generalized quadripolar model of a line affected by the most common kinds of fault.Research limitations/implicationsGeneralization to a greater number of fault cases, experimental tests.Practical implicationsUtilities are quite interested in such items, since the new required quality standards put severe constraints on faults management and clearance. On the other hand, the system requires a rather complete measurement equipment of secondary substations.Originality/valueThe paper presents a new diagnostic technique for faults identification, location and characterization in distribution systems.

—In this paper, the semi-orthogonal compactly sup- ported spline wavelets are used as basis functions for the efficient solution of the thin-wire electric field integral equation (EFIE) in frequency domain. The method of moments (MoM) is used via the Galerkin procedure. Conventional MoM directly applied to the EFIE, leads to dense matrix which often becomes computation- ally intractable when large-scale problems are approached. To overcome these difficulties, wavelets can be used as a basis set so obtaining the generation of a sparse matrix; this is due to the local supports and the vanishing moments properties of the wavelets. In the paper, this technique is applied to analyze electromagnetic transients in a lightning protection systems schematized as a thin-wire structure. The study is carried out in frequency domain; a discrete fast Fourier transform algorithm can be used to compute time profiles of the electromagnetic interesting quantities. The unknown longitudinal currents are expressed by using multiscale wavelet expansions. Thus, the thin-wire EFIE is converted into a matrix equation by the Galerkin method. Results for linear spline wavelets along with their comparison with conventional MoM that uses triangular basis functions and the point matching procedure are presented, for two case studies. Good agreement has been reached with a strong reduction of the computational complexity.

The paper illustrates the interventions for improving security of a WiFi communication system applied in the automatic management of a Medium Voltage network. The management system fails if the data measured at the secondary substations can’t flow regularly. In this paper the security of the transmission as function of the action range of the radio channel, on the data sending time of the IEEE 802.11 protocol, and of the out of use of a WiFi node. Then, a modified IEEE 802.11 protocol is described, for making secure the transmission in presence of a high number of WiFI nodes. Finally, a probabilistic analysis in presented for analyzing the problem from an economical point of view.

A high level of power quality in distribution networks is obtained by means of a diagnostic software, that establishes on-line the status of the network, by elaborating the measured data. An efficient telecommunication system is necessary, from whose reliability depends the security of the timely interventions on the network in case of fault. In the paper, after a brief examination of the diagnostic method, the telecommunication system is examined. The WiFi system has been considered most suitable, for its economy, for the diagnostic service, besides it is not suitably reliable for how it is managed by the IEEE 802.11 protocol for this application. In this work a new protocol derived by the existing IEEE 802.11 is described, highlighting the improvements that it introduces and verifying its capability for the diagnostic service. An application shows its potentiality