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

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 s…

Currents Distribution During a Fault in an MV Network: Methods and Measurements

When a single line to ground fault happens on the MV side of a HV/MV system, only a small portion of the fault current is injected into the ground by the ground-grid of the faulty substation. In fact the fault current is distributed between grounding electrodes and MV cables sheaths. In systems with isolated neutral or with resonant earthing this may be sufficient to provide safety from electric shock. Experimental measurements were performed on a real MV distribution network: a real single line to ground fault was made and fault currents were measured in the faulty substation and in four neighboring substations. In this paper the problem of fault current distribution is introduced, the tes…

Partial Discharge on-line measures in cable's EPR insulation

In this paper, an experimental study, carried out on an operating MV cable, is presented. The aim is to identify, locate and characterize defects in the cable's EPR (ethylene-propylene copolymer rubber) insulation. Direct partial discharge measurements have been compared to those obtained by high frequency electromagnetic field measures. The latter have been carried out using a sensor which does not require any galvanic connection with the system under test and that performs an intrinsic localization of the defect. Moreover, an analysis of an MV cable junction has been carried out using the same tools.

Sulla sincronizzazione delle misure wireless di scariche parziali con il segnale di tensione a 50 Hz

L’articolo descrive i vari aspetti dei sistemi di misura wireless delle scariche parziali (PD). In particolare, sul problema della sincronizzazione dell’angolo di fase della tensione per il rilevamento e la classificazione delle PD.

A Montecarlo Approach for a Study on the Impact of the domestic installation of Small PV and Thermal Solar Systems on the grid

Green Data Centres providing ancillary services to power grid

This work investigates the possibility for a Data Centre to provide services to the Grid. In particular, the paper simulates a sudden shift of frequency because of a power decrease and estimates how a real-life Data Centre can contribute the secondary frequency regulation.

FENOMENI DI INTERFERENZA TRA ELETTRODI DI IMPIANTI DI TERRA INTERCONNESSI

Comparison between Different Dynamic Reconfigurations of Electrical Connections for partially shaded PV Modules

This paper presents an economical investigation on the benefits related to the employment of reconfiguration systems for photovoltaic plants. More in detail, different structures of reconfigurators are proposed and, in order to evaluate the economical convenience on their installation, the Net Present Value is used as a validation element. Significant results are carried out from the proposed analysis.

An architecture Wi-fi and GPRS for efficient management of distribution electrical networks

In this paper, a telecommunication infrastructure for faults management is proposed. The complete automation of the electrical energy distribution requires the implementation of suitable data transmission systems able to easily interface with microprocessor based systems and to handle large amount of data. In particular, reliability and speed of the data transmission system are required in the fault diagnosis and post-fault management procedures, in order to guarantee high quality standards. The proposed diagnostic system indeed works by means of a set of intercommunicating MV/LV dasiaintelligent substationspsila. In this paper, after a brief description of the fault diagnostic system, an o…

A Multi-Port Approach to Solve Distribution Networks with Meshes and PV Nodes

A new methodology based on the backward/forward (b/f) technique for the load flow solution in distribution systems is here proposed. The methodology takes efficiently into account the fixed voltage nodes and uses a reduced bus impedance matrix. In this way, it is possible to attain, for the unknowns at the PV nodes, the same values that are attainable solving the network with the methods adopted for transmission systems. With the same methodology it is possible to take into account also the meshes. If the network contains only meshes, the relevant model is linear and it is the one including the compensation currents. The presence of PV nodes introduces non linearity in the model and an iter…

Studio di fattibilità e progettazione preliminare di dimostratori di reti elettriche di distribuzione per la transizione verso reti attive. Report 2 – Simulazioni e valutazioni di progetto per gli scenari selezionati

The Role of Technology in Participative Processes

Smart city is more and more, in the common feeling, the crossroad of technologies, but first and foremost, the place where humans, contexts and technologies meet and must interact. Technological systems thanks to the deep human interaction acquire an uncertain behaviour that can be hardly modelled and controlled. The resulting complexity, cannot be easily handled with the tools that are available to separate scientific fields. The interdisciplinarity that comes from the implementation of technologies and the dialogue between these and the territories requires new tools for classification and design. New urban design tools are needed allowing to identify in a standardized way adequate suppor…

New dispatching strategy for the integration of active-demand and distributed storage in the electricity market

The proliferation of Distributed Generation (DG) in power systems calls for a redesign of electricity network management, which should be able to accommodate large amounts of intermittent generation. This issue requires a discussion about the current dispatching regulation, giving distributed storage systems and qualified electricity consumption the opportunity to provide ancillary services to the distribution grid. In this work, a new dispatching strategy for the integration of active-demand and distributed storage in the Italian electricity market is presented. The strategy is focused on a distribution Smart Grid (SG), where customers can indirectly participate to the Day-Ahead (DA) and t…

Il PAES di Palermo: azioni ed interventi di una città in divenire CITTA' COME MOTORE DI SVILUPPO DEL PAESE - The Sustainable energy action plan of Palermo: actions and measures for a city in transformation

Il Patto dei Sindaci costituisce la cornice europea per coinvolgere attivamente le città nella strategia verso la sostenibilità energetica e ambientale. L’iniziativa, lanciata nel 2008 nell’ambito della seconda edizione della Settimana europea dell’energia sostenibile, ha portato all’adesione di oltre 1600 città tra cui 20 capitali europee e numerose città di paesi non membri dell’UE, con una mobilitazione di oltre 140 milioni di cittadini. Il Patto allo stato attuale si colloca tra i principali strumenti di sviluppo sul territorio nazionale dei principi di sostenibilità urbana, portando come valore aggiunto il merito di poter essere motore per il rilancio dell’economia e dell’immagine di m…

Energy self-consumers and renewable energy communities in Italy: New actors of the electric power systems

Abstract The new European Directive RED-II on the promotion of the use of renewable energy sources has introduced the concept of the Renewable Energy Community. This new entity has the potential to change the relations among end-users and the latter and the other actors of the energy sector. In particular, the electrical sector appears the most influenced by the implementation of this paradigm. Indeed, the need for self-consumption and for exploiting the full potential of renewable energy in a Renewable Energy Community influences how the end-users exchange energy with the power grid, the rules for their connection to the grid, the implementation of Demand Response and other energy manageme…

An integrated platform for electrical modeling of microgrids

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…

Magnetic Levitation – Modelling, Identification and Open Loop Verification

<p>The paper describes a procedure using the first principle modelling and experimental identification of the Magnetic Levitation Model CE 152. It is a modified version of the paper [1]. The difference is that the identification and verification is done in open loop and constraints logic is added in the current paper. The author optimized and simplified dynamic model to a minimum to what is needed to characterize given system for the simulation and control design purposes. Only few open-loop experiments are needed to estimate the unknown parameters. Model quality is verified in open loop where the real and simulated data are compared. The model can serve as a simulation model for some…

Challenges and directions for Blockchain technology applied to Demand Response and Vehicle-to-Grid scenarios

Abstract Nowadays, Blockchain is considered a consolidated technology supporting many different applications that integrate well with Artificial Intelligence and the Internet of Things, and supports the creation of Decentralized Autonomous Organizations. Within this wider framework, the energy blockchain applications are now deserving more and more attention, since blockchain architectures, on one hand, provide transparency and solve the information asymmetry problem, on the other, provide disintermediation. In this way, the dream of an energy market closer to end-users becomes a reality, although, still, the regulatory framework is not clear, especially for what concerns the tokenization o…

Transition of a Distribution System towards an Active Network. Part I: Preliminary Design and Scenario Perspectives

In an European perspective, the focus of Smart Grids initiatives (SET Plan - Strategic Energy Technology Plan) is strictly linked with the main commitment to achieve the goals of the Climate and Energy Package 20-20-20, at the light of the three main pillars of the European energy policy: competitiveness, sustainability and security of supply. Smart grid technologies will enable load levelling of the electrical grid, allowing a power company to run cleaner power sources - such as hydroelectric, wind, or solar - while reducing the need to use carbon-emitting gas, coal, or oil plants to meet peak demand. In this framework the proposed paper refers about the technical economical feasibility st…

Comparing the Impact of Electric Vehicles on Urban and Insular Networks

Transport sector is moving towards clean and green transportation with the growing market of electric vehicles globally. Electric vehicles are independent fossil fuels consumption, but the massive adoption of electric vehicles soon can lead to a significant burden on the power distribution networks. In this paper, a study on the potential impact of electric vehicles on the power distribution networks of two different regions with totally different realities of population density, an average number of cars per inhabitant, and travel habits has been carried out. The first region is the island of Favignana having an insular power distribution network, while the other region, the city of Palerm…

Proof of Concept of an Irradiance Estimation System for Reconfigurable Photovoltaic Arrays

In order to reduce the mismatch effect caused by non-uniform shadows in PV arrays, reconfigurable interconnections approaches have been recently proposed in the literature. These systems usually require the knowledge of the solar radiation affecting every solar module. The aim of this work is to evaluate the effectiveness of three irradiance estimation approaches in order to define which can be well suited for reconfigurable PV arrays. It is presented a real-time solar irradiance estimation device (IrradEst), implementing the three different estimation methods. The proposed system is based on mathematical models of PV modules enabling to estimate irradiation values by sensing a combination …

The Identification of Single Phase to Earth Faults in Overhead Lines of Electrical Power Distribution Systems

Service continuity is one of the aspects of greater importance in the definition of the quality of electrical energy. After the electrical energy market liberalization, distributors have moved towards new investments in research, first of all in the field of faults diagnostic. The Authors have already studied the problem of the service continuity and this paper represents the development of the research carried out in the field. The paper presents the extension, to overhead distribution lines, of the new diagnostic approach to identify, locate and characterize the faulty events, made up by the Authors. The proposed methodology must be integrated in an electrical distribution networks manage…

A Test Bench for a Blockchain-based Management of Smart Prosumers' Flexibility

To date, the European regulatory framework requires the development of new energy policies at the national level that can reduce overall consumption and support the implementation of customer-focused control and management systems. Therefore, it is necessary to study the feasibility of the various strategies available, especially for the involvement of residential users in services that can contribute to the management of the electricity grid. The advent of blockchain technology has enabled the development of new business models for the electricity market, opening this world to end users who previously did not have the opportunity to participate in energy trading and allowing the implementa…

Evolving non-dominated solutions in multiobjective service restoration for automated distribution networks

Abstract The problem here dealt with is that of Service Restoration (SR) in automated distribution networks. In such networks, configuration and compensation level as well as loads insertion status can be remotely controlled. The considered SR problem should be handled using Multiobjective Optimization, MO, techniques since its solution requires a compromise between different criteria. In the adopted formulation, these criteria are the supply of the highest number of loads and the minimum power losses. The Authors propose a new MO approach, the Non-dominated Sorting Fuzzy Evolution Strategy, NS_FES, which uses part of the Non-dominated Sorting Genetic Algorithm, NSGA, proposed by K. Deb. Th…

Un package di ottimizzazione per la riconfigurazione delle reti elettriche di distribuzione

Load modelling influence on voltage stability assessment in distribution systems. Part I: Stability index and critical power for a single-line system

The single-line equivalent model is commonly used for voltage stability studies in both distribution and transmission systems. Referring to a single-line system, in the companion paper [1] the authors presented the theoretical aspects of voltage stability related to the load characteristics. In particular, expressions of the stability index for constant power, constant impedance and constant current loads, singularly and in all the possible combinations have been obtained. This index indicates how far the load node is from its voltage collapse point, allowing the maximum load power beyond which voltage collapse takes place to be evaluated. In this paper a simple method to evaluate the param…

Ancillary Services in the Energy Blockchain for Microgrids

The energy blockchain is a distributed Internet protocol for energy transactions between nodes of a power system. Recent applications of the energy blockchain in microgrids only consider the energy transactions between peers without considering the technical issues that can arise, especially when the system is islanded. One contribution of the paper is, thus, to depict a comprehensive framework of the technical and economic management of microgrids in the blockchain era, considering, for the first time, the provision of ancillary services and, in particular, of the voltage regulation service. When more PV nodes are operating in the grid, large reactive power flows may appear in the branches…

Demand Response Service Certification and Customer Baseline Evaluation Using Blockchain Technology

The use of Distributed Ledger Technologies such as Blockchain for certifying Demand Response services allows for the creation of a distributed system in which customers can communicate with the system operator to provide their flexibility, in a secure, transparent and traceable way. Blockchain technology also supports incentive mechanisms for users taking part in the service through the generation of utility tokens to recognize the user's contribution. This paper presents the experimental test of a novel methodology for Demand Response programs implementation by using the Blockchain technology. The latter is employed for defining a distributed Demand Response service and a new system for it…

Blockchain review for battery supply chain monitoring and battery trading

The use of technologies such as Internet of Things (IoT), data processing and blockchain have allowed companies to serve their customers with better quality, efficiency, reliability and in the shortest possible time. The growing adoption of electric vehicles on the market has increased the demand for batteries that may have numerous manufacturers. Life expectancy is affected on manufacture, but also on operational conditions. A large number of parameters have a role on battery's health and thousands of data need to be evaluated and combined. The present work investigates the scenario of the battery industry in order to implement a blockchain-based platform for the supply chain implementatio…

Wave and Wind Energy Systems Integration in Vietnam: Analysis of Energy Potential and Economic Feasibility

Vietnam energy demand is currently growing at a very high annual rate, with the government being very interested in investments in renewable energies. Since the region with the highest solar and wind potential is far away from the big load centers, an investigation of offshore energy resources is here proposed. In this study, a review of previous energy potential assessments is provided. Moreover, the minimum feed-in-tariff to make the investments profitable is evaluated, showing that the current tariff for offshore wind plants is largely unattractive.

A Blockchain-based Platform for Positive Energy Districts

The reduction of climate change effects (mitigation) is now mainly driven by the limitation of CO2 emissions which is currently becoming increasingly necessary and urgent to achieve. In this context, within the past Horizon 2020 program, the Urban Europe Joint Programming Initiative aimed to promote the development and deployment of at least 100 Positive Energy Districts by 2025. The latter are flexible, energy-efficient urban areas or groups of buildings that produce zero net CO2 emissions and actively manage annual renewable energy surplus production at the local or regional level. As they are connected to the electric power system, Positive Energy Districts have the ability to offer flex…

A review on optimization and cost-optimal methodologies in low-energy buildings design and environmental considerations

Abstract The topic of low-energy buildings received a widespread and growing interest in last years, thanks to energy saving policies of developed countries. The design of a low-energy building is addressed with energy saving measures and renewable energy generation, but the correct assessment of phenomena occurring in a building usually requires to perform dynamic simulations and to analyze multiple scenarios to attain the optimal solution. The optimality of a technical solution may be subject to contrasting constraints and objectives. For this reason, designers may employ mathematical optimization techniques, a non-familiar topic to most of building designers. In this paper, a review on o…

A review of health assessment techniques for distribution transformers in smart distribution grids

Due to the large number of distribution transformers in the distribution grid, the status of distribution transformers plays an important role in ensuring the safe and reliable operation of the these grids. To evaluate the distribution transformer health, many assessment techniques have been studied and developed. These tools will support the transformer operators in predicting the status of the distribution transformer and responding effectively. This paper will review the literature in the area, analyze the latest techniques as well as highlight the advantages and disadvantages of current methodologies.

DOUBLE EARTH FAULT EFFECTS IN PRESENCE OF INTERCONNECTED EARTH ELECTRODES

The paper presents a study on the effects of double earth faults in Medium Voltage (MV) networks, in presence of electrical interconnection of the earthing systems of the secondary substations. In urban areas, indeed, the earth electrodes of the secondary substations are interconnected and, in many cases, they are also connected to the earth electrodes of the primary stations, in order to realize quasi-equipotential surfaces, intrinsically safe against electric shocks, named Global Earthing Systems (GES). The concept of GES has been introduced in the technical literature ten years ago in the Document HD 637 S1 by CENELEC, with the aim of providing a solution to the problems of designing and…

A New Crowded Comparison Operator in Constrained Multiobjective Optimization for Capacitors Sizing and Siting in Electrical Distribution Systems

This paper presents a new Crowded Comparison Operator (CCO) for NSGA-II to solve the Multiobjective and constrained problem of optimal capacitors placement in electrical distribution systems.

Strategie e scenari di aggregazione delle risorse distribuite nel mercato elettrico

L’articolo espone una modalità per ampliare la base di partecipazione di soggetti connessi alla rete elettrica (aggregatori di carico, sistemi di accumulo distribuiti, ecc.) ai mercati dei servizi già regolamentati, sfruttando opportune azioni di controllo di tipo Demand Response.

On multi-objective optimal reconfiguration of MV networks in presence of different grounding

The present work faces the traditional multi-objective optimal reconfiguration problem of a distribution grid including the safety issue in the objective functions. Actually, in many medium voltage networks still transformers with ungrounded neutral and with resonant grounded neutral coexist in the same area. This may be sometimes cause of problems during a single-line-to-ground fault if the ground electrodes of one or more cabins, initially designed for satisfying the safety conditions in a resonant grounded neutral network, after the reconfiguration are in a grounded neutral one or vice versa. In the paper a safety objective function is defined and the Non dominated Sorting Genetic Algori…

Some improvements in solving radial distributions networks through the backward/forward method

In the electrical radial distribution networks analysis, the backward/forward method shows good features in terms of robustness, independence from load nature, small use of hardware resources and limited calculation time. In the present paper, some procedures to improve the b/f method with the aim of reducing the calculation time are presented. The adopted procedures regard the choice of the initial values of the nodes voltages and the way in which the convergence criterion is applied. The results of some tests carried out on some electrical test systems here reported have shown the efficiency of the proposed methodology in terms of calculation time reduction, especially when solving heavil…

Managing electrical energy storage systems and shiftable loads with an innovative approach in energy districts

In this work, a power dispatch problem for a system composed of an aggregate of loads and an electrical energy storage system is considered. The approach to solve the optimal dispatch is innovative and shows good performances in limited calculation times. According to the more recent indications coming from the European distributors, the architecture for energy dispatch at distribution level will be hierarchical. The 'Aggregator' is the interface between groups of loads and the energy distributor and sends the individual consumers the desired load profiles, following which the user may gets a discount on the energy bill. On the other hand, the energy tariff may follow a given daily profile …

Technical, Environmental and Economical Aspects of Hybrid Systems Including Renewables and Fuel Cells

In this paper, some configurations including renewables and fuel cells are studied. Technical, environmental and economical aspects are treated in the frame of the EU regulations concerning the ‘emission trading’ issue and the way in which Italy has implemented the relevant EU directive. The study has been carried out considering some architectures including renewables such as photovoltaic and wind with a back up system to increase continuity of supply based on the application of fuel cells and of a hydrogen storage system. Performing several runs with different values of the cost of energy (COE) bought from the network and produced with traditional fuel, it has been observed that, for some…

Space charge behavior of different insulating materials employed in AC and DC cable systems

In this work, the space charge accumulation in three different XLPE based material has been carried out by using the PEA (Pulsed Electro-Acoustic) method. The specimens provided by a cables industry have been subjected to the same DC stress during polarization time at environment temperature. Afterwards, the high voltage generator has been turned off and the amount residual charge has been evaluated. The space charge profiles during polarization and depolarization have been carried out and compared. Finally, the distribution of electric field within the samples has been reported. In particular, the maximum distortion of electric field has been calculated by taking into account the distribut…

Optimal Operating Point Calculation for Medium Voltage Distribution Systems

The paper deals with the calculation of the optimal working point of a distribution system, equipped with several distributed generators, able to operate also autonomously, i.e. disconnected from the main grid. When connected to the main grid, it appears in general convenient to assign the slack bus role to the bus that represents such a connection. The problem becomes more complex when maximum power transfer constraints through the connection must be taken into account. The adequate slack bus treatment is even more important when the optimal operating condition must refer to the condition subsequent to an intentional or unintentional disconnection from the main grid. The paper presents an …

ANALYSIS OF IMPACTS ON ELECTRIC POWER SYSTEM OPERATION OF LOAD MANAGEMENT IN RESIDENTIAL AND TERTIARY BUILDINGS

Load management includes all the techniques, logics, actions and programs through which the electric utilities and the customers are able to manage loads absorption in a more prudent and efficient way; it determines economic benefits for the users, but also allows a network management and operation simpler and cheaper, determining technical and economic benefits. The present paper constitutes a detailed study of interventions and techniques to control demand in the residential and tertiary sectors and the effects that these actions have on the entire electrical system and its management. It discusses the implications of such control actions in terms of reduction of network losses and relate…

An optimized diagnostic architecture for real-time monitoring of MV networks

Due to the electrical energy market liberalization, the Authority for electrical energy and gas (AEEG) in Italy and the other regulatory organizations in other European countries have concentrated their attention on the quality of the electrical service. One of the aspect of major importance in the definition of the quality of a public service is its continuity. In the aim of regulating this field the Authority has defined some continuity indicators, for example the number of interruptions per year and the cumulate duration of the interruptions per year. Recent statistics on these indicator show that the 80% of the number of interruptions in one year is caused by MV network. For this reason…

Smart renewable generation for an islanded system. Technical and economic issues of future scenarios

The subject addressed in this paper is the analytical study of the transition of an energy generation system for a real MV/LV distribution system from one that is “fuel-based” to a distributed and smart “renewables-based” system. The paper outlines both the technical and the economic issues related to such a transition from one type of system to the other. The study is carried out for a real islanded network located in the Island of Pantelleria (Mediterranean Sea). The results obtained are presented and discussed, putting into evidence the technical, environmental and economic benefits of using smart technologies and renewable energy sources.

Optimization of photovoltaic energy production through an efficient switching matrix

This work presents a preliminary study on the implementation of a new system for power output maximization of photovoltaic generators under non-homogeneous conditions. The study evaluates the performance of an efficient switching matrix and the relevant automatic reconfiguration control algorithms. The switching matrix is installed between the PV generator and the inverter, allowing a large number of possible module configurations. PV generator, switching matrix and the intelligent controller have been simulated in Simulink. The proposed reconfiguration system improved the energy extracted by the PV generator under non-uniform solar irradiation conditions. Short calculation times of the pro…

A Comparison of Special Bonding Techniques for Transmission and Distribution Cables under Normal and Fault Conditions

In this article, a review of the existing special bonding techniques for medium voltage and high-voltage cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The literature review shows various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of each technique are performed in MATLAB/Simulink, to compare their strengths and drawbacks both under normal conditions and in the presence of a single-line-to-ground fault.

The Industrial Applicability of PEA Space Charge Measurements, for Performance Optimization of HVDC Power Cables

Cable manufacturing industries are constantly trying to improve the electrical performance of power cables. During the years, it was found that one of the most relevant degradation factors influencing the cable lifetime is the presence of space charge in the insulation layer. To detect the accumulated charge, the pulsed electro-acoustic (PEA) method is the most used technique. Despite the wide use of the PEA cell, several issues are still present. In particular, the PEA output signal is strongly disturbed by the acoustic waves reflections within the PEA cell. This causes the distortion of the output signal and therefore the misinterpretation of the charge profiles. This, in turn, may result…

A generalized methodology for distribution systems faults identification, location and characterization

Service continuity is of basic importance in the definition of the quality of the electrical energy, for this reason, the research in the field of faults diagnostic for distribution systems is spreading ever more. In this paper, a new methodology for diagnostic management of automated distribution systems is presented. The technique is based on the solution of a circuital model of the electrical system resulting from the composition of distributed parameters quadripoles. The solution gives as a result the identification of the type of fault, of its characteristic parameters and location. The paper shows an application to line to line grounded and ungrounded faults in which also its precisio…

Simplified Energy Model and Multi-Objective Energy Consumption Optimization of a Residential House

Featured Application: The potential application of the proposed model is a computationally inexpensive semi- or fully automated system for the optimization of operation in residential buildings in terms of energy consumption. Some analyses state that buildings contribute to overall energy consumption by 20–40%, which, in the context of the recent geopolitical energy crisis, makes them a critical issue to study. Finding solutions for better energy management in buildings can have a significant impact on the energy sector, thus reducing EU energy dependencies and contributing to the fulfillment of the REPowerEU goals. This paper focuses on proposing a simplified model of a residential house c…

An Efficient Procedure for Solving Radial Distribution Networks through the Backward/Forward Method

In the paper, after having presented the general backward/forward methodology for radial systems analysis, a new b/f procedure showing some interesting features that improve its performance in terms of convergence speed and calculation effort is presented. The features that fundamentally are responsible for such improvements concern the main steps of the b/f procedure. The starting voltage profile solution is different from the flat profile and is suitably modified. In the backward phase and starting from the second iteration, the branch currents variations due to the loads changes are evaluated; the latter variations are calculated on the basis of the difference of nodal voltages at the be…

Technical and Economical Analysis of Different Measures for Efficient Operation of a Distribution Network in a Mediterranean Island

The paper performs a technical and economical comparison of different measures to improve the efficiency of a MV system for power distribution in the Mediterranean island of Lampedusa. The study takes into consideration three possible measures: 1) rated voltage increase from 10 kV to 20 kV; 2) reactive power compensation with fixed capacitor banks; 3) reactive power compensation with switchable capacitor banks. While the study of the first two considered measures is carried out with classical design methods, the optimal reactive design with switchable capacitor banks is carried out by means of a specific software set up at the DIEET and implementing the multiobjective optimization genetic a…

Heuristic-Based Shiftable Loads Optimal Management in Smart Micro-Grids

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…

Smart rules for smart cities- Managing efficient cities in euromediterrenean countries

Modern cities require new and different codes, taking into account environmental and energy issues, pillars of the contemporary urban development. The existing urban communities are highly energy consuming systems, strongly contributing to greenhouse gas emissions. Contemporary cities cannot be thought of and defined as static systems, as they were in the past, with a few urban functions. ‘The Church, the square and the court, the marketplace and the government palace were in the past the places where the urban functions were taking place’ (E. Salzano ). Today, the reference frame has changed even due to the demographic increase more and more concentrated in the cities that are now large co…

An Algorithm for Optimal Sizing of BESS in Smart Islands Energy Communities: the Case of Pantelleria

Energy Communities (EC) are a promising solution to reduce both the carbon footprint and the impact of Renewable Energy Sources (RES) on the distribution grid. Based on a simple energy sharing principle, EC can be decisive in the next future energy transition of some problematic territories, like small islands not supplied by the main power grid. By integrating Battery Energy Storage Systems (BESS), it is possible to improve the EC performance. However, due to the still high BESSs unit prices, the goal of this work is to find the optimal size of BESSs, under various conditions, which combines the need to maximize shared energy and the possible revenue of EC actors. To set this multi-objecti…

Real-Time Minimization Power Losses by Driven Primary Regulation in Islanded Microgrids

Islanded microgrids are small networks that work independently from the main grid. The frequency and voltage in islanded microgrids are affected directly by the output power of distributed generators and power demand variations. In this work, a real-time driven primary regulation, which relies on optimized P-f droop coefficients, is proposed. In all operating conditions, it minimizes the power losses for islanded microgrids. The proposed configuration will allow the optimization modules to interact with each other and adjust parameters producing a suitable power sharing among generators. The methodology is tested based on a hardware-in-the-loop experimental set-up where distributed generato…

An algorithm for simulating end-user behaviour in a real time pricing market

The energy market has changed radically over the last decade, mainly due to an increased penetration of renewable energies. Now the end users have directly access to the energy market and can actively take part to the electricity market. Electricity customers can indeed modify their behavior through Demand Response, namely by means of pricing strategies that support a change in the end-users habits. This can be accomplished through a 'loads aggregator', a third party that collects the requests and signals for Active Demand-based services coming from the markets and the different actors of energy market. This paper describes a simulation framework to generate the simulated optimal behavior o…

Inter-area oscillations in the 500-kV Vietnamese power system

The paper presents the study of the 500-kV Vietnamese power system. The oscillatory response of the system is analyzed both with a modal analysis and a time domain analysis. The 500-kV system of Vietnam is modeled in details, including all the power plants with the corresponding regulators. The model is developed in collaboration with the Institute of Energy Science IES-VAST of Vietnam and it is validated with the data provided by the National Load Dispatch Centre (NLDC) of Vietnam. The simulation results reveal a clear identification of potential inter-area oscillations between North and South of the Country. A worsening of the observed phenomenon should be considered as possible, especial…

Hierarchical control with virtual resistance optimization for efficiency enhancement and State-of-Charge balancing in DC microgrids

This paper proposes a hierarchical control scheme which applies optimization method into DC microgrids in order to improve the system overall efficiency while considering the State-of-Charge (SoC) balancing at the same time. Primary droop controller, secondary voltage restoration controller and tertiary optimization tool formulate the complete hierarchical control system. Virtual resistances are taken as the decision variables for achieving the objective. simulation results are presented to verify the proposed approach.

Modelli e strategie per la definizione di strumenti software per la simulazione integrata di distretti energetici in ambiente dedicato

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 collaborazio…

Transition of a distribution system towards an active network. Part II: Economical analysis of selected scenario

This paper outlines the economical issues related to the transition of the energy generation for a real MV/LV distribution system from a ‘fuel based’ one to a distributed and smart ‘renewables based’ one. It is the prosecution of a companion paper, which addressed the technical issues connected to such transition. The study has been carried out by University of Palermo and ENEA (Italy), on a portion of real MV/LV distribution system of the research center ENEA of Casaccia (Rome, Italy). The analysis is carried out for a specific scenario chosen among those proposed in the companion paper.

Multi-Objective Building Envelope Optimization through a Life Cycle Assessment Approach

This work describes a methodology for the identification of the optimal features for the envelope of a residential building. The optimization process allows minimizing operating energy consumption, investment costs and life cycle energy and environmental embodied impacts. A dynamic model for the estimation of building energy consumption during its use phase has been employed, while literature data were adopted for embodied energy and global warming potential impacts. The considered variables refer to the envelope of the building, i.e. external walls and roof insulation and external walls thermal mass. The model was obtained combining EnergyPlus building energy simulator and MOBO, a versatil…

Considering safety issues in minimum losses reconfiguration for MV distribution networks

This paper offers a new perspective over the traditional problem of the multiobjective optimal reconfiguration of electrical distribution systems in regular working state. The issue is indeed here formulated including also safety issues. Indeed, dimensioning the earth electrodes of their own secondary substations, distribution companies take into account the probable future configurations of the network due to transformations of overhead lines into cable lines or realization of new lines. On the contrary, they do not consider that, during normal working conditions. the structure of the network can be modified for long periods as a consequence of reconfiguration manoeuvres, with differences …

Smart Cities Atlas Western and Eastern Intelligent Communities

The book discusses the concept of the smart city, and is based on a multi-service and multi-sectoral approach to urban planning, including various urban functions and the human capital of cities. The work is divided into three parts. The first is an introductory section which covers definitions, policies and tools used at European level for the development and classification of a smart city. The second presents a selection of examples of Western and Eastern communities, which experienced technologies and strategies that have made them smart. The third describes in detail the main three possible approaches (economical, technological and social) to the smart city concept which are the focus a…

A Model for Assessing the Magnitude and Distribution of Sheath Currents in Medium and High-Voltage Cable Lines

In this article, the authors discuss a simulation model to study the effect of cross-bonding of metallic sheaths, and/or nonmagnetic armors, of single-core medium- and high-voltage cables in the same circuit. In single-core cables, the resistive losses due to the induced circulating currents in cable sheaths or armors cause an increase of the cable temperature, which therefore reduces its ampacity. This is a serious issue affecting the distribution and transmission lines. In addition, the risk of electric shock due to induced voltages may be present if a person is in contact with the armor/sheath at its unbounded end. For these reasons, special bonding techniques of metal sheaths are employ…

Technical Rules for Connecting PV Systems to the Distribution Grid: A Critical Comparison of the Italian and Vietnamese Frameworks

In the last two decades, starting from the Kyoto protocol, decarbonization has promoted worldwide the rise of distributed generation from renewable energy sources. Currently, Vietnam is still showing a strong dependence on fossil fuels but with a great interest in investing in renewable, especially in photovoltaic (PV) systems. In this paper, the current Vietnamese technical and administrative framework for the connection of PV systems to the power grid is presented and critically compared to the Italian one, in order to define the bases for future cooperation in distributed generation and renewable sectors.

Distributed optimal power flow for islanded microgrids: An application to the Smart Polygeneration Microgrid of the Genoa University

In this work, the application of an original distributed optimal power flow method to test a microgrid in the Savona area, Italy is proposed. The microgrid shows different types of Distributed Energy Resources (DERs) and is connected to the main grid through a fixed power bus. Due to the high computational speed, the applied distributed Optimal Power Flow can be performed almost in real time, i.e. every 5 minutes or less. The operating solution found for generators, simply using local information, corresponds to a suboptimal condition with reduced losses, bus voltages and line currents within constrained intervals. The distributed optimization algorithm is iterative, but also fast. It is ba…

A mathematical approach for studying interconnected earthing systems inside MV networks

PurposeThe purpose of this paper is to define a new methodology for studying interconnected earthing system inside unearthed medium voltage (MV) networks.Design/methodology/approachThe developed methodology is based on the division of the MV network into simpler sub‐systems and its resolution using a multiport approach.FindingsThe methodology has been applied to various situations giving precious information on the behaviour of the interconnected earthing systems. The comparison between the results of the simulations and measurements done on a really existing network has shown that the methodology is able to provide accurate results.Research limitations/implicationsSome factors can influenc…

DEMAND Project: A Peak Load Shaving Strategy for End-User Consumers

Battery energy storage systems (BESS) are becoming increasingly widespread in modern power systems, thanks to the important benefits they can provide to the electricity grid. Indeed, BESS can be used in time shifting applications, storing energy during off-peak periods and discharging during peak times (when the cost of electricity is high). When BESS are used for peak shaving purposes, they also contribute to relieve peak demand charges, thus ensuring a saving for the consumers. This paper describes a peak load shaving strategy defined within the DEMAND project. The strategy is able to guarantee the flattest daily power diagram and the maximum benefit for the electricity consumers, reducin…

Atlante delle Smart cities

Forecasting energy output of a solar power plant in curtailment condition based on LSTM using P/GHI coefficient and validation in training process, a case study in Vietnam

This study presents how to improve the short-term forecast of photovoltaic plant's output power by applying the Long Short-Term Memory, LSTM, neural networks for industrial-scale solar power plants in Vietnam under possible curtailment operation. Since the actual output power does not correspond to the available power, new techniques (Global Horizontal Irradiance - GHI interval division, P/GHI factor addition (P - Power)) have been designed and applied for processing errors and missing data. The prediction model (LSTM network, structure of hidden layers, number of nodes) has been developed by the authors in a previous work. In this new version of the model, the training technique is improve…

Challenges and Opportunities for Renewable-Based Microgrids Integration in Vietnam

Vietnam is among the South-Asian regions the one that better supplies remote areas. However, many islands and remote areas are still not connected to the main grid and this fact jeopardizes their development, while forcing people to move to urban areas. With a high potential from renewable energy sources and a lot of islands, Vietnam has thus many favorable environmental features for developing the microgrids technology. In this chapter, a detailed analysis about opportunities and challenges for widespread deployment of microgrids technology in Vietnam is considered. Such analysis is based on the assessments of the potential from renewable energy sources in the country and of the national p…

Data Compensation with Gaussian Processes Regression: Application in Smart Building's Sensor Network

Data play an essential role in the optimal control of smart buildings’ operation, especially in building energy-management for the target of nearly zero buildings. The building monitoring system is in charge of collecting and managing building data. However, device imperfections and failures of the monitoring system are likely to produce low-quality data, such as data loss and inconsistent data, which then seriously affect the control quality of the buildings. This paper proposes a new approach based on Gaussian process regression for data-quality monitoring and sensor network data compensation in smart buildings. The proposed method is proven to effectively detect and compensate for low-qu…

Smart city and public lighting

The smart city is increasingly becoming a concept of reference for what concerns the planning and the spatial development of cities. The concept of smart city cannot be easily standardized. It is based on a multi-service and multi-sectorial planning regarding various urban functions (energy, mobility, waste, etc.) and places them under a common denominator: the use of advanced technologies for minimizing resources consumption and simultaneously increase the quality of life of the citizens. This paper aims to give an overview on the concept of smart city and outline what, at present, are the main intervention areas considered at European level. Then the paper focuses on the public lighting t…

Multiobjective ant colony search algorithm optimal electrical distribution system planning

A dynamic multiobjective, MO, algorithm based on the ant colony search, the multiobjective ant colony search algorithm, MOACS, is presented. The application domain is that of dynamic planning for electrical distribution systems. A time horizon of H years has been considered during which the distribution system are modified according to the new internal (loads) and external (market, reliability, power quality) requirements. In this scenario, the objectives the Authors consider most important for utilities in strategical planning are: the quality requirement connected to the decrease of the expected number of interruptions per year and customer, in the considered time frame, and the choice fo…

A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units

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.

Optimal Electrical Distribution Systems Reinforcement Planning Using Gas Micro Turbines by Dynamic Ant Colony Search Algorithm

Distribution systems management is becoming an increasingly complicated issue due to the introduction of new energy trading strategies and new technologies. In this paper, an optimal reinforcement strategy to provide reliable and economic service to customers in a given time frame is investigated. In the new deregulated energy market and considering the incentives coming from the political and economical fields, it is reasonable to consider distributed generation (DG) as a viable option for systems reinforcement. In the paper, the DG technology is considered as a possible solution for distribution systems capacity problems, along several years. Therefore, compound solutions comprising the i…

Flexibility Services to Minimize the Electricity Production from Fossil Fuels. A Case Study in a Mediterranean Small Island

The design of multi-carrier energy systems (MESs) has become increasingly important in the last decades, due to the need to move towards more efficient, flexible, and reliable power systems. In a MES, electricity, heating, cooling, water, and other resources interact at various levels, in order to get optimized operation. The aim of this study is to identify the optimal combination of components, their optimal sizes, and operating schedule allowing minimizing the annual cost for meeting the energy demand of Pantelleria, a Mediterranean island. Starting from the existing energy system (comprising diesel generators, desalination plant, freshwater storage, heat pumps, and domestic hot water st…

Earth resistance measurements in urban contexts: Problems and possible solutions

Both EN 50522 and IEEE Std. 81 propose the Fall of Potential Method (FPM) to carry out the measurement of the resistance to earth of an Earthing System (ES). However, in urban areas, the recommended distances between the ES and auxiliary electrodes are not easy to respect, due to the presence of buildings and tarmac. Moreover, unknown buried metallic parts, as well as the interconnection among the ESs made by the Distributor System Operator, could modify the earth potential profile of the area, affecting the measurement results. In this paper, the issues that could affect the measurement result if FPM is used in an urban context are presented. A parametric analysis, carried out with Comsol …

Technical and Economical Aspects on Integrated PV-UPS Systems

This paper shows a technical-economical analysis of a novel Uninterruptible Power Systems (UPS) configuration, in which the backup batteries would be replaced by a photovoltaic (PV) system. Many interesting technical and economical issues concerning the proposed configuration are discussed against the traditional UPS and backup batteries solution. Moreover the technical solutions concerning the proposed integrated system realized using a double conversion UPS are motivated. Finally the operating costs of the proposed integrated PV-UPS system and the classical system with UPS and batteries with different sizes, and as the back-up time varies, are also compared and interesting results have be…

Smart Cities and Municipal Building Regulation for Energy Efficiency

The “Smart Cities & Communities Initiative” of the Strategic Energy Technology Plan is the strategic European response to lead cities and regions to a carbon free future. In this contest energy efficiency in buildings has a crucial role and must be considered in a holistic approach to the urban planning. In order to implement the minimum requirements stated by the European Directive about the Energy Performance of Buildings, and in order to consider different planning layers with the view to a smart city planning, local regulations are a key factor aiming at sustainable territorial planning. This paper investigates the possibility to draft a basic structure of Municipal Building Regulat…

An Optimization Package for Electrical Distribution Network Reconfiguration

Multiobjective Ant Colony Search Algorithm for optimal electrical distribution system strategical planning

Green Data Centres integration in smart grids: New frontiers for ancillary service provision

Abstract The paper presents a study, conceived within the GEYSER FP7 co-funded European research project, on the ancillary services that Green Data Centres (GDCs) can provide, focusing, in particular, on spinning reserve. More in detail, the main contribution of the paper is to show how GDCs can be involved in the secondary frequency regulation process of a smart distribution grid, for contrasting the disturbing effects of unexpected variation of the energy production. With this aim, a real data centre, owned by Engineering S.p.A., is simulated as connected to the Medium Voltage IEEE 14-bus test grid where some RES-based generators are supposed to exist. Simulations are carried out in order…

Partial Discharges analysis and parameters identification by continuous Ant Colony Optimization

The technique of ant colony optimization has been employed in this paper to efficiently deal with the problem of parameters identification in partial discharge, PD, analysis. The latter is a continuous optimization problem. From the technical point of view the identification of these parameters allows the modeling of the phenomenon of Partial Discharges in dielectrics. In this way it is possible the early diagnosis of defects in Medium Voltage cable lines and components and thus it is possible to prevent possible outages and service interruptions. Analytically, the problem consists of finding the Weibull parameters of the Pulse Amplitude Distribution (PAD) distributions allowing the identif…

A load model for EV parking lots

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 …

Optimal power flow in islanded microgrids using a simple distributed algorithm

In this paper, the problem of distributed power losses minimization in islanded distribution systems is dealt with. The problem is formulated in a very simple manner and a solution is reached after a few iterations. The considered distribution system, a microgrid, will not need large bandwidth communication channels, since only closeby nodes will exchange information. The correction of generated active powers is possible by means of the active power losses partition concept that attributes a portion of the overall power losses in each branch to each generator. The experimental part shows the first results of the proposed method on an islanded microgrid. Simulation results of the distributed…

A comparative analysis of different methods of reactive power pricing

Load Flow Solution of radial distribution networks with ZI loads

In this paper, a methodology to solve radial distribution networks, with constant current and/or impedance loads, is proposed. The techniques currently available to solve such systems are based either on iterative methods or on the bus impedance matrix. The method developed is the extension of a technique that is valid to solve networks made of impedances with one supply point. The methodology can be applied to directly and rapidly solve large distribution systems in which the loads are modeled as constant current/impedance. It is also able to solve meshed systems having voltage-dependent loads, inside an iterative backward/forward method.

Earthing system’s design in presence of non-uniform soil

The authors propose a practical approach for facing the problem of the design of the earthing systems in two-layer soils. The approach is based on the calculation of an equivalent resistivity of the non-uniform soil through which the designer can treat this one as it was uniform. The purpose of the Authors is to provide an innovative simple method and some easy-to-use graphs for an easy earthing systems' design in two-layer soils.

Dynamic programming and Munkres algorithm for optimal photovoltaic arrays reconfiguration

Abstract In this paper, an original formulation of the control problem for optimal PV array reconfiguration, following a Total Cross Tied layout, is proposed. The formulation follows the well-known subset sum problem, which is a special case of the knapsack problem. The reconfiguration is a measure devoted to mitigate the mismatch effect and maximize the output power of small photovoltaic plants under non-homogeneous working conditions. Therefore, reconfiguration means changing the connections of the solar panels adaptively by a dynamic switching matrix. The control system implements an easy dynamic programming algorithm to change the switches layout. The use of the Munkres assignment metho…

FROM FUEL BASED GENERATION TO SMART RENEWABLE GENERATION: PRELIMINARY DESIGN FOR AN ISLANDED SYSTEM. PART II: SELECTION OF FUTURE SCENARIO AND ECONOMICAL ISSUES

The subject addressed in this paper is the analytical study of the transition of the energy generation system for a real MV/LV distribution system from a ‘fuel based’ one to a distributed and smart ‘renewables based’ one. The paper outlines the economical issues related to such transition from one type of system to the other and it is the prosecution of a companion work addressing the technical topics concerning this subject. The study is carried out for a real islanded MV/LV distribution network.

Composite laminates buckling optimization through Levy based Ant Colony Optimization

In this paper, the authors propose the use of the Levy probability distribution as leading mechanism for solutions differentiation in an efficient and bio-inspired optimization algorithm, ant colony optimization in continuous domains, ACOR. In the classical ACOR, new solutions are constructed starting from one solution, selected from an archive, where Gaussian distribution is used for parameter diversification. In the proposed approach, the Levy probability distributions are properly introduced in the solution construction step, in order to couple the ACOR algorithm with the exploration properties of the Levy distribution. The proposed approach has been tested on mathematical test functions…

How Decarbonization, Digitalization and Decentralization are changing key power infrastructures

Abstract This paper addresses the impact over key power infrastructures of the three main drivers for change of these times: Decarbonization, Digitalization and Decentralization. The three phenomena, according to prominent observers, are affecting all fields of our lives but, in the literature, it is difficult to find an analysis of their impact on electrical power systems. The framework proposed in this paper, based on the main power systems evolution models proposed by CIGRE, uses data from open databases and tries to find out general guidelines for power systems development at a worldwide level. Taking as reference the European and COP21 environmental objectives and beyond, the technolog…

A Coexistence Analysis of Blockchain, SCADA Systems, and OpenADR for Energy Services Provision

The advent of blockchain technology allows the raise of new business models for the electricity market, opening the way also to end-users and letting them offer regulation services to the power grid. Thanks to the characteristic of being distributed, the blockchain technology could be a solution to balancing problems caused by the penetration of renewable sources, implementing a platform for Demand-Response programs delivery. Demand-Response allows consumers to respond to market signals by increasing or reducing their energy consumption, contributing to greater flexibility and stability of the grid and to a more efficient use of infrastructures and energy resources. Currently, Demand-Respon…

Pulsed Electro-Acoustic Method for specimens and cables employed in HVDC systems: Some feasibility considerations

Recent experiments on the use of the PEA method for testing dielectric materials in specimens and comparison with a detailed model provide an insight of the phenomenon and suggest the need of adopting similar models also for cables. What is said is even more important considering the possible future adoption of the PEA methodology to test DC cables for Pre-Qualification and Type Tests. The use of an accurate model of the PEA cell used for testing specimens and related experiments prove that the thickness of the different parts composing the PEA setup is a basic element for providing accurate charge reading and interpretation of the phenomenon. Both simulation and experimental results, carri…

Modelling energy storage systems using Fourier analysis: An application for smart grids optimal management

In this paper, a new and efficient model for variables representation, named F-coding, in optimal power dispatch problems for smart electrical distribution grids is proposed. In particular, an application devoted to optimal energy dispatch of Distributed Energy Resources including ideal storage devices is here considered. Electrical energy storage systems, such as any other component that must meet an integral capacity constraint in optimal dispatch problems, have to show the same energy level at the beginning and at the end of the considered timeframe for operation. The use of zero-integral functions, such as sinusoidal functions, for the synthesis of the charge and discharge course of bat…

A new method for forecasting energy output of a large-scale solar power plant based on long short-term memory networks a case study in Vietnam

Abstract This paper proposes a new model for short-term forecasting power generation capacity of large-scale solar power plant (SPP) in Vietnam considering the fluctuations of weather factors when applying the Long Short-Term Memory networks (LSTM) algorithm. At first, a configuration of the model based on the LSTM algorithm is selected in accordance with the weather and operating conditions of SPP in Vietnam. Not only different structures of LSTM model but also other conventional forecasting methods for time series data are compared in terms of error accuracy of forecast on test data set to evaluate the effectiveness and select the most suitable LSTM configuration. The most suitable config…

Analysis of Interconnected Earthing Systems of MV/LV Substations in Urban Areas

The paper proposes a study of the fault current distribution in an extended interconnection of earthing systems, belonging to secondary substations, during a single-line-to-earth fault. By applying the analysis methodology defined by the same authors in some previous works, the paper shows how the value of some important geometrical and electrical parameters of a MV network can influence the value of the earth current at the fault location.

Demand Response for Integrating Photovoltaic Plants in Lampedusa Island

This paper presents the results of a simulation study concerning different Demand Response logics applied to Electric Storage Water Heaters on the island of Lampedusa. Electric Storage Water Heaters are the devices that are primarily used on the island to produce domestic hot water. Starting from measured load profiles collected in Lampedusa, a domestic hot water consumption profile was derived, to simulate the energy usage of the Storage Water Electric Heaters during the day. This work was carried out as a preliminary feasibility study for the BloRin project, financed by cohesion funds in the Sicilian region. According to the project, which also includes the installation of domestic photov…

Multi-modal search for multiobjective optimization: an application to optimal smart grids management

This paper studies the possibility to use efficient multimodal optimizers for multi-objective optimization. In this paper, the application area considered for such new approach is the optimal dispatch of energy sources in smart microgrids. The problem indeed shows a non uniform Pareto front and requires efficient optimal search methods. The idea is to exploit the potential of agents in population-based heuristics to improve diversity in the Pareto front, where solutions show the same rank and are thus equally weighted. Since Pareto dominance is at the basis of the theory of multi-objective optimization, most algorithms show the non dominance ranking as quality indicator, with some problem i…

Studio di fattibilità e progettazione preliminare di dimostratori di reti elettriche di distribuzione per la transizione verso reti attive. Report 1 – Caratterizzazione delle reti attuali e analisi di possibili scenari di sviluppo

Remote voltage synchronization for wireless Partial Discharge diagnostics

The main objective of this paper is the assessment of the exact phase angle displacement of each Partial Discharge, PD, pulse with respect to the voltage reference waveform. Such problem also referred to as ‘synchronization’ is relevant when the cable is not accessible and the PD measure is carried out in wireless mode. It is well known, that the angle phase shift, due to the propagation phenomenon on the transmission line, can be calculated knowing the line type and length and typical operating conditions of the transmission line. The setup comprises a customized electronic device, the “Phase check”, a server to collect remote measurements and a Look up table to provide corrections to the …

Economic feasibility of a customer-side energy storage in the Italian electricity market

Electricity prices show significant short-term variations during the day due to the need of balancing supply and demand in real time. Normally, customers are not exposed to these variations but pay a constant electricity price. In an attempt to reduce the volatility of the wholesale prices, several utilities are moving from conventional fixed-rate pricing schemes to new market-based models, where the electricity price can fluctuate during the day depending on the market conditions. Examples of time-dependent pricing schemes are Time-Of-Use (TOU) tariffs, where the electricity price can take two or three price levels during the day, or Real-Time Pricing (RTP) tariffs, where the energy price …

A simple unsynchronized two‐end algorithm for faults location and identification in electrical distribution systems

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 no…

FROM FUEL BASED GENERATION TO SMART RENEWABLE GENERATION: PRELIMINARY DESIGN FOR AN ISLANDED SYSTEM. PART I: TECHNICAL ISSUES AND FUTURE SCENARIOS

The subject addressed in this paper is the analytical study of the transition of the energy generation system for a real MV/LV distribution system from a ‘fuel based’ one to a distributed and smart ‘renewables based’ one. The paper outlines the technical issues related to such transition from one type of system to the other. The study is carried out for a real islanded MV/LV distribution network located in the Island of Pantelleria. The economical issues regarding the above transition are focused in a companion paper.

Assessment of the production costs curve in micro-grids: a comparative analysis

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, maybe using demand response programs. In this paper, price responsive policies and its programs are discussed to answer this question. A case study of a micro-grid with one microturbine and two photovoltaic generators in Italy is analyzed to assess the overall production cost in order to build a price re…

Demand Response Pricing Strategies for Islanded Microgrids

In this paper, Time of Use and Critical Peak Pricing policies are designed and their effects on optimized operation is evaluated. For this purpose, an optimal operation algorithm is employed and the relevant production costs are derived. As far as the Time of Use policy is concerned, such costs are observed to be different in two time intervals of the day, due to the loads changing effect and the production of renewable energy. Whereas in the Critical Peak Pricing Policy, a peak time interval is identified to set up different pricing rates. The optimization algorithm used to carry out the work described above minimizes the microgrid's energy losses, the production costs and the Green House …

A new model for a safety analysis in a system of earthing systems interconnected through bare‐buried conductors

PurposeThe purpose of this paper is to present a mathematical model for studying the effects of the interconnection through bare‐buried conductors (BBC) of the secondary substations' earthing system of an urban area.Design/methodology/approachThe developed methodology is based on three main points: the solution of the transmission lines' equations for the formulation of a lumped parameters model of a BBC considering the conductive effect; the division of the distribution network into simpler sub‐systems; and the calculation of all the voltages and currents of the medium voltage (MV) network and of the earthing systems using a multiport approach.FindingsThe methodology has been applied to va…

Introduction of Offshore Wave, Wind and Solar Energies in Vietnam

In Vietnam, the energy demand shows an ever-increasing trend. To limit the utilization of fossil fuels and the following consequences for the environment, renewable energy sources must be adopted. In this context, the paper assesses the utilization of offshore wind and sea wave, by considering a commercial wind turbine and a prototypical wave energy converter. Solar energy can be optionally also collected by this device. An algorithm is introduced to find the best composition of the three sources able to cover a desired share of energy demand. The approach is applied to Ca Mau, a province in the southern part of Vietnam. Finally, the results encourage the adoption of these energy sources th…

An optimization approach for efficient management of EV parking lots with batteries recharging facilities

In this paper an optimization approach to devise efficient management strategies for Electric Vehicles parking lots is proposed. A Monte Carlo approach is used to evaluate the load consumption profile for groups of Electric Vehicles showing different features. The Monte Carlo approach allows to combine the different social and economical features affecting the commercial penetration of Electric Vehicles with the technical aspects. The basic feature to be assessed is the initial State Of Charge, which in turn depends on the distance travelled by the vehicle since the last recharge and thus by the usage of the vehicle (private, professional). The model is then used to optimize some objective …

Application to an italian distribution system of a multiobjective optimal Volt/VAR control strategy: improvements and management problems

In this paper, the experiences and results deriving from the application of a multiobjective optimal management strategy to a distribution network supplying an area in province of Palermo, Italy, are presented. The adopted strategy allows, through the interventions on the Under Load Tap Changers (ULTC) of the primary substations and on tie-switches, to reduce power losses and improve the voltage profiles. To solve the optimization problem, an evolutionary approach has been adopted; it employs fuzzy logic for an adequate and simultaneous fulfilment of the different objectives. The application section presents a deep technical and economical analysis of the results attained, applying the opti…

Fall of Potential Measurement of the Earth Resistance in Urban Environments: Accuracy Evaluation

Both Standards EN 50522 and IEEE 81 propose the fall of potential method (FPM) to carry out the measurement of the resistance to earth ( $R_{\text{ES}}$ ) of an earthing system (ES). However, in urban areas, the recommended distances between the ES and auxiliary electrodes are not easy to respect, due to the presence of buildings and tarmac. Furthermore, unknown buried metallic parts and interconnections among ESs could modify the earth potential profile of the area, affecting the measurement results. In this paper, the key-issues that influence the measured $R_{\text{ES}}$ when the FPM is used in an urban environment are presented. A parametric analysis, carried out with Comsol Multiphysic…

CLCA for Assessing Environmental Impacts of Power Sector in the GHG Policy Context

Purpose: Current greenhouse gas (GHG) policy aims at reducing emissions from power sector. However, there are some known trade-offs of GHG emission reductions, in terms of other types of environmental impacts and impacts on other economic sectors. Consequential life cycle assessment (CLCA) has been developed to assess the environmental impacts of the power sector in relation with changes in the policy and its indirect impacts on other economic sectors. Methods: A systematic review of CLCA method is conducted in the power sector. CLCA studies since 2005 are reviewed in terms of obtained results and methodology to identify whether CLCA is a more suitable approach for assessing environmental i…

Applicational Aspects of a New Diagnostic Methodology for Fault Location in MV Networks: Problems, Solutions and Improvements

The electrical energy market liberalization has encouraged utilities to make new investments at distribution level so as to attain higher quality levels. 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 faults diagnostic for distribution systems is spreading ever more. The Authors have just developed a new methodology for diagnostic management of automated distribution systems. The technique is based on the use of circuital models of the electrical system resulting from the composition of quadripoles. In this paper, after a brief description of the proposed approach, the is…

A study on the assessment of the production costs curves in micro-grids

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…

A hierarchical architecture for increasing efficiency of large photovoltaic plants under non-homogeneous solar irradiation

Abstract Under non-homogeneous solar irradiation, photovoltaic (PV) panels receive different solar irradiance, resulting in a decrease in efficiency of the PV generation system. There are a few technical options to fix this issue that goes under the name of mismatch. One of these is the reconfiguration of the PV generation system, namely changing the connections of the PV panels from the initial configuration to the optimal one. Such technique has been widely considered for small systems, due to the excessive number of required switches. In this paper, the authors propose a new method for increasing the efficiency of large PV systems under non-homogeneous solar irradiation using Series-Para…

Economic Feasibility of Measures for Energy Efficiency

In this chapter the economic impact of some measures for energy efficiency, both using automation of technical infrastructures (according to EN 15232) as well as implementing passive measures concerning the use of building materials and techniques (according to EN 15271), is studied. The chapter is organized as follows. First, a technical-economical study on the evaluation of the impact on residential buildings of Building Automation Control, BAC, and Technical Building Management, TBM, systems is presented. Then the same assessment of some passive measures that can be employed is carried out using the Passive House Standard for Mediterranean warm climates is shown. Numerical elaborations h…

A New Meta-Heuristic Multi-Objective Approach For Optimal Dispatch of Dispersed and Renewable Generating Units in Power Distribution Systems

The application of stochastic methods in engineering research and optimization has been increasing over the past few decades. Ant Colony Optimization, in particular, has been attracting growing attention as a promising approach both in discrete and continuous domains. The present work proposes a multi-objective Ant Colony Optimization for continuous domains showing good convergence properties and uniform coverage of the non-dominated front. These properties have been proved both with mathematical test functions and with a complex real world problem. Besides the second part of the chapter presents the application of the new algorithm to the problem of optimal dispatch of dispersed power gene…

Conceptual Design and Modeling of Fast Discharge Unit for Quench Protection of Superconducting Toroidal Field Magnets of DTT

The paper deals with the modelling and simulation of a Fast Discharge Unit (FDU) for quench protection of the Toroidal Field (TF) magnets of the Divertor Tokamak Test, an experimental facility under design and construction in Frascati (Italy). The FDU is a safety key component that protects the superconducting magnets when a quench is detected through the fast extraction of the energy stored in superconducting magnets by adding in the TF magnets a dump (or discharge) resistor. In the paper, two different configurations of dump resistors (fixed and variable respectively) have been analysed and discussed. As a first result, it is possible to underline that the configuration with variable dump…

Smart multi-carrier energy system: Optimised energy management and investment analysis

This paper proposes an optimised Energy Management System for a multi-carrier hub, which integrates two energy distribution networks, for hydrogen and electricity. The economic sustainability of a real-life instantiation of such a system has been analysed as well. The Energy Management System has been developed by means of a multi-objective optimisation algorithm, the Non-dominated Sorting Genetic Algorithm II, implemented using MATLAB®. The achieved results consist in a series of set-points defining the working conditions of the plant for a chosen time horizon. Data provided by this process also show the effectiveness of the adopted optimisation approach. The financial analysis is performe…

A heuristic approach for optimal operation of grid connected source-battery-load systems

In the paper an optimal management procedure for a system composed of a renewable energy source, storage batteries and a load, permanently connected to a distribution network, is presented. The issue follows two objectives: a) maximum economic benefit for the system, and b) minimum energy exchange with the network. The operation cost of storage facilities, as well as the technical and economic constraints on power exchanges between the system and the network and the technical constraints about charging and discharging cycles of the batteries are considered. The effectiveness of the management procedure is numerically tested and the results are presented.

Load modelling influence on voltage stability assessment in distribution systems. Part II: Extension to a complex radial system and applications

The single-line equivalent model is commonly used for voltage stability studies in both distribution and transmission systems. Referring to a single-line system, in the companion paper [1] the authors presented the theoretical aspects of voltage stability related to the load characteristics. In particular, expressions of the stability index for constant power, constant impedance and constant current loads, singularly and in all the possible combinations have been obtained. This index indicates how far the load node is from its voltage collapse point, allowing the maximum load power beyond which voltage collapse takes place to be evaluated. In this paper a simple method to evaluate the param…

Wireless partial discharge tracking on cross-linked polyethylene MV and HV cables

Medium voltage (MV)/high voltage (HV) cable lines are high-value assets and require substantial costs for their installation or replacement. For this reason, the capability to assess the condition of cable lengths and accessories on site is of great importance. Cross-linked polyethylene (XLPE) insulation is extensively used for MV, HV, and extra-high voltage (EHV) class cables [1] thanks to its excellent voltage-endurance and thermomechanical properties. In particular, XLPE-insulated cables feature substantially lower losses, easier manufacturing and jointing procedures, better environmental compatibility, and higher operating temperature compared with impregnated paper cables, which lead t…

Certifying battery usage for V2G and second life with a blockchain-based framework

This paper describes a blockchain-based approach for sharing data among all the actors involved in Vehicle-to-Grid programs. The shared information is used both for monitoring the health status of the vehicle’s battery and for remuneration in Vehicle-to-Grid programs. A blockchain platform and a set of appropriate smart contracts have been developed for supporting the interactions among the different actors and for creating battery usage profiles. To protect sensitive data, we limit the visibility scope of such data only to subsets of actors using blockchain channels. This approach preserves the privacy of the car owner on one hand and guarantees the compliance to correct charging and disch…

Atlante delle smart city - Modelli di sviluppo sostenibile per città e territori (2 edizione)

Questa nuova edizione presenta un atlante aggiornato e arricchito di contenuti relativi a nuovi esempi di città che hanno sperimentato tecnologie, azioni e strategie in grado di renderle “intelligenti”. Sviluppa poi le tematiche emergenti riguardanti l’integrazione della pianificazione urbanistica ed energetica nel caso di Stoccolma, alcune esperienze siciliane che affrontano il tema della partecipazione dei cittadini nella città del futuro e una simulazione di smart island che riguarda l’isola di Pantelleria.

Fast solution of radial distribution networks with automated compensation and reconfiguration

Abstract Optimal operation of radial distribution networks with automated compensation and reconfiguration requires the solution of a combinatorial optimisation problem, since the variables are the on/off status of capacitor banks and the open/close status of tie-switches. The solution approaches recently proposed use iterative algorithms such as genetic algorithms, simulated annealing and tabu search, for which the network needs to be solved in different configurations and at different compensation levels. The aim of this evaluation is that of attributing a quality index to each solution so that all the solutions can be suitably ordered. In an automated network, any configuration can be ob…

Market-oriented analysis for active distribution systems

Distribution networks are today the place where demand and offer are physically located and meet. Offer comes from Generation companies, through distributed generation, while demand is usually represented by simple users. Distribution company both buy and sell energy so they implement both sides. The EU promotes the free market and the renewable energy sources (RES) supported by the distributed generation technology. The technical-economical scenario in which distributed generation is thus growing is complex and comprises a large number of stakeholders. The authors, on the basis of previous studies want to analyse the problem of identifying sets of stakeholders sharing the common interest o…

A SURVEY ON SMART GRIDS ACTIONS AND COMPONENTS FOR ENERGY CONSUMPTIONS OPTIMIZATION

In the paper a survey on the features that a smart grid has to perform for energy consumptions optimization are presented and explained. By optimizing the loads usage with the grid priorities both end-users and the energy providers can save energy (and so CO2 emissions) and money. In the paper the conceive of an architecture in-home and at residential level is proposed to arrange a smart grid with its intelligent and connected load consumers. Qualitative results from the European research project “BeyWatch” are here mentioned in order to explain how the conceived main services in smart grid, like monitoring and control services, energy management services and load management services allow …

Municipal Building Regulations for Energy Efficiency in Southern Italy

The building sector is still one of the most energy consuming sectors in Italy, like developed countries in Europe. At European level, the main policy driver related to the energy use in buildings is the Energy Performance of Buildings Directive (EPBD, 2002/91/EC) and its recast. Through the EPBD in- troduction, requirements for certification, inspections, training or renovation are now imposed in Member States. In order to fulfill the expected changes, local regulations are a key factor aiming at sustainable territorial planning. It is thus required support the issue of local rules at municipal level in order to guide local administrators and technicians and to limit discretional power of …

The Blockchain in Microgrids for Transacting Energy and Attributing Losses

In recent years novel models for energy distribu- tion appeared and islanded microgrids quest for new ways to exchange energy between consumers and producers without the need of central authorities. The blockchain mechanism has emerged as a distributed solution for recording energy transactions in power systems. The blockchain has been used to permit users bartering and selling energy and to keep track of such exchanges without exposing them to tampering. In this work, we consider a novel application of the blockchain in islanded microgrids that includes also annotating energy losses caused by energy transactions, in order to have a more realistic matching between the physical status of the…

An experimental analysis of power quality in presence of single phase grid connected photovoltaic systems

In this paper, an experimental power quality analysis in presence of single phase grid connected PV systems is performed in a PV system installed at the Department of Electric Engineering of the University of Palermo through a measurement system set up by the Authors. In particular the analysis has been carried out focusing the attention on voltage and current distortion, as the solar radiation varies. The corresponding Total Harmonic Distortions in voltage and current terms are reported and compared with the standards limits. The presence of interharmonic components is also discussed.

A Review on Consequential Life Cycle Assessment in the Power Sector

The existing policy for greenhouse gas (GHG) abatement aims at decarbonisation of the power sector. The interrelations between the power sector and other economic sectors raise a question of whether the GHG emission reduction policy in the power sector is as effective as it is claimed. Consequential life cycle assessment (CLCA) has been developed to assess the environmental impacts of any industrial/productive sector in relation with changes in the policy and its indirect impacts on other economic sectors. This review is conducted on CLCA studies in the power sector in terms of system boundaries expansion and socio-economic interactions and the ability to quantify indirect environmental imp…

Decoupled solution of radial and weakly meshed distribution networks through a backward method

A methodology for the analysis of radial or weakly meshed distribution systems supplying voltage dependent loads is developed. The solution process is iterative and, at each step, the loads are simulated by means of impedances. The network is divided into two sub-networks which must be solved separately and sequentially; in the first, named RP-net, only the lines resistances and the loads shunt equivalent resistances are considered; in the second, named XQ-net, only the lines reactances and the shunt equivalent reactances are taken into account. After a brief presentation of the b/f method, which is currently the most commonly used technique to solve distribution networks, the proposed meth…

Pareto-optimal Glowworm Swarms Optimization for Smart Grids Management

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.

Ottimizzazione Multi-Obiettivo delle Prestazioni Energetiche e Ambientali di un Edificio Residenziale

Il presente lavoro, svolto nell’ambito dell’Annex 72 dell’International Energy Agency, descrive un approccio metodologico volto all’identificazione di interventi ottimali di ristrutturazione da effettuare sull’involucro di un edificio residenziale, permettendo di minimizzare contemporaneamente quattro funzioni obiettivo: i consumi energetici in fase d’uso, i costi d’investimento e gli impatti energetici e ambientali di ciclo di vita. L’ottimizzazione, eseguita tramite un algoritmo multi-obiettivo, ha permesso di identificare gli spessori di materiale isolante e di materiali massivi da aggiungere sul tetto e sulle pareti perimetrali dell’involucro edilizio per minimizzare le quattro funzioni…

CONSEQUENCES OF THE ELECTRICAL ENERGY MARKET LIBERALIZATION ON ELECTRICAL DISTRIBUTORS: ”COMPETION AND QUALITY OF THE ELECTRICAL SERVICE”

Critical Assessment of Feed-In Tariffs and Solar Photovoltaic Development in Vietnam

Vietnam became the world’s third largest market for solar photovoltaic energy in 2020. Especially after the Vietnamese government issued feed-in tariffs for grid-connected solar photovoltaic systems, the installed capacity of solar photovoltaic applications exploded in 2019. From studies carried out in the relevant literature, it can be said that support policies are highly important for the initial development of the renewable energy industry in most countries. This is especially true in emerging countries such as Vietnam. This paper reviews the feed-in tariffs issued and deployed in different regions of Vietnam for grid-connected solar photovoltaic applications. Moreover, the paper takes …

Reconfigurable electrical interconnection strategies for photovoltaic arrays: A review

Non-uniform irradiance significantly decreases the power delivered by solar photovoltaic arrays. A promising technique for compensating these power losses relies on dynamically reconfiguring the electrical connections between photovoltaic modules. This paper presents the current state-of-the-art strategies for photovoltaic array reconfiguration in order to increase the power output under partial shading and mismatch conditions. The different approaches have been compared in terms of effectiveness of the control algorithms, monitored electrical and environmental variables, overall hardware complexity and specific features of each solution. Finally, the most challenging aspects of the reconfi…

A Simulation Study for Assessing the Minimum Number of V2G Recharge Points in Favignana

Issues related to the stability of non-interconnected grids are of high relevance given the increasing presence of renewable sources in the power generation system. In order to ensure adequate levels of system's reliability, it is necessary to find new methods to ensure the stability of the electric grid. The present work proposes a methodology for the definition of the minimum number of Vehicle-to-Grid (V2G) charging points that would allow the integration of 1 MW of photovoltaic power in the power grid of the Italian island of Favignana, electrically disconnected from the continental grid. Primary frequency regulation simulations are carried out in Matlab/Simulink environment for differen…

A Model for the Study of Sheath Currents in Medium Voltage Cables for Industrial Application

In this paper, the implementation of a simulation model for studying the effect of cross-bonding of metallic sheaths and/or non-magnetic armor of single-core medium voltage cables in the same circuit is discussed. With the use of single-core cables, the resistive losses due to the induced circulating currents in cable sheaths or armors causes an increase of cable temperature that reduces its ampacity. In addition, the risk of electric shock due to induced voltages may be present if a person is exposed to the armor/sheath at the unbounded end. For this reason, special bonding techniques are used to significantly reduce these currents. The authors have implemented a model that could be used t…

A double-shell design approach for multiobjective optimal design of microgrids

This work develops a new double shell approach to optimal design for multi-objective optimally managed systems. The cost of each design solution can be defined by the evaluation of operational issues and capital costs. In most systems, the correct definition of operational issues can be deduced by means of the solution of a multi-objective optimization problem. The evaluation of each design solution must thus be deduced using the outcome of a multi-objective optimization run, namely a Pareto hyper-surface in the n-dimensional space of operational objectives. In the literature, the design problem is usually solved by considering a single objective formulation of the operational issue. In thi…

A Generalized Framework for Optimal Sizing of Distributed Energy Resources in Micro-Grids Using an Indicator-Based Swarm 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 usin…

Optimal power flow for technically feasible energy management systems in islanded microgrids

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 …

A fuzzy-logic based evolutionary multiobjective approach for automated distribution networks management

In this paper, a methodology to treat constrained scheduling problems based on the repeated application of a fuzzy-logic-based multiobjective algorithm is presented. The application domain is that of automated distribution systems management. In particular, the problem of voltage regulation and power loses minimization is here considered. The classical formulation of the problem of optimal control of shunt capacitor banks and under load tap changers, ULTC, located at high voltage/medium voltage (HV/MV) substations has been coupled with the optimal control of tie-switches and capacitor banks on the feeders of a large radially operated meshed distribution system with the aim of attaining mini…

Minimum Losses Reconfiguration of MV Distribution Networks through Local Control of Tie Switches

This paper deals with the problem of optimal reconfiguration of radial distribution networks for minimum loss operation. The proposed control strategy of the open-closed status of the tie-switches is distributed, since every MV/LV node is provided with local controllers having some measured entities as input. It also does not prevent the system from the future implementation of centralized control; instead it may represent the first step toward a complete automation of the distribution system. The proposed strategy is indeed organized in hierarchic levels, the highest of which may be in the future a central control. After introducing the general problem of networks reconfiguration, a review…

Near zero energy islands in the Mediterranean: Supporting policies and local obstacles

Abstract Based on a recent technical–economical analysis on the island of Pantelleria, a policy feasibility study for a complete upgrading of the energy system of this Mediterranean Island is carried out. Pantelleria, situated between Sicily and Africa, owns a large potential in terms of renewable energy resources, although there are some obstacles in turning it into a Near Zero Energy system. Starting from a deep energy system audit, the study proposes the project for a near zero energy island, through the efficient transformation of the different existing natural energy resources into electrical energy and heat: the solar, the wind-based and the geothermal systems. In this way, the island…

Overcoming synchronization issues in wireless technology Partial Discharge measurement

In this paper, several aspects of the fundamentals of wireless Partial Discharge (PD) measurements are first discussed. Then, the relevance of the problem of voltage synchronization in PD wireless diagnosis is outlined. When portable instruments are used for PD detection, the main issue is the voltage measurement at the site where the PD detection is carried out. When such analysis is carried out over shielded cables, the AC (50/60 Hz) voltage reference signal is not easily detectable, while one of the basic parameters for PD diagnosis, the displacement of the inception voltage of the PD as compared to the reference voltage, is not available. Even if highperformance sensors are readily avai…

Critical issues in the PD testing methodology for XLPE-insulated MV cables: An experimental case

This paper describes some critical issues arising during the partial discharge (PD) testing of a 500m delivery length of an XLPE-insulated MV cable. At first, conventional PD measurements were performed on the whole length by using a standard acquisition system; PDs activity was detected, but the system allowed the operator to localize the PDs only on a length of 70 m. A visual inspection of this section highlighted the presence of an excoriation in the outer sheet. Aiming at a more accurate pin-pointing of the defect, more measurements were carried out in the proximity of the outer defect using a portable PD detection system. These measurements showed PDs activity, whose source was located…

A Two-End Traveling Wave Fault Location System for MV Cables

In this paper, a new low-cost device is proposed for fault location in power distribution system. The device is part of a system that should include several units installed in couples at the two ends of medium voltage (MV) cable lines. Their low cost justifies a widespread installation of these devices, moreover other functionalities could be considered so as to enrich the potential of the system for MV cables monitoring and asset management. The system exploits a two-end traveling wave technique, low complexity, and low-cost solutions both for the analog front end as well as for the communication infrastructure. A LoRa network is indeed considered as wireless modulation technique perfectly…

Voltage Regulation and Power Losses Minimization in Automated Distribution Networks by an Evolutionary Multiobjective Approach

In this paper, the problem of voltage regulation and power losses minimization for automated distribution systems is dealt with. The classical formulation of the problem of optimal control of shunt capacitor banks and Under Load Tap Changers located at HV/MV substations has been coupled with the optimal control of tie-switches and capacitor banks on the feeders of a large radially operated meshed distribution system with the aim of attaining minimum power losses and the flattening of the voltage profile. The considered formulation requires the optimization of two different objectives; therefore the use of adequate multiobjective heuristic optimization methods is needed. The heuristic strate…

Optimal energy management in the smart grid

The Smart Grid is a modern electricity grid allowing for distributed, renewable intermittent generation, partly owned by consumers. This requires advanced control and communication technologies in order to provide high quality power supply and secure generation, transmission and distribution. This book outlines these emerging technologies. Topics covered include an introduction to smart grid architecture; smart grid communications and standards; measurement and sensing devices for smart grids; smart transmission and wide area monitoring system; bad data detection in smart grids; optimal energy management in smart grids; communication and control for the smart grid; smart consumer systems; i…

Microgrid supervisory controllers and energy management systems:A literature review

Abstract Microgrids (MGs), featured by distributed energy resources, consumption and storage, are designed to significantly enhance the self-sustainability of future electric distribution grids. In order to adapt to this new and revolutionary paradigm, it is necessary to control MGs in intelligent and coordinated fashion. To this aim, a new generation of advanced Microgrid Supervisory Controllers (MGSC) and Energy Management Systems (EMS) has emerged. The aim of this paper is to summarize the control objectives and development methodologies in the recently proposed MGSC/EMS. At first, a classification of control objectives is made according to the definition of hierarchical control layers i…

SVILUPPO DI ALGORITMI DI OTTIMIZZAZIONE FINALIZZATI A DIMENSIONAMENTO E GESTIONE MULTICRITERIO DI SISTEMI INGEGNERISTICI

A new model for a safety analysis in a system of earthing systems interconnected through bare buried conductors

The Role of Right Interpretation of Space Charge Distribution for Optimized Design of HVDC Cables

In the field of high-voltage transmission systems, different degradation phenomena affect the reliability of the employed components. In particular, under dc stress, the space charge accumulation phenomenon is believed to be the most responsible of the dielectrics lifetime reduction. To measure the accumulated space charges in flat specimens, the pulsed electro-acoustic (PEA) method is one of the most used techniques. The working principle of the PEA cell is based on the acoustic waves propagation and detection. As is well known, the acoustic waves propagating in different means are partially transmitted and partially reflected. Therefore, the piezoelectric sensor of the PEA cell is subject…

DEMAND Project: Bottom-Up Aggregation of Prosumers in Distribution Networks

The paper explains the concept of the DEMAND project, whose aim is to develop a technical framework for allowing a Bottom-Up aggregation of prosumers connected to the distribution grid. Load and generation aggregation is a very current issue given the great potential that the coordinated management of distributed resources has on power systems operation and design. The novelty in DEMAND is the absence of a physical aggregator and the recourse to a virtual aggregation environment (VAE) for allowing the exchange of information among the prosumers in order to provide a service to the DSO. After a general description of the research project, the paper presents the services that the aggregated c…

Sharing practices in the digital age: inclusive processes and new citizens in the intelligent city

Il modello smart city sta diventando un nuovo approccio di vita basato su processi inclusivi e pratiche innovative che coinvolgono cambiamenti correlati alle sfide delle città. I drivers (energia, mobilità, economia,etc..) della smart city sono realmente collegati dalla componente ICT che connette tutto in una logica omni-inclusiva. Attori e utilizzatori finali di queste trafsormazioni sono i cittadini, persone che con i loro smart phones diventano sensori della città recettiva e sensibile. La città in tempo reale viene analizzata attraverso mappe prodotte con sistemi GIS offrendo un altro modo di leggere le nuove funzioni urbane. E’ possibile quasi immediatamente attraverso App dedicate co…

Optimal Energy Management in Smart-Grid

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 Kirchho…

A method for the evaluation of fault current distribution in complex high voltage networks

Abstract The paper presents a method for the study of large interconnected earthing systems in High Voltage networks. The mathematical model proposed for calculating the distribution of the Single-line-to-Earth fault current is useful for a methodical and accurate analysis of complex systems having meshed configuration and more sources, and has practical application for the Transmission System Operator. Two case studies are provided. The first one considers a fault occurring inside and outside a station in a real 220 kV transmission network. In the second example, the proposed methodology is compared with the classical “Double-sided elimination” method.

Optimizing Renewable Power Management in Transmission Congestion. An Energy Hub Model Using Hydrogen Storage

Energy production from distributed renewable power plants underwent a takeoff in last years as never before. Nevertheless, the installation of technologies based on variable energy resources and their connection on transmission power lines might cause congestions due to the transmission capacity limits. This paper describes the modelization of a HV transmission line with local renewable production and its optimal management through an Energy Hub model. Aim of the study is to identify the optimal size of the power storage, based on an electoryzer, a hydrogen storage and a fuel cell, in order to minimize the congestion risks and to maximize the exploitation of renewable energy production.

La smart mobility come fattore chiave verso una smart city. Alcune esperienze europee

The study and the analysis of some fruitful experiences in Europe we find that the smart mobility is one of the central pillars for initiating processes and best practices sensitive to environmental issues and sustainable development. The city of Stockholm has called his plan sustainable precisely “The Walkable City” meaning that achieve a planning instrument that brings the city to be crossed easily by bicycle, on foot, but also with public transport efficient and low impact on the climate. For this reason the city has the goal of being fossil fuel free by 2050. Freiburg, however, with the urban district of Vauban is definitely an inno- vative model focuses on the use of sustainable public…

A NEW REPRESENTATION OF ENERGY STORAGE SYSTEMS OPERATION USING FOURIER THEORY IN OPTIMAL SMART GRIDS MANAGEMENT

This paper investigates the possibility to use a new modeling of Energy Storage Systems based on zero integral functions. Such functions represent the course of the energy level stored in batteries during the solution of optimal management problems in smart-grids. Storage devices, such as all the other components that are required to meet an integral capacity constraint along the dispatch time, must show the same State of Charge at the start and at the end of the timeframe considered for operation. In this paper, a set of sinusoidal functions have been used for the synthesis of the charge and discharge course of energy Storage Systems. Such representation allows to eliminate the difficult c…

Optimal Sizing and Siting of Distributed Energy Resources Considering Public and Private Incentive Policies

The present work presents the formulation and solution approach for the problem of optimal sizing and siting of distributed energy resources based on Photovoltaic, PV, technology. The considered system is an isolated grid (small island) and the parts involved are the utility and the customers. As it happens in islands, the same utility generates and delivers energy to customers, for this reason, the installation of dispersed generation units is beneficial for reducing power losses, regularizing the voltage profile, but also for increasing the profit. The problem is solved by means of the Non dominated sorting Genetic Algorithm II, NSGA-II, identifying the optimal size and location of PV sys…

Architetture e logiche di controllo ottimale di microreti per la razionalizzazione energetica Report 1 – Identificazione ed analisi di architetture e logiche di controllo ottimale di microreti per la razionalizzazione energetica

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 designat…

Optimal Power Flow in three-phase islanded microgrids with inverter interfaced units

In this paper, the solution of the Optimal Power Flow (OPF) problem for three phase islanded microgrids is studied, the OPF being one of the core functions of the tertiary regulation level for an AC islanded microgrid with a hierarchical control architecture. The study also aims at evaluating the contextual adjustment of the droop parameters used for primary voltage and frequency regulation of inverter interfaced units. The work proposes a mathematical method for the OPF solution also considering the droop parameters as variables. The output of the OPF provides an iso-frequential operating point for all the generation units and a set of droop parameters for primary regulation. In this way, …

Sustainable Energy Supply in Vietnam

The steep growth of electricity demand in Vietnam (11% per year on average since 2006) calls for a deep rethinking of the Vietnamese electrical power system. Its topological structure indeed may not be well suited for a deep penetration of renewable energy sources and a predictable increase of reactive industrial loads. The Vietnamese power system is described and a few analytical methods are considered for its study both in steady state and in dynamic conditions in different scenarios. The power system simulation software Neplan is used for the implementation of the system’s model and the performing of the dynamic analysis.

A Self-Adapting Approach for Forecast-Less Scheduling of Electrical Energy Storage Systems in a Liberalized Energy Market

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 th…

A Technical Approach to the Energy Blockchain in Microgrids

The present paper considers some technical issues related to the “energy blockchain” paradigm applied to microgrids. In particular, what appears from the study is that the superposition of energy transactions in a microgrid creates a variation of the power losses in all the branches of the microgrid. Traditional power losses allocation in distribution systems takes into account only generators while, in this paper, a real-time attribution of power losses to each transaction involving one generator and one load node is done by defining some suitable indices. Besides, the presence of P–V nodes increases the level of reactive flows and provides a more complex technical perspective. For this re…

A Simple Method to Assess Loadability of Radial Distribution Networks

This paper proposes a simple method to asses loadability in radial distribution systems. The relevant problem of voltage stability has been dealt with in past times with reference to higher voltage systems for generation and transmission. In more recent papers, the problem has been considered also at distribution level, since the new electrical energy market requirements and the increasing loadings are now more and more influencing these systems. The proposed method is based on a static approach and proceeds by first evaluating the stability indices and then the different loadability factors (related to real, reactive and apparent power). These calculations are carried out by identifying, s…

Damage identification by Lévy ant colony optimization

This paper deals with the identification of incipient damage in structural elements by non-destructive test based on experimentally measured structural dynamical response. By applycation of the Hilbert transform to the recorded signal the so-called phase of the analytical signal is recovered and a proper functional is constructed in such a way that its global minimum gives a measure of the damage level, meant as stiffness reduction. Minimization is achieved by applying a modified Ant Colony Optimization (ACO) for continuous variables, inspired by the ants’ forageing behavior. The modification consists in the application of a new perturbation operator, based on alpha stable Lévy distribution…

A HEURISTIC LOAD MANAGEMENT APPROACH FOR DOMESTIC APPLIANCES

In this paper, an innovative heuristic for domestic loads management is proposed. The method is straightforward and easy to be implemented on embedded systems. The idea is to start from the mathematical modeling of loads and to perform a profile based scheduling, namely loads will try to fit a given schedule. The solution of the scheduling is based on a rolling horizon of 24 hours and is recomputed when an ON signal is provided to the considered appliance. Experimental results show the pertinence of the approach and how it may be profitably used to lower the energy costs for the end user.

An economic study about the installation of PV plants reconfiguration systems in Italy

This paper shows the economic convenience of the application of a reconfiguration system for photovoltaic plants, considering the incentives system in Italy and its recent modifications. The reconfiguration is an alternative to the Distributed Maximum Power Point Tracking, DMPPT, technique used to overcome the mismatch problem in Photovoltaic, PV, plants. The reconfiguration techniques employ a microprocessor-based system that modifies the layout of the PV plant by physically changing the connections among modules. After the explanation of the working principle of the PV reconfiguration system allowing the improvement of the efficiency of the same plant and the relevant installation, the ma…

A Remuneration Model of Energy Community Members in Italy

The Directive (EU) 2018/2001 (RED II) requires Member States to authorize the constitution of consumers as self-consumers of renewable electricity by ensuring them non-discriminatory and disproportionate treatment. Member States must establish a favorable framework for promoting and facilitating the development of self-consumption, including in collective form (art. 21). According to the Directive, the granting of rights to renewable energy self-consumers who act collectively allows to increase the energy efficiency of households and helps to combat energy poverty by reducing consumption and supply tariffs. In Italy, the decree n. 162/2019 and then amended with Decree 199/2021 has partially…

Performance of the Glass Block in Photovoltaic Generation

In this article is presented the preliminary evaluation of the performance of radiation transmission of glass block, used in support of photovoltaic cells, investigating different internal surface points of the block, which are subject to different shading during daylight hours. The aim is to establish how the edging setting, the only opaque element, can reduce the amount of light radiation during the day, introducing in this way a reduction of efficiency of the entire generation system. The generation system can be based on traditional photovoltaic cells or on the most suitable dye sensitized solar cells. An experimental measurement setup employing a microprocessor-based instrument has bee…

On the architectural and energy classification of existing buildings: a case study of a district in the city of Palermo

Town Administrations are increasingly facing the challenge to identify smart planning actions to reduce the cities' energy demand by improving the efficiency of the urban energy systems. Buildings play an important role in this regarding both the demand and supply energy. In this scenario, the neighborhood or district scale seems to be the most appropriate to implement a multi-disciplinary approach on which smart planning relies. This paper shows the application, to a district of the city of Palermo (Sicily, Italy), of a methodology for architectural-energy classification of existing buildings. Such methodology provides, regarding the building sector, an easy tool that can support smart pla…

Smart city: casi studio

Il capitolo effettua un'ampia ricognizione delle smart city nel mondo, dagli esempi europei più noti alle smart city nelle città asiatiche. Da Masdar negli Emirati Arabi a Stoccolma, che in questi ultimi anni ha rigenerato con un'ottica smart interi quartieri (Hammarby Syostad e il Royal Seaport), cambiando complessivamente il volto della città. Il capitolo in questa terza edizione dedica un'attenzione speciale alle città asiatiche - la Cina ad esempio - che oggi si confrontano con profondi mutamenti socio-economici e imponenti e veloci fenomeni di urbanizzazione.

Mixed heuristic-non linear optimization of energy management for hydrogen storage-based multi carrier hubs

In this paper, an heuristic and non-linear programming based algorithm to optimally operate an energy hub plant is proposed. The energy hub plant described in this work is the test system for the European INGRID research project. The Energy Management System defines the optimal energy flows dispatch in order to obtain the energy balance and the maximum profit for the owner of the plant. The problem is highly constrained and non-linear, for this reason the methodology cannot rely on Linear Programming (LP) methods. The Energy Management System manages two energy carriers, electricity and hydrogen, interfacing three distribution networks: the electricity, the hydrogen and the methane networks…

A Novel Operating Strategy for Customer-Side Energy Storages in Presence of Dynamic Electricity Prices

In the wholesale energy market, electricity prices are determined by the balance between supply and demand. Normally, customers are not exposed to these variations but pay a constant electricity price. In an attempt to reduce demand peaks, several utilities are moving from a conventional fixed-rate pricing scheme to a new market-based model, based on time-of-use or real-time pricing, able to closely reflect the wholesale energy price. Electricity customers can thus take profit from the installation of storage systems, shifting their energy consumption from on-peak to off-peak periods. This paper presents a novel charging strategy to manage customer storage systems in presence of hourly elec…

Faults identification, location and characterization in electrical systems using an analytical model-based approach

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 Au…

Predictive Model of Energy Consumption of a Home

The usage of the renewable energy sources and electric vehicles is rising which might result in a problem with the energy grid stabilization. Some works state that buildings contribute to the overall energy consumption by 20–40% which makes them a great subject to study. Finding solutions for better energy management can have a significant impact on the energy sector. This work focuses on proposing a simplified model of a home considering main appliances, heating and cooling, a photovoltaic system, an electric vehicle and weather and solar irradiance forecasts. The model is created in MATLAB as a simulation script with defined parameters. It uses a 5 day weather forecast to predict energy d…

Life-Cycle Land-Use Requirement for PV in Vietnam

Over the last 15 years, photovoltaics (PV) in Vietnam has experienced development. The increased installed capacity of PV requires more land for installation sites as well as for manufacturing the plants’ component and waste treatment during the plants’ decommissioning. As a developing country, in which more than 80% of the population’s livelihood depends on agriculture, there are concerns about the competition of land for agriculture and solar development. This paper estimates the life-cycle land-use requirement for PV development in Vietnam, to provide the scientific-based evidence for policy makers on the quantity of land required, so that the land budget can be suitably allocated. The d…

A Comparison of Special Bonding Techniques for Transmission and Distribution Cables

In this paper, a review of the existing special bonding techniques for medium voltage (MV) and high-voltage (HV) cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The authors present a literature review to identify various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of the most used techniques have been performed in Matlab/Simulink, to compare their strengths and drawbacks.

An execution, monitoring and replanning approach for optimal energy management in microgrids

abstract 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 environme…

A New Method for the Price Determination of the Reactive Power Supply

This paper addresses the development of an accurate model for the pricing of reactive power supply as an ancillary service. Reactive power supply is one of the most important ancillary services in the field of transmission systems security. The present work is focused on building a reactive power market at which the Distributors can also take part in injecting reactive power at the connected HV/MV nodes. The authors have studied the particular case of the reactive power supplied by sub-transmission or distribution networks, connected to the nodes of the transmission system. The aim of this work is to establish a reactive power price by crossing demand and offer curves.

Optimal power flow based on glow worm-swarm optimization for three-phase islanded microgrids

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.

Lévy Flights for Ant Colony Optimization in Continuous Domains

In this paper, the authors propose the use of the Levy probability distribution as leading mechanism for solutions differentiation in an efficient and bio-inspired optimization algorithm, ant colony optimization in continuous domains, ACOR. In the classical ACOR, new solutions are constructed starting from one solution, selected from an archive, where Gaussian distribution is used for parameter diversification. In the proposed approach, the Levy probability distributions are properly introduced in the solution construction step, in order to couple the ACOR algorithm with the exploration properties of the Levy distribution.

RICONFIGURATORE DELLE CONNESSIONI DI SISTEMI FOTOVOLTAICI SOTTOPOSTI AD OMBREGGIAMENTO PARZIALE

Earthing System's Design in presence of non-uniform soil

The Authors propose a practical approach for facing the problem of the design of the earthing systems in two-layer soils. The approach is based on the calculation of an equivalent resistivity of the non-uniform soil through which the designer can treat this one as it was uniform. The purpose of the Authors is to provide an innovative simple method and some easy-to-use graphs for an easy earthing systems’ design in two-layer soils.

An Improved IEEE 802.11 Protocol for Reliable Data Transmission in Power Distribution Fault Diagnosis

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…

Smart Urban Energy Districts and Energy Policies

The deployment of smart cities appears a strategic factor for reducing environmental impact and increasing competitivity of economic systems across the world. Although terminology is similar worldwide, the different political assets and social enviroments largely affect the development models. Drivers indeed are quite different, such as the speed at which transformations take place. As a result, implementation of measures is carried out differently and realizations of smart city projects can be strongly different. Europe, China and U.S.A. approaches are compared in this paper to provide the reader with a broader view about different smart city implementations, with a focus on the electricit…

A novel heuristics-based energy management system for a multi-carrier hub enriched with solid hydrogen storage

In this paper, an efficient optimization algorithm for the energy management of a grid-connected energy hub plant is proposed. The Simulated Annealing algorithm is adopted for the solution of the energy management problem aiming at the profit maximization for the owner of the energy hub plant. The use of a heuristic algorithm was required by the non-linearity of the efficiencies of each component in the energy transformation stages. The proposed heuristics is applied to a large energy hub, corresponding to the simulation of the test-bed that is being designed and developed inside the ongoing INGRID European research project.

On the Non-Intrusive Load Monitoring in dwellings: a feasibility perspective

The oncoming modernization process of the power grids, driven above all by decarbonisation objectives and the continuous improvement of digital technologies, is encouraging active participation in the electricity market by consumers through the Demand-Response mechanism. From this perspective, the introduction of smart meters and energy consumption monitoring devices plays a fundamental role, being able to give benefits to consumers, suppliers and the electricity grid itself. This paper proposes a supervised method of non-intrusive load monitoring (NILM) based on the recognition of patterns in the time domain with the Dynamic Time Warping algorithm which is suitable for low-cost smart meter…

Multi-objective long term optimal dispatch of distributed energy resources in micro-grids

The amount of distributed generators in power distribution systems is evermore increasing, and the potential benefits and drawbacks are becoming clearer. The optimal management of Distributed Energy Resources (DER) in microgrids is essential to guarantee their best exploitation. Optimal operation allows to maximize their benefits, such as reduction of network energy losses, reduction of carbon emissions and to minimize the negative effects of a strong DER penetration, such as the increase of infrastructural investment and operational costs. Hence, DER management is a multi-objective problem in which many objectives of interest, often conflicting, need to be optimized simultaneously. In this…

Architetture e logiche di controllo ottimale di microreti per la razionalizzazione energetica Report 2 Applicazioni in reti di distribuzione

Il presente Rapporto descrive, le attività svolte dal personale del DIEET dell’Università degli Studi Palermo nell’ambito della seconda 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. Il presente Rapporto riporta le implementazioni della logica di controllo con una particolare attenzione al software che sovrintende alla gestione energeticamente efficiente dei sistemi individuati. Le implementazioni sono sviluppate in un ambiente di programmazione ad oggetti con una grafica di interfaccia che consente di se…

Transparency in transactive energy at distribution level

A recent report from the German Energy Agency analyzes the possible introduction of the blockchain technology in energy transactions in power distribution. The issue deserves attention since the extensive digitalization of business models puts new challenges to utilities in the power sector. The German decision makers in the energy field claim that blockchain appears as a close perspective and, at the same time, the Gartner hypecycle puts this technology at the peak of inflated expectations in 2016. Diffuse perception however provides hints for further investigation on the topic. This paper provides insight into the problem of peer-to-peer energy exchange from a technical perspective, provi…

Apparato di commutazione

La presente invenzione si riferisce ad un apparato di commutazione per il controllo e l'impostazione della configurazione circuitale dei pannelli di un modulo fotovoltaico.

Sensitivity Analysis and Frequency Dynamics of Grid-Connected Converters with Virtual Inertia

For the participation in the frequency control of the system, power converters can be controlled with different strategies and methods, sharing the common concept of virtual inertia capability. In this work, a sensitivity analysis of two main categories of converter controls with virtual inertia is presented. The considered schemes are a grid-following current vector control with additional virtual inertia block and a grid-forming control scheme based on virtual synchronous machine concept. A proper basis for the comparison is first assessed providing an analytical correlation between the control parameters of the two schemes. For the two control strategies, the sensitivity analysis of the …

Sustainable integration of Renewable Energy Systems in a Mediterranean island: a case study

Starting from a previous technical and economical feasi-bility study, this paper analyzes the integration of Renewable Energy Sources into an existing territory with specified features of the natu-ral landscape and of the built environment. The work puts into evi-dence that territories development must use suitable tools and rules based on integrated knowledge, since technical feasibility studies do not assess the sustainability of the proposed infrastructures within the built environment and landscape. The studied system is in the is-land of Pantelleria situated between Sicily and northern Africa.

Optimizing the generation system in a microgrid with power, thermal energy and mobility demands

Microgrids are widely known to be the future of generation and distribution systems. This paper presents a method to optimize the size of the main components in a microgrid to supply the demands for electricity, heating and hydrogen for mobility through an Energy Hub model. The electricity production from a wind turbine, a CHP and a fuel cell satisfies the local electricity demand. The green hydrogen produced in the hub from renewable power in off-peak hours is used to feed the fuel cell or to meet the mobility demand. The heating power from CHP and fuel cell is used to feed the local district heating network.

Frequency Dynamics in Fully Non-Synchronous Electrical Grids: A Case Study of an Existing Island

The operation of a power system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the design and the control of the system. Existing literature on the integration of renewable energy sources in isolated systems mainly focuses on energy aspects or steady-state issues, and only a few studies examine the dynamic issues of autonomous networks operated with fully non-synchronous generation. A lack of research can be found in particular in the determination of the required amount of grid-forming power, the selection of the number and rated power of the units which should implement the grid-forming controls, and the relative locations of …

A Dynamic Electrical Scheme for the optimal reconfiguration of PV modules under non-homogeneous solar irradiation

This paper presents a strategy for the maximization of the output power of photovoltaic (PV) systems under non homogeneous solar irradiation by means of automatic reconfiguration of the PV arrays layout. The innovation of the proposed approach is the employment of a simple Dynamic Electrical Scheme (DES), allowing a large number of possible modules interconnection, to be installed between the PV generator and the inverter. The models of the PV generator and of the DES have been realized and simulated with Simulink (Dynamic System Simulation for MATLAB). The attained experimental results appear to be quite interesting in terms of the attainable benefit in power and thus energy terms. The lim…

Feasible Domain-Driven Genetic Operators for Distribution Systems Optimal Reconfiguration

In this paper, the problem of minimum losses reconfiguration in weakly meshed medium voltage (MV) distribution systems is dealt with. The presence of meshes can either be a cause of the presence of particular loads, favoured customer (FC) nodes, requiring a double supply path or of distributed generation (DG) nodes, that cannot work in islanded mode. The problem has been brought back to the more general problem of radial networks reconfiguration with the major aim of minimising power losses subject to constraints on voltage drops at load nodes and current in branches as well as on the partition of power generated among supply nodes in the network. The problem is non-linear and combinatorial…

Le smart community infrastructures: la città dei servizi nella smart city

Nell’ottica della smart city, a partire dalle nuove possibilità derivate dalle infrastrutture di comunicazione, è possibile reinventare la città ed i suoi servizi. I servizi offerti dalle infrastrutture che servono una comunità, come le reti energetiche, idriche, dei rifiuti, della mobilità e le tecnologie dell’Informazione e della Comunicazione (ICT), possono essere implementati e resi più efficienti in diversi modi. Il capitolo, dopo aver delineato i contenuti del documento ISO TC 268 / SC “Smart Community Infrastrutture” dell’ International Standardization Organization, ISO, evidenzia due diversi possibili approcci alla pianificazione delle infrastrutture mutiservizio per città esistenti…

A New Mathematical Approach for Faults Identification and Location in Distribution Systems

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.

Review of space charge measurement systems: acoustic, thermal and optical methods

In the last decade, remarkable developments have concerned the methods of space charge measurement in the field of insulation systems diagnostic. In particular, methods based on acoustic and thermal phenomena have been largely used. The present review provides a broad overview on the different techniques used describing, for each of them, the working principle, the main features and the most relevant applications. Further details are provided for the Pulsed Electro-Acoustic (PEA) method, as it seems to be the most used. This article provides more details on its historical evolution, showing evidence for its technological limits and taking into consideration the advantages and drawn from the…

Analisi e definizione di strategie di gestione e controllo di sistemi di accumulo elettrico per applicazioni in reti di distribuzione attive automatizzate Report 2 – Applicazioni in reti isolate e interconnesse

Il presente Report riferisce sui contenuti e sui risultati della seconda fase delle attività svolte nell’ambito della ricerca dal titolo: “Analisi e definizione di strategie di gestione e controllo di sistemi di accumulo elettrico per applicazioni in reti di distribuzione attive automatizzate”, oggetto dell’Accordo di Collaborazione tra ENEA e DIEET sottoscritto nel corso del 2011, e in relazione agli esiti della prima fase della ricerca, di cui si riferisce nel precedente Report [1]. Le attività sono state condotte in sinergia con il personale tecnico di ENEA e sono state svolte prevalentemente all’interno dei locali e dei laboratori del DIEET di Palermo. Il Report è articolato in due part…

Analisi e definizione di strategie di gestione e controllo di sistemi di accumulo elettrico per applicazioni in reti di distribuzione attive automatizzate Report 1 – Analisi dello stato dell’arte

Il presente Report riferisce sui contenuti e sui risultati della prima fase delle attività svolte nell’ambito della ricerca dal titolo: “Analisi e definizione di strategie di gestione e controllo di sistemi di accumulo elettrico per applicazioni in reti di distribuzione attive automatizzate”, oggetto dell’Accordo di Collaborazione tra ENEA e DIEET sottoscritto nel corso del 2011. Nel corso della prima fase delle attività, a partire da un inquadramento generale dei diversi tipi di accumulo di energia elettrica (elettrochimico, meccanico ed elettrico), è stata condotta un’analisi preliminare su metodologie, sistemi d’interfaccia e tecniche di controllo dei sistemi di accumulo, in una visione …