Technological and legislative status point of stationary energy storages in the EU

Abstract European renewable generation has been supported through several policy instruments in the last decades, and this has caused a significant growth of the renewable energy sector, spurred by the ambitious climate and energy policy targets. Despite this impetuous growth, the electricity infrastructure is not yet ready to accept increasing shares of variable renewable energy sources (RES) generation, and this is causing grid balance challenges, due to the inherently variable nature of the PV and wind energy. In order to overcome this issue, allowing higher shares of renewable generation in the energy sector, energy storage (ES) systems are becoming increasingly competitive in the globa…

SAG-TENSION CALCULATION METHODS FOR OVERHEAD LINES

New High Voltage Interconnections with Islands in the Mediterranean Sea: Malta and Sicily. Analysis of the Effects on Renewable Energy Sources Integration and Benefits for the Electricity Market

The present paper shows the benefits coming from the operation of the recent electrical high voltage (HV) interconnections between Sicily, Malta and mainland Italy. These new interconnections allow zonal prices of electricity considerably lower than in the past, ensuring greater flexibility to the system and a better integration of Renewable Energy Sources (RES). After briefly illustrating the two high-voltage electrical systems (Sicily and Malta), and having provided a description of the interconnection cable with Malta and its protection devices, the authors hypothesized two modes of operation (Sicily-Malta system islanded or interconnected to the rest of Europe). For the first case (isla…

EU transition in power sector

Abstract In the past, much of Europe’s electricity grid network has been designed in consideration of the locations of conventional generation plants. However, a large share of today's renewables production – notably variable wind and solar – does not correspond to this grid architecture. Interconnectors, in addition to internal infrastructure, are key to creating new electricity corridors to connect areas of surplus to areas of scarcity. In this context, in 2014 the European Council, in recognizing that a fundamental role of transmission infrastructure is to enable the integration of areas of high renewable energy potential with main consumption areas, endorsed the proposal by the European…

Real-time pricing for aggregates energy resources in the Italian energy market

Abstract Over the last decade, the architecture of the energy market has radically changed. In many countries end-users are now able to directly access the market, which has given rise to the question of how they can actively participate in that market. End-users can comprise a critical mass through aggregation that is carried out by a third party – to wit the “loads aggregator.” This paper proposes a new framework for generating feasible real-time price curves for those end-users in a demand-response management process. The underlying algorithm generates output curves as the solution to a constrained optimization problem whose objective function is the aggregator's economic benefit. A case…

Contract for the support of household appliances control and monitoring application interworking specification

Master-Slave Control of Battery/Supercapacitor Based Hybrid Energy Storage System for E-Vehicle Application

In this paper, management and control problem of hybrid energy storage system (HESS) has been solved by master-slave control strategy. Heuristic fuzzy rules based algorithm is developed for optimal power sharing between different power sources. The master control is followed by a slave level controller, designed by using terminal synergetic control method for tracking. Moreover, the stability analysis of closed-loop system has been carried out by using lyapunov theory. Finally, the proposed method has been tested in MATLAB/Simulink environment under Worldwide Harmonised Light Vehicle Test Procedure (WLTP).

An Investigation of Protection Devices Coordination Effects on Distributed Generators Capacity in Radial Distribution Systems

In the recent years, with the concept of Smart Grid, there are a great interest in integration of renewable energy based distributed generation (DG) units at distribution level. Along with a number of benefits, penetration of DG units in the distribution system imposes some serious challenges; protection requirements turns up as one of the most critical challenge in DG integration. In this paper the possibility and the potentiality of occurring mis-coordination between protection devices in radial distribution network is studied. The impacts of protection devices coordination on DG capacity are investigated. The penetration level, number, and location of interconnected DGs are used as param…

Agricultural feedstocks of two Brassica oilseed crops and energy cogeneration with pure vegetable oil for a sustainable short agro-energy chain in Sicily (Italy)

Abstract Potential energy feedstocks from conventional agriculture usually include pure vegetable oil (PVO) and agricultural/forest residues. Their uses can represent a starting point for the development of short agro-energy chains in the south areas of the Mediterranean region. This paper focused on testing and awareness raising of biofuel production for the cogeneration of electricity and heat from PVO of two Brassica oilseed crops in Sicily (Italy). The main aims of this study were: i) to evaluate the agronomic performance of rapeseed (Brassica napus L. var. oleifera D.C.) and Ethiopian mustard (Brassica carinata A. Braun) in semi-arid climate condition; ii) to analyze the quality of PVO…

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

A new approach to increase the integration of RES in a mediterranean island by using HTLS conductors

Today, in many countries, it is very difficult to build new power lines, especially because of right of way authorization problems. Furthermore, the production of electricity from renewable sources is growing more and more. For these reasons Terna S.p.A. (Italian TSO) has to take advantage of existing overhead transmission lines. In order to increase the transmission capacity and the exportation of RES (Renewable Energy Sources) from Sicily to the mainland, the existing high-voltage power grid in Sicily has been studied and analysed by Neplan®, which is a powerful software tool able to analyze, plan, optimize and simulate electrical power grids. This paper, after a description of existing p…

No-Load Energization of Very Long EHV Mixed Overhead-Cable Lines

DE.DU.ENER.T. project: A prototype of a sustainable energy microsystem

The paper presents a prototype of a microsystem for the integration and the optimal management of renewable energy sources in order to attain a reduction of the total energy consumption of a not residential building. The system composed by the building and the prototype is an energy sustainable microsystem and is located in Italy in the city of Valderice. The microsystem has been conceived in the ENPI (European Neighborhood and Partnership Instrument) cross-border cooperation Italy - Tunisia 2007-2013 DE.DU.ENER.T. (Le DEveloppement DUrable dans la production ENERgetique dans le Territoire) research project framework. In the paper the purposes of the DE.DU.ENER.T. project are presented and …

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…

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…

Transient behaviour of a “mixed” overhead-cable EHV line under lightning events

Recently, in many countries have been undergone or are planning links with AC extra-high voltage (EHV) underground cables. Cable lines offer the possibility of a reduced environment impact and for this reason they are often the only alternative for the reinforcement or the expansion of power system accepted by public opinion. The coexistence of overhead and cable line in the so called ¿mixed¿ lines, however, raises several questions regarding their behaviour both in steady state and in transient. The purpose of this work is to investigate the transient behaviour of a mixed overhead-cable EHV line under lightning events, describing the effects of the following overvoltages on the system. The…

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…

Dynamic Thermal Rating degli elettrodotti in Alta Tensione. Un caso studio nella rete siciliana

I dispositivi DTR (Dynamic Thermal Rating) permettono un miglior utilizzo degli elettrodotti esistenti, in un’ottica di ottimizzazione dell’infrastruttura elettrica.

Energy Management of a Hybrid Photovoltaic-Wind System with Battery Storage: A Case Report

This work presents a case report related to the management and the monitoring of a hybrid photovoltaic-wind system with battery energy storage, installed at the administrative offices building of the municipality of Valderice (Italy) within the framework of the Italy-Tunisia ENPI cooperation project Le Développement Durable Dans la Production Energétique Dans le Territoire (DE.DU.ENER.T.). The paper describes the hybrid system and briefly reports the monitoring data for a whole year, comparing the real production with the expected one and evaluating some performance indexes of the system. The performance indexes are very simple and have been defined only with the purpose of sh…

The Energy Market Impact of Climate Change on Electricity Generation in Europe

In this paper, the policy trend in Europe towards the emission reduction target in the energy sector, as planned from the Paris Agreement, is analyzed. Although renewable energy sources are improving their share, the large use of coal as primary fuel and the uncertainty about nuclear production makes the transition hard. It's well known that future emission patterns from energy generation influence the climate change trend, but as shown in the following, there is also a reverse interrelation, due to the different environmental conditions caused by climate change affecting all generation technologies. Furthermore, energy prices, which derive from this changed framework likewise will influenc…

CONDUCTORS FOR THE UPRATING OF OVERHEAD LINES

Methodologies for the Exploitation of Existing Energy Corridors. GIS Analysis and DTR Applications

The exploitation of power lines currently in operation has now become a common practice among electric system operators. The construction of new power lines requires taking economic, political and social problems into consideration. This paper considers two methodologies adopted by the Italian Transmission System Operator (TSO), Terna S.p.A.: Dynamic Thermal Rating (DTR) and Laser Imaging Detection and Ranging-Geographic Information System (L-GIS). DTR systems dynamically calculate the real transport capacity of a power line. The L-GIS system allows, after the geo-referencing of the power line, the management of any interference between the line and the nearby obstacles, permitting the opti…

Improving angle stability by switching shunt reactors in mixed overhead cable lines. An Italian 400 kV case study

Stringent environmental constraints make the construction of new transmission overhead lines more and more difficult. Alternatively, today it is possible to use cable lines for high (HV) and extra-high (EHV) voltage systems. The configuration of the so-called mixed lines can create some problems in the operation of the electrical system, both during steady-state and transient conditions. In particular, the system stability is one of the main concerns when analyzing the dynamic response of power systems. In this paper, the study of angular stability of a system containing a mixed line is presented: a specific control logic applied to the shunt reactors of the mixed line is proposed as improv…

Analisi economico-finanziaria degli investimenti sul fotovoltaico in Italia

Alla luce del meccanismo incentivante vigente in Italia a favore degli impianti fotovoltaici e dei risultati raggiunti in termini di numero di impianti e potenza installata, si riporta un’analisi di sensitività degli indici di redditività dell’investimento e le prospettive di sviluppo potenziale del fotovoltaico in Italia sino al 2020.

COMPORTAMENTO TERMICO DEI CONDUTTORI PER LINEE AEREE

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 the roadmap to supergrid in Sicily: LiDAR technology and HTLS conductors for uprating the 150 kV lines

Difficulties in building new power lines in Italy because of authorization problems, and the production of electricity from renewable sources growing more and more, induces Terna S.p.A. (Italian TSO) to take advantage of existing overhead transmission lines. In order to increase the transmission capacity, Terna has used a software in GIS (Geographic Information System) environment which allows for the management of the interferences according to all the legislative bonds by referring to the LIDAR (Laser Imaging Detection and Ranging) remote sensing technology. This paper, after a description of the GIS and the LiDAR technology, shows how the calculation of the current capacity of some High …

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…

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.

Uprating an Overhead Line. Italian TSO Applications for Integration of RES

The increase of Renewable Energy Sources (RES) production units has caused significant changes in the electrical system configuration. The existing structural asset isn't adequate to dispatch these new power flows that, at same time, should be favorite by various TSOs in order to obtain incentives. The outage of primary substations on the grid and the increase of consumptions have caused growing load currents on existing overhead line. This paper, after introducing thermal resistant conductors and Dynamic Rating (DR) solutions, reports an applications used by TERNA Group S.p.A. (Italian TSO). These systems are already installed on lines and they are contributing to increase power flows than…

Transient stability assessment of SMIB System with Mixed overhead-cable line – Sensitivity analysis

Steady-state security analysis on the transmission grid for various scenarios of wind generation in Sicily

The proposed paper is part of a research aimed at assessing the impact of wind generation on the transmission grid of Sicily, second among the Italian regions for wind power installed. After describing the current state of wind energy generation in Sicily, the paper reports and comments the results of the steady-state security analysis done for various scenarios of wind penetration. For each scenario (maximum and minimum load conditions), the redistribution of power flows on the transmission network, the voltage profiles at nodes, the analysis of contingencies and losses variations are reported.

Sicilia-Malta: il nuovo collegamento RTN a 220 kV in corrente alternata

Descrizione dettagliata degli aspetti tecnologici e delle prestazioni funzionali di maggiore rilevanza sui cavi utilizzati, sui sistemi e sulle logiche di protezione contro i guasti. Vantaggi, potenzialità e criticità legate all’esercizio.

An experimental study on relationship between LED lamp characteristics and non image-forming

The general aim of the experimental study, presented in this paper, was that to investigate the relationship between the characteristics of five different types of LED (Light Emitting Diode) lamps, which are nowadays those allowing the highest energy consumption reduction, and the humans non image-forming (NIF) reactions.

HTLS Conductors: A Way to Optimize RES Generation and to Improve the Competitiveness of the Electrical Market—A Case Study in Sicily

Stringent environmental constraints make more difficult to identify new energy corridors and build new power lines. The increase in the generation of electricity from renewable energy sources (RESs) makes the operation of electrical systems increasingly difficult in some areas. The transmission system operators (TSOs), in Italy Terna, are forced to exploit the existing overhead transmission lines, increasing the possibility of dispatching energy, in particular RES, optimizing the transmission capacity. Therefore, after a brief presentation of the Sicilian electricity system and a brief description of high-temperature low-sag (HTLS) conductors, a case study is presented. It is shown how it i…

A Simulation Analysis for Assessing the Reliability of AC/DC Hybrid Microgrids - Part I: Underground Station and Car Parking

This paper reports the results of a simulation study with the aim of evaluating the capability of two portions of a hybrid AC/DC MV/LV network of maintaining their operation in off-grid mode during the loss of the main AC grid due to a failure. In particular, the study aims to verify, in the case of islanded operation of the two microgrids, the continuity of the electricity service by exploiting the local generation plants, Energy Storage Systems (ESSs), and other flexible resources managed by suitable algorithms in different energy scenarios. The analysis was carried out considering two microgrids: an underground station and a car parking with Electric Vehicles (EVs). For assessing the per…

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…

Optimization of BESS Capacity Under a Peak Load Shaving Strategy

Battery energy storage systems (BESSs) are becoming increasingly competitive in the global energy landscape, thanks to the strong cost reduction that has taken place in recent years and it is expected to continue in the next future. Among the many benefits BESSs can provide, time shifting can be exploited by electricity consumers to save on the electricity bill, charging the storage during the off-peak hours and discharging when the cost of electricity is high. This paper describes a simple procedure to optimize the BESS capacity under a peak load shaving strategy, in presence of a time-of-use (TOU) electricity rate, able to guarantee, at the same time, the flattest daily power diagram and …

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…

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.

Economic analysis on dynamic photovoltaic systems in new Italian "feed in tariffs" context

Dynamic photovoltaic generators, based on the application of solar-trackers, are able to give an increment to the electric energy production from solar source. Their realization and maintenance costs are certainly higher than those of fixed ones. In this paper the Authors propose a method to estimate the increment of electrical energy generation that must be guaranteed by a dynamic photovoltaic generator, so as its realization could be more favorable with respect to that of a fixed generator one with the same rated power. This method, developed by means of classical economic indexes like the Pay-Back-Period and the Net Present Value, takes in to account the economic incentives for the PV sy…

Fixed speed wind turbine generator model validation and dynamic simulation using Matlab/Simulink

In the last two decades an increasing amount of electricity has been generated from renewable sources in order to mitigate the environmental impact of the conventional power plants. In the next future wind turbines may affect the behaviour of electrical power system. This paper describes the model of a typical fixed speed wind turbine connected to the grid; the model is developed in the simulation tool Matlab/Simulink. It’s composed by the aerodynamic system, the shaft model (two-mass system), the induction generator (fifth order model) and the stall control system of the wind turbine rotor. The validation of the wind turbine model is made in steady-state operation, and the results are veri…

THE GRID SIMULATOR

Dynamic Control of Static Converters for the Transition from Grid-on to Grid-off Operation of AC/DC Microgrids

In this paper, specific control logics defined for generators, controllable loads and electric energy storage systems are illustrated in order to improve the reliability of AC/DC hybrid microgrids in their grid-off operation following failure events such as short-circuits, line breaks, sudden disconnections of generating units or loads, etc. After defining specific control schemes, these were modelled in a digital environment and finally tested with dynamic simulations. Finally, the paper highlights the role of virtual synchronous machine control for the self-healing capacity of islanded hybrid microgrids.

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…

Angle Stability Improvement by Switching Shunt Reactors in Mixed Overhead-Cable Lines

Challenges in Energy Systems for the Smart- Cities of the Future

In the last years the European Union has actively promoted the renewable energies and the Combined Heat and Power (CHP) also for residential and tertiary buildings. The exploitation of renewable sources and cogeneration seems hampered by the regulatory wall that prohibit for residential, tertiary and commercial buildings the constitution of users clusters. In fact, the unification up to a threshold value of some tens of kVA, at least, can facilitate the installation of renewable energy power plants as solar PV modules or CHP systems (cogeneration) or CCHP systems (tri-generation), overcoming technical and economical barriers and combining several load profiles. The actual distribution syste…

Simulation of photovoltaic installation connected to the grid with storage system

Abstract In the present paper, a new approach for the management of energy resources in a research laboratory is proposed and evaluated. A simulation study for the photovoltaic (PV) installation was conducted under the Tunisian-Italian cooperation project DE.DU.ENER.T, using renewable energy and economic criteria. The aim of the study is to improve the energy efficiency in order to minimize the electricity cost consumed in the laboratory. A Hybrid Renewable Energy System consisting of a photovoltaic field of 12KWc was installed to reduce the exorbitant bills, due to intensive energy equipment such as drying ovens and workstations, using sustainable, green and clean sources. In addition, a s…

Energy saving and user satisfaction for a new advanced public lighting system

Abstract The retrofit of urban lighting systems is often an advantageous means of achieving notable energy savings and improvements in the quality of light. User habits, expectations and lifestyle can contribute to the design of these systems, for example in deciding on the most appropriate control strategies or the light quality. The influence of such variables can be extended to the overall system performance. This paper presents a method of street lighting design based on two kinds of analysis carried out in a defined test area: measurements (by means of a monitoring study) and user preferences (by means of a survey). The results of this data analysis create the basis for the final desig…

Maximizing energy transfer and RES integration using dynamic thermal rating. Italian TSO experience

The production of electricity from wind and other renewable sources is rapidly increasing all over the world, causing significant changes in the management of electrical systems. The current structural asset is not adequate to manage this growing generation of energy. The hypothesis of construction of new power lines would mean taking into consideration economic, political and social problems. The following paper reports the experience gained by the Italian TSO, Terna S.p.A, on the use of the DTR (Dynamic Thermal Rating), which is able to dynamically calculate the real transport capacity of an overhead power line. The results obtained are en- couraging as they show how it is possible to inc…

Risk evaluation and creep in conventional conductors caused by high temperature operation

The advent of electricity market deregulation, the increased operating and overload temperatures of transmission line conductors have caused concern among TSOs (Transmission System Operators) and DSOs (Distribution System Operators) about the effect of elevated temperatures on conventional bare conductors of existing line. Nowadays building new lines is very difficult cause of increased costs to obtain rights of way, public intervention, etc.... Cost and lead times required to place new lines into service are now increased and the business in electric market is reduced for the limited possibility of transmission. Therefore, utilities are attempting to gain as much capacity as possible modif…

A bottom-up approach for the evaluation of the flexible quota of aggregated loads

The paper presents a bottom-up approach for building the aggregated load profile of numerous passive/active users connected to the low voltage electrical system. The approach is based on the Monte Carlo method and on the knowledge of the single electric and thermal loads, generators and thermal and geometrical characteristics of the building of the single end-user. The method proposed is able to differentiate the quota of flexible and not flexible aggregate load.

Effects of Demand Side Management on the Operation of an Isolated LV Microgrids

The work presents the results of a study regarding the impact of Demand Side Management actions on flexible loads distributed at the domestic end-users' facilities in an isolated low voltage microgrid. Aim of the research study is to evaluate how the implementation of local control actions on the end-user's side can impact on the operation of the isolated microgrid. The Demand Side Management is applied by each domestic user to optimize the operation of its own resources following well-defined operative steps. The study is carried out implementing a suitable model of the microgrid in Neplan environment, while the daily controlled load profiles of the end-users are evaluated using the Montec…

The evolution of the FIT mechanism in Italy for PV systems: a critical analysis

The paper presents an analysis of the Feed'in Tariffs (FIT) mechanism development in Italy from 2005 to 2013 and named “Conto Energia”. In particular the work examines the five editions of the “Conto Energia”, highlighting both advantages and critical issues for the PV market development in Italy; this analysis is particular interesting due to the fact that the cap on FITs in Italy has been reached in June 2013.

Agronomic performance and energetic potential of two Brassica oilseed species in Sicily, Italy

Industrial crops for energy purposes are object of increasing interest worldwide and play an important role as a source of renewable energy. The aims of this study were to evaluate: i) the agronomic performance of Brassica napus L. var. oleifera D.C. and Brassica carinata A. Braun in a semi-arid environment; ii) to evaluate the economic viability of a pilot combined heat and power (CHP) plant operating on pure vegetable oil (PVO). The research was carried out in Sicily (Italy). The main biometric and yield parameters of the two species were determined. Chemical-physical characterizations were carried out on PVO for each species using specific protocols. The cogeneration of renewable energy …

Energy Management via Connected Household Appliances

The study reported hereafter provides results based on a campaign of simulations conducted by University of Palermo on the basis of its knowledge in the field Energy Value Chain and in the field of Energy Management (EM) for household appliances. Inputs from CECED Convergence WG has been fundamental to base that study on realistic data and cases. Moreover, the so called EM study, offers also a clear picture about the opportunity to have energy management applications and services in house, being those opportunities strictly related to the cost of in- frastructure needed and to the benefits belonging to different actors in the energy value chain. Energy savings have been considered both in t…

Innovative algorithms for the management of combined RES-BESS systems

The issue of the optimal management of the available energy resources also at end-user level is getting more and more attention. The paper deals with the definition of innovative algorithms for managing electrical storage systems in hybrid photovoltaic and wind plants, also taking into account different pricing periods and a grid emergency condition in which the Utility can request an injection of power by the end-user. Application examples for explaining the operation of the algorithms are presented.

Wind Turbine Mechanical Characteristics and Grid Parameters Influence on the Transient Voltage Stability of a Fixed Speed Wind Turbine

This paper describes the effect of wind turbine mechanical characteristic of construction and grid parameters on the transient voltage stability of a fixed speed wind turbine (FSWT) connected to a simple grid. The model of FSWT has been developed in Matlab/Simulink. Using this model, a three-phase fault is applied close to the wind turbine (WT) and cleared by disconnecting the faulted line. The effects of mechanical construction of WT and of grid parameters on the voltage stability of this simple case are evaluated and discussed. The considered parameters are the inertia coefficient of the WT, the short-circuit power at the connection bus, the hub-generator resonant frequency, the wind spee…

Experimental study of the combined RES-based generators and electric storage systems for public buildings

Abstract In the present paper, a new approach to the management of energy resources in the Research and Technology Centre of Energy (CRTEn -Tunisia) is proposed and evaluated by the monitoring of a PV installation realized for the cooperation project DE.DU.ENER.T, using renewable energy and economic criteria. The aim of this project is to improve energy efficiency order to minimize the electricity cost consumed at the CRTEn laboratory. According to the bills of electricity received, we noticed that there is a high consumption of electrical current. So, we targeted to install a photovoltaic field of 12KWc to reduce these bills by using the sustainable, green and clean sources. A theoretical …

Analysis of the new submarine interconnection system between Italy and Malta: Simulation of transmission network operation

In this paper, some simulations of the interconnected Sicilian and Maltese transmission systems are performed, in order to assess this new system configuration. The HVAC submarine interconnection between Italy and Malta came into operation in 2015 and is part of a European programme for transmission grid interconnection improvement. This new line has been built in order to allow a better management of the power system of both the islands. Firstly, a brief description of the interconnection system is given. Moreover, the transmission systems of Sicily and Malta are depicted and their structures are shown. The simulations are carried out by means of a model of the interconnected system create…

A Power Sector in Transition Understanding Transition Towards a Cleaner Grid and how Distributed Energy Resources Affect the Design and Operation of Electric Power Systems

Important changes in the supply and the demand side of electricity apparatus are now underway, triggered by a combination of drivers dramatically affecting the transmission sector of power systems: greenhouse gas emissions, distributed generation, energy efficiency and the full integration of the European energy market. A variety of accelerating factors - including active consumer, aggregators, energy storage, e-vehicles, etc..- are creating a new era for the many stakeholders, incl. system operators, regional entities, industry and consumer organizations, producers or their trade bodies, Regulators, public decision makers and the society at large. Entraining this background, ENTSO-E and th…

On the effects of BAC systems and load control programs on the utility grid

The electricity demand increasing for the comfort improvement in residential buildings is nowadays stressing the MV and LV networks in urban areas. In this framework, the Distribution System Operators (DSO) are exposed to the risk of reliability decrease and there is, earlier than expected, the issue of new and substantial investments for enhancing the network infrastructure. Nevertheless, DSOs have a very strong inclination to defer investment in new facilities in favour of more "flexible measures" for improving the life of the existing components. Solutions of this type are primarily based on demand management, i.e. activities aimed at encouraging the end-users to a different/smart electr…

A comparative analysis of different methods of reactive power pricing

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.

Transient stability simulation of a fixed speed wind turbine by Matlab/Simulink

This paper describes the dynamic behavior of a typical fixed speed wind turbine connected to the grid; the model is developed in the simulation tool Matlab/Simulink and created as a modular structure. The pitch control system is used for stabilization of the wind turbine at grid faults. In this way, voltage stability of the system with grid-connected wind turbines can be improved by using blade-angle control for a temporary reduction of the wind turbine power during a short-circuit fault in the grid. This paper shows a new variable control for maintaining of voltage stability, when a three-phase fault is applied close to the wind turbine and cleared by disconnecting the affected line. In th…

Effects of Electrical Parameters of Induction Generator on the Transient Voltage Stability of a Fixed Speed Wind Turbine

This paper describes the effect of electrical parameters of the induction generator on the transient voltage stability of a fixed speed wind turbine connected to a simple grid; the dynamic behavior of a wind turbine connected to the grid is examined. The model of the fixed speed wind turbine has been developed in the simulation tool Matlab/Simulink. Itpsilas composed by the induction generator, the shaft system, the aerodynamic model of the wind turbine rotor and the pitch control system. Using this model, a three-phases fault is applied close to the wind turbine and cleared by disconnecting the faulted line. The effect of different electrical parameters of the induction generator on the vo…

A statistic approach of cables ageing in MV lines on thermal and electrical combined stress

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

2015–2020. Sicily and Italy as electricity hub in the mediterranean area for the development of the European power grids interconnections

Falling demand and explosion of Renewable Energy Sources (RES) are redesigning the criteria for planning the power grids interconnections by ENTSO-E. In particular, the interconnections between networks of different countries have been acquiring importance more and more, in view of an unique European market for electricity and an increase of RES. Italy and Sicily, placed in the centre of the Mediterranean Sea, play a fundamental role as a bridge between Central Europe, North Africa area and Mediterranean islands (electricity hub). This paper aims to show how power system exchanges tend to follow the direction from South to North, and how the impact of North-African power — mainly generated …

Control of solid-state fault current limiter for DG-integrated distribution systems

Fault current limier (FCL) is a device that limits the system current under fault conditions without disconnecting the system and affecting the power system protection components such as circuit breakers. Many types of FCLs have been proposed to limit the magnitude of the fault current. Solid-state fault current limiters (SSFCLs) can limit the peak value of the fault current by applying several methods, such as controlling the system impedance or controlling the voltage that appears across the fault. In this paper, a new control scheme for the SSFCL circuit is presented. The control method is based on controlling the duty cycle of solid state switches to control the rms value of the system …

Demand side management and Distributed on Site actions benefits

Global warming and energy demand are nowadays becoming one of the major issues of the third millennium, mainly because human activities seem to have a clear impact on the raise of CO2 emissions as never it has been experienced in the past. Among the different factors affecting CO2 emissions, energy demand from buildings constitutes one of the most important actors. Energy Management (EM) actions can reduce the energy consumption of the system and minimize peaks-level, by using a distributed control over every house. These local actions can greatly contribute to reduce the impact on the global CO2 emissions. An evaluation of the potential energy saving and CO2 emissions reduction on building…

Investigating the effect of distributed generators on traditional protection in radial distribution systems

The recent changes in power network structure, development in green energy technologies and increased attention on environmental concerns have led to increase the installation of renewable energy based distributed generations (DG) in distribution networks. The increasing penetration of distributed generation in the distribution power system creates new technical and economical challenges; protection is one important topic of these challenges. High penetration of DG will have unfavorable impact on the traditional protection methods; the impact depends on the number, location and size of injected DG. To ensure safe and selective protection devices coordination, the impact of DG should be take…

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

A stochastic approach for self-healing capability evaluation in active islanded AC/DC hybrid microgrids

This paper aims to implement a resilience assessment in AC/DC hybrid microgrids using a stochastic simulation approach. Self-healing measures including load shedding, control of distributed generation and flexible devices, like Energy Storage Systems (ESS) and Electrical Vehicles (EVs), are simulated to enable AC/DC hybrid microgrids to supply critical loads in islanded mode, assuming a disconnection of these microgrids from the main AC grid due to a fault. To perform this analysis, a two-stage process is proposed: first, a Monte-Carlo simulation-based stochastic approach is adopted to generate samples to simulate intermittent loads, power generation from Renewable Energy Sources (RESs), an…

New Energy Corridors in the Euro-Mediterranean Area: The Pivotal Role of Sicily

The present paper deals with the new opportunities deriving from the interconnections of the European and North African transmission systems. In order to achieve a single international market for electricity exchanges, interconnections between networks in different countries are becoming increasingly important and Sicily, for its geographical position in the middle of the Mediterranean Sea, will undoubtedly play an important role as an electrical bridge between Europe and the North Africa in the near future. The paper, presenting the actual electro-energetic context of Tunisia, reports the new important interconnection already realized in South Italy (in particular in Sicily) and describe t…

CONSIDERATIONS RELATING TO THE USE OF HIGH TEMPERATURE CONDUCTORS

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.

Study and simulation of photovoltaic installation connected to the grid with storage system

In the present paper, a new approach to the management of energy resources in a research laboratory is proposed and evaluated by a simulation for the PV installation realized for the Tunisian-Italian cooperation project DE.DU.ENER.T, using renewable energy and economic criteria. The aim of this project is to improve energy efficiency order to minimize the electricity cost consumed at the laboratory, because according to the bills of electricity received we noticed that there is a high consumption of electrical current, from the STEG grid, and especially by the energy intensive equipment such as drying ovens and all the workstations. So we targeted to install a photovoltaic field of 12KWc to…

Monitoring of renewable energy prototype for the DEDUENERT research project

In this paper, we present a renewable energy sustainable micro-system installed upon a platform located in the Research and Technology Centre of Energy in Borj Cedria Techno park (Tunisia). This prototype has been conceived within the ENPI (European Neighborhood and Partnership Instrument) cross-border cooperation Italy-Tunisia 2007–2013 research project framework. This project's overall goal is to develop a common strategy for the deployment of renewable energy and energy efficiency by endorsing the cooperation between Italy and Tunisia. The focus is to implement the use of sustainable energy microsystems that generate electricity from various renewable sources (solar thermal, photovoltaic…

CONDUTTORI TERMO-RESISTENTI

Maximizing energy transfer and RES integration using dynamic thermal rating

Abstract The production of electricity from wind and other renewable sources is rapidly increasing all over the world, causing significant changes in the management of electrical systems. The current structural asset is not adequate to manage this growing generation of energy. The hypothesis of construction of new power lines would mean taking into consideration economic, political and social problems. The following paper reports the experience gained by the Italian TSO, Terna S.p.A, on the use of the DTR (Dynamic Thermal Rating), which is able to dynamically calculate the real transport capacity of an overhead power line. The results obtained are encouraging as they show how it is possible…

Effect of voltage deviations on power distribution losses in presence of DG technology

Integration of distributed generation (DG) units in power distribution network has become increasingly attractive multi-faceted paradigm as economic and environmental factors drive new technologies to be more efficient and less polluting than their earlier counterparts. The installation of DGs impacts critically on the planning and operating characteristics of the distribution network. Type, location, number and capacity of DG are essential factors for studying the effect of DGs on the system behavior. In this paper the effect of DG on the power losses of a distribution network is investigated for different types of DG units. Also, the impact of DG on the voltage profile is demonstrated bef…

Experimentation of sustainable energy microsystems: The DE.DU.ENER.T. research project

The paper focuses on an energy sustainable prototype micro-system installed upon a roof of a building in Valderice (Italy). This micro-system has been conceived in the ENPI (European Neighborhood and Partnership Instrument) cross-border cooperation Italy - Tunisia 2007–2013 DE.DU.ENER.T. (Le DEveloppement DUrable dans la production ENERgetique dans le Territoire) research project framework. The main aim of this project is the construction of a sustainable energy micro-system prototype suitable for the optimal integration and management of renewable energy resources (photovoltaic, wind and solar thermal) and to reduce the building's energy consumption. In the paper the project and the protot…

CONDUTTORI TERMORESISTENTI PER AUMENTARE LA CAPACITA' DI TRASPORTO DELLE LINEE ELETTRICHE AEREE

Building Automation and Control Systems and Electrical Distribution Grids: A Study on the Effects of Loads Control Logics on Power Losses and Peaks

Growing home comfort is causing increasing energy consumption in residential buildings and a consequent stress in urban medium and low voltage distribution networks. Therefore, distribution system operators are obliged to manage problems related to the reliability of the electricity system and, above all, they must consider investments for enhancing the electrical infrastructure. The purpose of this paper is to assess how the reduction of building electricity consumption and the modification of the building load profile, due to load automation, combined with suitable load control programs, can improve network reliability and distribution efficiency. This paper proposes an extensive study on…

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

This work examines the operation of the autonomous power system of a geographical island assuming the integration of significant generation shares from renewable energy sources and the installation of the required storage systems. The frequency stability of the system is investigated considering different operating conditions, in terms of load demand and renewable power generation. The main focus of the work is an original control strategy specifically designed for power converters interfacing storage units to the grid. The proposed strategy is based on an extended frequency droop control, which selects specific droop settings depending on the operating mode—charge or discharge—of the stora…

GIS systems and LIDAR technology for the operation of HV lines. Sicilian transmission network applications

The difficulties to build new power lines within the national territory cause of authorization problems, and the evermore growing production of electricity from renewable sources, induces Terna S.p.A. (Italian TSO) to take advantage of existing overhead transmission lines. Therefore, in order to increase the transmission capacity, and to optimize the maintenance and management of power lines, for some years Terna has been using a software in GIS environment (Geographic Information System) that referring to the LIDAR (Laser Imaging Detection and Ranging) remote sensing technology, allows to manage the interferences according to all the requirements and legislative bonds and to fulfill the im…

Reassessment of voltage stability for distribution networks in presence of DG

There is a growing interest in integrating renewable energy based distributed generation (DG) in the electrical power distribution networks. The installation of DG units at distribution level impacts critically the planning and operation characteristics of the network. The type, location, number and capacity of the integrated DGs affects system behavior and performance. In this paper the effect of installing new DGs on the distribution network voltage stability is studied. The optimal location of the newly installed DGs are decided based on the Power Stability Index (PSI) and Voltage Stability Index (VSI). Moreover, Voltage Stability Margin (VSM) of the interconnected DG distribution networ…

CONDUCTORS FOR THE UPRATING OF OVERHEAD LINES

EU transition in power sector: How RES affects the design and operations of transmission power systems

In the past, much of Europe's electricity grid network has been designed in consideration of the locations of conventional generation plants. However, a large share of today's renewables production – notably variable wind and solar – does not correspond to this grid architecture. Interconnectors, in addition to internal infrastructure, are key to creating new electricity corridors to connect areas of surplus to areas of scarcity. In this context, in 2014 the European Council, in recognizing that a fundamental role of transmission infrastructure is to enable the integration of areas of high renewable energy potential with main consumption areas, endorsed the proposal by the European Commissi…

Verifying the effect of distributed generators on voltage profile, power losses and protection system in radial distribution networks

In the recent years the electrical power networks are undergoing rapid restructuring and developing process worldwide. Advancement in technologies and concern about the environmental impacts have led to increase interconnection of renewable energy based distributed generations (DGs) in distribution networks. The DGs have significant impacts on the distribution systems; these impacts may be either positively or negatively depending on the modified interconnected DG distribution network structure. It will be necessary to consider many issues concerning these impacts. In this paper, an investigation of DGs impacts on voltage profile, power losses, and protection system in radial distribution n…

ALTERNATING CURRENT (AC) RESISTANCE OF HELICALLY STRANDED CONDUCTORS

The electrical resistance of helically-stranded conductors (aluminium and aluminium alloy), intended for use in distribution and transmission lines, depends on the conductor cross-section area, the conductivity of the aluminium alloy, the lay length of the aluminium layers, and the presence or absence of a steel reinforcing core. The presence of a stranded steel core both reduces the conductor resistance due to the conductivity of the galvanized steel wires and increases the resistance due to core magnetizing effects. This brochure describes a process of calculation for stranded aluminium conductors both with and without a steel reinforcing core. APPENDIX A provides a MathCad programme to d…

A Simulation Analysis for Assessing the Reliability of AC/DC Hybrid Microgrids - Part II: Port Area and Residential Area

This paper reports the second part of a simulation study with the aim of evaluating the ability of two portions of a hybrid AC/DC MV/LV network in maintaining their operation in off-grid mode during the loss of the main AC grid due to a failure. In particular, this paper follows a dual purpose: first, it analysis two microgrids in a residential area and a port zone capability of operating in islanded mode, applying a probabilistic approach, while there is different energy use cases, and second is to evaluate some reliability indicators.

Impact of non-programmable renewable sources in Day-Ahead Market in Sicily. Reasons to make more flexible and smarter the national transmission grid.

This article describes technical and market aspects that characterize the Sicilian electrical system, the non-programmable renewable sources impacts on the energy markets (Day-Ahead Market and ancillary services market) and on Sicilian system operation, to evaluate the grid integration of renewable energy sources in a future Sicilian smart grid.

A framework to determine maximum capacity of interconnecting DGs in distribution networks

Interconnecting Distributed Generation (DG) in the distribution network is considered as an important area of power system planning. When the DG placed inappropriately, the DG can have negative impact on some important and critical characteristics of system performance such as increased power losses, degraded voltage profile, and mis-coordination between protection devices. This paper introduces a framework to determine the maximum capacity limits of interconnecting DG units in radial distribution networks in order to keep protection scheme unchanged, while the voltage profile remains within acceptable range and on the same time having the minimum power losses in the network; applying this …

Le fonti rinnovabili in Sicilia: impatti sul mercato zonale e sulla gestione del sistema elettrico

L’articolo descrive gli aspetti tecnici e di mercato del sistema elettrico siciliano mettendo in evidenza le cause che hanno portato all’aumento del prezzo zonale nelle ore serali, gli effetti che le FRNP hanno sui mercati elettrici (MGP e MSD) e sulla gestione del sistema elettrico siciliano.

Feasibility analysis and study of a grid-connected hybrid electric system: Application in the building sector

This paper represents the feasibility study and analysis of a grid-connected hybrid (PV-Wind) system with battery, realized within the project DE.DU.ENER.T and installed in the research centre CRTEn located in the northern Tunisia in the city of Borj-Cedria. The main objective of this work is to exploit renewable sources of electrical energy production to electrify the desired building. So, to minimize electricity consumption costs, reduce the adverse effects of pollutants products from the diesel power systems and sometimes happen to sell the surplus of energy produced. The HOMER (Hybrid Optimization Model of Electric Renewable) software is used to estimate system size and its performance …

Numerical implementation of active power flow tracing methods: Practical implications on transmission networks and DR programs support

The goal of this paper is to demonstrate the powerful contribution of the electric active power flow tracing methods on studying the electric transmission systems operating conditions. The tracing methods allow to impute to every generation unit and/or load the responsibility of the power flows of all the elements connected to the network. This study propose the numerical implementation of two different tracing methods on two transmission networks through Matlab® scripts developed on purpose; then the analysis is focused on identifying the loads which mostly affect the power line flows of the system. The results of this analysis point out the loads on which the application of the Demand Res…

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.

A simple operation strategy of battery storage systems under dynamic electricity pricing: An Italian case study for a medium-scale public facility

In the electricity market, wholesale energy prices depend on the balance between energy production and load demand. In the last few years, electricity market has become more and more flexible as many utilities have started to replace the fixed retail prices schemes with prices changing during the day. Dynamic pricing, also known as Real-Time Pricing (RTP), reflects the trend of the wholesale market and allows to reduce the volatility of the wholesale prices, also contributing to a reduction of demand peaks. Electricity customers take advantage of dynamic pricing by shifting their consumption according to the real-time prices or by using Battery Energy Storage Systems (BESS) to shift electri…

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…

SAG-TENSION CALCULATION METHODS FOR OVERHEAD LINES

Methodologies to uprate an overhead line. Italian TSO case study

The amount of wind power and other time-variable non-dispatchable electricity generation is rapidly increasing across the world, causing a significant change in the electrical system configuration. The existing structural asset isn't adequate to dispatch these new power that have a priority in the energy dispatching. In addiction the outage of substations on the grid and the increase of consumptions have caused growing load currents. In order to satisfy these needs, TSOs have adopted new measures on existing power lines and N-1 criteria to ensures the electrical grid security. These particular devices are Dynamic Thermal Rating (DTR) systems. After introducing thermal resistant conductors a…

Application of Monte Carlo technique to evaluate the power injectable on electrical grid by wind farms

This paper is part of a research aimed at assessing the impact of wind generation on the transmission grid of Sicily, second among the Italian regions for wind power installed. To assess the maximum degree of wind generation penetrability in full compliance with the safe operation of the system, it seemed necessary to investigate the reports of contemporary winds and their territorial correlations when load assumes the peak or the minimum. Given the nature of the problem, it has been used a method of analysis based on the application of stochastic simulation techniques type Monte Carlo. In the paper, after describing the current state of wind energy generation in Sicily and development scen…

I Sistemi GIS e la tecnologia LIDAR nella gestione degli elettrodotti AT. Applicazioni nella rete elettrica siciliana.

L’articolo, dopo la descrizione dei sistemi GIS e della tecnologia LIDAR, riporta il calcolo della portata in corrente di alcuni elettrodotti AT all’interno del territorio siciliano, al fine di sfruttare al meglio le linee esistenti e di verificare i franchi elettrici imposti dal DM n. 449 del 1988

ALTERNATING CURRENT (AC) RESISTANCE OF HELICALLY STRANDED CONDUCTORS

2015-2020. Sicily and Italy as Electricity Hub in the Mediterranean Area for the Development of the European Power Grids Interconnections

Falling demand and explosion of Renewable Energy Sources (RES) are redesigning the criteria for planning the power grids interconnections by ENTSO-E. In particular, the interconnections between networks of different countries have been acquiring importance more and more, in view of an unique European market for electricity and an increase of RES. Italy and Sicily, placed in the centre of the Mediterranean Sea, play a fundamental role as a bridge between Central Europe, North Africa area and Mediterranean islands (electricity hub). This paper aims to show how power system exchanges tend to follow the direction from South to North, and how the impact of North-African power – mainly generated …

A simulation study for assessing the impact of energy storage systems for Fast Reserve with additional synthetic inertia control on the Continental Europe synchronous area

This article shows the results of a simulation study on the application of battery storage systems for providing fast frequency regulation (the so-named Fast Reserve) with additional synthetic inertia control. The aim of the study is to assess the impact of the extension of the regulation provided by the FRUs to all the Continental Europe synchronous grid, with the same power proportions of the first Italian FRU auction. The simulations are conducted in two different scenarios: a base one related to 2020 and a future one related to 2040 and based on ENTSO-E projections for load and generation. The results show that, for the reference incident of 3000 MW, the frequency quality parameters in …

Challenges in Energy Systems for the Smart-Cities of the Future

In the last years the European Union has actively promoted the renewable energies and the Combined Heat and Power (CHP) also for residential and tertiary buildings. The exploitation of renewable sources and cogeneration seems hampered by the regulatory wall that prohibit for residential, tertiary and commercial buildings the constitution of users clusters. In fact, the unification up to a threshold value of some tens of kVA, at least, can facilitate the installation of renewable energy power plants as solar PV modules or CHP systems (cogeneration) or CCHP systems (tri-generation), overcoming technical and economical barriers and combining several load profiles. The actual distribution syste…

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.

Critical assessment of support for the evolution of photovoltaics and feed-in tariff(s) in Italy

Abstract The feed-in tariff(s) mechanism involves an obligation on the part of an electricity provider to purchase electricity generated by renewable energy sources in its relevant area, paying a tariff determined by public authorities and guaranteed for a specific time period. Feed-in tariff(s) have been the primary mechanism used for supporting the development of renewable energy sources in the EU and, up to date, they are being applied in 20 EU Member Countries. On 6 July 2013, the Italian experience with feed-in tariff(s) for photovoltaic systems finished. During its lifetime of eight years, this incentive mechanism, named “Conto Energia”, was characterized by periods of great success f…

Uprating an overhead line. Italian TSO applications to increase system N-1 security

This paper analyzes innovative devices to optimize the energy flows transmission on existing overhead lines. Indeed sometimes the structural asset isn’t adequate to manage energy generated by Renewable Energy Source (RES) in particular operating conditions. In addiction the outage of primary substations on the grid and the increase of consumptions have caused growing load currents. In order to satisfy these needs, TSOs have adopted new measures on existing power lines and N-1 criteria to ensures the electrical grid security. These particular devices are Dynamic Rating systems. After introducing thermal resistant conductors and Dynamic Rating (DR) solutions, paper reports two different appli…

Benefit at Grid Level by Using DoS Actions via Combined Photovoltaic and Solar Panel System

Economic analysis on dynamic photovoltaic systems in new Italian “feed in tariffs” context

Dynamic photovoltaic generators, based on the application of solar-trackers, are able to give an increment to the electric energy production from solar source. Their realization and maintenance costs are certainly higher than those of fixed ones. In this paper the Authors propose a method to estimate the increment of electrical energy generation that must be guaranteed by a dynamic photovoltaic generator, so as its realization could be more favorable with respect to that of a fixed generator one with the same rated power. This method, developed by means of classical economic indexes like the Pay-Back-Period and the Net Present Value, takes in to account the economic incentives for the PV sy…

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…

Integration Issues of Distributed Generators Considering Faults in Electrical Distribution Networks

In the recent years there is a great interest in integration of distributed generation (DG) units at distribution level; this integration leads to planning as well as operational challenges. Some possibilities to handle grid planning issues are addressed in this paper. Effects on grid protection, fault current level, and voltage profile are investigated and described for different types of DG units; the classification of DG units is based on their terminal characteristics in terms of real and reactive power delivering capability. Different scenarios for mis-coordination problems caused by DG interconnection are discussed. The effect of the DG on the voltage profile of a distribution network…

Transitions from grid-connected to island operation of Smart Microgrids

In this paper a control methodology is presented to perform a bumpless transition from the on-grid to the offgrid of a smart microgrid. The derived controller manages the internal production in order to get to zero the tie-line active and reactive power flows so that the opening of the tie line breaker does not produce significant perturbations. Experimental tests performed on the microgrid built at the Polytechnic University of Bari demonstrated the effectiveness of the proposed control strategy.

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.