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

2016

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…

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

2021

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…

Comparing the Impact of Electric Vehicles on Urban and Insular Networks

2022

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…

Ancillary Services in the Energy Blockchain for Microgrids

2019

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…

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

2015

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…

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

2014

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 …

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

2012

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…

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

2015

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…

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

2020

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…

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

2019

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…

Aggregation and remuneration in Demand-Response with a blockchain-based framework

2020

This paper describes the possibility to use the blockchain technology for load and generation aggregation in a new distributed Demand Response (DR) service and customers remuneration system. The blockchain technology and the use of smart contracts for DR allow the creation of a distributed system in which customers can communicate directly, in a transparent, secure and traceable way, with the grid operator to provide their flexibility. In this paper, the DR problem formulation takes into account several aspects, which are periodically executed. First, the blockchain records customers’ energy consumption or production, then, the smart contract starts calculating the baseline and the potentia…

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

2018

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

2016

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…

Urban Energy Hubs and Microgrids: Smart Energy Planning for Cities

2017

In this chapter, we try to connect the urban design features with energy consumption and consequent pollution parameters. After a review of a selected set of approaches to Urban Energy Systems study with a special focus on electrical power systems, urban energy systems are proposed as networks of multi-source hybrid energy hubs, where different energy flows are collected at the same bus and can be stored, delivered or transformed as needed. Resources at the hub and infrastructures interact with each other; therefore, both definition and boundaries of such energy systems at urban level are difficult to be clearly outlined. Similarly, the possibility to generate new operational models based o…

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

2013

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.

Earth resistance measurements in urban contexts: Problems and possible solutions

2017

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 …

Optimal power flow in islanded microgrids using a simple distributed algorithm

2015

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…

How Decarbonization, Digitalization and Decentralization are changing key power infrastructures

2018

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…

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

2014

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…

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

2012

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…

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

2012

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…

Blockchain for power systems:Current trends and future applications

2020

Abstract Today, the blockchain is synonymous of technological innovation, being recognized among the 10 top strategy technologies in 2018 by the consulting company Gartner, it is more and more adopted in different sectors. However, the initial enthusiasm around this technology is going beyond the peak of inflated expectations, towards more stable applications in money transactions, cryptocurrencies and Digital Commodity Exchanges. Essentially, misguided efforts, the overuse of blockchain, and the Bitcoin's price drop have been the main reasons for this decay in expectations. Nevertheless, the exploitation of the blockchain technology in the power systems area appears largely underexplored, …

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

2013

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 …

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

2019

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…

SOIL IONIZATION DUE TO HIGH PULSE TRANSIENT CURRENTS LEAKED BY EARTH ELECTRODES

2009

This paper proposes a numerical model of the soil ionization phenomena that can occur when earth electrodes are injected by high pulse transient currents, as the one associated with a direct lightning stroke. Based on finite difference time domain numerical scheme, this model ascribes the electrical breakdown in the soil to the process of discharge in the air. In fact, as soon as the local electric field overcomes the electrical strength, the air in the voids trapped among soil particles is ionized, and the current is conducted by ionized plasma paths locally grown. The dimension of these ionized air channels is strictly dependent upon the local temperature. Thus, a local heat balance is en…

The Blockchain in Microgrids for Transacting Energy and Attributing Losses

2017

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…

Pareto-optimal Glowworm Swarms Optimization for Smart Grids Management

2013

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.

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

2022

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 …

Driven Primary Regulation for Minimum Power Losses Operation in Islanded Microgrids

2018

The paper proposes an improved primary regulation method for inverter-interfaced generating units in islanded microgrids. The considered approach employs an off-line minimum losses optimal power flow (OPF) to devise the primary frequency regulation curve’s set-points while satisfying the power balance, frequency and current constraints. In this way, generators will reach an optimized operating point corresponding to a given and unique power flow distribution presenting the minimum power losses. The proposed approach can be particularly interesting for diesel-based islanded microgrids that face, constantly, the issue of reducing their dependency from fossil fuels and of enhancing their gener…

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

2022

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 double-shell design approach for multiobjective optimal design of microgrids

2010

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

2014

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…

A distributed minimum losses optimal power flow for islanded microgrids

2017

Abstract In this work, the minimum losses optimal power dispatch problem for islanded microgrids with distributed energy resources (DER) is solved by means of a distributed heuristic approach. Optimal power management is performed almost in real time, with a predefined schedule, i.e. every 5 min, and the solution is applied to generators when the current operating solution violates voltage or current constraints or when the current configuration produces too large power losses. The operating point of both inverter-interfaced generation units as well as rotating production systems can be modified simply using local information. The latter are voltage measurements and power injections or load…

Optimal energy management in the smart grid

2017

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…

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

2015

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.

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

2012

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…

Critical Assessments of the Potential for Integrating Renewable Energy into Isolated Grids on Vietnamese Islands: The Case of the An-Binh Grid

2023

Renewable electricity for off-grid areas is widely seen as one of the top choices in supporting local economic development in most countries, and so is Vietnam. Over the years, many isolated networks using renewable energy sources have been deployed for off-grid areas in Vietnam. However, the use of these energy sources in Vietnam’s isolated networks is still facing many challenges due to its infancy here. The issues of reliability and vulnerability of these networks are not given the expected attention. Another challenge is that the issues of the operational security of these systems could also be negatively affected by the variable nature of renewable sources, including static and dynamic…

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

2015

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, …

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

2013

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

2018

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…

Review of potential and actual penetration of solar power in Vietnam

2020

With the average solar radiation reaching up to 5 kWh/m2, Vietnam is considered as a country showing an excellent potential for solar power production. Since the year 2000, there have been a lot of studies about the potential of this source in Vietnam. So far, many applications of solar power have been implemented on small, medium, and large scales. In fact, the total capacity of current grid-connected solar power plants has exceeded the planned capacity by 2020 nearly 6 times. However, the studies of solar potential in Vietnam are still incomplete. The policies and mechanisms for developing solar power projects have received attention from the authorities but have not been really satisfact…

A Remuneration Model of Energy Community Members in Italy

2022

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…

On the Interconnections of HV–MV Stations to Global Grounding Systems

2019

The interconnection of grounding systems of HV-MV stations via the armors of medium voltage cables, is herein analyzed to verify the effects on touch voltages in ground-fault conditions. The major contributions of this paper are two: the analysis of the impact of an HV ground-fault on a global grounding system (GGS), and the analysis of the parameters that may affect safety due to the interconnection between HV-MV stations and the GGS. The authors have analyzed cases when the connection of an HV-MV station to a GGS improves safety, and then may introduce hazards under ground-fault conditions. Two main issues are herein discussed: 1) the transfer of dangerous voltages to substations, due to …

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

2005

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…

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

2011

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…

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

2014

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.

Transparency in transactive energy at distribution level

2017

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…

Implementazione di funzioni aggiuntive per la rappresentazione e la gestione ottimizzata di risorse energetiche distribuite in un distretto energetic…

2013

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…

FENOMENI DI INTERFERENZA TRA ELETTRODI DI IMPIANTI DI TERRA INTERCONNESSI

2012

An integrated platform for electrical modeling of microgrids

2012

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…

Analisi del fenomeno della ionizzazione del terreno nel comportamento dinamico di elettrodi interrati sottoposti ad elevate correnti impulsive

2006

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

2005

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…

Modello per la simulazione di scariche parziali con approccio probabilistico

2011

CARATTERIZZAZIONE ELETTROMAGNETICA DEL COMPORTAMENTO DINAMICO DI ELETTRODI INTERRATI IN PRESENZA DI IONIZZAZIONE DEL TERRENO

2009

Approccio campistico per lo studio del fenomeno di ionizzazione del suolo mediante il metodo FDTD

2004

HARVESTING DALLE PRECIPITAZIONI

2013

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

2012

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…

Un modello per l’analisi dei disturbi di modo comune indotti su azionamenti in presenza di fulminazione atmosferica

2011

Un modello di simulazione della ionizzazione del terreno nel comportamento dinamico di elettrodi interrati disperdenti elevate correnti impulsive

2007

Simulazione numerica dell’interferenza elettromagnetica radiata in sistemi elettrici automobilistici a 42 V

2005

STUDIO SULLA FORMA DI RIVELATORI WIRELESS DI SCARICHE PARZIALI

2013

A load model for EV parking lots

2012

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 …

CARATTERIZZAZIONE ELETTROMAGNETICA DI IGBT IN PRESENZA DI SCARICHE PARZIALI

2014

Studio di applicabilità e di fattibilità di tecniche diagnostiche CND basate su prove elettriche

2007

Soil ionization of earth electrodes under high pulse transient currents

2007

This paper proposes a numerical model of soil ionization phenomena that can occur when earth electrodes are injected by high pulse transient currents. The model is solved by a finite difference time domain numerical scheme. It has been developed from a thorough analysis of the available studies in technical literature about the peculiar physical dynamics of soil ionization phenomena. As already underlined, soil ionization can occur, for example, when the earth electrode has to drain a lightning current into the soil. In this case, the electric field can overcome the electrical strength and conductive plasma paths can locally grow. The dimension of these ionized air channels are strictly dep…

Un modello dinamico per la simulazione della ionizzazione di terreni non omogenei in presenza di elettrodi disperdenti elevate correnti impulsive

2008

La caratterizzazione elettromagnetica del comportamento dinamico di elettrodi interrati, disperdenti elevate correnti impulsive, costituisce uno degli aspetti primari nella progettazione di un sistema di protezione dalle fulminazioni atmosferiche (LPS). D’altra parte, elevate correnti impulsive possono causare l’insorgere di fenomeni di ionizzazione del terreno, nelle zone prossime agli elettrodi interrati, nei punti in cui il campo elettrico totale supera il valore critico. Modelli teorici e misure sperimentali correlano l’insorgere di variazioni di conducibilità del terreno in prossimità di elettrodi interrati interessati da elevate correnti impulsive al fenomeno della ionizzazione del te…

Ground Potential Rise at Transition Poles of Combined Overhead-Cable Line

2008

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

2016

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 …

SVILUPPO DI UN SISTEMA DI ENERGY HARVESTING DALLA PIOGGIA

2014

Ground potential rise at transition poles of combined overhead-cable lines due to the fault application transfer phenomenon

2008

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

2014

Optimal Energy Management in Smart-Grid

2017

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…

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

2011

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…

Processo di denoising mediante wavelet di segnali dovuti alle scariche parziali

2005

APPROCCIO PROBABILISTICO NELLA MODELLAZIONE IBRIDA DEI FENOMENI DI SCARICHE PARZIALI

2013

Impiego di metodi numerici meshfree per l’analisi elettromagnetica

2004

RICONFIGURATORE DELLE CONNESSIONI DI SISTEMI FOTOVOLTAICI SOTTOPOSTI AD OMBREGGIAMENTO PARZIALE

2014

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

2010

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…

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

2010

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…

Soil ionization of hearth electrodes under high pulse transient current

2007

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

2011

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…

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

2009

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.

Analisi e definizione di strategie di gestione e controllo di sistemi di accumulo elettrico per applicazioni in reti di distribuzione attive automati…

2011

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…

A Study of a large interconnection of earthing systems during an earth fault inside a MV/lv substation

2005