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Publications (92)
This chapter is centered on the design, modeling and energy management of heavy-duty transportation systems. After showing general definitions and conventions, the problem of energy management is addressed with reference to heuristic approaches and global optimization control techniques. After presenting the problem in the most general formulation,...
This paper gathers experiences and results from several demonstration projects in the field of grid integration of electric vehicles. The analyzed research projects are selected among research institutes and universities that are part of the European Energy Research Alliance Joint Program on Smart Grids. The paper provides an overview of recent tre...
This paper presents a technique to estimate the State-Of-Charge of lithium cells, based on a Luenberger state estimator. Although this approach is not new, in this paper several practical implementation details are discussed, including techniques to find numerical parameters of the required cell model with tests that give enough precision with limi...
One of the main concerns regarding energy storage systems during their normal operation is the possibility to perform an accurate state-of-charge estimation. This cannot be done by simple ampere-hour counting, unless drift correction means are put in place to avoid accumulation of measurement errors over time. In this paper, a state-of-charge estim...
The most common system for railway high‐speed lines electric supply and the somehow de‐facto standard is a special AC industrial frequency system called 2 × 25 kV system. Although several studies exist showing the performance of this system in frequency and time domains, there is a lack of studies analysing how geometric parameters influence the sy...
In the past years, forklift manufacturers have started to hybridise their products under the worldwide interest toward electrification. This is generally made starting from existing standard products, and converting them into hybrid versions, rather than start from scratch and designing fully new vehicles. This approach involves several gaps from t...
Simulation of multi‐engineering systems typically requires many issues to be solved, which are to be addressed by developing appropriate modeling and simulation programming techniques. In the last years, the authors have participated in several studies in which they analyzed in detail electrified railway systems and simulated them using Modelica la...
Electrified guided vehicles typically face routes having a large number of acceleration and braking phases. The braking energy, since the feeding line presents nonreversible electrical feeding substations, can be recovered in the presence of other nearby vehicles. To improve braking energy recovery, one or more storage systems can be positioned alo...
MC’s PlotXY, in the following just called PlotXY, is a free piece of software able to make line plots and bar charts from data deriving from measuring devices or simulation programs using several formats. It allows to visualize and post-process these data without the need to have on the target computer the original software that generated it. It wa...
This paper evaluates, in a case study with real data, the advantages of using a stationary electrochemical storage system in a railway node, to recover and store braking energy considering different train typologies. The railway traffic inside the node is widely analysed, by utilization of numerical simulation models to determine energy and power f...
Nowadays the electric power system is facing new challenges related to the integration of renewable sources, more and more frequently combined with energy storage systems. The use of these technologies is very promising, although it requires sophisticated control architectures in order to successfully balance the intermittence and unpredictability...
Nowadays the electric power system is facing new
challenges related to the integration of renewable sources, more
and more frequently combined with energy storage systems. The
use of these technologies is very promising, although it requires
sophisticated control architectures in order to successfully balance
the intermittence and unpredictability...
Vanadium redox flow battery (VRFBs) is one of the most promising large-scale energy storage systems; however, a widespread VRFB development is still limited by the poor electrochemical activity of the graphite electrode and a poor understanding of redox reactions occurring at electrode/electrolyte interfaces.
In this work, DFT were performed to stu...
The growing attention to environmental sustainability of transport systems made necessary to investigate the possibility of energy optimization even in sectors typically characterised by an already high level of sustainability, as in particular the railway system. One of the most promising opportunity is the optimization of the braking energy recov...
Today’s AC railway feeding systems are composed by several conductors with various connections to each other. The return current is shared between rails, ground wires connected to rails, ground; current flows to ground are determined by rail-to-ground distributed conductance. This paper gives formulas to deal with all these complexities, both for p...
Since there is a growing interest worldwide in reducing pollution from sea transport and sea ports activities, one of the biggest issues is to reduce energy consumption and emissions from ground transportation within ports to cranes and other logistic activities. In particular, Rubber Tired Gantry cranes with Diesel engine coupled with electric dri...
In the last years, energy storage systems are increasingly involved in applications in which they are required to deliver or adsorb significant charging or discharging currents in short intervals of time, typically a few seconds. Thanks to their high specific power, supercapacitors may represent one of the most promising technologies for this kind...
There is a growing interest worldwide in reducing pollution and CO2 emissions from transportation field. Indeed, in recent years bus manufacturers have developed hybrid and electric versions of their products. In this regard, this study shows through a structured methodology how to model and design powertrains for pure electric and series-hybrid bu...
Recent innovations introduced in the electric power system, especially the significant usage of unpredictable renewable energy sources, are making to perform the needed matching of generated and absorbed electricity more difficult than in the past. To facilitate this matching, market regulation can provide economical drivers that stimulate cost-eff...
The hybrid electric vehicle (HEV) is an excellent option for simultaneous reduction of fuel consumption and exhaust emissions in urban areas. A large European project, the hybrid commercial vehicles (HCV) project, started with the participation of 18 European organizations and with the scope to develop and demonstrate the current heavy duty (HD) HE...
A typical operating condition of storage batteries requires to deliver and absorb small currents in large intervals of time, in order of minutes or hours. However, in the last years lithium batteries have been more and more considered in “power oriented” applications, in which they are required to manage large currents in short intervals of time, t...
Hybrid energy systems represent today one optimal solution for different mobility areas. This is shown in the paper by describing three applications. The first one refers to a tramway system: regenerative braking has been enhanced by introducing some stationary storage capability in correspondence of electrical feeding substations. The second one r...
Abstract In response to growing concerns on the environment and the need to save energy, working machine manufacturers have started to consider hybridization of their products. This paper presents a systematic modelling approach to identify the most promising hybrid configurations for existing skid loaders. This approach involves accurate modelling...
In the last few decades a lot of good papers have been published proposing techniques for optimizing energy management on-board hybrid vehicles. However the large majority of them focused on specific architectures, and suggested algorithms valid just for them. This paper, on the contrary, performs a very basic analysis, in which hybrid vehicles are...
In the framework of the transition towards the new paradigm of electricity grids, the exploitation of intrinsic energy storage or deliberately installed storage systems (either thermal or electric) plays a major role in enabling the actual controllability of the various sources and loads connected to the system. Controllability, for different purpo...
This paper evaluates the cost effectiveness of using regenerative braking in a tram line in case of non-reversible substations equipped with battery energy storage. It shows, by the combination of results by numerical simulation model and experimental tests, how it is possible to effectively transform an existing tramway to improve its energy effic...
This paper explains the basic opportunities and issues of using Modelica language and tools in simulating electromechanical railroad systems, i.e. systems containing electrical feeding substations, contact lines, trains, and, possibly storage stations. It shows that the Modelica language has achieved a significant level of flexibility and reliabili...
To downsize a spark ignited (SI) internal combustion engine (ICE), keeping suitable power levels, the application of turbocharging is mandatory. The possibility to couple an electric drive to the turbocharger (electric turbo compound, ETC) can be considered, as demonstrated by a number of studies and the current application in the F1 Championship,...
Nowadays road transportation contributes in a large amount to the urban pollution and greenhouse gas emissions. One solution in urban environment, also in order to mitigate the effects of traffic jams, is the use of tramways.
The most important bonus comes from the inherent reversibility of electric drives: energy can be sent back to the electricit...
This book serves as a tool for any engineer who wants to learn about circuits, electrical machines and drives, power electronics, and power systems basics. From time to time, engineers find they need to brush up on certain fundamentals within electrical engineering. This clear and concise book is the ideal learning tool for them to quickly learn th...
This paper evaluates, in a case study with real data, the advantages of using regenerative braking in a tram line, both in case of non-reversible substations and substations equipped with battery energy storage. It shows that the addition of storage enhances energy efficiency a lot, and therefore this is a very cost-effective solution.
The lithium iron phosphate (LFP) cell chemistry is finding wide acceptance for energy storage on-board hybrid electric vehicles (HEVs) and electric vehicles (EVs), due to its high intrinsic safety, fast charging, and long cycle life. However, three main challenges need to be addressed for the accurate estimation of their state of charge (SOC) at ru...
With increasingly stringent regulations on fuel emissions, working and agriculture machine manufactures have started to consider hybrid and electric versions of their vehicles. This paper presents a systematic approach to develop the hybrid version of an existing skid loader through powertrain modelling. The approach involves accurate modelling of...
The study, made by ENEA in cooperation with the University of Pisa as part of the activities supported by the Italian Ministry of Economic Development in the framework of the Program Agreement for the Research on the Electric System, is related to the situation of Italian market and demonstrates the feasibility of the electrification for off-road v...
The study, made by ENEA in cooperation with the University of Pisa as part of the activities supported by the Italian Ministry of Economic Development in the framework of the Program Agreement for the Research on the Electric System, is related to the situation of Italian market and demonstrates the feasibility of the electrification for off-road v...
The growing need for accurate simulation of advanced lithium cells for powertrain electrification demands fast and accurate modeling schemes. Additionally, battery models must account for thermal effects because of the paramount importance of temperature in kinetic and transport phenomena of electrochemical systems. This paper presents an effective...
Rapid developments in the lithium-ion battery technology in the last decade have made it the overwhelming choice over lead-acid batteries, especially for advanced vehicles like hybrid and electric vehicles. However, for the traditional starting-lighting-ignition (SLI) application, the lead-acid technology continues to be dominant due to its low cos...
Lithium batteries are increasingly being considered for installation as power sources in electric and hybrid vehicles, because of their high specific energy and power. To effectively size the vehicle Rechargeable Energy Storage System, it is very important to be able to mathematically model their behaviour. Battery modelling is also very useful for...
We present a basic model of supercapacitor based on a theoretical analysis discussing the frequency dependence of the electric permittivity. Directly from the Maxwell’s theory, an equivalent parallel capacitance and conductance is deduced having frequency dependence. Dynamic behavior is assessed in the frequency range up to 20 Hz which is typical f...
Hybrid vehicles require an energy storage device capable of delivering or absorbing high specific powers (powers per unit of the device size), and still, in some cases, adequate levels of specific energy. The paper shows that high power Lithium Batteries already on the market are able to fulfil this task satisfactorily, by means of experimental tes...
Electric vehicles are an important option to reduce pollution and greenhouse effect in the environment. The main problems for battery fed electric vehicles are related to the small ranges, and large recharging times. A possible solution is constituted by electric vehicles in which the energy is produced on-board by a fuel cell based electricity gen...
This paper approaches the problem of optimizing energy consumption onboard hybrid vehicles in a general way, considering the main issues to be solved in their conceptuality and, therefore, that are often abstracted from the actual structure of the particular drive train that the authors considered. The methods that were described are a harmonizatio...
1 Summary This paper presents a method for evaluating quantitatively the environmental relative value of different vehi-cle typologies. The method allows comparing different environmental effects of road transport, both local (pollutants such as CO, NOx, HC, that pose a threat to citizen health) and global (global warming, depletion of natural re-s...
To supply small loads located very far from low-cost generation areas local Diesel generation or transmission from the generation areas to loads are the alternatives to be considered. The competitiveness of the latter solution can be improved by the use of static devices, able to compensate active and/or reactive powers, installed in suitable locat...
The paper approaches the problem of optimising energy consumption onboard hybrid vehicles in a general way, considering the main issues to be solved in their conceptuality, and therefore often abstracted from the actual structure of the particular drive-train considered. The methods described are an harmonisation of those used by the authors in pas...
This paper describes the system of higher education in the Pisan area of Tuscany (Italy) in the topic of electric systems for land and sea vehicles. It is shown that this system is based on two education levels: - a Laurea Specialistica (a degree similar to master degree of U.K. and U.S.A.) in land vehicle engineering that gives important space to...
The use of a simulation package for hybrid vehicle designers is essential to determine the power train component sizes or to evaluate specific energy management strategies. This paper shows a hybrid drive train simulation program with a user-friendly man machine interface, developed in Matlab-Simulinktrade environment. The simulation algorithm is b...
The paper presents the results of a two year study regarding the use of an innovative drive-train, having a parallel-hybrid structure, in a small scooter, in which a conventional internal combustion engine is coupled with an electric motor for the vehicle propulsion. The developed architecture enhances the maximum vehicle power, by exploiting the b...
Objective of this work is to point out the advantages of using a Lab VIEW™ platform for the developing of the vehicle management system (VMS) and testing of the overall control system of a hybrid vehicle without the need of a hardware implementation of the VMS. The effectiveness of the proposed methodology is shown by means of its application to tw...
This paper shows the results of experimental tests carried out on two types of batteries for electric vehicles to evaluate their efficiency when subjected to small cycles (microcycles) around operating points characterised by different states of charge. These efficiency data can de useful for designer of energy manager systems for hybrid-electric v...
The paper presents an innovative drive-train for a small scooter, taking advantage of an hybrid (mechanical-electrical) structure. The single parts of this drive train have been dimensioned and the resulting system has been introduced in a simulation program. According to the simulation results the hybridisation is able to enhance the maximum power...
In the frame of the project for building a new experimental center for certifying the rolling stock able to circulate on Italian and European railroad networks, an important role is played by the electric supply system and the feeder simulation. For covering all possible supply conditions and offering a multiple and complete service for experimenta...
The deregulation of electricity markets, now coming into force in several countries, has a strong impact on the behavior of electricity customers and stimulates the use of tools for increasing the flexibility of consumption, since markets encourage price responsive demand. Load management and customer aggregation can improve the role of demand with...
A simplified dynamical model of a fuel cell of the proton exchange membrane (PEM) type, based on physical–chemical knowledge of the phenomena occurring inside the cell has been developed by the authors.The model has been implemented in the MATLAB/SIMULINK environment.Lab tests have been carried out at ENEA’s laboratories; and a good agreement has b...
In a series hybrid electric vehicle (SHEV), an electric generator
feeds a DC busbar (containing an electrochemical accumulator), which, in
turns, feeds the vehicle traction system. A very important part of the
vehicle is its control system, which has to maximize the vehicle
efficiency while keeping the emissions within predetermined limits. To
atta...
In a series hybrid electric vehicle (SHEV), an electric generator feeds a dc busbar (containing an electrochemical accumulator), which, in turn, feeds the vehicle traction system. A very important part of the vehicle is its control system that has to maximize the vehicle efficiency, while keeping the emissions within predetermined limits. To attain...
This paper explains how the lead-acid models described previous paper can be utilized in practice. That paper does not supply detailed information on how to identify the several parameters of the proposed models, and it defines a whole family of models, but does not discuss which model of the family is adequate for a given purpose. These two issues...
It is expected that dispersed generation (DG) will play an increasing role in electric power systems in the near future. Among the benefits that DG can give to the power system operators and to the electricity customers, one of the most attractive is the possibility of improving the continuity of power supply. DG plants can be designed to supply po...
This paper presents an algorithm that has been developed to
estimate the residual range of an electric vehicle, i.e., the distance
that can still be covered with the energy stored inside the battery. The
algorithm takes into account the complexity of the behavior of
electrochemical batteries, with special reference to lead-acid
batteries, as well a...
Diffused generation (DG) is predicted to play an increasing role
in the electric power system of the near future. DG gives the
opportunity to reduce the cost needed to supply the load by deferring
generation and grid upgrade, by increasing customers contractual
flexibility and by improving power quality. Among all the benefits that
DG can introduce...
The article presents a simplified dynamical model of a fuel cell of the Proton Exchange Membrane
(PEM) type, based on physical-chemical knowledge of the phenomena occurring inside the cell.
Since the anodic overvoltages influence the cell behaviour to a lower extent than cathodic and ohmic
overvoltages, they have been disregarded for simplicity.
T...
This paper documents the main results of studies that have been
carried out, during a period of more than a decade, at University of
Pisa in co-operation with other technical Italian institutions, about
models of electrochemical batteries suitable for the use of the
electrical engineer, in particular for the analysis of electrical
systems with batt...
Present-day operating systems have graphical user interfaces (GUI)
that are of great help in designing good user interfaces for application
programs. Also, there have been dramatic improvements in computer power
and power-to-price ratio. Acknowledgement is growing, even in technical
environments, that good man-machine interfaces (MMI) have so many...
In the present paper, the possibility of using the neural networks to forecast the power absorbed by a user of electric energy, in order to exploit better the contractual interface with the utility, is investigated. The network chosen for this purpose is a radial basis function trained with leave-one-out cross validation. A prototype device, able t...
The use of DC links with battery storage in LV distribution networks provides several advantages for both the final user and the electric utility. In particular, with the use of DC links between the LV windings of the distribution transformers and the load, the following advantages can be obtained: improvement of the power quality of the energy sup...
The recent developments in power electronics technology make possible the use in power systems of devices called Thyristor Controlled Braking Resistors. These have the advantage over the traditional (electro-mechanical) braking resistors of a higher speed of intervention and the possibility to modulate the current, and consequently the power, drawn...