A General Mathematical Formulation for the Determination of Differential Leakage Factors in Electrical Machines with Symmetrical and Asymmetrical Full or Dead-Coil Multiphase Windings

This paper presents a simple and general mathematical formulation for the determination of the differential leakage factor for both symmetrical and asymmetrical full and dead-coil windings of electrical machines. The method can be applied to all multiphase windings and considers Görges polygons in conjunction with masses geometry in order to find an easy and affordable way to compute the differential leakage factor, avoiding the adoption of traditional methods that refer to the Ossanna's infinite series, which has to be obviously truncated under the bound of a predetermined accuracy. Moreover, the method described in this paper allows the easy determination of both the minimum and maximum values of the differential leakage factor, as well as its average value and the time trend. The proposed method, which does not require infinite series, is validated by means of several examples in order to practically demonstrate the effectiveness and the easiness of application of this procedure

Numerical modeling of bifacial PV string performance: Perimeter effect and influence of uniaxial solar trackers

The bifacial photovoltaic (PV) systems have recently met large interest. The performance of such systems heavily depends on the installation conditions and, in particular, on the albedo radiation collected by the module rear side. Therefore, it is of crucial importance to have an accurate performance model. To date, in the scientific literature, numerous models have been proposed and experimental data collected to study and optimize bifacial PV system performance. Currently, 3D and 2D models of bifacial PV devices exist. Though the former are more mathematically complex, they can lead to more accurate results, since they generally allow to fully consider the main aspects influencing a bifacial PV system performance. Recently, we have proposed and validated through experimental data a 3D model tested as a function of module height, tilt angle, and ground albedo. In this work, through such a model, we studied the role played by the perimeter zones surrounding the PV string, by considering PV strings of 30 or 60 modules. We considered the cases of fixed installation with optimal PV module tilt and of installation with uniaxial horizontal solar tracker. We evaluated the PV energy yield as a function of the size of the perimeter zones for the two cases, i.e., both with and without the solar tracker. In optimal perimeter conditions, we then studied the behavior of bifacial and mono-facial PV strings by varying the geographical location in a large latitude range

Design and simulation of a fast DC recharging station for EV

In this paper a detailed description of the design and simulation of a DC ultra-fast recharging station for Electric Vehicles is carried out. The system consist of a single AC/DC grid connected inverter, a DC-Bus and two DC/DC converter to recharge the batteries of the EVs. The system also has the vehicleto- grid (V2G) capability. The design of the components of the system and the control schemes are explained and a simulation of the system, performed in Matlab/Simulink environment is presented

Computer Aided Optimization Via Simulation Tools of Energy Generation Systems With Universal Small Wind Turbines

This paper considers the general issues in the project and the optimization of energy generation systems using small universal wind turbines, suitable in Distributed Generation (DG) and computer aided optimization for a better exploitation of wind source. Optimization in this field reveal to be more and more important because the local generation and consumption of electrical power, even for grid connected generators can suffers for unevenness of wind source exploitation, also in terms of wrong directions and in not regular wind flows. Computer aided design and optimization of small plants may give significant improvements in the development of the wind source also in accordance with the projections of future energy policies that foresee a significant increase of the wind generated energy for the future market. The effectiveness of computer aided optimization tools is illustrated in the present paper with the exposition of two case studies. In the first of them a Wind Electrical Energy Generating System is moved by a Modular Multiple Blade Fixed Pitch Wind Turbine coupled with an asynchronous wound rotor generator. In the second case study the optimization regards a Savonius wind turbine and a PM synchronous generator with particular reference to the development of wind source for the wind turbine and the reduction of saturation and of harmonic content in the emf for the electrical machines

An exact method for the determination of differential leakage factors in electrical machines with non-symmetrical windings

An exact and simple method for the determination of differential leakage factors in polyphase ac electrical machines with non-symmetrical windings is presented in this paper. The method relies on the properties of G\uf6rges polygons that are used to transform an infinite series expressing the differential leakage factor into a finite sum in order to significantly simplify the calculations. Some examples are shown and discussed in order to practically demonstrate the effectiveness of the proposed method

A review of multiple faults diagnosis methods in Voltage Source Inverters

This paper examines, as in short review, the methods of diagnosis of simple and multiple faults on Voltage Source Inverter (VSI). The methods examined here are essentially based on the inspection of the load currents. Some of these diagnosis methods are characterized by low computational effort, other for a better reliability avoiding faultless positive tests. Some solutions are characterized by a share of these benefits while others prefer an enforcement of trustworthiness, in spite of the lower calculation amount. The analysis of the technical literature, certainly, offers a glimpse about the creation of new algorithms and significant advances for the future

Determination of differential leakage factors in electrical machines with non-symmetrical full and dead-coil windings

In this paper Görges polygons are used in conjunction with masses geometry to find an easy and affordable way to compute the differential leakage factor of non symmetrical full and dead coil winding. By following the traditional way, the use of the Ossanna's infinite series which has to be obviously truncated under the bound of a predetermined accuracy is mandatory. In the presented method no infinite series is instead required. An example is then shown and discussed to demonstrate practically the effectiveness of the proposed method

Electrical characterization of CIGSSe photovoltaic modules

This work describes the electrical characterization of CIG(S,Se)2 sub-modules in order to compare the related performances with those obtained from traditional silicon photovoltaic modules. This characterization has been performed through means of a test bench, mainly composed by a solar simulator equipment, allowing the determination of the parameters of the prototypes under test at different irradiances and temperatures

Design of a grid connected inverter for sustainable small wind farms

The actual definition of sustainability is nowadays widely accepted. It provides a very general indication on what it is, but it reveals unable to assert how it should be reached. However, if one considers the multiplicity of human activities that have led to talk of real process of human settlement on the environment, it is then understood how it is close to the particular mankind activities. Then the task of providing a guidance on what to do within the sustainability concept is delegated case by case. In this paper, with reference to wind renewable source, The Authors give some indications in the design of a voltage source inverters aimed to optimal use of the wind source. In particular the design of the inverter is more focused on the control system planning, with a particular glance on the grid synchronization problem

Approccio allo Sviluppo di Sistemi Diagnostici per il Funzionamento Fault Tolerant delle Micro-grid

Il progressivo aumento del livello di penetrazione della generazione distribuita(GD) \ue8 destinato a provocare un profondo mutamento nelle esistenti reti di distribuzione che non sono pi\uf9 considerate come terminazioni passive del sistema elettrico complessivo. Una soluzione possibile \ue8 quella relativa alla realizzazione di piccole reti, le micro-grid, che riproducono, al loro interno, la struttura del sistema di produzione e distribuzione dell\u2019energia elettrica. Per ottenere una adeguata affidabilit\ue0 della micro-grid risulta importante la individuazione e la gestione dei guasti ai fini del perseguimento dell\u2019esercizio "fault tolerant" della micro-grid stessa. Nel presente lavoro, dopo aver introdotto le finalit\ue0 dei sistemi diagnostici ed i convertitori fault tolerant per le micro-grid, vengono passate in rassegna le principali tecniche diagnostiche attualmente disponibili per la diagnosi dei guasti delle macchine elettriche ed infine viene proposto un approccio per lo sviluppo di sistemi diagnostici per l\u2019esercizio fault tolerant delle migro-grid