Silvano Vergura

Politecnico di Bari | Poliba · Dipartimento di Ingegneria Elettrica e dell’Informazione

Small PV plants are frequently not equipped with a meteorological station, that is decisive to monitor the energy performance of a PV plant and to detect low-intensity anomalies, as premature ageing, before they become faults. The paper proposes a methodology for PV plant not equipped with a weather station and it is based on a violin plot, that is...

Supervision and monitoring are mandatory for large PhotoVoltaic (PV) plants, because failures can cause high power loss, due to the large number of PV modules. InfraRed (IR) analysis is effective and reliable to detect anomalies or failures in PV modules, but it is time consuming and then expensive, when the infrared inspection of large PV plants i...

Photovoltaic plants are helping to reduce CO2 emissions, but the energy performance of photovoltaic systems must remain high throughout their operational life. Supervision and monitoring are mandatory for large photovoltaic plants because failures can cause high power losses due to the large number of photovoltaic modules. Infrared analysis is effe...

This Article Proposes a Methodology to Monitor the energy performance of photovoltaic (PV) plants without using the environmental parameters, i.e., when a weather station is absent, as it occurs in small-to-medium-size PV plants. This approach is valid for multiarray PV plants and exploits the mutual comparison of the energy performance of the arra...

This paper presents the modeling and simulation of a Multi-Source Power System (MSPS)—composed of two renewable energy sources and supported by a Battery Energy Storage System (BESS)—to supply the ventilation and heating system for a temperature-controlled agricultural greenhouse. The first one is a photovoltaic (PV) generator connected to a DC/AC...

The development and optimization of a hybrid system composed of photovoltaic panels, wind turbines, converters, and batteries connected to the grid, is first presented. To generate the maximum power, two maximum power point tracker controllers based on fuzzy logic are required and a battery controller is used for the regulation of the DC voltage. W...

An agricultural greenhouse is a complex and Multi-Input Multi-Output MIMO system in which the internal parameters create a favorable microclimate for agricultural production. Temperature and internal humidity are two parameters that have a major impact on greenhouse yield. The objective of this study was to propose a simulated dynamic model in a MA...

The technological development of photovoltaic (PV) devices (perovskite-based or bifacial modules, etc.) has progressed considerably, but the commercial PV modules do not show analogous improvements and their efficiency is still low. Therefore, a diagnostic tool that can check the current operation of installed PV modules and their aging is importan...

Monitoring the performance of a photovoltaic (PV) system when environmental parameters are not available is very difficult. Comparing the energy datasets of the arrays belonging to the same PV plant is one strategy. If the extension of a PV plant is limited, all the arrays are subjected to the same environmental conditions. Therefore, identical arr...

Abstract—This paper presents the optimization and simulation of a hybrid power system composed of two renewable energy sources to supply the actuators of an agricultural greenhouse. The first system is a PhotoVoltaic (PV) generator connected to a DC/AC inverter and the second system is a wind turbine connected to a Permanent Magnet Synchronous Gene...

An agricultural greenhouse is a complex and Multi-Input Multi-Output MIMO system in which the internal parameters create a favorable microclimate for agricultural production. Temperature and internal humidity are two parameters that have a major impact on greenhouse yield. The objective of this study was to propose a simulated dynamic model in a MA...

The paper proposes a cloud platform for analyzing the radiometric infrared videos uploaded by drones which patrol large photovoltaic plants. Thanks to artificial vision algorithms, it does not require any human support to select and associate the framed PV modules to the corresponding ones in the topology of the photovoltaic plant. The algorithm im...

The concept of a smart city includes a high degree of information technology integration, but goes beyond the use of ICT for better resource use and less emissions. [...]

The paper is focused on the energy performance of the photovoltaic systems constituted by several arrays. The main idea is to compare the statistical distributions of the energy dataset of the arrays. For small-medium-size photovoltaic plant, the environmental conditions affect equally all the arrays, so the comparative procedure is independent fro...

This paper deals with the monitoring of the performance of a photovoltaic plant, without using the environmental parameters such as the solar radiation and the temperature. The main idea is to statistically compare the energy performances of the arrays constituting the PV plant. In fact, the environmental conditions affect equally all the arrays of...

The recent technological realization of perpendicular magnetic tunnel junction (MTJ) with two reference layers has opened a new route for scaling the overall size of spin-transfer torque MRAM. This is because for an antiparallel configuration of the magnetization of the reference layers the two spin-transfer torques add each other constructively gi...

The aim of this paper is the monitoring of the energy performance of Photovoltaic (PV) plants in order to detect the presence of low-intensity anomalies, before they become failures or faults. The approach is based on several statistical tools, which are applied iteratively as the data are acquired. At every loop, new data are added to the previous...

The modern Power Distribution Systems (PDS) operate more and more often with distributed generators and the optimal operation of the utility distribution systems has to take into account the possibility of bi-directional energy flows, although this event may only occur for some of the PDS. For this reason, the analysis methods that are usually empl...

A comparison between the experimental current-voltage (I-V) and power-voltage (P-V) characteristics of PhotoVoltaic (PV) modules, and the prediction of an explicit empirical model has been carried out. The model consists of an explicit expression for the current as a function of the voltage; the only inputs are the parameters that are always direct...

Although recent laboratory tests are showing promising progresses in the materials and production technologies of photovoltaic (PV) devices, the commercial PV modules do not show analogous impressive improvements. Therefore, a diagnostic approach, able to check the current state of health of already installed PV systems, as well as their trend of a...

The analysis of electrical signals is a pressing requirement for the optimal design of power distribution. In this context, this paper illustrates how to use a variety of numerical tools, such as the Fourier, wavelet, and Hilbert-Huang transforms, to obtain information relating to the active and reactive power absorbed by different types of users....

This paper, Part II, deals with the software platform that implements the workflow described in Part I, i.e., a thermography-based diagnostics able to provide a detailed, clear, and unambiguous information on the health state of photovoltaic (PV) modules. The methodology, in fact, allows a numerical and qualitative evaluation of each cell of the PV...

We discuss about the possibility of reproducing the behavior of a magnetic material at micromagnetic scale with a phenomenological vector model of hysteresis based on the definition of a vector hysteron. Data computed by means of two different static magnetic models are compared. The former is based on the solution of Brown's equation (micromagnetic...

This paper proposes a procedure based on statistical tools for diagnosis of PhotoVoltaic (PV) plants. As the data are acquired, statistical analyses are realized. At every new loop other data are added to the previous ones implementing a cumulative statistical analysis. In this way, it is possible to follow the trend of some specific parameters and...

The increase of grid-connected renewable energy sources represents an hot topic for the operation and management of a smart grid, because the power injected into the grid by the most of them is unpredictable. Some constraints depend on the environmental condition, while some others depend on the need to guarantee stability, security and power quali...

The energy performance of PhotoVoltaic (PV) fields has to be constantly monitored after setting a PV plant up. For this aim the paper proposes a Neural Network (NN)-based diagnostic methodology, able to detect the performance losses due to typical PV plants failure modes like ageing, dust deposition on modules glass, and so on. The NN has a feedfor...

Advanced signal processing tools can provide significant information on power systems. In this field of research, the present paper illustrates a time-frequency analysis to detect some properties of the power required by different types of users. Fourier and Wavelet transforms, in particular, are the numerical instruments to reveal the periodicity...

The Duffing oscillator represents an important model to describe mathematically the nonlinear behavior of several phenomena occurring in physics and engineering. In this paper, analytical and numerical solutions to the nonlinear cubic Duffing equation governing the time behaviour of an electrical signal are found as a function of the magnitude and...

The paper proposes two mathematical models of a photo-voltaic (PV) cell - the complete model and the simplified model - which can be used also for modeling a PV module or a PV string under any environmental condition. Both of them are based on the well-known five-parameters model, while the approach allows to write a new descriptive equation, whose...

The broad diffusion of renewable energy-based technologies has introduced several open issues in the design and operation of smart grids (SGs) when distributed generators (DGs) inject a large amount of power into the grid. In this paper, a theoretical investigation on active and reactive power data is performed for one active line characterized by...

A Matlab based model of the primary loop of a Concentrating Solar Power plant (CSP) is proposed. The modelled system considers the technology of parabolic troughs with a binary mixture of salts as the heat transfer fluid. The model is based on the layout of a pilot project to be implemented in the South of Italy, but it can be also used for differe...

This paper deals with the issue to supervise the state of health of a PhotoVoltaic (PV) system by means of a cheap approach based only on the processing of the data stored into a standard monitoring system, thus no specific equipment is requested. The proposed solution is based on a linear predictor of an index strictly related to the producible en...

This contribution proposes a study of the energy nedeed to the greenhouse for a fixed cultivation and with the evaluation of the Levelized Cost Of Energy (LCOE). Since the micro-climate condition is a pre-requisite for each cultivation, then a devoted design is absolutely necessary. For this aim, a comparison has been made among three typologies of...

The recent laboratory tests are showing progresses in both materials and production technology of Photo-Voltaic (PV) modules, nevertheless their efficiency yet results relatively low. Moreover, efficiency is also a very critical issue for already installed PV modules, because they were produced employing a less performing technology. In this scenar...

This paper introduces a micromagnetic model able to characterize the magnetization dynamics in three terminal magnetic tunnel junctions, where the effects of spin-transfer torque and spin-orbit torque are taken into account. Our results predict that the possibility to separate electrically those two torque sources is very promising from a technolog...

This paper is part of a wider work– developed in the context of URBANETS project - Sustainable Management of Urban Networks with the Use of ICT – and of scientific research projects, mainly, on traffic and environmental requirements for Brindisi and Gallipoli. The paper is structured by considering different aspects having as an objective the satis...

This paper proposed a MATLAB based model of the primary loop of a Concentrating Solar Power plant (CSP). Among the available technologies for the CSP, the parabolic troughs with a binary mixture of salts as heat transfer fluid is considered here. The model accepts some input data related to the both the location (for example daily solar irradiance)...

The paper deals with the issues to monitor the energy performance of PhotoVoltaic (PV) fields by means of low cost hardware. In fact, the monitoring systems for low or medium rated power PV plants are often constituted by a limited number of sensors and low processing capacity. These systems allow a supervision of the PV fields when strong reductio...

The recent laboratory tests are showing progresses in both materials and production technology of Photo-Voltaic (PV) modules, nevertheless their efficiency yet results relatively low. Moreover, efficiency is also a very critical issue for already installed PV modules, because they were produced employing a less performing technology. In this scenar...

The paper deals with the study of the energy necessary to the greenhouse for the roses cultivation. Each cultivation requires specific micro-climate condition, then generic design is not an effective solution. In order to determine the best material to be used, a comparison has been made among three typologies, i.e. single glass, polycarbonate, and...

Modelling of PhotoVoltaic (PV) devices is today used for a number of activities such as systems monitoring, power forecasting, fault diagnosis, etc. Explicit empirical models based on the datasheet parameters are quite easy to implement in computer-aided calculations and therefore they allow fast evaluations of the electrical behavior, whatever is...

The recent laboratory tests are showing progresses in both materials and production technology of Photo-Voltaic (PV) modules, nevertheless their efficiency yet results relatively low. Moreover, efficiency is also a very critical issue for already installed PV modules, because they were produced employing a less performing technology. In this scenar...

This paper deals with the issue of forecasting energy production of a Photo-Voltaic (PV) plant, needed by the Distribution System Operator (DSO) for grid planning. As the energy production of a PV plant is strongly dependent on the environmental conditions, the DSO has difficulties to manage an electrical system with stochastic generation. This imp...

The paper, starting from the well-known fiveparameters model, proposed a new mathematical model of a Photo-Voltaic (PV) cell which can be used also for modeling a PV module or a PV string in any environment condition. The proposed approach allows to write a new descriptive equation, whose terms are function of the information always available in th...

The paper deals with the issue related to the homework mobility of the employees. This issue is very important because many employees have similar working hours, starting at the same hour and finishing at the same hour. The result is a significant increase of traffic congestion and pollution in these hours. Similar situation occurs for students who...

This paper introduces a micromagnetic model able to characterize the magnetization dynamics in three terminal magnetic tunnel junctions, where the effects of spin-transfer torque and spin-orbit torque are taken into account. Our results predict that the possibility to separate electrically those two torque sources is very promising from a technolog...

This paper summarizes all research advancements obtained by the Politecnico di Bari through the RES NOVAE Project activities in the field of the smart grids. Such activities have been aimed at bringing substantial contributions in the development of smart grid in medium-voltage and low-voltage distribution systems. Since the scientific approach to...

The Magnetic Equivalent Circuits (MECs) technique is a powerful tool for machine analysis and power losses computation. Here, use is made of the Diagonal Mesh Equivalent (DME) to solve the equivalent electrical circuit for the branch fluxes to be easily computed and related to the machine compartments of technical interest. These are represented by...

The broad diffusion of renewable energy-based technologies has introduced several open issues in the design and operation of Smart Grids (SGs). Recently, several studies have focused attention on the Power Quality (PQ) when Distributed Generators (DGs) connected to SGs inject a large amount of power. This paper discusses the influence of PhotoVolta...

The paper introduces the issue of the typical defects in photovoltaic (PV) cells and focuses the attention on three specific defects: linear edge shunt, hole, and conductive intrusion. These defects are modeled by means of finite-element method and implemented in Comsol Multiphysics environment to analyze the temperature distribution in the whole d...

The paper proposes the Matlab based model of a Concentrating Solar Power plant (CSP), rated of 40 MW. The modelled system considers the technology of parabolic through and follows the layout of a pilot project, to be realized in the south of Italy. As that project contains also the thermal storage, the input and output temperature are well-defined....

The paper proposes the Simulink based model of a grid-connected PV plant. The model considers standard monocrystalline PV modules, even if any typology of sylicon based PV module can be used, because the values of the technical specifications can be easily modfied by the user by means of masks. The proposed model considers a multi-inverter PV plant...

The paper proposes the Matlab based model of a Concentrating Solar Power plant (CSP), rated of 40 MW. The modelled system considers the technology of parabolic through and follows the layout of a pilot project, to be realized in the south of Italy. As that project contains also the thermal storage, the input and output temperature are well-defined....

This investigation is focused in answering if the location and sector of activity of energy companies located in the Euro-zone impact the performance of these companies. A database of 18 largest energy companies in the Euro-zone between 2005 and 2009 was constructed. The method of linear regressions with panel data was applied. Results get possible...

The paper deals with the economic-financial aspects of two typologies of solar energy sources: PhotoVoltaic (PV) plant and Concentrating Solar Power (CSP) plant. The aim of the paper is to analyze the initial costs, the maintenance costs and benefits deriving from both the government economic incentives and the selling of energy between a 40 MWp PV...

After setting PhotoVoltaic (PV) plant up, it needs to monitor its energy performance in order to verify the correct or incorrect operation. For this aim, PV plants can be equipped with simple dataloggers or SCADA systems. When several PV plants have to be monitored, a unique supervision centre is implemented, even if each PV plant is independent fr...

The aim of the paper is to propose a procedure to process InfraRed (IR) images of PV modules. In fact, when an IR image is acquired by thermo-camera, three possibilities can happen. The first one regards the acquisition of an IR image of a well-working PV module; in this case the IR image reveal no anomaly. The second case regards the acquisition o...

The paper introduces the issue of the typical defects in PhotoVoltaic (PV) cells and focuses the attention on two specific defects: linear edge shunt and hole. These defects are modeled by means of Finite Element Method (FEM) and implemented in Comsol Multiphysics environment in order to analyze the temperature distribution in the whole defected PV...

Frequently several PhotoVoltaic (PV) plants has to be monitored by an unique supervision centre (we can say that the plants constitute a “constellation” from the point of view of storing and transferring data). In this case the analysis of the whole population of data by means of statistical approach requires long time and it is not always possible...

The aim of the paper is to propose the tridimensional model of a photovoltaic cell implemented in Comsol Multiphysics environment, a finite element method (FEM) based software. The analysis of the thermal behaviour of the implemented model has been conducted to simulate the behaviour of the device under operating conditions. The model has been impl...