Search results for " Photovoltaic systems"

Effects of the Italian financial crisis on the photovoltaic dissemination in a southern city

2013

Abstract The aim of this paper is to estimate how the profitability of grid-connected PV (photovoltaic) systems may vary month by month due to the changes in all parameters involved in the economic evaluation (discount rate, PV electricity selling price, inflation rate, price of PV devices etc.). The effects of these variations were investigated for a district of a city in the South Italy (Palermo). The results of the analysis provided the trend of the actual coverage of the district power demand from June 2010 to August 2012. In particular the load match index, which considers the daily energy demand covered by PV systems, ranged from almost 30% to less than 12%, which is less than the val…

Experimental characterization of series arc faults in AC and DC electrical circuits

2014

This paper presents an experimental characterization of the arc fault phenomenon, for both AC and DC systems, focusing the attention on series arcs. The aim of the study is to find some current characteristics, which can be significant for the purpose of arc detection. The arcing current signal is analyzed in both time and frequency domain. For the AC analysis, the test conditions are chosen in accordance with the “unwanted tripping tests” and the “operation inhibition tests” reported in the Standard UL 1699. The DC study is carried out on the currents waveforms acquired during some on-field tests on a PV plant. Starting from the study herein presented, the authors have found that is it pos…

Urban Energy Hubs Economic Optimization and Environmental Comparison in Italy and Vietnam

2018

This paper aims to perform the minimization of the yearly energy supply cost from the main electricity and natural gas grids related to an energy district, considering the installation of different equipments. The case study refers to energy consumption of a medium density urban district and involves the exploitation of different energy sources and devices (photovoltaic systems, electrical energy storage, heat pumps and cogenerators). The analysis of the district energy supply is accomplished through an energy hub model. After a cost analysis related to the considered energy systems, a MILP algorithm was used for the optimization of a cost function and the simulation of various scenarios. M…

ARC FAULT DETECTION EQUIPMENT AND METHOD USING LOW FREQUENCY HARMONIC CURRENT ANALYSIS

2012

An arc fault detection circuit includes a current sensing circuit coupled to a line conductor carrying a current. The current sensing circuit operates to sense current and output data indicative of the sensed current. A processing circuit implements a frequency transform algorithm to transform the output data to frequency data in a low frequency range and with a high spectral resolution where a minimum short time observation window is concerned. The processing circuit identifies an arc fault condition on the line conductor by identifying differences in said frequency data between at least two subsequent observation windows and identifying characteristics which exceed thresholds.

Theoretical and Experimental Comparison of Total Harmonic Distortion Factors for the Evaluation of Harmonic and Interharmonic Pollution of Grid-Conne…

2006

Grid connected photovoltaic systems are increasingly used in electrical distribution systems. However, they inject distorted currents. Therefore special attention must be paid to harmonic and interharmonic measurements. The new edition of IEC 61000-4-7 introduces the concept of harmonic and interharmonic groups, which implies new expressions for Total Harmonic Distortion factors. In the paper a theoretical and experimental comparison is made between the different total harmonic distortion factors in order to show which of the currently defined distortion factors is best-suited to detect harmonic and interharmonic pollution. Experimental tests were carried out first by means of a calibrator …

Assessment of Energy and Economic Effectiveness of Photovoltaic Systems Operating in a Dense Urban Context

2013

A methodology that permits testing the level of integration of the photovoltaic technology in urban areas is presented. The percentage of coverage of the electricity demand of grid-connected photovoltaic systems installed on the roofs of buildings were investigated in a district of the city of Palermo (Sicily). After classifying roofs according to their shape, orientation and pitch by means of satellite images provided by Google Earth, the ratio of the productivity of the PV systems and the consumption of electricity of the households was analysed. The results of the energy assessment have been screened considering the economic feasibility of grid-connected photovoltaic systems: the energy …

Series arc faults in AC and DC electrical circuits. Characterization and detection methods

2013

This paper analyzes the problem of the arc faults in both AC and DC low voltage electrical circuits. The state-of-the-art of the arc fault detection methods is analyzed together with the UL 1699 and UL 1699B Standard requirements for protection devices against arc faults (AFCIs). An experimental characterization is carried out of the arc fault phenomenon, for both AC and DC systems, focusing the attention on series arcs. The experimental measurements are carried out on a proper test bench, which has been developed in order to reproduce significant arcing conditions, in accordance with the UL 1699 Standard requirements.

Caratterizzazione e metodi di riconoscimento degli arc faults per applicazioni in sistemi di bassa tensione

2013

Proper sizing of energy storage for grid connected photovoltaic system

2014

Masteroppgave i fornybar energi ENE 500 Universitetet i Agder 2014 The requirement of an energy storage to a grid connected PV system, is highly desirable in cases like power outages. Another importance is to reduce the peak time electricity buying from the utility grid and discharging the battery stored energy to the load. This project investigates the optimum dimensioning of a battery energy storage in a grid connected Photovoltaic system, for the customers who purchase and sell the electricity to the utility grid. The aim was to provide an optimal method that helps electricity customers equipped with PV systems, in making decisions to install economically sized battery energy storage. Th…