IMEKO Event Proceedings Search

   

Page 445 of 977 Results 4441 - 4450 of 9762

Andrea Sosso, Paolo Durandetto, Matteo Fretto, Vincenzo Lacquaniti
Superconductivity in primary voltage metrology at INRiM

Primary electrical Metrology is among the first and, to date, one of the most active and successful research field for superconducting devices. Voltage standards based on the Josephson effect are in use since few years after it discovery and have enormously reduced the uncertainty of DC voltage calibrations. INRIM the Italian National Metrology Institute has a long tradition in research on the application of superconductivity to electrical standards. This paper is an overview of main results and ongoing activities.

Francesco Barra, Marco Balato, Luigi Costanzo, Daniele Gallo, Carmine Landi, Mario Luiso, Massimo Vitelli
Dynamic and Reconfigurable Photovoltaic Emulator Based on FPAA

A photovoltaic (PV) emulator is an electronic device which allows, without using real PV modules, to reproduce the current vs. voltage characteristics of PV sources in the desired operating conditions as concerns the values of the irradiance and of the temperature. This is very useful since it is possible to evaluate the performances of the electronic DC/DC or DC/AC converters adopted in PV systems, under perfectly replicable operating conditions. Moreover, it is possible to fairly compare advantages and drawbacks of different MPPT algorithms under perfectly controlled stationary or dynamic atmospheric conditions. In this paper a dynamic and reconfigurable photovoltaic emulator which allows to reproduce the PV current vs. voltage characteristics both in stationary and dynamic environmental conditions, is presented and discussed. It is based on the implementation of the circuital model of the considered PV module in a Field Programmable Analog Array. The field Programmable Analog Array provides a suitable time varying reference signal to the control circuitry of a step-down DC-DC converter. The output port of such a DC/DC converter emulates the current versus voltage characteristic which is obtained at the terminals of the considered PV module in the desired atmospheric conditions. The main advantages of the proposed PV emulator are represented by the simplicity of programming of the FPAA and by its low cost. The results of numerical simulations and of experimental activities are reported and discussed.

Alberto Reatti, Lorenzo Ciani, Marian K. Kazimierczuk,
Monitoring System for a Solar Photovoltaic and Thermal Concentrator Plant

A practical demonstration of a monitoring system for PV/T concentrating system is presented in this paper. The solar module under test is a PV/T double axis concentrating system using a primary spherical reflector and a secondary parabolic reflector. The overall system can provide both electrical and thermal energy. The concentrating system and the monitoring system have been developed under the European Community grant of UPPSol (Urban Photovoltaics: Polygeneration with Solar Energy). The presented monitoring system, based on a main central processor, is able to monitor both electrical and thermal characteristics acquired from the solar and thermal plant.

Christian Schuss, Toni Kotikumpu, Bernd Eichberger, Timo Rahkonen
Impact of Dynamic Environmental Conditions on the Output Behaviour of Photovoltaics

This paper discusses the influences of dynamic environmental conditions on the output performances of photovoltaics. Commonly, photovoltaic (PV) modules are installed on the roofs of houses, onto which shading is caused by clouds and surrounding objects such as trees and other buildings. These ambient conditions can be referred as static environmental conditions. We also elaborate on the differences in the rate of change in the solar radiation level if PV modules are mounted onto the top of battery-powered electric vehicles (BEVs) and hybrid electric vehicles (HEVs). We present a comparison of static and dynamic environmental conditions which is helpful in evaluating the performance of maximum power point tracking (MPPT) techniques.

Massimiliano Bestetti, Giancarlo Bernasconi, Sergio Brofferio, Loredana Cristaldi
Simulation of colouring methods for Silicon PV cells

One of the elements opposed to an increasingly widespread dissemination of photovoltaic systems on residential and public building , is represented by the architectural constraints often imposed on buildings of historical interest or located in neighborhoods where there are strict planning rules. In order to obtain PV systems that meet so severe constraints of integration, it is necessary to rethink the technologies currently used to produce traditional panels; a good compromise between the performance of the panels and the need of a colouring effect as close as possible to the typical red brick of the roofs of buildings subjected to architectural constraints is required. This paper presents and discusses the state of the art of coloured cells and modules. Based on such a review a novel solution in the field of coloured PV cell techniques is proposed: it simulates the potentialities and limits of using a mixture of precursor gases for the deposition (PECVD) or Sputtering of a reflecting filter on the top of a standard PV Silicon cell.

Silvano Vergura
Big Data and Efficiency of PV Plants

Sometimes many PhotoVoltaic (PV) plants have to be monitored by an unique supervision centre. In these cases the real-time analysis of the whole population of data by means of statistical approach requires long time and it is not always possible. After an introduction on Big Data and statistical approaches, the paper presents a procedure of analysis based on sampled data and on the whole population, only for inefficient PV plants. The paper proposes a resampling method, so-called bootstrap, able to approximately describe the sampling distribution. Its peculiarity consists in taking information about the population of the data (whichever its distribution is) and giving quickly preliminary information about the operation of the PV plants.

Salvatore Caldara, Rosario Miceli, Pietro Romano, Ciro Spataro, Fabio Viola
Uncertainty management in the measurements of low frequency magnetic fields

The paper deals with low-frequency magnetic field measurements carried out by using a broadband and isotropic instrument. These measurements are characterized by very high uncertainty values, which imply a high risk of wrong decisions when there is the need to establish if a site complies or does not comply with specified emission limits. To reduce this risk, we decided to perform the so called “uncertainty management” that is the discipline of optimizing the cost of a measurement versus the uncertainty target. The task is achieved by using the PUMA method that is an iterative technique originally conceived for geometrical and mechanical measurements. The approach is completely based on the “Guide to the Expression of Uncertainty in Measurement” rules, but provides a more engineering methodology. By using this approach, it is possible to avoid the usage of too expensive instrumentations or, on the contrary, too expensive resources for the uncertainty estimation.

Irwin A. Diaz-Diaz, Ilse Cervantes
Design and implementation of a power quality monitoring system over internet

In order to raise awareness about energy waste, an energy monitoring system able to be used either in residential or commercial applications is proposed in this paper. The acquisition system is based on Arduino Due (ArD), X-Bee and free software. The system has been designed considering low-power consumption and low-component count while meeting international standards. The prototype is constituted by a signal conditioning circuit capable to conditioning up to 8 channels (4 for voltage and 4 for current) and an Arduino Due capable to acquire 8 channels simultaneously. The prototype was tested at a laboratory and in an residential application, an evidence of its performance is given.

Jacopo Bongiorno, Andrea Mariscotti
Experimental validation of the electric network model of the Italian 2x25 kV 50 Hz railway

The preliminary activity of validation of an integrated electromagnetic railway simulator is presented, with particular attention to the verification of the experimental data used as a validation reference and to the quantification of the model quality. Visual comparison between simulated and experimental results is not quantitative, is subjective, but captures features that deserve to be adequately quantified for the validation process to be repeatable and objective.

Adam Szeląg, Tadeusz Maciołek, Marek Patoka
Correlation analysis of results of measurements in AC power supply of DC traction substations for identification of harmonic disturbances

The conducted study case, which is presented in the paper, created a basis for identification of the causes for occurrence of voltage distortions and development of proposals solution assuring voltage of appropriate quality parameters, which enabled supplying sensitive loads from the same 15 kV grid as traction substations. With regard to noticeable disturbances in a 15 kV network, observed at non-traction loads and devices of a 3 kV DC traction substation (especially smoothing filters and signalling and control traffic equipment), it was required to perform a set of measurements of voltage quality in a PCC both at the level of 15 and 110 kV. The measurements were performed under various operational conditions and schemes of connection of the supplied loads. An analysis of the correlation between specific harmonics, THD coefficients and the current load was undertaken.

Page 445 of 977 Results 4441 - 4450 of 9762