Introduzione

Questo numero di Welfare ed Ergonomia propone una riflessione sul peso che l\u2019et\ue0 ha nella societ\ue0 attuale, evidenziando la distanza tra l\u2019et\ue0 anagrafica, quella valutata collettivamente, in base a parametri sanitari e complessi calcoli economici, e quella individualmente percepita, nel gap fra l\u2019ordine prescrittivo dei ruoli prestabiliti e le performance che giovani, adulti e anziani ritengono di interpretare nelle diverse \u201cprovince di significato\u201d (Schutz 1979)

Reliability analysis and repair activity for the components of 350 kw inverters in a large scale grid-connected photovoltaic system

The reliability of photovoltaic (PV) generators is strongly affected by the performance of Direct Current/Alternating Current (DC/AC) converters, being the major source of PV under-performance. However, generally, their reliability is not investigated at component level: thus, the present work presents a reliability analysis and the repair activity for the components of full bridge DC/AC converters. In the first part of the paper, a reliability analysis using failure rates from literature is carried out for 132 inverters (AC rated power of 350 kW each) with global AC power of 46 MW in a large scale grid-connected PV plant. Then, in the second part of the work, results from literature are compared with data obtained by analyzing industrial maintenance reports in the years 2015–2017. In conclusion, the yearly energy losses involved in the downtime are quantified, as well as their availability

Maintenance Activity, Reliability, Availability, and Related Energy Losses in Ten Operating Photovoltaic Systems up to 1.8 MW

In general, photovoltaic (PV) plants do not include components with moving parts and, as a consequence, they are wrongly considered maintenance-free. Thus, this article presents a maintenance, reliability, and availability analysis of ten PV systems, with different inverter configurations, in the context of the intermittent renewable energy source systems, including the wind farms. The first part of the analysis consists of the evaluation of reliability using failure rates from the literature. In the second part, these results are compared with data obtained from industrial maintenance reports in the years 2016-2018. Finally, the yearly energy losses and the availability of each PV plant are assessed

In-field monitoring of eight photovoltaic plants: Degradation rate over seven years of continuous operation

The results of more than seven years (October 2010-December 2017) of continuous monitoring are presented in this paper that refer to eight outdoors PhotoVoltaic (PV) plants. The monitored plants are based on different technologies: mono-crystalline silicon (m-Si), poli-crystalline silicon (p-Si), string ribbon silicon, Copper Indium Gallium Selenide (CIGS) thin film and Cadmium Telluride (CdTe) thin film. Thin-film and m-Si modules are used both in fixed installation and on x-y tracking systems. The results are expressed in terms of degradation rate of the efficiency of each PV plant, which is estimated from the measurements provided by a multi-channel data-acquisition system that senses both electrical and environmental quantities. A comparison with the electrical characterization of each plant obtained by means of the transient charge of a capacitive load is also proposed. In addition, three of the monitored plants have been characterized at module level and the estimated degradation rates have been compared to the values obtained with the monitoring system. The main outcome of this work can be summarized in a higher degradation rate of thin-film based PV modules with respect to silicon-based PV modules

Assessing the role of fluctuating renewables in energy transition: Methodologies and tools

Due to the environmental impacts brought by current energy schemes, the energy transition, a new paradigm shift from fossil fuels to renewable energy, has been widely accepted and is being realized through collective international, regional, and local efforts. Electricity, as the most direct and effective use of renewable energy sources (RES), plays a key role in the energy transition. In this paper, we first discuss a viable pathway to energy transition through the electricity triangle, highlighting the role of RES in electricity generation. Further, we propose methodologies for the planning of wind and solar PV, as well as how to address their uncertainty in generation expansion problems. Finally, by using a web-based tool, “RES-PLAT”, we demonstrate the scheme in a case study in Egypt, which evaluates the impacts and benefits of a large-scale RES expansion

Comparison of correction methods of wind speed for performance evaluation of wind turbines

The performance of horizontal axis wind turbines strongly depends on the speed of the wind that enters in the rotor of the turbine. Unfortunately, this quantity is rarely available since the wind speed is measured on the back of the turbine, where a lower value is present. For this reason, two correction methods are usually employed that require two input quantities: the wind speed on the back of the turbine nacelle and the wind speed detected by a meteorological station close to the investigated turbine. Since an anemometric station is not always available, a third method is here proposed that does not require this input quantity. The proposed method relies on the wind speed on the back of the turbine and the manufacturer power curve. The effectiveness of such a method is shown by comparison to the results obtained with the standard methods implemented on a wind power plant in Southern Italy

A novel mppt technique based on mutual coordination between two pv modules/arrays

A novel maximum power point tracking (MPPT) technique based on mutual coordination of two photovoltaic (PV) modules/arrays has been proposed for distributed PV (DPV) systems. The proposed technique works in two stages. Under non-mismatch conditions between PV modules/arrays, superior performance stage 1 is active, which rectifies the issues inherited by the perturb and observe (P&O) MPPT. In this stage, the technique revolves around the perturb and observe (P&O) algorithm containing an intelligent mechanism of leader and follower between two arrays. In shading conditions, stage 2 is on, and it works like conventional P&O. Graphical analysis of the proposed technique has been presented under different weather conditions. Simulations of different algorithms have been performed in Matlab/Simulink. Simulation results of the proposed technique compliment the graphical analysis and show a superior performance and a fast response as compared to others, thus increasing the efficiency of distributed PV systems

Experimental testing of a horizontal-axis wind turbine to assess its performance

This paper describes a test procedure to investigate the performance of a micro wind turbine with horizontal-axis. A 3D model of a rotor with five blades has been designed by a MATLAB software; its airfoil is optimized to efficiently work at low wind speed. The rotor is coupled to an electric generator and this equipment is tested in a wind tunnel. An anemometer is used to measure and set the desired wind speeds. Electric quantities, i.e., voltage, current and power, are acquired by a digital multimeter. A variable resistance is used to change the operating point of the generator. Preliminary results are reported that refer to the application of the proposed test procedures to a wind turbine with a 0.2 m2 swept area