5,180 research outputs found

    Design of an Integrated, Six-Phase, Interleaved, Synchronous DC/DC Boost Converter on a Fuel-Cell-Powered Sport Catamaran

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    This paper describes the preliminary analysis, design and implementation phases of a DC/DC boost converter dedicated to the Futura catamaran propulsion chain developed by the UniBoAT team at the University of Bologna. The main goal of the project was the reduction of the converter’s weight by eliminating the use of heat sinks and by reducing the component size, especially inductors and capacitors. The obtained converter is directly integrated into the structure containing the fuel-cell stack. The realized converter was based on an interleaved architecture with six phases controlled through the average current mode control. The design was validated through simulations carried out using the LT-Spice software, whereas experimental validations were performed by means of both bench tests and on-field tests. Detailed thermal and efficiency analyses were provided with the bench tests under the two synchronous and non-synchronous operating modes and with the adoption of the phase-shedding technique. Prototype implementation and performance in real operating conditions are discussed in relation to on-field tests. The designed converter can be used in other applications requiring a voltage-controlled boost converter

    Smart charging for electric car-sharing fleets based on charging duration forecasting and planning

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    Electric car-sharing (ECS) is an increasingly popular service in many European cities. The management of an ECS fleet is more complex than its thermal engine counterpart due to the longer ”refueling“ time and the limited autonomy of the vehicles. To ensure adequate autonomy, the ECS provider needs high-capacity charging hubs located in urban areas where available peak power is often limited by the system power rating. Lastly, electric vehicle (EV) charging is typically entrusted to operators who retrieve discharged EVs in the city and connect them to the charging hub. The timing of the whole charging process may strongly differ among the vehicles due to their different states of charge on arrival at the hub. This makes it difficult to plan the charging events and leads to non-optimal exploitation of charging points. This paper provides a smart charging (SC) method that aims to support the ECS operators’ activity by optimizing the charging points’ utilization. The proposed SC promotes charging duration management by differently allocating powers among vehicles as a function of their state of charge and the desired end-of-charge time. The proposed method has been evaluated by considering a real case study. The results showed the ability to decrease charging points downtime by 71.5% on average with better exploitation of the available contracted power and an increase of 18.8% in the average number of EVs processed per day

    Electric Vehicles Charging Management System for Optimal Exploitation of Photovoltaic Energy Sources Considering Vehicle-to-Vehicle Mode

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    The growing penetration of distributed renewable energy sources (RES) together with the increasing number of new electric vehicle (EV) model registrations is playing a significant role in zero-carbon energy communities’ development. However, the ever-larger share of intermittent renewable power plants, combined with the high and uncontrolled aggregate EV charging demand, requires an evolution toward new planning and management paradigms of energy districts. Thus, in this context, this paper proposes novel smart charging (SC) techniques that aim to integrate as much as possible RES generation and EV charging demand at the local level, synergically acting on power flows and avoiding detrimental effects on the electrical power system. To make this possible, a centralized charging management system (CMS) capable of individually modulating each charging power of plugged EVs is presented in this paper. The CMS aims to maximize the charging self-consumption from local RES, flattening the peak power required to the external grid. Moreover, the CMS guarantees an overall good state of charge (SOC) at departure time for all the vehicles without requiring additional energy from the grid even under low RES power availability conditions. Two methods that differ as a function of the EV power flow direction are proposed. The first SC only involves unidirectional power flow, while the second one also considers bidirectional power flow among vehicles, operating in vehicle-to-vehicle (V2V) mode. Finally, simulations, which are presented considering an actual case study, validate the SC effects on a reference scenario consisting of an industrial area having a photovoltaic (PV) plant, non-modulable electrical loads, and EV charging stations (CS). Results are collected and performance improvements by operating the different SC methods are compared and described in detail in this paper

    Last improvements in the data assimilation scheme for the Mediterranean Analysis and Forecast system of the Copernicus Marine Service

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    The Mediterranean Forecasting System (MFS) is a numerical ocean prediction system that produces analyses, reanalyses and short term forecasts for the entire Mediterranean Sea and its Atlantic Ocean adjacent areas. The system is now part of the Copernicus Marine Environment Monitoring Service (CMEMS) providing regular and systematic information about the physical state and dynamics of the Mediterranean Sea through the Med-MFC (Mediterranean Monitoring and Forecasting Center). MFS has been implemented in the Mediterranean Sea with 1/16o horizontal resolution and 72 vertical levels and is composed by the hydrodynamic model NEMO (Nucleus for European Modelling of the Ocean) 2-way online coupled with the third generation wave model WW3 (WaveWatchIII) and forced by ECMWF atmospheric fields at 1/8o horizontal resolution. The model solutions are corrected by the data assimilation system (3D variational-3Dvar scheme adapted to the oceanic assimilation problem, Dobricic and Pinardi, 2008) with a daily assimilation cycle of satellite Sea Level Anomaly (SLA) and vertical profiles of Temperature and Salinity. In this study we present a new estimate the of the background error covariance matrix with vertical Empirical Orthogonal Functions (EOFs) that are defined at each grid point of the model domain in order to better account for the error covariance between temperature and salinity in the shelf and open ocean areas. Moreover the Error covariance matrix is z-dependent and varies in each month. This new dataset has been tested and validated for more than 2 years against a background error correlation matrix varying only seasonally and in thirteen sub-regions of the Mediterranean Sea. Latest developments include the implementation of an upgraded 3Dvar (Storto et al. 2012) for a high-resolution model, 1/24o in the horizontal and 141 vertical levelsPublishedBergen, Norway3SR. AMBIENTE - Servizi e ricerca per la Societ

    Last improvements in the data assimilation scheme for the Mediterranean Analysis and Forecast system of the Copernicus Marine Service

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    The Mediterranean Forecasting System (MFS) is a numerical ocean prediction system that produces analyses, reanalyses and short term forecasts for the entire Mediterranean Sea and its Atlantic Ocean adjacent areas. The system is now part of the Copernicus Marine Environment Monitoring Service (CMEMS) providing regular and systematic information about the physical state and dynamics of the Mediterranean Sea through the Med-MFC (Mediterranean Monitoring and Forecasting Center). MFS has been implemented in the Mediterranean Sea with 1/16o horizontal resolution and 72 vertical levels and is composed by the hydrodynamic model NEMO (Nucleus for European Modelling of the Ocean) 2-way online coupled with the third generation wave model WaveWatchIII (Clementi et al., 2017a) and forced by ECMWF atmospheric fields at 1/8° horizontal resolution. The model solutions are corrected by the data assimilation system (3D variational scheme, Dobricic and Pinardi, 2008) with a daily assimilation cycle of along track satellite Sea Level Anomaly (SLA) and vertical profiles of Temperature and Salinity from ARGO and gliders. In this study we present a new estimate of the background error covariance matrix with vertical Empirical Orthogonal Functions (EOFs) that are defined at each grid point of the model domain in order to better account for the error covariance between temperature and salinity in the shelf and open ocean areas. Moreover the Observational error covariance matrix is z-dependent and varies in each month. This new dataset has been tested and validated for more than 2 years against a background error correlation matrix varying only seasonally and in thirteen sub-regions of the Mediterranean Sea (Dobricic et al. 2005).PublishedBergen, Norway3SR. AMBIENTE - Servizi e ricerca per la Societ

    A 1/24° resolution Mediterranean physical analysis and forecasting system for the Copernicus Marine Environment Monitoring Service

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    This study describes a new model implementation for the Mediterranean Sea that has been achieved in the framework of the Copernicus Marine Environment Monitoring Service (CMEMS). The numerical ocean prediction system, that operationally produces analyses and forecasts of the main physical parameters for the entire Mediterranean Sea and its Atlantic Ocean adjacent areas, has been upgraded by increasing the grid resolution from 1/16o to 1/24o in the horizontal and from 72 to 141 unevenly spaced vertical levels, by increasing the number of fresh water river inputs and by updating the data assimilation scheme. The model has a non-linear explicit free surface and it is forced by surface pressure, interactive heat, momentum and water fluxes at the airsea interface. The focus of this work is to present the new modelling system which will become operational in the near future and the validation assessment including the comparison with an independent non assimilated dataset (coastal moorings) and quasi-independent (in situ vertical profiles and satellite) datasets. The results show that the higher resolution model is capable of representing most of the variability of the general circulation in the Mediterranean Sea, however some improvements need to be implemented in order to enhance the model ability in reproducing specific hydrodynamic features particularly the Sea Level Anomaly.PublishedBergen, Norway3SR. AMBIENTE - Servizi e ricerca per la Societ

    A 1/24 degree resolution Mediterranean analysis and forecast modeling system for the Copernicus Marine Environment Monitoring Service

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    The Mediterranean Forecasting System (MFS) is a numerical ocean prediction system that operationally produces analyses, reanalyses and short-term forecasts of the main physical parameters for the entire Mediterranean Sea and its Atlantic Ocean adjacent areas. This work is specifically focused on the description and evaluation of the analysis and forecast modeling system that covers the analysis of the current situation and produces daily updates of the following 10 days forecast. The system has been recently upgraded in the framework of the Copernicus Marine Environment Monitoring Service (CMEMS) by increasing the grid resolution from 1/16o to 1/24o in the horizontal and from 72 to 141 vertical levels, by increasing the number of fresh water river inputs and by updating the data assimilation scheme. The model has a non-linear explicit free surface and it is forced by surface pressure, interactive heat, momentum and water fluxes at the air-sea interface. In order to validate the modeling system and to estimate the accuracy of the model products, a quality assessment is regularly performed including both pre-operational qualification and near real time (NRT) validation procedures. Pre-operational qualification activities focus on testing the improvements of the quality of the new system with respect to the previous version and relies on past simulation and historical data, while NRT validation activities aim at routinely and on-line providing the skill assessment of the model analysis and forecasts and relies on the NRT available observations. The focus of this work is to present the new operational modeling system and the skill assessment including comparison with independent (insitu coastal moorings) and quasi-independent (insitu vertical profiles and satellite) datasets.PublishedBergen, Norway3SR. AMBIENTE - Servizi e ricerca per la Societ

    The Copernicus Marine Service ocean forecasting system for the Mediterranean Sea

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    The Mediterranean Monitoring and Forecasting Center (MED-MFC) is part of the Copernicus Marine Environment and Monitoring Service (CMEMS) and provides regular and systematic information on the time-evolving Mediterranean Sea physical (including waves) and biogeochemical state. The systems consist of 3 components: 1) Med-Physics, a numerical ocean prediction systems, based on NEMO model, that operationally produces analyses, reanalysis and short term forecasts of the main physical parameters; 2) Med-Biogeochemistry, a biogeochemical analysis, reanalysis and forecasting system based on the Biogeochemical Flux Model (BFM) which provides information on chlorophyll, phosphate, nitrate, primary productivity, oxygen, phytoplankton biomass, pH and pCO2; 3) Med-Waves based on WAM model and providing analysis, forecast and reanalysis products for waves. The systems have been recently upgraded at a resolution of 1/24 degree in the horizontal and 141 vertical levels. The Med-Physics analysis and forecasting system is composed by the hydrodynamic model NEMO 2-way coupled with the third-generation wave model WaveWatchIII and forced by ECMWF atmospheric fields. The model solutions are corrected by the 3DVAR data assimilation system (3D variational scheme adapted to the oceanic assimilation problem) with a daily assimilation cycle of sea level anomaly and vertical profiles of temperature and salinity. The model has a non-linear explicit free surface and it is forced by surface pressure, interactive heat, momentum and water fluxes at the air-sea interface. The biogeochemical analysis and forecasts are produced by means of the MedBFM v2.1 modeling system (i.e. the physical-biogeochemical OGSTM-BFM model coupled with the 3DVARBIO assimilation scheme) forced by the outputs of the Med-Physics product. Seven days of analysis/hindcast and ten days of forecast are bi-weekly produced on Wednesday and on Saturday, with the assimilation of surface chlorophyll concentration from satellite observations. In-situ data are mainly used to estimate model uncertainty at different spatial scales. The Med-Waves modelling system is based on the WAM Cycle 4.5.4 wave model code. It consists of a wave model grid covering the Mediterranean Sea at a 1/24° horizontal resolution, nested to a North Atlantic grid at a 1/6° resolution. The system is forced by ECMWF winds at 1/8°. Refraction due to surface currents is accounted by the system which assimilates altimeter along-track significant wave height observations. On a daily basis, it provides 1-day analysis and 5-day forecast hourly wave parameters. Currently, wave buoy observations of significant wave height and mean wave period along with satellite observations are used to calibrate and validate the Med-waves modelling system.PublishedHalifax, Nova Scotia, Canada4A. Oceanografia e clim
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