1,720,973 research outputs found
Vehicles to Grid (V2G) concept applied to a Virtual Power Plant Structure
No full textRenewable energy sources will play an increasingly central role in the power network of the future. The will to reduce the dependence on fossil sources as well as growing environmental awareness, both individually and governmentally, is forcing governments throughout the world to invest an enormous amount of capital in renewable energy sources. The European Union, through its Energy and Climate Policy, has fixed an ambitious target: to provide, 20% of electricity from renewable sources by 2020. The additional volatility introduced by renewable energy source to the grid can be compensated by energy storage systems as well as by demand control measurements and by the reinforcement of the power grid. These solutions can improve the system reliability of the electric grid and the efficiency of the energy supply and give more flexibility to the system. This study analyzes the possibilities to use electric vehicles connected to the grid as energy storage system within a Virtual Power Plant structure. Through the formulation of an optimization problem the optimal number of electric vehicles has been evaluate
A simplified charging battery model for smart electric vehicles applications
No full textThis paper proposes a simple and generalized battery model dedicated to lithium rechargeable batteries of electric vehicles, oriented to the energy management of off-board charging stations. In particular, the mathematical description of the used algorithm, the identification of model parameters and the validation of its use for time emulation of fast charging processes are reported and discussed in detail. The comparison between the emulated charging battery behaviours of a Lithium Iron Phosphate battery and the experimental results is reported in order to confirm the accuracy of the model. Finally, an application control scheme for the coordination and energy management of off-board charging stations within the smart grid paradigm is described
A Non-Linear Dynamic Electrical Model of Sodium-Nickel Chloride Batteries
No full textIn this paper a non-linear second order circuit model of high temperature Sodium-Nickel Chloride batteries (SNBs) is presented. The aim is the development of an accurate model easily implementable in microgrids Energy Management System and suitable for their real-time control. The proposed model is based on the analysis of the experimental performance of a commercial 23.5 kWh SNB. In particular, the mathematical description of the used algorithm, the model parameters identification method as well as the measurement tests carried out for their evaluation are reported and discussed in detail. Then, the model is validated using a measured current-voltage profile, developed in order to trigger the whole battery operative range. The comparison between the experimental data and simulations has confirmed the good accuracy of the proposed model in a defined SOC range. However, due to the particular chemical composition of the battery positive electrode, a novel modelling approach specific for the SNB technology has been finally demonstrated to be necessary
Analysis of Vehicle to Grid and Energy Storage Integration in a Virtual Power Plant
No full textIn this paper the integration between the Vehicle to
Grid technology and a stationary energy storage system in a
Virtual Power Plant (VPP) has been investigated. In order to
evaluate the effects of such energy storage systems in an
autonomous VPP, an Energy Management System (EMS),
oriented to improve the local matching between electrical energy
demand and production, has been proposed. To achieve this
target and optimize the local energy production exploitation, an
energy system design procedure, based on the minimization of
the VPP total cost through an annual emulation of the VPP’s
EMS strategy, has been applied. The proposed methodology,
tested on a benchmark VPP, considers the contribution of both
electric vehicles and stationary battery in different possible
configurations. The comparison among three different cases of
study has finally presented at the aim of pointing out the
technical and economic benefits
A Virtual Power Plant Management Model Based on Electric Vehicle Charging Infrastructure Distribution
No full textThe exploitation of distributed generation based on
intermittent renewable energy sources (RES) has increased the
load and generation profile variability. The resort to distributed
energy storage systems (DESSs) is usually proposed to
compensate the volatility introduced by RES. In particular, plugin
electric vehicles (EVs) are considered one of the most
interesting solutions for providing DESSs with the aim of
exploiting RES production and matching the distributed
electrical generation to the local demand. The aim of this paper is
to analyze the impact of vehicle-to-grid technology on an weakly
interconnected Virtual Power Plant (VPP) in order to evaluate
the effects that distribution and availability of EVs charging
structures can have on VPP total cost. A novel mathematical
modeling of the mobility system is firstly developed to calculate
the probabilistic distribution of parking places. Thereafter, the
economic impact on a VPP has been evaluated for different plugin
ratio and charging station scenarios
Preliminary Evaluation of HCPV System In – Field Energy Production in the Mediterranean Area
No full textThis paper describes the preliminary tests developed in order to evaluate the outdoor performance of a High Concentrator Photovoltaic (HCPV) system located in the south Sardinia (Italy). Because of the plant location, the presented evaluation is useful in assessing the HCPV systems electrical productivity in the Mediterranean area, in different seasons of the year. The obtained results were referred to the weather conditions and the correlation between the energy production (EP) and the environmental parameters is presented. The results, in terms of electrical productivity obtained for the HCPV system, were compared with those of a traditional flat plate silicon photovoltaic plant, installed in the same location. The performances of both systems were analyzed for the same seasons and weather conditions. The obtained preliminary results provide a data base which is useful to compare the energy production of different photovoltaic technologies. Finally, the test results highlight the potentiality of HCPV technology in the Mediterranean area of Italy, confirming that CPV systems can be an important energy source in this region of Europe
Performance Analysis of Non-Linear Load Effects on a Micro-Grid Supplied by Photovoltaic Power Plants
No full textIn this paper the power quality analysis of a micro-grid characterised by a relevant presence of non-linear electric loads and non-linear electrical generators, like photovoltaic (PV) systems, is presented. The presence of nonlinear loads, such as PCs, printers, electronic equipment and other such devices, determines a time varying evolution of micro-grid active and reactive powers and causes currents imbalance in the three-phase system. Moreover, non-linear loads introduce current distortions that pollute the electrical network with harmonic components. In this framework it is interesting to analyze how the introduction of PV plants can influence the power quality (PQ). In fact, the harmonic pollution associated with the presence of non-linear loads can interfere with PV energy conversion systems, determining high voltage distortion and worsening the micro-grid stability and reliability. However, under particular energy balance conditions the introduction of PV plants could improve the power quality reducing the harmonic components. In the present paper, the impact of two different PV systems on the power quality of the tested micro-grid has been analyzed for different load conditions. Total harmonic distortion (THD) indexes have been correlated with the active power profile and their evolutions have been discussed referring to the active power absorbed and generated
Characterization of a CPV module prototype for design and performance improvement
No full textThe purpose of this paper is to highlight that a detailed electrical and optical characterization is a basic step to improve the design of a concentrating photovoltaic (CPV) module and enhance its overall performance. The complete characterization of the preliminary CPV module prototype, designed according the state of art, has been carried out revealing lower performances than expected. The reasons of the energy losses have been determined by an accurate optical and electrical analysis. The results of these tests permitted to introduce upgrades into the design of a second version of the CPV module in order to overcome the main defects previously identified. The full characterization of this new version revealed significantly higher performances. Overall, the obtained outcomes demonstrate the benefits of an accurate characterization, allowing both the identification of the system problems design and the evaluation of the effects of the adopted solutions
A Concentrator Photovoltaic Panel Prototype: Realization and Characterization
No full textIn this paper the prototype of concentrator photovoltaic (CPV) panel with Fresnel lenses primary optical elements has been characterized. The module has been developed by the National Institute for Astrophysics (INAF) of Cagliari. The testing and characterization process has been developed at the Sardegna Ricerche PV Laboratory. The optical and mechanical design of the proposed CPV module is firstly reported. Afterwards the outdoor testing results are presented. Most of panel components have been characterized in order to understand the weight of each element on the energy conversion process and on energy efficiency. In particular, the performances of primary and secondary optical elements, photovoltaic multi-junction cell and solar receiver heat sink have been assessed. A special attention has been paid to the evaluation of the module angle acceptance and to the analysis of the spatial distribution of the concentrated solar radiation on the cell plane in order to understand the influence of tracker accuracy and irradiance non-uniformity on the CPV prototype electrical performances. The characterization activity has been completed with an accurate analysis of the meteorological conditions measurements at the Sardegna Ricerche outdoor Photovoltaic Laboratory test bench, in order to verify the suitability of the site to the IEC 62670 standard draft
A Cassegrain Concentrator Photovoltaic System: comparison between dichroic and multijunction photovoltaic configurations
No full textIn the present paper a novel configuration of high
concentrator photovoltaic (HCPV) systems based on Cassegrain
optics has been presented. The proposed system has been
designed in order to be suitable for the implementation of both
multi-junction and spectrum splitting configurations. The
Cassegrain optic design, the components and material choices for
the development of HCPV receivers have been described.
Subsequently, the proposed HCPV system has been implemented
considering a multi-junction and dichroic photovoltaic solar cells
configurations. Finally, the outdoor characterization of the two
receiver prototypes has been carried out in order to determine
their energy conversion performances. The obtained outcomes
are then compared and discussed in order to highlight the worth,
and the effectiveness of the proposed HCPV configurations
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