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Special Issue "Selected Papers from 16 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2016)"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (15 March 2017)

Special Issue Editor

Guest Editor
Prof. Dr. Rodolfo Araneo

Department of Astronautical, Electrical and Energetic Engineering University of Rome La Sapienza Via Eudossiana 18 – 00184, Rome, Italy
Website | E-Mail

Special Issue Information

Dear Colleagues,

EEEIC 2016 is the 16th annual conference, making it  one of Europe’s largest, longest-running, professional networking and educational event of its kind. EEEIC is an annual energy and environment conference held in 2016 in Florence, Italy, where the delegates make presentations and discuss various issues, including clean and renewable energy solutions for the protection of our environment.

Submissions related to any of the following topics are welcomed:

1. Renewable energy sources and storages

  • Solar energy

  • Photovoltaic cell technology

  • Hydro and wind energy

  • Biomass and biofuels

  • Energy management and storage

  • High-performance cogeneration

2. Power systems and smart grids

  • Power quality

  • Microgrids

  • Design, control and management

  • Protection

  • RAM (reliability, availability, maintainability)

  • Management of distribution grids

  • ICT for power systems

  • Power line communications

3. Materials

  • Nanotechnology for renewable energy

  • Novel materials for energy harvesting

4. Environmental phenomena and pollution

  • EM spectrum management

  • Power quality and harmonics

5. Power electronics and components

  • Electrical generators

  • Converters for renewable energies

  • Converters for storage

  • Low-frequency EMC

6. Regulation and electricity markets

  • Regulatory issues and delivery standards

  • Dispatching in power systems

  • Generation and transmission expansion

  • Dispersed generation and distribution system

7. Smart buildings

  • Home and building automation

  • Lighting systems and components

  • Metering systems

  • Sensors

  • Nearly zero energy buildings

  • Demand side management

  • Supervisory systems

8. Mobility

  • Sustainable transport systems

  • Electrical vehicles

  • Automotive

9. Maintenance, operation and safety

  • Designing for Safety

  • Grounding

  • Lightning

  • Hazard – Electric shock, arc flash, fire and explosion

  • Maintenance and operation of electric power systems

  • Work practices and procedures

  • Electrical safety training

10. Measurements

  • Environmental measurements

  • Electrical measurements

  • Advanced instrumentation and data acquisition systems

  • Intelligent distributed systems and remote control

  • Signal and image processing

  • EMC measurements

11. Circuits, sensors and actuators

  • Circuits and systems theory and application

  • Electromagnetic compatibility and application

  • Nonlinear systems

  • Signal processing and identification

  • Sensors and actuators for energy conservation

  • Smart circuits

  • Systems modeling

Thank you very much!

Prof. Dr. Rodolfo Arane
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 700 CHF (Swiss Francs, 50% discount).

Published Papers (25 papers)

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Research

Open AccessArticle Prediction in Photovoltaic Power by Neural Networks
Energies 2017, 10(7), 1003; doi:10.3390/en10071003
Received: 11 April 2017 / Revised: 11 July 2017 / Accepted: 12 July 2017 / Published: 15 July 2017
Cited by 1 | PDF Full-text (13480 KB) | HTML Full-text | XML Full-text
Abstract
The ability to forecast the power produced by renewable energy plants in the short and middle term is a key issue to allow a high-level penetration of the distributed generation into the grid infrastructure. Forecasting energy production is mandatory for dispatching and distribution
[...] Read more.
The ability to forecast the power produced by renewable energy plants in the short and middle term is a key issue to allow a high-level penetration of the distributed generation into the grid infrastructure. Forecasting energy production is mandatory for dispatching and distribution issues, at the transmission system operator level, as well as the electrical distributor and power system operator levels. In this paper, we present three techniques based on neural and fuzzy neural networks, namely the radial basis function, the adaptive neuro-fuzzy inference system and the higher-order neuro-fuzzy inference system, which are well suited to predict data sequences stemming from real-world applications. The preliminary results concerning the prediction of the power generated by a large-scale photovoltaic plant in Italy confirm the reliability and accuracy of the proposed approaches. Full article
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Open AccessArticle Low-Cost Solar Irradiance Sensing for PV Systems
Energies 2017, 10(7), 998; doi:10.3390/en10070998
Received: 18 January 2017 / Revised: 3 July 2017 / Accepted: 10 July 2017 / Published: 14 July 2017
Cited by 1 | PDF Full-text (4680 KB) | HTML Full-text | XML Full-text
Abstract
Determination of solar irradiance is a critical asset to ensure efficient working conditions for a photovoltaic (PV) system. This work analyze the feasibility of assessing solar irradiance on a PV device assuming the knowledge of the device temperature and the voltage/current operating point.
[...] Read more.
Determination of solar irradiance is a critical asset to ensure efficient working conditions for a photovoltaic (PV) system. This work analyze the feasibility of assessing solar irradiance on a PV device assuming the knowledge of the device temperature and the voltage/current operating point. This work proposes an approach based on a manipulation of the analytic expressions found in the reduced form of the “single diode” circuit model for a silicon PV device. The approach was validated through different practical experiments, and the results obtained are comparable to the ones of a commercial instrument for irradiance sensing. The ease of construction and the reduced costs involved make a device based on the proposed approach suitable for large-scale integration in a PV plant. Full article
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Open AccessArticle The Influence of Small-Scale Power Plant Supporting Schemes on the Public Trader and Consumers
Energies 2017, 10(6), 800; doi:10.3390/en10060800
Received: 13 February 2017 / Revised: 2 June 2017 / Accepted: 6 June 2017 / Published: 12 June 2017
PDF Full-text (3066 KB) | HTML Full-text | XML Full-text
Abstract
The mechanism of support schemes for achieving the required share of renewable energy sources (RES) was implemented into the energy sector. The issued amount of support requires state subsidies. The end-users of electricity are paying the mandatory procurement component taxes to cover these
[...] Read more.
The mechanism of support schemes for achieving the required share of renewable energy sources (RES) was implemented into the energy sector. The issued amount of support requires state subsidies. The end-users of electricity are paying the mandatory procurement component taxes to cover these subsidies. The article examines the way of minimizing the influence of the existing RES supporting schemes on the consumers. The fixed purchased electricity price in the case of RES does not encourage producers to operate at hours of peak consumption or when the price is high. Modification of the RES support mechanisms at the legislative level, firstly, could minimize the influence of the mandatory procurement component on the end-users’ electricity price, and secondly, could provide a great opportunity for the public trader to forecast the operation of small power plants and their generation abilities. Numerical experiments with models of two types of power plants (biofuel and hydropower) prove the existence of a problem and the presence of a solution. This problem constitutes the main subject of the present paper. Full article
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Open AccessArticle Assessment of Energy Storage Operation in Vertically Integrated Utility and Electricity Market
Energies 2017, 10(5), 683; doi:10.3390/en10050683
Received: 15 February 2017 / Revised: 18 April 2017 / Accepted: 10 May 2017 / Published: 12 May 2017
PDF Full-text (910 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this paper is to compare the operational pattern of an energy storage system (ESS) in a vertically-integrated utility and in a deregulated market environment for different levels of wind integration. As the main feature of a vertically-integrated utility is a
[...] Read more.
The aim of this paper is to compare the operational pattern of an energy storage system (ESS) in a vertically-integrated utility and in a deregulated market environment for different levels of wind integration. As the main feature of a vertically-integrated utility is a centralized decision-making process, all of the investment and operating decisions are made with a single goal of minimizing the overall system operating costs. As a result, an ESS in such an environment is operated in a way that is optimal for the overall system economics. On the other hand, the system operator in a deregulated market has less power over the system resources, and commitment and dispatch decisions are a result of the market clearing procedure. In this setting, the ESS owner aims at maximizing its profit, which might not be in line with minimizing overall system operating costs or maximizing social welfare. To compare the ESS operation in these two environments, we analyze the storage operation in two different settings. The first one is a standard unit commitment model with the addition of centrally-controlled storage. The second one is a bilevel model, where the upper level is a coordinated ESS profit maximization problem, while the lower level a simulated market clearing. The case study is performed on a standardized IEEE RTS-96 system. The results show a reduction in the generation dispatch cost, online generation capacity and wind curtailment for both models. Moreover, ESS significantly increases social welfare in the market-based environment. Full article
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Open AccessArticle Identification of Non-Stationary Magnetic Field Sources Using the Matching Pursuit Method
Energies 2017, 10(5), 655; doi:10.3390/en10050655
Received: 16 February 2017 / Revised: 23 April 2017 / Accepted: 4 May 2017 / Published: 9 May 2017
PDF Full-text (4677 KB) | HTML Full-text | XML Full-text
Abstract
The measurements of electromagnetic field emissions, performed on board a vessel have showed that, in this specific environment, a high level of non-stationary magnetic fields (MFs) is observed. The adaptive time-frequency method can be used successfully to analyze this type of measured signal.
[...] Read more.
The measurements of electromagnetic field emissions, performed on board a vessel have showed that, in this specific environment, a high level of non-stationary magnetic fields (MFs) is observed. The adaptive time-frequency method can be used successfully to analyze this type of measured signal. It allows one to specify the time interval in which the individual frequency components of the signal occur. In this paper, the method of identification of non-stationary MF sources based on the matching pursuit (MP) algorithm is presented. It consists of the decomposition of an examined time-waveform into the linear expansion of chirplet atoms and the analysis of the matrix of their parameters. The main feature of the proposed method is the modification of the chirplet’s matrix in a way that atoms, whose normalized energies are lower than a certain threshold, will be rejected. On the time-frequency planes of the spectrograms, obtained separately for each remaining chirlpet, it can clearly identify the time-frequency structures appearing in the examined signal. The choice of a threshold defines the computing speed and precision of the performed analysis. The method was implemented in the virtual application and used for processing real data, obtained from measurements of time-vary MF emissions onboard a ship. Full article
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Open AccessArticle Wide Area Information-Based Transmission System Centralized Out-of-Step Protection Scheme
Energies 2017, 10(5), 633; doi:10.3390/en10050633
Received: 15 February 2017 / Revised: 26 April 2017 / Accepted: 28 April 2017 / Published: 5 May 2017
PDF Full-text (8526 KB) | HTML Full-text | XML Full-text
Abstract
A wide area monitoring system (WAMS) with reliable telecommunication infrastructure can be expanded and enhanced with additional protection and control functionalities using synchronized phasor data measurements. With that aim, we have developed a multifunctional line protection (MFLP) model with both system and back-up
[...] Read more.
A wide area monitoring system (WAMS) with reliable telecommunication infrastructure can be expanded and enhanced with additional protection and control functionalities using synchronized phasor data measurements. With that aim, we have developed a multifunctional line protection (MFLP) model with both system and back-up protection functions. Theoretical premises based on transmission and relay protection system knowledge, together with the experience gathered from the operation of existing wide area systems, were used to develop the proposed model. Four main groups of simulation scenarios were defined in order to test the newly implemented functions. The results of the simulation process confirm the assumptions underlying the design of our MFLP module. Simulation results are then used for definition of the protection criteria required for implementation of the wide area protection algorithm in a control center. Conclusions drawn from the protection responses of the proposed algorithm that strengthen the algorithm design process are elaborated in the paper. The main contribution of the paper is the design and development of a centralized MFLP algorithm based on synchronized phasor data that is able to issue a trip command to a circuit breaker before an out-of-step condition occurs. Full article
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Open AccessArticle Design Optimization of a High Power LED Matrix Luminaire
Energies 2017, 10(5), 639; doi:10.3390/en10050639
Received: 16 February 2017 / Revised: 5 April 2017 / Accepted: 6 April 2017 / Published: 5 May 2017
PDF Full-text (5841 KB) | HTML Full-text | XML Full-text
Abstract
This work presents a methodology for optimizing the layout and geometry of an m×n high power (HP) light emitting diode (LED) luminaire. Two simulators are used to analyze an LED luminaire model. The first simulator uses the finite element method (FEM)
[...] Read more.
This work presents a methodology for optimizing the layout and geometry of an m × n high power (HP) light emitting diode (LED) luminaire. Two simulators are used to analyze an LED luminaire model. The first simulator uses the finite element method (FEM) to analyze the thermal dissipation, and the second simulator uses the ray tracing method for lighting analysis. The thermal and lighting analysis of the luminaire model is validated with an error of less than 10%. The goal of the optimization process is to find a solution that satisfies both thermal dissipation and light efficiency. The optimization goal is to keep the LED temperature at an acceptable level while still obtaining uniform illumination on a target plane. Even though no optical accessories or active cooling systems are used in the model, the results demonstrate that it is possible to obtain satisfactory results even with a limited number of parameters. The optimization results show that it is possible to design luminaires with 4, 6 and up to 8 HP-LEDs, keeping the LED temperature at about 100 C. However, the best uniformity on a target plane was found by the heuristic algorithm. Full article
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Open AccessArticle Management System for Large Li-Ion Battery Packs with a New Adaptive Multistage Charging Method
Energies 2017, 10(5), 605; doi:10.3390/en10050605
Received: 14 February 2017 / Revised: 28 March 2017 / Accepted: 21 April 2017 / Published: 1 May 2017
PDF Full-text (15441 KB) | HTML Full-text | XML Full-text
Abstract
Among the wide diversity of existing technologically mature batteries, lithium-ion (Li-ion) batteries have become popular because of their longevity, high energy density, high efficiency and lack of memory effect. Differential charging of cells with age has turned balancing management systems into an important
[...] Read more.
Among the wide diversity of existing technologically mature batteries, lithium-ion (Li-ion) batteries have become popular because of their longevity, high energy density, high efficiency and lack of memory effect. Differential charging of cells with age has turned balancing management systems into an important research subject. This paper proposes a new battery management system (BMS) to improve the capacity usage and lifespan of large Li-ion battery packs and a new charging algorithm based on the traditional multistage method. The main advantages of the proposed system are its versatility and ability to implement different charging and balancing methods in a very accessible way. The combination of charging methods with balancing methods represents an evolution when compared with other works in the literature. Full article
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Open AccessArticle Harvesting-Aware Energy Management for Environmental Monitoring WSN
Energies 2017, 10(5), 607; doi:10.3390/en10050607
Received: 14 February 2017 / Revised: 20 April 2017 / Accepted: 21 April 2017 / Published: 1 May 2017
PDF Full-text (826 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks can be used to collect data in remote locations, especially when energy harvesting is used to extend the lifetime of individual nodes. However, in order to use the collected energy most effectively, its consumption must be managed. In this work,
[...] Read more.
Wireless sensor networks can be used to collect data in remote locations, especially when energy harvesting is used to extend the lifetime of individual nodes. However, in order to use the collected energy most effectively, its consumption must be managed. In this work, forecasts of diurnal solar energies were made based on measurements of atmospheric pressure. These forecasts were used as part of an adaptive duty cycling scheme for node level energy management. This management was realized with a fuzzy logic controller that has been tuned using differential evolution. Controllers were created using one and two days of energy forecasts, then simulated in software. These controllers outperformed a human-created reference controller by taking more measurements while using less reserve energy during the simulated period. The energy forecasts were comparable to other available methods, while the method of tuning the fuzzy controller improved overall node performance. The combination of the two is a promising method of energy management. Full article
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Open AccessArticle Load Signature Formulation for Non-Intrusive Load Monitoring Based on Current Measurements
Energies 2017, 10(4), 538; doi:10.3390/en10040538
Received: 14 February 2017 / Revised: 28 March 2017 / Accepted: 10 April 2017 / Published: 16 April 2017
PDF Full-text (3773 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present a new methodology for the formulation of efficient load signatures towards the implementation of a near-real time Non-Intrusive Load Monitoring (NILM) approach. The purpose of this work relies on defining representative current values regarding the 1st, 3rd and
[...] Read more.
In this paper we present a new methodology for the formulation of efficient load signatures towards the implementation of a near-real time Non-Intrusive Load Monitoring (NILM) approach. The purpose of this work relies on defining representative current values regarding the 1st, 3rd and 5th harmonic orders to be utilized in the load signatures formulation. A measurement setup has been developed and steady-state measurements have been performed in a Low Voltage residence. A data processing methodology is proposed aiming to depict representative current values for each harmonic order in order to keep the load signature short and simple. In addition, a simple disaggregation scheme is proposed under linear equations for the disaggregation mode in order to examine the near-real time application of the methodology. The analysis indicates that the developed load signatures could be efficient for a per second application rate of the NILM algorithm. The results show that the higher harmonic currents facilitate the identification performance. Finally, the analysis concludes that for combinations that include appliances with intense harmonic content, the phase angle of the higher for harmonic currents should also be considered to the load signatures formulation. Full article
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Open AccessArticle Validation of the Measurement Characteristics in an Instrument for Power Quality Estimation—A Case Study
Energies 2017, 10(4), 536; doi:10.3390/en10040536
Received: 15 February 2017 / Revised: 3 April 2017 / Accepted: 6 April 2017 / Published: 15 April 2017
PDF Full-text (3064 KB) | HTML Full-text | XML Full-text
Abstract
An acceptable quality of electrical energy is seen today as an important component of ecology. Several instruments for estimating the quality of electrical power have been elaborated. Each supplier assures that the instrument meets the applicable standards and that the uncertainty of the
[...] Read more.
An acceptable quality of electrical energy is seen today as an important component of ecology. Several instruments for estimating the quality of electrical power have been elaborated. Each supplier assures that the instrument meets the applicable standards and that the uncertainty of the measurement results obtained using the instrument does not exceed the established levels. The accuracy of the measurement results depends on a couple of things, e.g., the correctness of the measurement algorithms implemented in the instrument and the quality of its calibration. In this paper, the basic features of an “estimator/analyzer” (E/A) instrument, as well as the calibration methods of the instrument, the verification of its measurement algorithms, and also the obtained exemplary results, are shown. The proposal of the strategy of the reliable validation of embedded measurement algorithms for the identification of parameters characterizing electrical power quality in the power grid is discussed. Full article
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Open AccessArticle A Framework for Real-Time Optimal Power Flow under Wind Energy Penetration
Energies 2017, 10(4), 535; doi:10.3390/en10040535
Received: 9 February 2017 / Revised: 27 March 2017 / Accepted: 6 April 2017 / Published: 14 April 2017
Cited by 2 | PDF Full-text (3835 KB) | HTML Full-text | XML Full-text
Abstract
Developing a suitable framework for real-time optimal power flow (RT-OPF) is of utmost importance for ensuring both optimality and feasibility in the operation of energy distribution networks (DNs) under intermittent wind energy penetration. The most challenging issue thereby is that a large-scale complex
[...] Read more.
Developing a suitable framework for real-time optimal power flow (RT-OPF) is of utmost importance for ensuring both optimality and feasibility in the operation of energy distribution networks (DNs) under intermittent wind energy penetration. The most challenging issue thereby is that a large-scale complex optimization problem has to be solved in real-time. Online simultaneous optimization of the wind power curtailments of wind stations and the discrete reference values of the slack bus voltage which leads to a mixed-integer nonlinear programming (MINLP) problem, in addition to considering variable reverse power flow, make the optimization problem even much more complicated. To address these difficulties, a two-phase solution approach to RT-OPF is proposed in this paper. In the prediction phase, a number of MINLP OPF problems corresponding to the most probable scenarios of the wind energy penetration in the prediction horizon, by taking its forecasted value and stochastic distribution into account, are solved in parallel. The solution provides a lookup table for optional control strategies for the current prediction horizon which is further divided into a certain number of short time intervals. In the realization phase, one of the control strategies is selected from the lookup table based on the actual wind power and realized to the grid in the current time interval, which will proceed from one interval to the next, till the end of the current prediction horizon. Then, the prediction phase for the next prediction horizon will be activated. A 41-bus medium-voltage DN is taken as a case study to demonstrate the proposed RT-OPF approach. Full article
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Open AccessArticle Modelling and Optimization in Microgrids
Energies 2017, 10(4), 523; doi:10.3390/en10040523
Received: 5 December 2016 / Revised: 16 March 2017 / Accepted: 11 April 2017 / Published: 12 April 2017
Cited by 2 | PDF Full-text (3299 KB) | HTML Full-text | XML Full-text
Abstract
The expansion of renewable energies is progressing strongly. The influence on the power supply networks by the variability of the infeed must be met with new concepts. In this paper, we investigate the possibilities of integrating microgrids as a cooperating unit in the
[...] Read more.
The expansion of renewable energies is progressing strongly. The influence on the power supply networks by the variability of the infeed must be met with new concepts. In this paper, we investigate the possibilities of integrating microgrids as a cooperating unit in the power supply network to support further expansion of renewable energy sources (RES) power plants. In this paper, a differentiation of microgrids from similar network structures is established, and a classification of proposed groups is made. Then, after the description of the simulation of the components in a microgrid, with practical advice, an example model is shown, which aids the dimensioning of the components within a microgrid to achieve a specified goal. Full article
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Open AccessArticle Active, Reactive and Harmonic Control for Distributed Energy Micro-Storage Systems in Smart Communities Homes
Energies 2017, 10(4), 448; doi:10.3390/en10040448
Received: 8 February 2017 / Revised: 20 March 2017 / Accepted: 24 March 2017 / Published: 1 April 2017
Cited by 2 | PDF Full-text (1615 KB) | HTML Full-text | XML Full-text
Abstract
This paper aims to provide control strategies for distributed micro-storage energy systems at the residential level to contribute to smart grid goals. A simulation model of an energy storage system (ESS) charger has been implemented to test these proposed control strategies. The smart
[...] Read more.
This paper aims to provide control strategies for distributed micro-storage energy systems at the residential level to contribute to smart grid goals. A simulation model of an energy storage system (ESS) charger has been implemented to test these proposed control strategies. The smart community energy management system (SCEMS), acting as an aggregator of resources in the community according to the expected demand and production, sends to each individual home the active and reactive power set-points. Besides, in case the ESS has available capacity, once the SCEMS requirements are satisfied, it is used to absorb the harmonic current components demanded by the household circuitry. It allows a local improvement in the power quality of the demanded current, and thus contributes to the global power quality consumption of the community. Simulation results showing the operation of a local ESS at a home in a Smart Community are presented to validate the proposed control strategies. Full article
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Open AccessArticle Energy Management with Support of PV Partial Shading Modelling in Micro Grid Environments
Energies 2017, 10(4), 453; doi:10.3390/en10040453
Received: 19 February 2017 / Revised: 17 March 2017 / Accepted: 24 March 2017 / Published: 1 April 2017
Cited by 1 | PDF Full-text (2274 KB) | HTML Full-text | XML Full-text
Abstract
Although photovoltaic power plants are suitable local energy sources in Micro Grid environments, when large plants are involved, partial shading and inaccurate modelling of the plant can affect both the design of the Micro Grid as well as the energy management process that
[...] Read more.
Although photovoltaic power plants are suitable local energy sources in Micro Grid environments, when large plants are involved, partial shading and inaccurate modelling of the plant can affect both the design of the Micro Grid as well as the energy management process that allows for lowering the overall Micro Grid demand towards the main grid. To investigate the issue, a Photovoltaic Plant simulation model, based on a real life power plant, and an energy management system, based on a real life Micro Grid environment, have been integrated to evaluate the performance of a Micro Grid under partial shading conditions. Using a baseline energy production model as a reference, the energy demand of the Micro Grid has been computed in sunny and partial shading conditions. The experiments reveal that an estimation based on a simplified PV model can exceed by 65% the actual production. With regards to Micro Grid design, on sunny days, the expected costs, based on a simplified PV model, can be 5.5% lower than the cost based on the double inverter model. In single cloud scenarios, the underrating can reach 28.3%. With regard to the management process, if the energy yield is estimated by means of a simplified PV model, the actual cost can be from 17.1% to 21.5% higher than the theoretical cost expected at design time. Full article
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Open AccessArticle Methodology for Determination of the Number of Equipment Malfunctions Due to Voltage Sags
Energies 2017, 10(3), 401; doi:10.3390/en10030401
Received: 15 February 2017 / Revised: 14 March 2017 / Accepted: 15 March 2017 / Published: 20 March 2017
PDF Full-text (9922 KB) | HTML Full-text | XML Full-text
Abstract
This article deals with the assessment of the reliability of sensitive equipment due to voltage sags. The most frequent problems of power quality are voltage sags. Equipment that cannot withstand short-term voltage sag is defined as sensitive device. Sensitivity of such equipment can
[...] Read more.
This article deals with the assessment of the reliability of sensitive equipment due to voltage sags. The most frequent problems of power quality are voltage sags. Equipment that cannot withstand short-term voltage sag is defined as sensitive device. Sensitivity of such equipment can be described by the voltage–tolerance curves. A device (generator) to generate voltage sags (also interruptions) with duration at least 1 ms has been designed and developed for this purpose. Equipment sensitive to voltage sags was tested using this generator. Overall, five types of sensitive equipment were tested: personal computers, fluorescent lamps, drives with speed control, programmable logic controllers, and contactors. The measured sensitivity curves of these devices have been used to determine the number of trips (failures) due to voltage sags. Two probabilistic methods (general probability method and cumulative probability method) to determine probability of equipment failure occurrence are used. These methods were applied to real node in the distribution system with its actual performance of voltage sags/swells. The calculations also contain different levels of sensitivity of the sensitive equipment. Full article
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Open AccessArticle Equivalent Electrical Circuits of Thermoelectric Generators under Different Operating Conditions
Energies 2017, 10(3), 386; doi:10.3390/en10030386
Received: 10 February 2017 / Revised: 13 March 2017 / Accepted: 15 March 2017 / Published: 18 March 2017
Cited by 1 | PDF Full-text (635 KB) | HTML Full-text | XML Full-text
Abstract
Energy harvesting has become a promising and alternative solution to conventional energy generation patterns to overcome the problem of supplying autonomous electrical systems. More particularly, thermal energy harvesting technologies have drawn a major interest in both research and industry. Thermoelectric Generators (TEGs) can
[...] Read more.
Energy harvesting has become a promising and alternative solution to conventional energy generation patterns to overcome the problem of supplying autonomous electrical systems. More particularly, thermal energy harvesting technologies have drawn a major interest in both research and industry. Thermoelectric Generators (TEGs) can be used in two different operating conditions, under constant temperature gradient or constant heat flow. The commonly used TEG electrical model, based on a voltage source in series with an electrical resistance, shows its limitations especially under constant heat flow conditions. Here, the analytical electrical modeling, taking into consideration the internal and contact thermal resistances of a TEG under constant temperature gradient and constant heat flow conditions, is first given. To give further insight into the electrical behavior of a TEG module in different operating conditions, we propose a new and original way of emulating the above analytical expressions with usual electronics components (voltage source, resistors, diode), whose values are determined with the TEG’s parameters. Note that such a TEG emulation is particularly suited when designing the electronic circuitry commonly associated to the TEG, to realize both Maximum Power Point Tracking and output voltage regulation. First, the proposed equivalent electrical circuits are validated through simulation with a SPICE environment in static operating conditions using only one value of either temperature gradient or heat flow. Then, they are also analyzed in dynamic operating conditions where both temperature gradient and heat flow are considered as time-varying functions. Full article
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Open AccessArticle Lithium-ion Battery Electrothermal Model, Parameter Estimation, and Simulation Environment
Energies 2017, 10(3), 375; doi:10.3390/en10030375
Received: 13 February 2017 / Revised: 10 March 2017 / Accepted: 13 March 2017 / Published: 16 March 2017
Cited by 2 | PDF Full-text (5720 KB) | HTML Full-text | XML Full-text
Abstract
The market for lithium-ion batteries is growing exponentially. The performance of battery cells is growing due to improving production technology, but market request is growing even more rapidly. Modeling and characterization of single cells and an efficient simulation environment is fundamental for the
[...] Read more.
The market for lithium-ion batteries is growing exponentially. The performance of battery cells is growing due to improving production technology, but market request is growing even more rapidly. Modeling and characterization of single cells and an efficient simulation environment is fundamental for the development of an efficient battery management system. The present work is devoted to defining a novel lumped electrothermal circuit of a single battery cell, the extraction procedure of the parameters of the single cell from experiments, and a simulation environment in SystemC-WMS for the simulation of a battery pack. The electrothermal model of the cell was validated against experimental measurements obtained in a climatic chamber. The model is then used to simulate a 48-cell battery, allowing statistical variations among parameters. The different behaviors of the cells in terms of state of charge, current, voltage, or heat flow rate can be observed in the results of the simulation environment. Full article
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Open AccessArticle Tomographic Environmental Sections for Environmental Mitigation Devices in Historical Centers
Energies 2017, 10(3), 351; doi:10.3390/en10030351
Received: 23 December 2016 / Revised: 20 February 2017 / Accepted: 27 February 2017 / Published: 11 March 2017
PDF Full-text (8132 KB) | HTML Full-text | XML Full-text
Abstract
Urban heat waves and the overall growing trend in the annual global temperature underline the importance of urban/architectural resilience and the need to reduce energy consumption. By designing urban voids, it is possible to create thermodynamic buffers, i.e., bubbles of controlled atmosphere that
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Urban heat waves and the overall growing trend in the annual global temperature underline the importance of urban/architectural resilience and the need to reduce energy consumption. By designing urban voids, it is possible to create thermodynamic buffers, i.e., bubbles of controlled atmosphere that act as mediators between the natural and built environments, between the human body and the surrounding air, between meteorology and physiology (meteorological architecture). Multiple small actions in the urban fabric’s open spaces, such as replacing dark pavements or inserting vegetation and green spaces, are intended to improve outdoor comfort conditions and therefore the resilience of the city itself. This not only benefits the place’s quality, which is intrinsic to the new project, but also the insulating capacity of buildings, which are relieved of an external heat load. The design emphasis therefore changes from solid structures to the climate and weather conditions, which are invisible but perceivable. To design and control these constructed atmopheres, tomographic sections processed with computational fluid dynamics software (tomographic environmental section, TENS) becomes necessary. It allows the effects of an extreme event on an outdoor environment to be evaluated in order to establish the appropriate (adaptive) climate mitigation devices, especially in historical centers where energy retrofits are often discouraged. By fixing boundary conditions after a local intervention, the virtual environment can be simulated and then "sliced" to analyze initial values and verify the design improvements. Full article
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Open AccessArticle The Influence of BMSs on the Characterization and Modeling of Series and Parallel Li-Ion Packs
Energies 2017, 10(3), 273; doi:10.3390/en10030273
Received: 3 January 2017 / Revised: 21 February 2017 / Accepted: 22 February 2017 / Published: 25 February 2017
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Abstract
This work analyzes the effects of a BMS (battery management system) on the characterization and modeling of series and parallel connections of Li-ion cell packs. The Li-ion pack studied consists of four series modules connected in parallel. This pack has been characterized by
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This work analyzes the effects of a BMS (battery management system) on the characterization and modeling of series and parallel connections of Li-ion cell packs. The Li-ion pack studied consists of four series modules connected in parallel. This pack has been characterized by means of charge, discharge and frequency tests. As a result of these tests, series and parallel influence on battery parameters have been determined. A model considering the effects of a BMS is established and compared with a model based on a single-cell approach. Experimental validations show that the single cell based approach gives poor results in comparison with a model that considers BMS effects. Full article
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Open AccessArticle Optimization Models for Islanded Micro-Grids: A Comparative Analysis between Linear Programming and Mixed Integer Programming
Energies 2017, 10(2), 241; doi:10.3390/en10020241
Received: 23 December 2016 / Accepted: 10 February 2017 / Published: 16 February 2017
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Abstract
This paper presents a comparison of optimization methods applied to islanded micro-grids including renewable energy sources, diesel generators and battery energy storage systems. In particular, a comparative analysis between an optimization model based on linear programming and a model based on mixed integer
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This paper presents a comparison of optimization methods applied to islanded micro-grids including renewable energy sources, diesel generators and battery energy storage systems. In particular, a comparative analysis between an optimization model based on linear programming and a model based on mixed integer programming has been carried out. The general formulation of these models has been presented and applied to a real case study micro-grid installed in Somalia. The case study is an islanded micro-grid supplying the city of Garowe by means of a hybrid power plant, consisting of diesel generators, photovoltaic systems and batteries. In both models the optimization is based on load demand and renewable energy production forecast. The optimized control of the battery state of charge, of the spinning reserve and diesel generators allows harvesting as much renewable power as possible or to minimize the use of fossil fuels in energy production. Full article
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Open AccessArticle Equivalence of Primary Control Strategies for AC and DC Microgrids
Energies 2017, 10(1), 91; doi:10.3390/en10010091
Received: 12 July 2016 / Revised: 1 December 2016 / Accepted: 4 January 2017 / Published: 12 January 2017
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Abstract
Microgrid frequency and voltage regulation is a challenging task, as classical generators with rotational inertia are usually replaced by converter-interfaced systems that inherently do not provide any inertial response. The aim of this paper is to analyse and compare autonomous primary control techniques
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Microgrid frequency and voltage regulation is a challenging task, as classical generators with rotational inertia are usually replaced by converter-interfaced systems that inherently do not provide any inertial response. The aim of this paper is to analyse and compare autonomous primary control techniques for alternating current (AC) and direct current (DC) microgrids that improve this transient behaviour. In this context, a virtual synchronous machine (VSM) technique is investigated for AC microgrids, and its behaviour for different values of emulated inertia and droop slopes is tested. Regarding DC microgrids, a virtual-impedance-based algorithm inspired by the operation concept of VSMs is proposed. The results demonstrate that the proposed strategy can be configured to have an analogous behaviour to VSM techniques by varying the control parameters of the integrated virtual-impedances. This means that the steady-state and transient behaviour of converters employing these strategies can be configured independently. As shown in the simulations, this is an interesting feature that could be, for instance, employed for the integration of different dynamic generation or storage systems, such as batteries or supercapacitors. Full article
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Open AccessArticle The Energy Audit Activity Focused on the Lighting Systems in Historical Buildings
Energies 2016, 9(12), 998; doi:10.3390/en9120998
Received: 28 September 2016 / Revised: 5 November 2016 / Accepted: 21 November 2016 / Published: 27 November 2016
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Abstract
The energy audit for a building is a procedure designed mainly to obtain adequate knowledge of the energy consumption profile, identify, and quantify opportunities for energy savings by a cost-benefit analysis and report, clearly and comprehensively, about the obtained results. If the audit
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The energy audit for a building is a procedure designed mainly to obtain adequate knowledge of the energy consumption profile, identify, and quantify opportunities for energy savings by a cost-benefit analysis and report, clearly and comprehensively, about the obtained results. If the audit is referred to a building with a significant historical and artistic value, a compatibility evaluation of the energy saving interventions with the architectural features should also be developed. In this paper, analysing the case study of a historical building used as public offices in Pisa (Italy), the authors describe how it is possible to conduct an energy audit activity (especially dedicated to the lighting system) and they show how, for this type of buildings, it is possible to obtain significant energy savings with a refurbishment of the lighting system. A total number of seven interventions on indoor and outdoor lighting sub-systems were analysed in the paper. They are characterised by absolute compatibility with the historical and artistic value of the building and they show short payback times, variable between 4 and 34 months, allowing a reduction of the electrical energy consumption for the artificial indoor and outdoor lighting variable from 1.1 MWh/year to 39.0 MWh/year. The followed methodology and the evaluation results described in the paper, although based on a case study, can be extended to numerous historical buildings used as public offices, a recurring situation in the centres of Italian historical cities. Full article
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Open AccessArticle Investigation the Influence of Different Salts on the Degradation of Organic Dyes Using Non-Thermal Plasma
Energies 2016, 9(11), 874; doi:10.3390/en9110874
Received: 28 July 2016 / Revised: 16 October 2016 / Accepted: 20 October 2016 / Published: 26 October 2016
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Abstract
In dye decolorization tests a non-thermal plasma (NTP) corona discharge generated by a high voltage pin-to-ground plate displayed 82% color removal within 11 min. Total color removal was accomplished after 28 min. Different salts such as KCl, NaCl, CaCl2 and AlCl3
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In dye decolorization tests a non-thermal plasma (NTP) corona discharge generated by a high voltage pin-to-ground plate displayed 82% color removal within 11 min. Total color removal was accomplished after 28 min. Different salts such as KCl, NaCl, CaCl2 and AlCl3 were utilized to check the influence of conductivity changes on the dye decolorization process. Higher dye solution conductivity improved the color removal efficiency. The discharge energy and degradation efficiency were computed for diverse concentrations for NaCl, KCl, CaCl2 and AlCl3, whereby it was noticed that the salts generally have a small impact on the level of dye decolorization using corona discharge. In addition, the essential reactive species involved in the oxidation of organic dye compounds such as ozone (O3) generated in treated water and hydrogen peroxide (H2O2) were investigated and the energetic species that produced the non-thermal plasma at the optimum operation time were determined. Energy yields for decolorization and Electrical Energy per Order (EE/O) were calculated for different concentrations of NaCl, KCl, CaCl2 and AlCl3. This work may help in designing plasma systems appropriate for treatment of industrial wastewaters polluted by dyes. Full article
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Open AccessArticle Sensitivity-Based Model of Low Voltage Distribution Systems with Distributed Energy Resources
Energies 2016, 9(10), 801; doi:10.3390/en9100801
Received: 29 July 2016 / Accepted: 19 September 2016 / Published: 4 October 2016
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Abstract
A key issue in Low Voltage(LV) distribution systems is to identify strategies for the optimal management and control in the presence of Distributed Energy Resources (DERs). To reduce the number of variables to be monitored and controlled, virtual levels of aggregation, called Virtual
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A key issue in Low Voltage(LV) distribution systems is to identify strategies for the optimal management and control in the presence of Distributed Energy Resources (DERs). To reduce the number of variables to be monitored and controlled, virtual levels of aggregation, called Virtual Microgrids (VMs), are introduced and identified by using new models of the distribution system. To this aim, this paper, revisiting and improving the approach outlined in a conference paper, presents a sensitivity-based model of an LV distribution system, supplied by a Medium/Low Voltage (MV/LV) substation and composed by several feeders, which is suitable for the optimal management and control of the grid and for VM definition. The main features of the proposed method are: it evaluates the sensitivity coefficients in a closed form; it provides an overview of the sensitivity of the network to the variations of each DER connected to the grid; and it presents a limited computational burden. A comparison of the proposed method with both the exact load flow solutions and a perturb-and-observe method is discussed in a case study. Finally, the method is used to evaluate the impact of the DERs on the nodal voltages of the network. Full article
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