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10th Anniversary of Applied Sciences: Invited Papers in Energy...
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10th Anniversary of Applied Sciences: Invited Papers in Energy Section

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Energy Science and Technology".

Deadline for manuscript submissions: closed (10 July 2021) | Viewed by 65920

Special Issue Editors

Prof. Dr. Frede Blaabjerg

grade E-Mail Website
Guest Editor
Department of Energy Technology, Aalborg University, 9220 Aalborg, Denmark
Interests: power electronics and its applications in motor drives; wind turbines; PV systems; harmonics; reliability of power electronic systems
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. S. M. Muyeen

E-Mail Website
Guest Editor
Department of Electrical Engineering, Qatar University, Doha 2713, Qatar
Interests: renewable energy and smart grids
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Tomislav Dragicevic

E-Mail Website
Guest Editor
Department of Electrical Engineering, Center for Electric Power and Energy, Technical University of Denmark - DTU, 2800 Kgs, Lyngby, Denmark
Interests: renewable energy; power electronics; energy storage; e-mobility; artificial intelligence; IoT-driven digitalization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Applied Sciences is going to touch a remarkable milestone by publishing its 10th volume, and in celebration of this special occasion, we have taken the initiative to launch a Special Issue from Energy called "10th Anniversary of Applied Sciences: Invited Papers in Energy section". We would like to invite you to contribute a comprehensive review article on contemporary energy topics or an original research paper, for peer-review and possible publication. Topics include but are not limited to renewable energy, microgrids, IoT enabled inverters, TSO–DSO interactions, grid interfacing challenges, vehicle-to-grid, power electronics in energy harvesting, etc. The details for this Special Issue can be found at WEB LINK

In 2014, when we got the first impact factor for Applied Sciences, we published 35 manuscripts from 53 submissions, i.e., the acceptance rate was roughly 66%. However, we have now significantly improved the review quality; hence, in 2018, we published 2703 manuscripts from 9757 submissions, keeping the acceptance rate below 28%. This reasonably gave us an impact factor jump from 1.484 in 2014 to 2.217 in 2018. We have also reduced the manuscript turnaround time; presently, the median publication time is only 37 days, which will be further reduced in coming days, and we hope to increase the impact factor above 3.0 by 2019. Among all sections of Applied Sciences, Energy section is doing the best, it appears; published 775 articles have been published so far, along with 52 Special Issues. On this occasion, we would like to thank our all Editorial Board Members, Managing Editors, Reviewers, and Authors for their great contributions and continuous support. Please help us celebrate our 10th anniversary and submit your review article to the Anniversary Edition.

Prof. Frede Blaabjerg
Assoc. Prof. S M Muyeen
Assoc. Prof. Tomislav Dragicevic
Guest Editors

Manuscript Submission Information

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. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly 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 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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Research

Jump to: Review

13 pages, 4577 KiB  
Article
An Adaptive Model Predictive Voltage Control for LC-Filtered Voltage Source Inverters
by Hosein Gholami-Khesht, Pooya Davari and Frede Blaabjerg
Appl. Sci. 2021, 11(2), 704; https://0-doi-org.brum.beds.ac.uk/10.3390/app11020704 - 13 Jan 2021
Cited by 16 | Viewed by 2287
Abstract
The three-phase inductor and capacitor filter (LC)-filtered voltage source inverter (VSI) is subjected to uncertain and time-variant parameters and disturbances, e.g., due to aging, thermal effects, and load changes. These uncertainties and disturbances have a considerable impact on the performance of a VSI’s [...] Read more.
The three-phase inductor and capacitor filter (LC)-filtered voltage source inverter (VSI) is subjected to uncertain and time-variant parameters and disturbances, e.g., due to aging, thermal effects, and load changes. These uncertainties and disturbances have a considerable impact on the performance of a VSI’s control system. It can degrade system performance or even cause system instability. Therefore, considering the effects of all system uncertainties and disturbances in the control system design is necessary. In this respect and to tackle this issue, this paper proposes an adaptive model predictive control (MPC), which consists of three main parts: an MPC, an augmented state-space model, and an adaptive observer. The augmented state-space model considers all system uncertainties and disturbances and lumps them into two disturbance inputs. The proposed adaptive observer determines the lumped disturbance functions, enabling the control system to keep the nominal system performance under different load conditions and parameters uncertainty. Moreover, it provides load-current-sensorless operation of MPC, which reduces the size and cost, and simultaneously improves the system reliability. Finally, MPC selects the proper converter voltage vector that minimizes the tracking errors based on the augmented model and outputs of the adaptive observer. Simulations and experiments on a 5 kW VSI examine the performance of the proposed adaptive MPC under different load conditions and parameter uncertainties and compare them with the conventional MPC. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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9 pages, 1064 KiB  
Article
Bio-Energy Generation from Synthetic Winery Wastewaters
by Stanislaw Marks, Jacek Dach, Jose Luis Garcia-Morales and Francisco Jesus Fernandez-Morales
Appl. Sci. 2020, 10(23), 8360; https://0-doi-org.brum.beds.ac.uk/10.3390/app10238360 - 25 Nov 2020
Cited by 4 | Viewed by 2383
Abstract
In Spain, the winery industry exerts a great influence on the national economy. Proportional to the scale of production, a significant volume of waste is generated, estimated at 2 million tons per year. In this work, a laboratory-scale reactor was used to study [...] Read more.
In Spain, the winery industry exerts a great influence on the national economy. Proportional to the scale of production, a significant volume of waste is generated, estimated at 2 million tons per year. In this work, a laboratory-scale reactor was used to study the feasibility of the energetic valorization of winery effluents into hydrogen by means of dark fermentation and its subsequent conversion into electrical energy using fuel cells. First, winery wastewater was characterized, identifying and determining the concentration of the main organic substrates contained within it. To achieve this, a synthetic winery effluent was prepared according to the composition of the winery wastewater studied. This effluent was fermented anaerobically at 26 °C and pH = 5.0 to produce hydrogen. The acidogenic fermentation generated a gas effluent composed of CO2 and H2, with the percentage of hydrogen being about 55% and the hydrogen yield being about 1.5 L of hydrogen at standard conditions per liter of wastewater fermented. A gas effluent with the same composition was fed into a fuel cell and the electrical current generated was monitored, obtaining a power generation of 1 W·h L−1 of winery wastewater. These results indicate that it is feasible to transform winery wastewater into electricity by means of acidogenic fermentation and the subsequent oxidation of the bio-hydrogen generated in a fuel cell. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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13 pages, 1216 KiB  
Article
Effects of On-Site PV Generation and Residential Demand Response on Distribution System Reliability
by Sıtkı Güner, Ayşe Kübra Erenoğlu, İbrahim Şengör, Ozan Erdinç and João P. S. Catalão
Appl. Sci. 2020, 10(20), 7062; https://0-doi-org.brum.beds.ac.uk/10.3390/app10207062 - 12 Oct 2020
Cited by 6 | Viewed by 2511
Abstract
In the last few decades, there has been a strong trend towards integrating renewable-based distributed generation systems into the power grid, and advanced management strategies have been developed in order to provide a reliable, resilient, economic, and sustainable operation. Moreover, demand response (DR) [...] Read more.
In the last few decades, there has been a strong trend towards integrating renewable-based distributed generation systems into the power grid, and advanced management strategies have been developed in order to provide a reliable, resilient, economic, and sustainable operation. Moreover, demand response (DR) programs, by taking the advantage of flexible loads’ energy reduction capabilities, have presented as a promising solution considering reliability issues. Therefore, the impacts of combined system architecture with on-site photovoltaic (PV) generation units and residential demand reduction strategies were taken into consideration on distribution system reliability indices in this study. The load model of this study was created by using load data of the distribution feeder provided by Bosphorus Electric Distribution Corporation (BEDAS). Additionally, the reliability parameters of the feeder components were determined based on these provided data. The calculated load point and feeder side indicators were analyzed comprehensively from technical and economic perspectives. In order to validate the effectiveness of the proposed structure, four case studies were carried out in both DigSILENT PowerFactory and MATLAB environments. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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30 pages, 9896 KiB  
Article
A Human Health Toxicity Assessment of Biogas Engines Regulated and Unregulated Emissions
by Alarico Macor and Alberto Benato
Appl. Sci. 2020, 10(20), 7048; https://0-doi-org.brum.beds.ac.uk/10.3390/app10207048 - 11 Oct 2020
Cited by 11 | Viewed by 3006
Abstract
The aim of the work is to evaluate the damage to human health arising from emissions of in-operation internal combustion engines fed by biogas. The need of including also unregulated emissions like polycyclic aromatic hydrocarbons (PAHs), aldehydes and dioxins and furans is twofold: [...] Read more.
The aim of the work is to evaluate the damage to human health arising from emissions of in-operation internal combustion engines fed by biogas. The need of including also unregulated emissions like polycyclic aromatic hydrocarbons (PAHs), aldehydes and dioxins and furans is twofold: (i) to cover the lack in biogas engine emissions measurements and (ii) to complete the picture on biogas harmfulness to human health by identifying the substances with the highest impact. To this purpose, an experimental campaign is conducted on six biogas engines and one fed by natural gas all characterised by an electric power of 999 kWel. Collected data are used to perform an impact analysis on human health combining the Health Impact Assessment and the Risk Assessment. Measurements show that PAHs, aldehydes and diossin and furans are almost always below the detection limit, in both biogas and natural gas exhausts. The carcinogenic risk analysis of PAHs for the two fuels established their substantial equivalence. The analysis of equivalent toxicity of dioxins and furans reveals that biogas is, on average, 10 times more toxic than natural gas. Among regulated emissions, NOx in the biogas engines exhausts are three times higher than those of natural gas. They are the main contributors to human health damage, with approximately 90% of the total. SOx ranks second and accounts for about 6% of the total damage. Therefore, (i) the contribution to human health damage of unregulated emissions is limited compared to the damage from unregulated emissions, (ii) the damage per unit of electricity of biogas engines exhausts is about three times higher than that of natural gas and it is directly linked to NOx, (iii) obtaining a good estimation of the human health damage from both biogas and natural gas engines emissions is enough of a reason to consider NOx and SOx. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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25 pages, 3544 KiB  
Article
Model Predictive Control of Grid Forming Converters with Enhanced Power Quality
by Mohammed Alhasheem, Ahmed Abdelhakim, Frede Blaabjerg, Paolo Mattavelli and Pooya Davari
Appl. Sci. 2020, 10(18), 6390; https://0-doi-org.brum.beds.ac.uk/10.3390/app10186390 - 14 Sep 2020
Cited by 13 | Viewed by 2702
Abstract
This paper proposes an enhanced finite control set model predictive control (FCS-MPC) strategy for voltage source converter (VSC) with a LC output filter. The proposed control scheme is based on tracking the voltage reference trajectory by using only a single-step prediction within the [...] Read more.
This paper proposes an enhanced finite control set model predictive control (FCS-MPC) strategy for voltage source converter (VSC) with a LC output filter. The proposed control scheme is based on tracking the voltage reference trajectory by using only a single-step prediction within the controller horizon. Besides, the suitability of different frequency control schemes with the proposed scheme to prevent from inherent variable switching behaviour of conventional FCS-MPC is investigated. Based on that, the proposed method targets two major factors influencing power quality in grid forming applications by enhancing the output voltage harmonic distortion and also preventing variable switching behaviour of FCS-MPC. Although compared to multi-step prediction approaches, only a single-step multi-objective cost function to improve computation efficiency is utilized, the introduced control schemes are able to deliver higher power quality compared to its counterpart methods as well. Furthermore, the effect of different applied cost functions on the transient response of the system is studied and investigated for the future use of the VSC in microgrids (MGs). The effectiveness of the proposed scheme was assessed by simulation using MATLAB/SIMULINK and experiment using a 5.5 kVA VSC module and the results were in good agreement. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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19 pages, 7897 KiB  
Article
Small-Signal Analysis and Control of Soft-Switching Naturally Clamped Snubberless Current-Fed Half-Bridge DC/DC Converter
by Koyelia Khatun, Vakacharla Venkata Ratnam, Akshay Kumar Rathore and Beeramangalla Lakshminarasaiah Narasimharaju
Appl. Sci. 2020, 10(17), 6130; https://0-doi-org.brum.beds.ac.uk/10.3390/app10176130 - 03 Sep 2020
Cited by 3 | Viewed by 2950
Abstract
This paper presents small-signal analysis of a soft-switching naturally clamped snubberless isolated current-fed half-bridge (CFHB) DC-DC converter using state-space averaging. A two-loop average current controller was designed and implemented on a digital signal processor. The complete design procedure is presented here. Simulation results [...] Read more.
This paper presents small-signal analysis of a soft-switching naturally clamped snubberless isolated current-fed half-bridge (CFHB) DC-DC converter using state-space averaging. A two-loop average current controller was designed and implemented on a digital signal processor. The complete design procedure is presented here. Simulation results using software PSIM 11.1 are shown to validate the stability of the control system and the controller design. Experimental results for the step changes in load current vividly demonstrated satisfactory transient performance of the converter and validated the developed small-signal model and the control design. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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20 pages, 5337 KiB  
Article
Estimating Degradation Costs for Non-Cyclic Usage of Lithium-Ion Batteries
by Tomás Cortés-Arcos, Rodolfo Dufo-López and José L. Bernal-Agustín
Appl. Sci. 2020, 10(15), 5330; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155330 - 01 Aug 2020
Cited by 3 | Viewed by 2244
Abstract
Estimating the degradation costs of lithium-ion batteries is essential to the designs of many systems because batteries are increasingly used in diverse applications. In this study, cyclic and calendar degradation models of lithium batteries were considered in optimization problems with randomized non-cyclic batteries [...] Read more.
Estimating the degradation costs of lithium-ion batteries is essential to the designs of many systems because batteries are increasingly used in diverse applications. In this study, cyclic and calendar degradation models of lithium batteries were considered in optimization problems with randomized non-cyclic batteries use. Such models offer realistic results. Electrical, thermal, and degradation models were applied for lithium nickel cobalt manganese oxide (NMC) and lithium iron phosphate (LFP) technologies. Three possible strategies were identified to estimate degradation costs based on cell models. All three strategies were evaluated via simulations and validated by comparing the results with those obtained by other authors. One strategy was discarded because it overestimates costs, while the other two strategies give good results, and are suitable for estimating battery degradation costs in optimization problems that require deterministic models. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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44 pages, 4946 KiB  
Article
Conventional and Advanced Exergy-Based Analysis of Hybrid Geothermal–Solar Power Plant Based on ORC Cycle
by Massomeh Alibaba, Razieh Pourdarbani, Mohammad Hasan Khoshgoftar Manesh, Israel Herrera-Miranda, Iván Gallardo-Bernal and José Luis Hernández-Hernández
Appl. Sci. 2020, 10(15), 5206; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155206 - 28 Jul 2020
Cited by 11 | Viewed by 2740
Abstract
Today, as fossil fuels are depleted, renewable energy must be used to meet the needs of human beings. One of the renewable energy sources is undoubtedly the solar–geothermal power plant. In this paper, the conventional and advanced, exergo-environmental and exergo-economic analysis of a [...] Read more.
Today, as fossil fuels are depleted, renewable energy must be used to meet the needs of human beings. One of the renewable energy sources is undoubtedly the solar–geothermal power plant. In this paper, the conventional and advanced, exergo-environmental and exergo-economic analysis of a geothermal–solar hybrid power plant (SGHPP) based on an organic Rankin cycle (ORC) cycle is investigated. In this regard, at first, a conventional analysis was conducted on a standalone geothermal cycle (first mode), as well as a hybrid solar–geothermal cycle (second mode). The results of exergy destruction for simulating the standalone geothermal cycle showed that the ORC turbine with 1050 kW had the highest exergy destruction that was 38% of the total share of destruction. Then, the ORC condenser with 26% of the total share of exergy destruction was in second place. In the hybrid geothermal–solar cycle, the solar panel had the highest environmental impact and about 56% of the total share of exergy destruction. The ORC turbine had about 9% of all exergy destruction. The results of the advanced analysis of exergy in the standalone geothermal cycle showed that the avoidable exergy destruction of the condenser was the highest. In the hybrid geothermal–solar cycle, the solar panel, steam economizer and steam evaporator were ranked first to third from an avoidable exergy destruction perspective. The avoidable exergo-economic destruction of the evaporator and pump were higher than the other components. The hybrid geothermal–solar cycle, steam economizer, solar pane and steam evaporator were ranked first to third, respectively, and they could be modified. The avoidable exergo-environmental destruction of the ORC turbine and the ORC pump were the highest, respectively. In the hybrid geothermal–solar cycle, steam economizers, solar panel and steam evaporators had the highest avoidable exergy destruction, respectively. For the standalone geothermal cycle, the total endogenous exergy destruction and exogenous exergy destruction was 83.61% and 16.39%. Moreover, from an exergo-economic perspective, 89% of the total destruction rate was endogenous and 11% was exogenous. From an exergo-environmental perspective, 88.73% of the destruction rate was endogenous and 11.27% was exogenous. For the hybrid geothermal–solar cycle, the total endogenous and exogenous exergy destruction was 75.08% and 24.92%, respectively. Moreover, 81.82% of the exergo-economic destruction rate was endogenous and 18.82% was exogenous. From an exergo-environmental perspective, 81.19% of the exergy destruction was endogenous and 18.81% was exogenous. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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21 pages, 4610 KiB  
Article
Solutions to Increase PV Hosting Capacity and Provision of Services from Flexible Energy Resources
by Hannu Laaksonen, Chethan Parthasarathy, Hossein Hafezi, Miadreza Shafie-khah, Hosna Khajeh and Nikos Hatziargyriou
Appl. Sci. 2020, 10(15), 5146; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155146 - 27 Jul 2020
Cited by 21 | Viewed by 3287
Abstract
Future smart grids will be more dynamic with many variabilities related to generation, inertia, and topology changes. Therefore, more flexibility in form of several active and reactive power related technical services from different distributed energy resources (DER) will be needed for local (distribution [...] Read more.
Future smart grids will be more dynamic with many variabilities related to generation, inertia, and topology changes. Therefore, more flexibility in form of several active and reactive power related technical services from different distributed energy resources (DER) will be needed for local (distribution network) and whole system (transmission network) needs. However, traditional distribution network operation and control principles are limiting the Photovoltaic (PV) hosting capacity of LV networks and the DER capability to provide system-wide technical services in certain situations. New active and adaptive control principles are needed in order to overcome these limitations. This paper studies and proposes solutions for adaptive settings and management schemes to increase PV hosting capacity and improve provision of frequency support related services by flexible energy resources. The studies show that unwanted interactions between different DER units and their control functions can be avoided with the proposed adaptive control methods. Simultaneously, also better distribution network PV hosting capacity and flexibility services provision from DER units even during very low load situations can be achieved. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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14 pages, 248 KiB  
Article
Economic Effects of Individual Heating System and District Heating System in South Korea: An Input-Output Analysis
by Ju-Hee Kim, Sin-Young Kim and Seung-Hoon Yoo
Appl. Sci. 2020, 10(15), 5037; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155037 - 22 Jul 2020
Cited by 6 | Viewed by 2003
Abstract
When South Korea develops a new city, the government has made a preliminary decision on one of two heating systems, an individual heating system (IHS) or a district heating system (DHS). However, it is still unclear which system is desirable in terms of [...] Read more.
When South Korea develops a new city, the government has made a preliminary decision on one of two heating systems, an individual heating system (IHS) or a district heating system (DHS). However, it is still unclear which system is desirable in terms of maximizing the national economic effect. Thus, this article aims to derive quantitative information about the economic effects of the same amount of production or investment in the two systems through an input-output (IO) analysis using the recently published 2017 IO table. More specifically, the production-inducing effects, value-added creation effects, and wage-inducing effects are systematically analyzed focusing on the IHS and DHS sectors. The results show that one dollar of production or investment in IHS or DHS causes about 1.073 and 1.388 dollars of production, about 0.228 and 0.658 dollars of value-added, and about 0.051 and 0.108 dollars in wages, respectively, throughout the national economy. Overall, the economic effects of the DHS sector are greater than those of the IHS sector. That is, when the same amount of investment or production is made in the two sectors, DHS produces more economic effects than IHS. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
11 pages, 1891 KiB  
Communication
Assessment of the RACPC Performance under Diffuse Radiation for Use in BIPV System
by Stephania Foster, Firdaus Muhammad-Sukki, Roberto Ramirez-Iniguez, Daria Freier Raine, Jose Deciga-Gusi, Siti Hawa Abu-Bakar, Nurul Aini Bani, Abu Bakar Munir, Abdullahi Abubakar Mas’ud and Jorge Alfredo Ardila-Rey
Appl. Sci. 2020, 10(10), 3552; https://0-doi-org.brum.beds.ac.uk/10.3390/app10103552 - 21 May 2020
Cited by 2 | Viewed by 3094
Abstract
In the last four decades there has been a significant increase in solar photovoltaic (PV) capacity, which makes solar one of the most promising renewable energy sources. Following this trend, solar power would become the world’s largest source of electricity by 2050. Building [...] Read more.
In the last four decades there has been a significant increase in solar photovoltaic (PV) capacity, which makes solar one of the most promising renewable energy sources. Following this trend, solar power would become the world’s largest source of electricity by 2050. Building Integrated Photovoltaic (BIPV) systems, in which conventional materials can be replaced with PV panels that become an integral part of the building, can be enhanced with concentrating photovoltaic (CPV) systems. In order to increase the cost efficiency of a BIPV system, an optical concentrator can be used to replace expensive PV material with a lower cost option, whilst increasing the electrical output through the concentration of solar power. A concentrator called rotationally asymmetrical compound parabolic concentrator (RACPC) was analysed in this work under diffuse light conditions. Software simulations and experimental work were carried out to determine the optical concentration gain of the concentrator. Results from this work show that, under diffuse light, the RACPC has an optical concentration gain of 2.12. The experimental work showed a value of 2.20, which confirms the results with only a 3.8% difference. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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15 pages, 1658 KiB  
Article
Relationship between Buchholz’s Apparent Power and Instantaneous Power in Three-Phase Systems
by Vicente León-Martínez, Joaquín Montañana-Romeu, Elisa Peñalvo-López and Iván Valencia-Salazar
Appl. Sci. 2020, 10(5), 1798; https://0-doi-org.brum.beds.ac.uk/10.3390/app10051798 - 05 Mar 2020
Cited by 4 | Viewed by 2220
Abstract
Similarly to how Steinmetz developed his theory of alternating current in single-phase sinusoidal systems, a few formal relationships between expressions of the instantaneous and Buchholz’s apparent power in three-phase systems were identified in this paper. Based on these relationships, a methodology to express [...] Read more.
Similarly to how Steinmetz developed his theory of alternating current in single-phase sinusoidal systems, a few formal relationships between expressions of the instantaneous and Buchholz’s apparent power in three-phase systems were identified in this paper. Based on these relationships, a methodology to express Buchholz’s apparent power and its components in any three-phase, wye-configured system—sinusoidal or non-sinusoidal, balanced or unbalanced—through instantaneous power expressions was established. The application of the proposed method to the entire system allowed the determination of a novel quantity referred to as neutral-displacement power, which measured the impacts of the phenomena caused by the neutral path operation on the values of the source and load apparent power. These impacts were analyzed using a real-world urban installation with a neutral conductor deterioration simulation via an Excel platform as an application example. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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Review

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26 pages, 2518 KiB  
Review
New Tendencies in Wind Energy Operation and Maintenance
by Ángel M. Costa, José A. Orosa, Diego Vergara and Pablo Fernández-Arias
Appl. Sci. 2021, 11(4), 1386; https://0-doi-org.brum.beds.ac.uk/10.3390/app11041386 - 04 Feb 2021
Cited by 39 | Viewed by 9622
Abstract
Both the reduction in operating and maintenance (O&M) costs and improved reliability have become top priorities in wind turbine maintenance strategies. O&M costs typically account for 20% to 25% of the total levelized cost of electricity (LCOE) of current wind power systems. This [...] Read more.
Both the reduction in operating and maintenance (O&M) costs and improved reliability have become top priorities in wind turbine maintenance strategies. O&M costs typically account for 20% to 25% of the total levelized cost of electricity (LCOE) of current wind power systems. This paper provides a general review of the state of the art of research conducted on wind farm maintenance in recent years. It shows the new methods and techniques, focusing on trends and future challenges. In addition to this, this work includes a review of the following items: (i) operation and maintenance, (ii) failure rate, (iii) reliability, (iv) condition monitoring, (v) maintenance strategies, (vi) maintenance and life cycle and (vii) maintenance optimization As for offshore wind turbines, it is crucial to limit the maximum faults, since the maintenance of these wind farms is more complex both technically and logistically. Research into wind farm maintenance increased by 87% between 2007 and 2019, with more than 38,000 papers (Scopus) including “wind energy” as the main topic and some keywords related to O&M costs. The LCOE in onshore wind projects has decreased by 45%, while in offshore projects it has decreased by 28%. The O&M costs of onshore wind projects fell 52%, while in the case of offshore projects, they have declined 45%. Thus, the results obtained in this paper suggest that there is a change in research on wind farm operation and maintenance, as in recent years, scientific interest in failure has been increasing, while interest in the various techniques of wind farm maintenance and operation has been decreasing. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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28 pages, 6471 KiB  
Review
A Global Review of PWR Nuclear Power Plants
by Pablo Fernández-Arias, Diego Vergara and José A. Orosa
Appl. Sci. 2020, 10(13), 4434; https://0-doi-org.brum.beds.ac.uk/10.3390/app10134434 - 27 Jun 2020
Cited by 26 | Viewed by 14169
Abstract
Nuclear energy is presented as a real option in the face of the current problem of climate change and the need to reduce CO2 emissions. The nuclear reactor design with the greatest global impact throughout history and which has the most ambitious [...] Read more.
Nuclear energy is presented as a real option in the face of the current problem of climate change and the need to reduce CO2 emissions. The nuclear reactor design with the greatest global impact throughout history and which has the most ambitious development plans is the Pressurized Water Reactor (PWR). Thus, a global review of such a reactor design is presented in this paper, utilizing the analysis of (i) technical aspects of the different variants of the PWR design implemented over the past eight years, (ii) the level of implementation of PWR nuclear power plants in the world, and (iii) a life extension scenario and future trends in PWR design based on current research and development (R&D) activity. To develop the second analysis, a statistical study of the implementation of the different PWR variants has been carried out. Such a statistical analysis is based on the operating factor, which represents the relative frequency of reactors operating around the world. The results reflect the hegemony of the western variants in the 300 reactors currently operating, highlighting the North American and French versions. Furthermore, a simulation of a possible scenario of increasing the useful life of operational PWRs up to 60 years has been proposed, seeing that in 2050 the generation capacity of nuclear PWRs power plants will decrease by 50%, and the number of operating reactors by 70%. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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14 pages, 308 KiB  
Review
A Review on Wind Turbine Deterministic Power Curve Models
by Daniel Villanueva and Andrés Feijóo
Appl. Sci. 2020, 10(12), 4186; https://0-doi-org.brum.beds.ac.uk/10.3390/app10124186 - 18 Jun 2020
Cited by 13 | Viewed by 2081
Abstract
Over the last decades, wind energy has been arising as one of the most promising sources for the future of energy supply, and this trend should be reinforced in the future due to the foreseeable environmental and climatological catastrophe. Therefore, all technologies and [...] Read more.
Over the last decades, wind energy has been arising as one of the most promising sources for the future of energy supply, and this trend should be reinforced in the future due to the foreseeable environmental and climatological catastrophe. Therefore, all technologies and issues regarding its development are relevant. Among them, research on wind turbine power curve modeling is of importance for stakeholders and researchers because it allows them to easily obtain information about the amount of power and energy that can be captured from the primary resource, i.e., the wind. The task can be simplified by means of the use of wind turbine power curve models, and many researchers have been presenting their contributions on the topic in parallel with such a development. In this paper, a review on the formulation of wind turbine deterministic power curve models is presented. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
11 pages, 1294 KiB  
Review
Improved Performance of Li-ion Polymer Batteries Through Improved Pulse Charging Algorithm
by Judy M. Amanor-Boadu and Anthony Guiseppi-Elie
Appl. Sci. 2020, 10(3), 895; https://0-doi-org.brum.beds.ac.uk/10.3390/app10030895 - 29 Jan 2020
Cited by 24 | Viewed by 6955
Abstract
Pulse charging of lithium-ion polymer batteries (LiPo), when properly implemented, offers increased battery charge and energy efficiencies and improved safety for electronic device consumers. Investigations of the combined impact of pulse charge duty cycle and frequency of the pulse charge current on the [...] Read more.
Pulse charging of lithium-ion polymer batteries (LiPo), when properly implemented, offers increased battery charge and energy efficiencies and improved safety for electronic device consumers. Investigations of the combined impact of pulse charge duty cycle and frequency of the pulse charge current on the performance of lithium-ion polymer (LiPo) batteries used the Taguchi orthogonal arrays (OA) to identify optimal and robust pulse charging parameters that maximize battery charge and energy efficiencies while decreasing charge time. These were confirmed by direct comparison with the commonly applied benchmark constant current-constant voltage (CC–CV) charging method. The operation of a pulse charger using identified optimal parameters resulted in charge time reduction by 49% and increased charge and energy efficiencies of 2% and 12% respectively. Furthermore, when pulse charge current factors, such as frequency and duty cycle were considered, it was found that the duty cycle of the pulse charge current had the most impact on the cycle life of the LiPo battery and that the cycle life could be increased by as much as 100 cycles. Finally, the charging temperature was found to have the most statistically significant impact on the temporarily evolving LiPo battery impedance, a measure of its degradation. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences: Invited Papers in Energy Section)
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