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Energies, Volume 16, Issue 20 (October-2 2023) – 203 articles

Cover Story (view full-size image): There is growing interest in power generation from tidal streams by tidal turbine arrays. Turbine fatigue loading is an important design condition, and prediction requires understanding of the onset flow conditions—particularly shear, turbulence, and waves—that define unsteady loading. Three acoustic current profiler measurements and several numerical model predictions are analyzed to establish the occurrence of and spatial variation in such flows at a major tidal stream site, Raz Blanchard. Fatigue loads are assessed via the use of an unsteady blade element momentum model. Model predictions of shear and turbulence provide fatigue loads to within 8% of loads due to the measured conditions, falling to 3% if measured turbulence intensities are used. Both shear and turbulence vary across the site, contributing to the variation in predicted fatigue load. View this paper
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22 pages, 8805 KiB  
Article
A Feasibility Study on the Lateral Behavior of a 3D-Printed Column for Application in a Wind Turbine Tower
by In-Hwan Yang, Quang-The Bui, Ji-Hun Park and Seung-Tae Jeong
Energies 2023, 16(20), 7218; https://doi.org/10.3390/en16207218 - 23 Oct 2023
Viewed by 734
Abstract
Although 3D printing technology has been applied worldwide, the problem of connecting a printed structure and a foundation has rarely been examined. In particular, loads in the horizontal direction, such as wind loads and earthquake loads, can significantly affect the stability of a [...] Read more.
Although 3D printing technology has been applied worldwide, the problem of connecting a printed structure and a foundation has rarely been examined. In particular, loads in the horizontal direction, such as wind loads and earthquake loads, can significantly affect the stability of a printed structure. Therefore, in this study, the effect of lateral loads on printed columns that were connected to a foundation by two types of connectors was investigated. A steel angle with bolts and couplers was used to connect the printed column to a concrete footing. In addition, two types of lateral reinforcement were applied to the printed column to enhance its bonding strength and shear resistance. The lateral reinforcements were attached to the interface of the printed layers at distances of 100 and 200 mm to investigate the effect of lateral reinforcement distance on the lateral behavior of the printed column. The results showed that the use of couplers as connections between the columns and foundation significantly improved the load capacity. Furthermore, the effects of the lateral reinforcement types and lateral reinforcement distances were assessed. Full article
(This article belongs to the Topic Advances in Sustainable Materials and Products)
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32 pages, 14293 KiB  
Article
CO2 Injection via a Horizontal Well into the Coal Seam at the Experimental Mine Barbara in Poland
by Kamil Stańczyk, Robert Hildebrandt, Jarosław Chećko, Tomasz Urych, Marian Wiatowski, Shakil Masum, Sivachidambaram Sadasivam, Thomas Kempka, Christopher Otto, Priscilla Ernst and Hywel Rhys Thomas
Energies 2023, 16(20), 7217; https://doi.org/10.3390/en16207217 - 23 Oct 2023
Viewed by 892
Abstract
This study, conducted as part of the ROCCS project, investigates the potential of coal seams for CO2 sequestration through in situ tests. The in situ tests, performed at Experimental Mine Barbara in Mikołów, Poland, involved injecting CO2 through a horizontal well [...] Read more.
This study, conducted as part of the ROCCS project, investigates the potential of coal seams for CO2 sequestration through in situ tests. The in situ tests, performed at Experimental Mine Barbara in Mikołów, Poland, involved injecting CO2 through a horizontal well into a coal seam, with variable well lengths and injection parameters. The experiments included monitoring for CO2 leakage and migration within the coal seam. The objective was to examine the correlation between the CO2 injection rate and the coal–CO2 contact area, monitoring for any potential leakage. The total mass of CO2 injected was about 7700 kg. Significant leakage, probably due to the formation of preferential pathways, prevented pressure buildup in the injection well. The results provide insights into challenges regarding CO2 injection into coal seams, with implications for the design of commercial-scale CO2 storage installations. Full article
(This article belongs to the Collection Feature Papers in Carbon Capture, Utilization, and Storage)
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22 pages, 10233 KiB  
Article
Investigation of the Water-Invasion Gas Efficiency in the Kela-2 Gas Field Using Multiple Experiments
by Donghuan Han, Wei Xiong, Tongwen Jiang, Shusheng Gao, Huaxun Liu, Liyou Ye, Wenqing Zhu and Weiguo An
Energies 2023, 16(20), 7216; https://doi.org/10.3390/en16207216 - 23 Oct 2023
Cited by 1 | Viewed by 729
Abstract
Although improving the recovery of water-invaded gas reservoirs has been extensively studied in the natural gas industry, the nature of the efficiency of water-invaded gas recovery remains uncertain. Low-field nuclear magnetic resonance (NMR) can be used to clearly identify changes in water saturation [...] Read more.
Although improving the recovery of water-invaded gas reservoirs has been extensively studied in the natural gas industry, the nature of the efficiency of water-invaded gas recovery remains uncertain. Low-field nuclear magnetic resonance (NMR) can be used to clearly identify changes in water saturation in the core during high-pressure water-invasion gas. Here, we provide four types of water-invasion gas experiments (spontaneous imbibition, atmospheric pressure, high-pressure approximate equilibrium, and depletion development water-invasion gas) to reveal the impact of the water-invasion gas efficiency on the recovery of water-invasion gas reservoirs. NMR suggested that imbibition mainly occurs in medium to large pores and that residual gas remains mainly in large pores. The amount of gas driven out from the large pores by imbibition was much greater than that driven out from the small pores. Our findings indicate that the initial gas saturation, contact surface, and permeability are the main factors controlling the residual gas saturation, suggesting that a reasonable initial water saturation should be established before the water-invasion gas experiments. Additionally, the water-invasion gas efficiency at high pressures can be more reliably obtained than that at normal pressures. After the high-pressure approximate equilibrium water invasion for gas displacement, a large amount of residual gas remains in the relatively larger pores of the core, with a residual gas saturation of 42%. In contrast to conventional experiments, the residual gas saturation and water displacement efficiency of the high-pressure approximate equilibrium water invasion for gas displacement did not exhibit a favorable linear relationship with the permeability. The residual gas saturation ranged from 34 to 43% (avg. 38%), while the water displacement efficiency ranged from 32 to 45% (avg. 40%) in the high-pressure approximate equilibrium water invasion for gas displacement. The residual gas saturation in the depletion development water-invasion gas experiment was 26–40% (average: 33%), with an efficiency ranging from 45 to 50% (average: 48%), indicating that the depletion development experiment is closer to the actual development process of gas reservoirs. Our findings provide novel insights into water-invasion gas efficiency, providing robust estimates of the recovery of water-invasion gas reservoirs. Full article
(This article belongs to the Topic Petroleum and Gas Engineering)
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23 pages, 3064 KiB  
Article
A Novel Hybrid Power-Grid Investment Optimization Model with Collaborative Consideration of Risk and Benefit
by Changzheng Gao, Xiuna Wang, Dongwei Li, Chao Han, Weiyang You and Yihang Zhao
Energies 2023, 16(20), 7215; https://doi.org/10.3390/en16207215 - 23 Oct 2023
Viewed by 602
Abstract
Power-grid investment (PGI) optimization is crucial for boosting investment performance, lowering investment risks, and assuring the sustainable development of power-grid businesses. However, existing studies, which primarily concentrate on financial aspects, have not adequately considered the risk and benefit factors in the process of [...] Read more.
Power-grid investment (PGI) optimization is crucial for boosting investment performance, lowering investment risks, and assuring the sustainable development of power-grid businesses. However, existing studies, which primarily concentrate on financial aspects, have not adequately considered the risk and benefit factors in the process of PGI. In this context, this research suggests a novel hybrid PGI optimization model that collaboratively accounts for the risks and benefits. In the first step, risk and benefit indicator systems for PGI are built, and a comprehensive evaluation model based on the Bayesian best–worst method and TOPSIS is suggested. In the second stage, a PGI optimization model considering the investment amount, power demand, and low-carbon restrictions is further developed based on the evaluation results. Furthermore, the incomprehensible but intelligible-in-time logic algorithm is adopted to solve the problem. By conducting an empirical analysis of ten projects within a power-grid company, the optimal investment plan and a differentiated investment portfolio strategy are obtained by adjusting the key elements. Full article
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19 pages, 4149 KiB  
Article
Assessment of a Francis Micro Hydro Turbine Performance Installed in a Wastewater Treatment Plant
by Paweł Tomczyk, Krzysztof Mastalerek, Mirosław Wiatkowski, Alban Kuriqi and Jakub Jurasz
Energies 2023, 16(20), 7214; https://doi.org/10.3390/en16207214 - 23 Oct 2023
Cited by 1 | Viewed by 1186
Abstract
The purpose of this research work was to examine the hydroelectric potential of wastewater treatment plants by harnessing the kinetic and/or potential energy of treated wastewater for electricity generation. Such a concept encapsulates the essence of renewable energy and resonates with international sustainable [...] Read more.
The purpose of this research work was to examine the hydroelectric potential of wastewater treatment plants by harnessing the kinetic and/or potential energy of treated wastewater for electricity generation. Such a concept encapsulates the essence of renewable energy and resonates with international sustainable development mandates and climate change adaptation strategies. The primary objective was to analyze the performance parameters of the Francis turbine, a key component of this energy generation system. An experimental analysis encompassed model tests on the Francis turbine, simulating varied flow conditions using the GUNT turbine. Additionally, historical data from the Toruń Wastewater Treatment Plant (WWTP) 2018 annual wastewater discharge were employed to validate the findings and shed light on real-world applications. The tested efficiency of the Francis turbine peaked at 64.76%, notably below the literature-reported 80%. The turbine system’s overall efficiency was approximately 53%, juxtaposed against the theoretical value of 66.35%. With respect to the Toruń WWTP data, the turbine’s power output was highest at 24.82 kW during maximum wastewater flow, resulting in a power production of 150.29 MWh per year. The observed turbine efficiencies were consistent with the previously documented range of 30% to 96%. The turbine displayed optimal outputs during heightened flow rates and maximized production at more frequent, lower flow rates throughout the year. Implementing such turbines in wastewater treatment plants not only aligns with global renewable energy goals but also boasts lower construction costs and environmental impacts, primarily due to the utilization of existing infrastructure. Furthermore, wastewater flow consistency counters the seasonal variability seen in conventional water treatment plants. These findings pave the way for more energy-efficient design recommendations for turbines within wastewater treatment and hydropower plants. Full article
(This article belongs to the Section B: Energy and Environment)
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16 pages, 4297 KiB  
Article
Electric Vehicle Fleet Management for a Prosumer Building with Renewable Generation
by Matteo Fresia and Stefano Bracco
Energies 2023, 16(20), 7213; https://doi.org/10.3390/en16207213 - 23 Oct 2023
Cited by 3 | Viewed by 772
Abstract
The integration of renewable energy systems in buildings leads to a reduction in energy bills for end users and a reduction in the carbon footprint of such buildings, usually referred to as prosumers. In addition, the installation of charging points for the electric [...] Read more.
The integration of renewable energy systems in buildings leads to a reduction in energy bills for end users and a reduction in the carbon footprint of such buildings, usually referred to as prosumers. In addition, the installation of charging points for the electric vehicles of people working or living in these buildings can further improve the energy efficiency of the whole system if innovative technologies, such as vehicle-to-building (V2B) technologies, are implemented. The aim of this paper is to present an Energy Management System (EMS) based on mathematical programming that has been developed to optimally manage a prosumer building equipped with photovoltaics, a micro wind turbine and several charging points for electric vehicles. Capabilities curves of renewable power plant inverters are modelled within the EMS, as well as the possibility to apply power curtailment and V2B. The use of V2B technology reduces the amount of electricity purchased from the public grid, while the use of smart inverters for the power plants allows zero reactive power to be drawn from the grid. Levelized cost of electricity (LCOE) is used to quantify curtailment costs, while penalties on reactive power absorption from the distribution network are evaluated in accordance with the current regulatory framework. Specifically, the model is applied to a prosumer building owned by the postal service in a large city in Italy. The paper reports the main results of the study and proposes a sensitivity analysis on the number of charging stations and vehicles, as well as on the consideration of different typical days characterized by different load and generation profiles. This paper also investigates how errors in forecasting energy production from renewable sources impact the optimal operation of the whole system. Full article
(This article belongs to the Special Issue Power System Analysis Control and Operation)
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20 pages, 1116 KiB  
Article
Future Challenges of the Electric Vehicle Market Perceived by Individual Drivers from Eastern Poland
by Monika Stoma and Agnieszka Dudziak
Energies 2023, 16(20), 7212; https://doi.org/10.3390/en16207212 - 23 Oct 2023
Cited by 3 | Viewed by 1155
Abstract
In the past few years, it can be seen that the automotive market has been developing quite rapidly, especially when it comes to electric cars. This is because the development of sustainable cars seems to be an extremely important issue at the moment. [...] Read more.
In the past few years, it can be seen that the automotive market has been developing quite rapidly, especially when it comes to electric cars. This is because the development of sustainable cars seems to be an extremely important issue at the moment. Nowadays, cars with different propulsion systems (among others electric, hybrid, gas, or hydrogen) can be met on the roads. But, political action is mainly aimed at electric cars. Such an approach will certainly lead to fundamental changes in production processes in the near future via the emergence and development of new technologies in the field of electric passenger cars. Therefore, the manuscript discusses the concept of vehicles with different types of power supply, with the main emphasis on electric vehicles. The essence of electric vehicles, their genesis, rationale for development, and growth are indicated. The different markets around the world, through the prism of, on the one hand, programs supporting the purchase and use of this type of vehicle and, on the other hand, factors limiting and inhibiting their uptake, are also discussed. The research was conducted in a group of both current and potential drivers from Eastern Poland, with different categories of grouping variables used in the analyses. On the basis of the research carried out and the results obtained, it can be argued that due to various factors, the respondents’ opinions are varied, and there are no unambiguous conclusions stating that such solutions will soon be available. Indeed, a number of doubts and barriers were noted among respondents. Driver preferences are therefore a key issue, but production capacity and the profitability of investments in the purchase of vehicles with an electric power supply should also be taken into account. Full article
(This article belongs to the Special Issue Sustainable Development: Policies, Challenges, and Further II)
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19 pages, 7893 KiB  
Article
Smart Switching in Single-Phase Grid-Connected Photovoltaic Power Systems for Inrush Current Elimination
by Gerardo de J. Martínez-Figueroa, Santiago Bogarra and Felipe Córcoles
Energies 2023, 16(20), 7211; https://doi.org/10.3390/en16207211 - 23 Oct 2023
Cited by 1 | Viewed by 688
Abstract
Grid-connected photovoltaic (PV) power systems are one of the most promising technologies to address growing energy demand and ecological challenges. This paper proposes smart switching to mitigate inrush currents during the connection of single-phase transformers used in PV systems. An effective inrush current [...] Read more.
Grid-connected photovoltaic (PV) power systems are one of the most promising technologies to address growing energy demand and ecological challenges. This paper proposes smart switching to mitigate inrush currents during the connection of single-phase transformers used in PV systems. An effective inrush current mitigation contributes to the reliability of PV systems. The inrush current severity is influenced by the pseudorandom residual flux at the transformer core and the energization point-on-wave. The most common approach to avoid inrush currents is controlled connection, which requires prior knowledge of the residual flux. However, the residual flux can differ in each case, and its measurement or estimation can be impractical. The proposed smart switching is based on a comprehensive analysis of the residual flux and the de-energization trajectories, and only requires two pieces of data (ϕRM and ϕ0, flux values of the static and dynamic loops when the respective currents are null), calculated from two simple no-load tests. It has a clear advantage over common approaches: no need to estimate or measure the residual flux before each connection, avoiding the need for expensive equipment or complex setups. Smart switching can be easily implemented in practical settings, as it considers different circuit breakers with distinctive aperture features, making it cost-effective for PV systems. Full article
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20 pages, 4924 KiB  
Article
Explainable Approaches for Forecasting Building Electricity Consumption
by Nikos Sakkas, Sofia Yfanti, Pooja Shah, Nikitas Sakkas, Christina Chaniotakis, Costas Daskalakis, Eduard Barbu and Marharyta Domnich
Energies 2023, 16(20), 7210; https://doi.org/10.3390/en16207210 - 23 Oct 2023
Cited by 1 | Viewed by 838
Abstract
Building electric energy is characterized by a significant increase in its uses (e.g., vehicle charging), a rapidly declining cost of all related data collection, and a proliferation of smart grid concepts, including diverse and flexible electricity pricing schemes. Not surprisingly, an increased number [...] Read more.
Building electric energy is characterized by a significant increase in its uses (e.g., vehicle charging), a rapidly declining cost of all related data collection, and a proliferation of smart grid concepts, including diverse and flexible electricity pricing schemes. Not surprisingly, an increased number of approaches have been proposed for its modeling and forecasting. In this work, we place our emphasis on three forecasting-related issues. First, we look at the forecasting explainability, that is, the ability to understand and explain to the user what shapes the forecast. To this extent, we rely on concepts and approaches that are inherently explainable, such as the evolutionary approach of genetic programming (GP) and its associated symbolic expressions, as well as the so-called SHAP (SHapley Additive eXplanations) values, which is a well-established model agnostic approach for explainability, especially in terms of feature importance. Second, we investigate the impact of the training timeframe on the forecasting accuracy; this is driven by the realization that fast training would allow for faster deployment of forecasting in real-life solutions. And third, we explore the concept of counterfactual analysis on actionable features, that is, features that the user can really act upon and which therefore present an inherent advantage when it comes to decision support. We have found that SHAP values can provide important insights into the model explainability. In our analysis, GP models demonstrated superior performance compared to neural network-based models (with a 20–30% reduction in Root Mean Square Error (RMSE)) and time series models (with a 20–40% lower RMSE), but a rather questionable potential to produce crisp and insightful symbolic expressions, allowing a better insight into the model performance. We have also found and reported here on an important potential, especially for practical, decision support, of counterfactuals built on actionable features, and short training timeframes. Full article
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23 pages, 3551 KiB  
Article
Theoretical and Energy Biomass Potential of Heat and Electricity Production in Kosovo
by Ardit Sertolli, Attila Bai, Zoltán Gabnai, Tamás Mizik and Albiona Pestisha
Energies 2023, 16(20), 7209; https://doi.org/10.3390/en16207209 - 23 Oct 2023
Viewed by 1335
Abstract
The energy use of residues from agriculture, forestry, and solid waste can foster the transition towards a more renewable energy supply. This paper analyzes the energy potential of the above-mentioned sources for energy applications in Kosovo. The analysis is based on statistical data [...] Read more.
The energy use of residues from agriculture, forestry, and solid waste can foster the transition towards a more renewable energy supply. This paper analyzes the energy potential of the above-mentioned sources for energy applications in Kosovo. The analysis is based on statistical data from different studies and reports, analyzing and calculating them to determine the theoretical and energy biomass potential. Kosovo can increase its self-sufficiency by taking advantage of its rich but under-utilized potential of biomass energy sources. This is a novelty study in this area, considering Kosovo lignite-dominated heat energy and electricity consumption and the available special literature. According to our estimates, the theoretical potential is 6.13 million tons/year, while the biomass energy potential should be around 4.57 million tons/year, including approximately 74.6% of biomass, which can be used for energy needs (heating and electricity). Based on the data and calculations, the available and usable potential shows biomass as an energy source with high potential in Kosovo; its share is very low, but it is reasonable to grow for both environmental and economic reasons. Full article
(This article belongs to the Collection Renewable Energy and Energy Storage Systems)
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15 pages, 9042 KiB  
Article
Storage of Compressed Natural Gases
by Gulnur Zakirova, Evgeny Krapivsky, Anastasia Berezovskaya and Artem Borisov
Energies 2023, 16(20), 7208; https://doi.org/10.3390/en16207208 - 23 Oct 2023
Cited by 1 | Viewed by 911
Abstract
The article analyzes the modern theory and practice of transportation and storage of compressed natural gas. The expediency of the inclusion of a floating storage berth for the loading of gas carriers and container ships into the infrastructure of marine transportation of compressed [...] Read more.
The article analyzes the modern theory and practice of transportation and storage of compressed natural gas. The expediency of the inclusion of a floating storage berth for the loading of gas carriers and container ships into the infrastructure of marine transportation of compressed natural gas is considered. Requirements for storage berth are formulated. It is shown that without using a marine mooring storage facility, the loading time of a gas carrier will considerably increase, and the economic efficiency of compressed gas transportation will lower due to the considerable time of loading and unloading of a gas carrier. The construction of a storage berth is proposed, and calculations of storage parameters and calculation of its buoyancy are made. The possibility of using the REFPROP vs. 9.1 software package to automate the selection of the composition of a multicomponent hydrocarbon mixture for further use at the selected range of temperatures and pressures is substantiated. The use of the system is considered in the example of phase equilibrium of a multicomponent hydrocarbon mixture. Full article
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25 pages, 111184 KiB  
Article
Applying the Geometric Features of Cumulative Sums to the Development of Event Detection
by Men-Shen Tsai and Yen-Kuang Lin
Energies 2023, 16(20), 7207; https://doi.org/10.3390/en16207207 - 23 Oct 2023
Viewed by 696
Abstract
As a result of the severe energy shortage and the greenhouse effect, experts worldwide have been devoted to solving energy management problems. Smart grid construction is an essential technology for mastering energy allocation. Smart grids enable end users to adjust their energy consumption [...] Read more.
As a result of the severe energy shortage and the greenhouse effect, experts worldwide have been devoted to solving energy management problems. Smart grid construction is an essential technology for mastering energy allocation. Smart grids enable end users to adjust their energy consumption via incentive measures, reduce the frequency of power supply instability, and improve energy efficiency. Non-intrusive load monitoring (NILM) is a vital technology for smart grid construction. One of the fundamental steps of NILM is event detection. Proper event detection can increase the accuracy of load identification. Among traditional methods, especially the event detection method developed with the CUSUM method, although the accuracy is reasonable, the precision, recall, and f1 score are not relatively better. Thus, there is an opportunity to improve the performance of CUSUM. Additionally, many studies focus on the step-like event, but the long-transient event is often overlooked in event detection. Therefore, in this study, it was observed that when the transient current deviates from the steady-state current, the transient current can be regarded as a key indicator for event detection. With this observation, a method is proposed to convert the root mean square (RMS) current into a cumulative sum (CUSUM) diagram method and identify turning points representing events from the CUSUM geometry. Once the slope of the turning point has been determined, event detection is achieved. Compared with traditional methods, the proposed method is easy to implement, its recognition rate can reach around 98%, and the window length is reduced from 5 s to 3 s. Full article
(This article belongs to the Section A1: Smart Grids and Microgrids)
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11 pages, 3354 KiB  
Article
Evaluation of the Optional Wideband Accuracy of Inductive Current Transformers in Accordance with the Standard IEC 61869-1 Ed.2
by Ernest Stano, Piotr Kaczmarek and Michal Kaczmarek
Energies 2023, 16(20), 7206; https://doi.org/10.3390/en16207206 - 23 Oct 2023
Viewed by 676
Abstract
This paper presents the evaluation of tested inductive CTs’ accuracy for distorted current harmonics in accordance with the optional accuracy class WB1 introduced by the new edition of the standard IEC 61869-1 published in the year 2023. The tests were performed in compliance [...] Read more.
This paper presents the evaluation of tested inductive CTs’ accuracy for distorted current harmonics in accordance with the optional accuracy class WB1 introduced by the new edition of the standard IEC 61869-1 published in the year 2023. The tests were performed in compliance with the interpretation sheet IEC 61869-2:2012/ISH1:2022. Therefore, the resistive and the resistive–inductive loads of the secondary winding of tested inductive CTs were used, as this was required for the given test conditions. The results indicate that the units designed for the transformation of a sinusoidal current of a frequency of 50 Hz ensure the high wideband transformation accuracy of the distorted current harmonics, as demanded by the power quality monitoring and distorted electrical power and energy requirements. The key to this is proper design using modern magnetic material(s) for the magnetic core and its oversizing in relation to the requirements for a given accuracy class defined for the transformation of sinusoidal currents with a rated frequency. Both tested inductive CTs with a rated primary current RMS value equal to 300 A, class 0.2 and 0.5, ensured compliance with the requirements of the WB1 wideband accuracy class. Full article
(This article belongs to the Special Issue Condition Monitoring of Power System Components II)
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22 pages, 29407 KiB  
Article
Impacts of Pore Structure on the Occurrence of Free Oil in Lacustrine Shale Pore Networks
by Fuliang You, Guangdi Liu, Mingliang Sun, Cheng An, Chaozheng Li and Yishu Li
Energies 2023, 16(20), 7205; https://doi.org/10.3390/en16207205 - 23 Oct 2023
Cited by 1 | Viewed by 868
Abstract
The ultimate recovery of shale oil is mostly dependent upon the occurrence and content of free oil within the nano-scaled pore network of shale reservoirs. Due to the nanoporous nature of shale, quantitatively characterizing the occurrence and content of free oil in shale [...] Read more.
The ultimate recovery of shale oil is mostly dependent upon the occurrence and content of free oil within the nano-scaled pore network of shale reservoirs. Due to the nanoporous nature of shale, quantitatively characterizing the occurrence and content of free oil in shale is a formidable undertaking. To tackle this challenge, 12 lacustrine shale samples with diverse organic matter content from the Chang7 Member in the southern Ordos Basin were selected, and the characteristics of free oil occurrence were indirectly characterized by comparing changes in pore structure before and after organic solvent extraction. The free oil enrichment in shale was assessed using the oil saturation index (OSI), corrected oil saturation index (OSIcorr), and percentage of saturated hydrocarbons. The results revealed that slit-like interparticle pores with diameters less than 30 nm are dominant in the Chang7 shale. Conceptual models for the pore structures containing free oil were established for shale with total organic carbon (TOC) content less than 9% and greater than 9%, respectively. Shale samples with TOC content less than 9% exhibit a well-developed pore network characterized by relatively larger pore volume, surface area, and heterogeneity. Conversely, shale samples with TOC content exceeding 9% display a less developed pore network characterized by relatively smaller pore volume, surface area, and heterogeneity. Larger pore volume and lower organic matter abundance favor the enrichment of free oil within the lacustrine shale pore network. This study may have significant implications for understanding oil transport in shales. Full article
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21 pages, 3440 KiB  
Article
Optimal Planning Strategy for Reconfigurable Electric Vehicle Chargers in Car Parks
by Bingkun Song, Udaya K. Madawala and Craig A. Baguley
Energies 2023, 16(20), 7204; https://doi.org/10.3390/en16207204 - 23 Oct 2023
Cited by 1 | Viewed by 1173
Abstract
A conventional electric vehicle charger (EVC) charges only one EV concurrently. This leads to underutilization whenever the charging power is less than the EVC-rated capacity. Consequently, the cost-effectiveness of conventional EVCs is limited. Reconfigurable EVCs (REVCs) are a new technology that overcomes underutilization [...] Read more.
A conventional electric vehicle charger (EVC) charges only one EV concurrently. This leads to underutilization whenever the charging power is less than the EVC-rated capacity. Consequently, the cost-effectiveness of conventional EVCs is limited. Reconfigurable EVCs (REVCs) are a new technology that overcomes underutilization by allowing multiple EVs to be charged concurrently. This brings a cost-effective charging solution, especially in large car parks requiring numerous chargers. Therefore, this paper proposes an optimal planning strategy for car parks deploying REVCs. The proposed planning strategy involves three stages. An optimization model is developed for each stage of the proposed planning strategy. The first stage determines the optimal power rating of power modules inside each REVC, and the second stage determines the optimal number and configuration of REVCs, followed by determining the optimal operation plan for EV car parks in the third stage. To demonstrate the effectiveness of the proposed optimal planning strategy, a comprehensive case study is undertaken using realistic car parking scenarios with 400 parking spaces, electricity tariffs, and grid infrastructure costs. Compared to deploying other conventional EVCs, the results convincingly indicate that the proposed optimal planning strategy significantly reduces the total cost of investment and operation while satisfying charging demands. Full article
(This article belongs to the Special Issue Smart Electric Vehicle Charging Approaches for Demand Response)
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20 pages, 724 KiB  
Article
Detection of False Data Injection Attacks in a Smart Grid Based on WLS and an Adaptive Interpolation Extended Kalman Filter
by Guoqing Zhang, Wengen Gao, Yunfei Li, Xinxin Guo, Pengfei Hu and Jiaming Zhu
Energies 2023, 16(20), 7203; https://doi.org/10.3390/en16207203 - 23 Oct 2023
Cited by 1 | Viewed by 789
Abstract
An accurate power state is the basis of the normal functioning of the smart grid. However, false data injection attacks (FDIAs) take advantage of the vulnerability in the bad data detection mechanism of the power system to manipulate the process of state estimation. [...] Read more.
An accurate power state is the basis of the normal functioning of the smart grid. However, false data injection attacks (FDIAs) take advantage of the vulnerability in the bad data detection mechanism of the power system to manipulate the process of state estimation. By attacking the measurements, then affecting the estimated state, FDIAs have become a serious hidden danger that affects the security and stable operation of the power system. To address the bad data detection vulnerability, in this paper, a false data attack detection method based on weighted least squares (WLS) and an adaptive interpolation extended Kalman filter (AIEKF) is proposed. On the basis of applying WLS and AIEKF, the Euclidean distance is used to calculate the deviation values of the two-state estimations to determine whether the current moment is subjected to a false data injection attack in the power system. Extensive experiments were conducted to simulate an IEEE-14-bus power system, showing that the adaptive interpolation extended Kalman filter can compensate for the deficiency in the bad data detection mechanism and successfully detect FDIAs. Full article
(This article belongs to the Special Issue Advanced Electric Power System 2023)
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16 pages, 3427 KiB  
Article
Heat Production Performance from an Enhanced Geothermal System (EGS) Using CO2 as the Working Fluid
by Wentao Zhao, Yilong Yuan, Tieya Jing, Chenghao Zhong, Shoucheng Wei, Yulong Yin, Deyuan Zhao, Haowei Yuan, Jin Zheng and Shaomin Wang
Energies 2023, 16(20), 7202; https://doi.org/10.3390/en16207202 - 23 Oct 2023
Cited by 1 | Viewed by 1048
Abstract
CO2-based enhanced geothermal systems (CO2-EGS) are greatly attractive in geothermal energy production due to their high flow rates and the additional benefit of CO2 geological storage. In this work, a CO2-EGS model is built based on [...] Read more.
CO2-based enhanced geothermal systems (CO2-EGS) are greatly attractive in geothermal energy production due to their high flow rates and the additional benefit of CO2 geological storage. In this work, a CO2-EGS model is built based on the available geological data in the Gonghe Basin, Northwest China. In our model, the wellbore flow is considered and coupled with a geothermal reservoir to better simulate the complex CO2 flow and heat production behavior. Based on the fractured geothermal reservoir at depths between 2900 m and 3300 m, the long-term (30-year) heat production performance is predicted using CO2 as the working fluid with fixed wellhead pressure. The results indicate that the proposed CO2-EGS will obtain an ascending heat extraction rate in the first 9 years, followed by a slight decrease in the following 21 years. Due to the significant natural convection of CO2 (e.g., low viscosity and density) in the geothermal reservoir, the mass production rate of the CO2-EGS will reach 150 kg/s. The heat extraction rates will be greater than 32 MW throughout the 30-year production period, showing a significant production performance. However, the Joule–Thomson effect in the wellbore will result in a drastic decrease in production temperature (e.g., a 62.6 °C decrease in the production well). This means that the pre-optimization analyses and physical material treatments are required during geothermal production using CO2 as the working fluid. Full article
(This article belongs to the Special Issue The Status and Development Trend of Geothermal Resources)
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27 pages, 36052 KiB  
Article
Selective Catalytic Hydrogenation of Vegetable Oils over Copper-Based Catalysts Supported on Amorphous Silica
by Umberto Pasqual Laverdura, Leucio Rossi, Claire Courson, Antonio Zarli and Katia Gallucci
Energies 2023, 16(20), 7201; https://doi.org/10.3390/en16207201 - 23 Oct 2023
Cited by 1 | Viewed by 861
Abstract
This work aims to study the selective catalytic hydrogenation of vegetable oils to maximize oleic acid content and expand the range of non-edible uses. Oleic acid (C18:1) is suitable for use as a biodegradable lubricant and is a building block in producing polymers [...] Read more.
This work aims to study the selective catalytic hydrogenation of vegetable oils to maximize oleic acid content and expand the range of non-edible uses. Oleic acid (C18:1) is suitable for use as a biodegradable lubricant and is a building block in producing polymers and plastics from renewable resources. The challenge is the synthesis of heterogeneous catalysts, allowing for a maximum yield of C18:1 and low formation of the corresponding saturated acid (stearic acid). New copper-based catalysts on silica were synthesized via two synthesis methods: hydrolysis precipitation and ammonia-evaporation. Experimental tests were carried out at a lab scale operating in a semi-batch mode. The best conversion reached 90% for C18:3 and 80% for C18:2 HP Cu-silica catalyst results, the best candidate for an industrial case study. Good results were obtained in the selectivities of oleic acid production and cis/trans isomers ratio. The modified return on the investment of the designed hydrogenation plant provides the revenues of the capital costs in less than one year. Full article
(This article belongs to the Special Issue The Role of Thermochemical Treatments in Biorefinery)
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14 pages, 4369 KiB  
Article
Polynomial Regression Model Utilization to Determine Potential Refuse-Derived Fuel (RDF) Calories in Indonesia
by Luqman Luqman, Sarifuddin Madenda and Prihandoko Prihandoko
Energies 2023, 16(20), 7200; https://doi.org/10.3390/en16207200 - 22 Oct 2023
Viewed by 729
Abstract
Waste-to-energy (WTE) is one of the Indonesian government’s programs aiming to meet the target of achieving a new and renewable energy (NRE) mix, as well as one of the solutions proposed to overcome the problem of waste. One of the products of WTE [...] Read more.
Waste-to-energy (WTE) is one of the Indonesian government’s programs aiming to meet the target of achieving a new and renewable energy (NRE) mix, as well as one of the solutions proposed to overcome the problem of waste. One of the products of WTE is energy derived from raw material waste (refuse-derived fuel/RDF). Using the formula y = 0.00003 x5 − 0.0069 x4 + 0.6298 x3 − 24.3245 x2 + 432.8401 x + 55.7448 with R2 = 0.9963, which was obtained by comparing a scatter plot diagram from the RDF calorie test dataset produced through a bio-drying process, the potential RDF calories produced using the waste composition dataset taken from each region in Indonesia can be calculated. The results of the calculations using the determined equations produce a list of provinces with RDF calorie potential, ordered from the largest to the smallest, using which the government can determine which areas are the main priority for processing waste into energy. Thus, through this method, the target of 5.1% renewable energy sourced from waste can be achieved by 2025. Full article
(This article belongs to the Special Issue Biomass and Biofuel for Renewable Energy)
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20 pages, 2442 KiB  
Article
Climate Change Mitigation in Thailand’s Domestic Aviation: Mitigation Options Analysis towards 2050
by Arthit Champeecharoensuk, Shobhakar Dhakal and Nuwong Chollacoop
Energies 2023, 16(20), 7199; https://doi.org/10.3390/en16207199 - 22 Oct 2023
Viewed by 1609
Abstract
Thailand’s civil aviation industry has expanded rapidly in the past ten years resulting in increasing aviation greenhouse gas (GHG) emissions and energy consumption. The rapid growth in air transport is anticipated to continue further. Presently, domestic aviation and the economy of many countries [...] Read more.
Thailand’s civil aviation industry has expanded rapidly in the past ten years resulting in increasing aviation greenhouse gas (GHG) emissions and energy consumption. The rapid growth in air transport is anticipated to continue further. Presently, domestic aviation and the economy of many countries are recovering rapidly in the post-COVID-19 period, resulting in fuel consumption and GHG emissions gradually increasing again. However, despite implementing the ICAO’s CORSIA (International Civil Aviation Organization’s Carbon Offsetting and Reduction Scheme for International Aviation) rule for international aviation, GHG emissions in the domestic aviation sector are largely unregulated. Moreover, the literature lacks a GHG emissions analysis that considers this sector’s potential growth and mitigation policies for future GHG emissions. To close the gap, this study conducted a GHG emissions analysis from this sector under various scenarios through 2050 using historical data during 2008–2020 to forecast future trends. It evaluates the impact of the mitigation policies, such as fuel switching and aircraft technology, on improving fuel efficiency due to technological advancements in aircraft and carbon pricing. The results show that the fuel switching option would result in a significant long-term reduction in GHG emissions, whereas the carbon pricing option and aircraft technology option are desirable in reducing GHG emissions in the short term. Therefore, to meet GHG emissions reduction targets more successfully, all measures must be simultaneously executed to address short- and long-term mitigation strategies. These findings have significant implications for both present and future GHG emissions reduction measures, supporting Thailand’s 2050 climate targets and energy efficiency policies as the domestic aviation industry adjusts. Full article
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21 pages, 4994 KiB  
Article
Transient Behavior Analysis of the Infiltration Heat Recovery of Exterior Building Walls
by Alaa Alaidroos
Energies 2023, 16(20), 7198; https://doi.org/10.3390/en16207198 - 22 Oct 2023
Viewed by 601
Abstract
This research study investigated the transient behavior of the convection–diffusion model for the infiltration heat recovery (IHR) and the influence of the building envelope heat capacity, along with other factors. A transient numerical model was developed and validated to analyze the IHR under [...] Read more.
This research study investigated the transient behavior of the convection–diffusion model for the infiltration heat recovery (IHR) and the influence of the building envelope heat capacity, along with other factors. A transient numerical model was developed and validated to analyze the IHR under various conditions. The results highlight the role of heat capacity, thermal conductivity, wall thickness, airflow rate, airflow direction, and wall porosity on the temperature distribution and the heat recovery factor within the wall. Higher-heat-capacity walls displayed a delayed temperature rise, while low-thermal-conductivity walls reduced the conduction heat transfer and increased the IHR factor. The impact of heat capacity diminished with very low thermal conductivity walls but became evident for high-thermal-conductivity walls, particularly at higher Peclet numbers. Thicker walls enhanced the heat retention and improved the IHR, with a reduced influence of airflow rate. Higher IHR factors were associated with thicker walls, lower Peclet numbers, and higher heat capacities. The analysis also showed that the wall porosity affected the IHR with less significance than the other factors. Incorporating these findings into building energy modeling tools could improve the prediction accuracy of the thermal behavior of buildings. Accordingly, this study contributes to building physics by understanding IHR dynamics and thermal mass interactions, as well as improving building energy modeling accuracy for performance prediction. Future research can explore the impacts of additional factors on IHR and investigate the effect of IHR on the overall energy consumption of buildings. Full article
(This article belongs to the Special Issue Volume II: Heat Transfer and Heat Recovery Systems)
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21 pages, 836 KiB  
Article
Balancing Portfolios with Metals: A Safe Haven for Green Energy Investors?
by Rui Manuel Dias, Mariana Chambino, Nuno Teixeira, Paulo Alexandre and Paula Heliodoro
Energies 2023, 16(20), 7197; https://doi.org/10.3390/en16207197 - 22 Oct 2023
Viewed by 960
Abstract
This study investigates the relationship between energy metals and precious metals to assess their suitability as safe haven assets in clean energy investment portfolios. This study aims to conduct an effect analysis of the events that occurred during the years 2020 and 2022, [...] Read more.
This study investigates the relationship between energy metals and precious metals to assess their suitability as safe haven assets in clean energy investment portfolios. This study aims to conduct an effect analysis of the events that occurred during the years 2020 and 2022, characterized by substantial investments in the field of clean energy. The analysed period encompasses the period from 13 July 2018 to 11 July 2023. The study is carried out in multiple stages with the aim of investigating a highly tumultuous period in the global economy. To assess long-term relationships, the econometric methodology proposed by Gregory and Hansen will be employed. The research shows a positive association between energy metals (excluding nickel futures) and clean energy indexes, suggesting their potential as secure investments for green investors diversifying their portfolios. Additionally, the study confirms the reliability of precious metals, such as gold, silver, and platinum as safe havens for clean energy stock indexes. These findings highlight the stability that both energy and precious metals can offer within clean energy portfolios during market volatility, emphasizing their value in such investment strategies. In brief, this study affirms that energy and precious metals are invaluable pillars in the structure of clean energy portfolios, offering unwavering support during market turbulence. Full article
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15 pages, 259 KiB  
Article
Determining the Factors Affecting Solar Energy Utilization in Saudi Housing: A Case Study in Makkah
by Amin Barnawi, Mohamed A. Zohdy and Tarik Hawsawi
Energies 2023, 16(20), 7196; https://doi.org/10.3390/en16207196 - 22 Oct 2023
Viewed by 899
Abstract
This research paper examines the adoption of solar energy in residential buildings throughout Saudi Arabia, with a specific emphasis on Makkah. Despite the immense global demand for energy and growing environmental concerns, the adoption of solar energy in Saudi housing remains relatively low. [...] Read more.
This research paper examines the adoption of solar energy in residential buildings throughout Saudi Arabia, with a specific emphasis on Makkah. Despite the immense global demand for energy and growing environmental concerns, the adoption of solar energy in Saudi housing remains relatively low. While previous studies have examined the potential, feasibility, and policy support for solar energy, this research uniquely approaches the issue from the perspective of customers on a national scale. The study aims to identify the factors that influence customers’ intentions to use solar energy in Saudi Arabia, contributing to the development of a sustainable circular supply chain for renewable energy. To achieve this, the research integrates the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2). An online questionnaire was distributed, garnering responses from a total of 250 participants. A regression analysis was employed to analyze the data and examine the relationships between the proposed hypotheses. The study’s findings reveal that four critical factors wield significant influence over consumer behavior and their decisions regarding the adoption of solar PV technology. These factors are: Social Influence (SI), Performance Expectancy (PE), Effort Expectancy (EE), and Facilitating Conditions (FC). Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
19 pages, 3139 KiB  
Article
Promoting Energy Efficiency and Emissions Reduction in Urban Areas with Key Performance Indicators and Data Analytics
by Angel A. Juan, Majsa Ammouriova, Veronika Tsertsvadze, Celia Osorio, Noelia Fuster and Yusef Ahsini
Energies 2023, 16(20), 7195; https://doi.org/10.3390/en16207195 - 22 Oct 2023
Cited by 1 | Viewed by 1147
Abstract
With the increasing demand for sustainable urban development, smart cities have emerged as a promising solution for optimizing energy usage, reducing emissions, and enhancing the quality of life for citizens. In this context, the combined use of key performance indicators (KPIs) and data [...] Read more.
With the increasing demand for sustainable urban development, smart cities have emerged as a promising solution for optimizing energy usage, reducing emissions, and enhancing the quality of life for citizens. In this context, the combined use of key performance indicators (KPIs) and data analytics has gained significant attention as a powerful tool for promoting energy efficiency and emissions reduction in urban areas. This paper presents a comprehensive conceptual framework in which a series of KPIs are proposed to serve as essential metrics for guiding, monitoring, and assessing energy efficiency and emissions reduction levels in smart cities. Some of the included KPIs in the analysis are 'annual energy consumption per person', 'reduction in greenhouse gas emissions', 'public transport use', and 'adoption of renewable energy'. By incorporating these KPIs, city planners and policymakers can gain valuable insights into the effectiveness of sustainability initiatives. Furthermore, the paper explores how the integration of KPIs with data analytics can be used for monitoring and assessing the overall performance of the city in terms of energy efficiency, emissions reduction, and the enhancement of urban living conditions. Visualization tools, such as radar plots, and time series analysis forecasting methods allow data to be processed and patterns to be identified, enabling informed decision-making and efficient resource allocation. Real-life case studies of ongoing smart city projects are presented in the paper, which also provides a KPI comparison among different European cities, as well as models to forecast the evolution of KPIs related to energy usage and emissions reduction in different European cities. Full article
(This article belongs to the Section B: Energy and Environment)
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12 pages, 3075 KiB  
Article
Influence of PPD and Mass Scaling Parameter on the Goodness of Fit of Dry Ice Compaction Curve Obtained in Numerical Simulations Utilizing Smoothed Particle Method (SPH) for Improving the Energy Efficiency of Dry Ice Compaction Process
by Jan Górecki, Maciej Berdychowski, Elżbieta Gawrońska and Krzysztof Wałęsa
Energies 2023, 16(20), 7194; https://doi.org/10.3390/en16207194 - 22 Oct 2023
Cited by 1 | Viewed by 685
Abstract
The urgent need to reduce industrial electricity consumption due to diminishing fossil fuels and environmental concerns drives the pursuit of energy-efficient production processes. This study addresses this challenge by investigating the Smoothed Particle Method (SPH) for simulating dry ice compaction, an intricate process [...] Read more.
The urgent need to reduce industrial electricity consumption due to diminishing fossil fuels and environmental concerns drives the pursuit of energy-efficient production processes. This study addresses this challenge by investigating the Smoothed Particle Method (SPH) for simulating dry ice compaction, an intricate process poorly addressed by conventional methods. The Finite Element Method (FEM) and SPH have been dealt with by researchers, yet a gap persists regarding SPH mesh parameters’ influence on the empirical curve fit. This research systematically explores Particle Packing Density (PPD) and Mass Scaling (MS) effects on the agreement between simulation and experimental outputs. The Sum of Squared Errors (SSE) method was used for this assessment. By comparing the obtained FEM and SPH results under diverse PPD and MS settings, this study sheds light on the SPH method’s potential in optimizing the dry ice compaction process’s efficiency. The SSE based analyses showed that the goodness of fit did not vary considerably for PDD values of 4 and up. In the case of MS, a better fit was obtained for its lower values. In turn, for the ultimate compression force FC, an empirical curve fit was obtained for PDD values of 4 and up. That said, the value of MS had no significant bearing on the ultimate compression force FC. The insights gleaned from this research can largely improve the existing sustainability practices and process design in various energy-conscious industries. Full article
(This article belongs to the Special Issue Advances in Carbon Capture, Utilization and Storage (CCUS))
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11 pages, 5468 KiB  
Article
Examining Real-Road Fuel Consumption Performance of Hydrogen-Fueled Series Hybrid Vehicles
by Kaname Naganuma and Yuhei Sakane
Energies 2023, 16(20), 7193; https://doi.org/10.3390/en16207193 - 22 Oct 2023
Viewed by 967
Abstract
The use of hydrogen fuel produced from renewable energy sources is an effective way to reduce well-to-wheel CO2 emissions from automobiles. In this study, the performance of a hydrogen-powered series hybrid vehicle was compared with that of other powertrains, such as gasoline-powered [...] Read more.
The use of hydrogen fuel produced from renewable energy sources is an effective way to reduce well-to-wheel CO2 emissions from automobiles. In this study, the performance of a hydrogen-powered series hybrid vehicle was compared with that of other powertrains, such as gasoline-powered hybrid, fuel cell, and electric vehicles, in a simulation that could estimate CO2 emissions under real-world driving conditions. The average fuel consumption of the hydrogen-powered series hybrid vehicle exceeded that of the gasoline-powered series hybrid vehicle under all conditions and was better than that of the fuel cell vehicle under urban and winding conditions with frequent acceleration and deceleration. The driving range was longer than that of the battery-powered vehicle but approximately 60% of that of the gasoline-powered series hybrid. Regarding the life-cycle assessment of CO2 emissions, fuel cell and electric vehicles emitted more CO2 during the manufacturing process. Regarding fuel production, CO2 emissions from hydrogen and electric vehicles depend on the energy source. However, in the future, this problem can be solved by using carbon-free energy sources for fuel production. Therefore, hydrogen-powered series hybrid vehicles show a high potential to be environmentally friendly alternative fuel vehicles. Full article
(This article belongs to the Special Issue Electric, Hybrid and Fuel Cell Vehicles for Sustainable Mobility)
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19 pages, 3094 KiB  
Article
Using the Exact Equivalent π-Circuit Model for Representing Three-Phase Transmission Lines Directly in the Time Domain
by Juan Paulo Robles Balestero, Jaimis Sajid Leon Colqui and Sérgio Kurokawa
Energies 2023, 16(20), 7192; https://doi.org/10.3390/en16207192 - 21 Oct 2023
Viewed by 1425
Abstract
This paper presents a novel three-phase transmission line model for electromagnetic transient simulations that are executed directly within the time domain. This model relies on distributed and frequency-dependent parameters, as well as employs modal transformation for its implementation. The single-phase model of the [...] Read more.
This paper presents a novel three-phase transmission line model for electromagnetic transient simulations that are executed directly within the time domain. This model relies on distributed and frequency-dependent parameters, as well as employs modal transformation for its implementation. The single-phase model of the exact equivalent π-circuit is utilized for each propagation mode. This model combines discrete components, such as resistors, inductors, and capacitors, to accurately emulate the transmission line behavior via linear circuit elements. This model can be seamlessly integrated into various electrical circuit simulation software, thus allowing easy utilization and incorporating time-varying elements to analyze transmission lines. The JMarti model, which comes by default in the Alternative Transient Program, and the numerical Laplace transform method implemented in MATLAB were utilized to validate the proposed solution across various scenarios. An advantage of this model is its independence from the prior calculation of travel time and its exemption from convolutions, inverse Laplace transforms, and Fourier transforms, thus streamlining the simulation process. Full article
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17 pages, 2468 KiB  
Article
Refined Equivalent Modeling Method for Mixed Wind Farms Based on Small Sample Data
by Qianlong Zhu, Wenjing Xiong, Haijiao Wang and Xiaoqiang Jin
Energies 2023, 16(20), 7191; https://doi.org/10.3390/en16207191 - 21 Oct 2023
Viewed by 1083
Abstract
For equivalent modeling of mixed wind farms (WFs), existing clustering indicators cannot consider the complex coupling characteristics between different types of wind turbines (WTs). In this paper, a refined equivalent modeling approach based on artificial intelligence technology is proposed. Firstly, the electromechanical transient [...] Read more.
For equivalent modeling of mixed wind farms (WFs), existing clustering indicators cannot consider the complex coupling characteristics between different types of wind turbines (WTs). In this paper, a refined equivalent modeling approach based on artificial intelligence technology is proposed. Firstly, the electromechanical transient performance of mixed WFs is analyzed. The WT type, wind speed and direction, and voltage dip are considered the dominant factors affecting the external dynamic response of mixed WFs. Secondly, the equivalent node model is established, including the selection of independent and dependent variables. Then, the multiple artificial neural networks (ANNs) are trained one by one based on small sample data, to fit the nonlinear relationship between the dependent variables and the independent variables. Finally, the dynamic response of the power systems with a mixed WF is simulated in the MATLAB platform. A comparison of the errors in electromechanical phenomena demonstrates that the proposed model can reflect the external characteristics of the test mixed WF in different wind conditions and voltage dips. Full article
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18 pages, 8037 KiB  
Article
A Disturbed Voussoir Beam Structure Mechanical Model and Its Application in Feasibility Determination of Upward Mining
by Yujiang Zhang, Yining Wang, Bingyuan Cui, Guorui Feng, Shuai Zhang, Chunwang Zhang and Zhengjun Zhang
Energies 2023, 16(20), 7190; https://doi.org/10.3390/en16207190 - 21 Oct 2023
Cited by 8 | Viewed by 1086
Abstract
China is endowed with a large quantity of residual coal resources that require upward mining. The stability of interburden strata structures and accurate determination are crucial for safe mining. Therefore, we established a mechanical model of disturbed voussoir beam structures of interburden strata [...] Read more.
China is endowed with a large quantity of residual coal resources that require upward mining. The stability of interburden strata structures and accurate determination are crucial for safe mining. Therefore, we established a mechanical model of disturbed voussoir beam structures of interburden strata in upward mining. The model was solved, and stability analysis and instability mechanism analysis were conducted. Based on this model, a new method for determining the feasibility of upward mining was proposed and applied to the upward mining of coal seam No. 7 in Baijiazhuang Coal Mine. A physical simulation experiment and numerical simulation were conducted to validate the method. Through research, it was found that the model had two instability mechanisms: rotation instability and sliding instability. When the disturbance load crossed the critical block of the structures, the model was most likely to experience sliding instability. When the disturbance load acted entirely on the critical block, rotation instability was more likely to occur. The result of the determination, performed using the new method, showed that there was no rotation instability or sliding instability in the interburden strata structures of coal seam No. 7, indicating that the coal seam could be mined upward. This result was consistent with the determinations using the statistical method, “three-zone” method, and balanced surrounding rock method. Physical and numerical simulations revealed that the upward mining of coal seam No. 7 caused the subsidence, rotation, and separation compaction of the interburden strata structures but that the structures remained stable. The results indicate that the proposed model and method have accuracy and applicability, being able to guide the practical feasibility determination of upward mining. Full article
(This article belongs to the Special Issue Optimization of Coal Mining and Fossil Energy)
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25 pages, 8464 KiB  
Article
Hybrid Framework for Enhanced Dynamic Optimization of Intelligent Completion Design in Multilateral Wells with Multiple Types of Flow Control Devices
by Jamal Ahdeema, Morteza Haghighat Sefat and Khafiz Muradov
Energies 2023, 16(20), 7189; https://doi.org/10.3390/en16207189 - 21 Oct 2023
Viewed by 1094
Abstract
Multilateral wells (MLWs) equipped with multiple flow control devices (FCDs) are becoming increasingly favored within the oil sector due to their ability to enhance well-to-reservoir exposure and effectively handle unwanted fluid breakthrough. However, combining various types of FCDs in multilateral wells poses a [...] Read more.
Multilateral wells (MLWs) equipped with multiple flow control devices (FCDs) are becoming increasingly favored within the oil sector due to their ability to enhance well-to-reservoir exposure and effectively handle unwanted fluid breakthrough. However, combining various types of FCDs in multilateral wells poses a complex optimization problem with a large number of highly correlated control variables and a computationally expensive objective function. Consequently, standard optimization algorithms, including metaheuristic and gradient-based approaches, may struggle to identify an optimal solution within a limited computational resource. This paper introduces a novel hybrid optimization (HO) framework combining particle swarm optimization (PSO) and Simultaneous Perturbation Stochastic Approximation (SPSA). It is developed to efficiently optimize the completion design of MLWs with various FCDs while overcoming the individual limitations of each optimization algorithm. The proposed framework is further enhanced by employing surrogate modelling and global sensitivity analysis to identify critical parameters (i.e., highly sensitive) that greatly affect the objective function. This allows for a focused optimization effort on these key parameters, ultimately enhancing global optimization performance. The performance of the novel optimization framework is evaluated using the Olympus benchmark reservoir model. The model is developed by three intelligent dual-lateral wells, with inflow control devices (ICDs) installed within the laterals and interval control valves (ICVs) positioned at the lateral junctions. The results show that the proposed hybrid optimization framework outperforms all industry-standard optimization techniques, achieving a Net Present Value of approximately USD 1.94 billion within a limited simulation budget of 2500 simulation runs. This represents a substantial 26% NPV improvement compared to the open-hole case (USD 1.54 billion NPV). This improvement is attributed to more efficient water breakthrough management, leading to a notable 24% reduction in cumulative water production and, consequently, a 26% increase in cumulative oil production. Full article
(This article belongs to the Special Issue Recent Advances in Oil and Gas Recovery and Production Optimisation)
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