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Energies, Volume 14, Issue 14 (July-2 2021) – 320 articles

Cover Story (view full-size image): The new economic paradigm is based on optimising a triple-P relation among profits–planet–people, supported by several international commitments (i.e., Global Compact & Workplace Wellbeing—UN, Wellbeing Measures—OECD, European Green Deal—EU, Wellbeing Economy Alliance—WEF, etc.). This relation requests the technological advances or technovation to increase global wealth, protect nature and improve the world’s living standards, which means wellbeing for humankind. The former paradigm, the Welfare State Economic, was materialistic and focused on measuring GDP. However, the emergent paradigm, Wellbeing Economics (WBE), which includes several steps of the digital economy, is more immaterial and focused on the happiness pursuit (from 2012 onwards, it has been measured each year by the UN). View this paper
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Article
Investigation of Insulation Characteristics of GFRP Crossarm Subjected to Lightning Transient
Energies 2021, 14(14), 4386; https://doi.org/10.3390/en14144386 - 20 Jul 2021
Cited by 1 | Viewed by 674
Abstract
The advancement of material technology has contributed to the variation of high-performance composites with good electrical insulation and mechanical properties. Their usage in electrical applications has grown since then. In Malaysia, the composite made of Glass Fiber Reinforced Polymer (GFRP) has been adopted [...] Read more.
The advancement of material technology has contributed to the variation of high-performance composites with good electrical insulation and mechanical properties. Their usage in electrical applications has grown since then. In Malaysia, the composite made of Glass Fiber Reinforced Polymer (GFRP) has been adopted for crossarm manufacturing and has successfully served 275 kV lines for a few decades. However, the combination of extreme conditions such as lightning transient and tropical climate can impose threats to the material. These issues have become major topics of discussion among the utilities in the Southeast Asian (SEA) region, and also in previous research. In Malaysia, more than 50% of total interruptions were caused by lightning. Limited studies can be found on the composite crossarm, especially on the square tube GFRP filled crossarm used in Malaysia. Therefore, this paper proposes to study the behavior of the particular GFRP crossarm, by means of its insulation characteristics. Experimental and simulation approaches are used. Throughout the study, the GFRP specimen is known to have an average breakdown strength at 7.2 kV/mm. In addition, the CFO voltages of the crossarm at different lengths are presented, whereby the behavior under dry and wet conditions is comparably discussed. At the same time, the polarity effect on the CFO voltages is highlighted. The maximum E-fields at the immediate moment before breakdown are analyzed by adopting the finite element method (FEM). Non-uniform distribution of E-fields is witnessed at different parts of the crossarm structure. Simultaneously, the maximum field localized on the crossarm immediately before the breakdown is also presented. Full article
(This article belongs to the Section A: Electrical Engineering)
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Article
Can Nuclear Batteries Be Economically Competitive in Large Markets?
Energies 2021, 14(14), 4385; https://doi.org/10.3390/en14144385 - 20 Jul 2021
Cited by 1 | Viewed by 1435
Abstract
We introduce the concept of the nuclear battery, a standardized, factory-fabricated, road transportable, plug-and-play micro-reactor. Nuclear batteries have the potential to provide on-demand, carbon-free, economic, resilient, and safe energy for distributed heat and electricity applications in every sector of the economy. The cost [...] Read more.
We introduce the concept of the nuclear battery, a standardized, factory-fabricated, road transportable, plug-and-play micro-reactor. Nuclear batteries have the potential to provide on-demand, carbon-free, economic, resilient, and safe energy for distributed heat and electricity applications in every sector of the economy. The cost targets for nuclear batteries in these markets are 20–50 USD/MWht (6–15 USD/MMBTU) and 70–115 USD/MWhe for heat and electricity, respectively. We present a parametric study of the nuclear battery’s levelized cost of heat and electricity, suggesting that those cost targets are within reach. The cost of heat and electricity from nuclear batteries is expected to depend strongly on core power rating, fuel enrichment, fuel burnup, size of the onsite staff, fabrication costs and financing. Notional examples of cheap and expensive nuclear battery designs are provided. Full article
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Article
Comparative TCO Analysis of Battery Electric and Hydrogen Fuel Cell Buses for Public Transport System in Small to Midsize Cities
Energies 2021, 14(14), 4384; https://doi.org/10.3390/en14144384 - 20 Jul 2021
Cited by 3 | Viewed by 1805
Abstract
This paper shows the results of an in-depth techno-economic analysis of the public transport sector in a small to midsize city and its surrounding area. Public battery-electric and hydrogen fuel cell buses are comparatively evaluated by means of a total cost of ownership [...] Read more.
This paper shows the results of an in-depth techno-economic analysis of the public transport sector in a small to midsize city and its surrounding area. Public battery-electric and hydrogen fuel cell buses are comparatively evaluated by means of a total cost of ownership (TCO) model building on historical data and a projection of market prices. Additionally, a structural analysis of the public transport system of a specific city is performed, assessing best fitting bus lines for the use of electric or hydrogen busses, which is supported by a brief acceptance evaluation of the local citizens. The TCO results for electric buses show a strong cost decrease until the year 2030, reaching 23.5% lower TCOs compared to the conventional diesel bus. The optimal electric bus charging system will be the opportunity (pantograph) charging infrastructure. However, the opportunity charging method is applicable under the assumption that several buses share the same station and there is a “hotspot” where as many as possible bus lines converge. In the case of electric buses for the year 2020, the parameter which influenced the most on the TCO was the battery cost, opposite to the year 2030 in where the bus body cost and fuel cost parameters are the ones that dominate the TCO, due to the learning rate of the batteries. For H2 buses, finding a hotspot is not crucial because they have a similar range to the diesel ones as well as a similar refueling time. H2 buses until 2030 still have 15.4% higher TCO than the diesel bus system. Considering the benefits of a hypothetical scaling-up effect of hydrogen infrastructures in the region, the hydrogen cost could drop to 5 €/kg. In this case, the overall TCO of the hydrogen solution would drop to a slightly lower TCO than the diesel solution in 2030. Therefore, hydrogen buses can be competitive in small to midsize cities, even with limited routes. For hydrogen buses, the bus body and fuel cost make up a large part of the TCO. Reducing the fuel cost will be an important aspect to reduce the total TCO of the hydrogen bus. Full article
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Article
Application of an Improved Mayr-Type Arc Model in Pyro-Breakers Utilized in Superconducting Fusion Facilities
Energies 2021, 14(14), 4383; https://doi.org/10.3390/en14144383 - 20 Jul 2021
Cited by 4 | Viewed by 698
Abstract
Pyro-breaker, a fast-responding, highly reliable and explosive-driven circuit breaker, is utilized in several Quench Protection Systems (QPS). The commutation process and its parameters are the main technical considerations in the process of designing a new pyro-breaker. The commutation parameters, such as the commutation [...] Read more.
Pyro-breaker, a fast-responding, highly reliable and explosive-driven circuit breaker, is utilized in several Quench Protection Systems (QPS). The commutation process and its parameters are the main technical considerations in the process of designing a new pyro-breaker. The commutation parameters, such as the commutation time and the current change rate, are not only determined by the electrical parameters of the commutation circuit but also the arc behavior during the operation. The arc behavior is greatly affected by the structure and the driving mechanism of the Commutation Section (CS) in the pyro-breaker. The arc model was developed decades ago and the black-box arc model is considered a valid method to study arc behavior. In this paper, the Schavemaker black-box arc model, an improved Mayr-type arc model, is applied to study the commutation process of a newly designed pyro-breaker. Unlike normal circuit breakers, the arc discussed in this paper is discharged in deionized water. A parameter selection method is proposed. The practicability of the method is verified by numerical calculation in Power Systems Computer Aided Design (PSCAD) and experimentally. Full article
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Article
Theoretical and Numerical Study on Electrical Resistivity Measurement of Cylindrical Rock Core Samples Using Perimeter Electrodes
Energies 2021, 14(14), 4382; https://doi.org/10.3390/en14144382 - 20 Jul 2021
Viewed by 592
Abstract
The estimation of hydraulic and mechanical properties of bedrock is important for the evaluation of energy-related structures, including high-level nuclear waste repositories, hydraulic fracturing wells, and gas-hydrate production wells. The hydraulic conductivity and stress–strain curves of rocks are conventionally measured through laboratory tests [...] Read more.
The estimation of hydraulic and mechanical properties of bedrock is important for the evaluation of energy-related structures, including high-level nuclear waste repositories, hydraulic fracturing wells, and gas-hydrate production wells. The hydraulic conductivity and stress–strain curves of rocks are conventionally measured through laboratory tests on cylindrical samples. Both ASTM standards for hydraulic conductivity and compressive strength involve the use of the planar bases of a cylindrical sample. Hence, an alternative test method is required for the simultaneous measurement of hydraulic conductivity and stress–strain curves. This study proposes a novel electrical resistivity estimation method using two perimeter electrodes for the estimation of hydraulic properties. The theoretical background for the perimeter electrode setup is derived and the COMSOL MultiPhysics® finite element numerical simulation tool is employed to verify the derived theoretical equation. The accuracy of the numerical simulation tool is first validated by simulating the ASTM standard testing method for electrical resistivity. The electrical resistance values derived from the theoretical equation and numerical simulation are compared for different electrical resistivity and electrode radius. The assumed equidistant, circular equipotential surface results in a theoretical lower bound for the measured electrical resistance in the cylindrical specimen. The introduction of a phenomenological distortion factor to correct for the theoretical equipotential surface results in a good fit with the numerical simulation results. The effects of electrode length and equivalent strap electrodes were investigated to assess the applicability of the suggested method for laboratory testing. Consequently, this study presents an effective alternative theoretical assessment method for the lower bound electrical resistivity of cylindrical rock core samples under confining conditions when the installation of base electrodes is infeasible. Full article
(This article belongs to the Section G: Geo-Energy)
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Article
Oxygen Transfer Effects in a Two-Phase System of an Aqueous Phase and Liquid Perfluorochemical Subjected to Continuous Wave-Assisted Agitation in Disposable Bioreactor
Energies 2021, 14(14), 4381; https://doi.org/10.3390/en14144381 - 20 Jul 2021
Viewed by 575
Abstract
Systems of two immiscible liquid phases—aqueous phase (i.e., distilled water (dH2O) or phosphate-buffered saline (PBS)) and liquid perfluorochemical (i.e., perfluorodecalin (PFD))—were subjected to wave-assisted agitation, i.e., oscillatory rocked, in a disposable bag-like container in a ReadyToProcess WAVETM25 bioreactor, to [...] Read more.
Systems of two immiscible liquid phases—aqueous phase (i.e., distilled water (dH2O) or phosphate-buffered saline (PBS)) and liquid perfluorochemical (i.e., perfluorodecalin (PFD))—were subjected to wave-assisted agitation, i.e., oscillatory rocked, in a disposable bag-like container in a ReadyToProcess WAVETM25 bioreactor, to recognize oxygen transfer effects and effectivity of the surface aeration. According to the DoE methodology, values of the volumetric liquid-side mass transfer (kLa) coefficient for dH2O, PBS, dH2O-PFD, and PBS-PFD systems were determined for the whole range of operating parameters of the WAVE 25 bioreactor. A significantly higher maximal value of kLa was found for waving dH2O than for dH2O-PFD (i.e., 0.00460 s−1 vs. 0.00331 s−1, respectively) compared to more equal maximal values of kLa reached for PBS and PBS-PFD (0.00355 s−1 vs. 0.00341 s−1, respectively). The interface development factor (f) depended on the interfacial area a, and the enhancement factor (EPFD), depending on kLa, was introduced to quantitatively identify the mass transfer effects in the systems of waving two immiscible liquids. The phase of PFD was identified as the reservoir of oxygen. Dimensional correlations were proposed for the prediction of the kLa coefficient, in addition to the f and EPFD factors. The presented correlations, and the set of kLa values, can be directly applied to predict oxygen transfer effects reached under continuous oscillatory rocked systems containing aqueous phase and liquid perfluorochemical. Full article
(This article belongs to the Special Issue Multiphase Flows)
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Article
Identifiability Analysis of Degradation Model Parameters from Transient CO2 Release in Low-Temperature PEM Fuel Cell under Various AST Protocols
Energies 2021, 14(14), 4380; https://doi.org/10.3390/en14144380 - 20 Jul 2021
Cited by 4 | Viewed by 828
Abstract
The detrimental effects of the catalyst degradation on the overall envisaged lifetime of low-temperature proton-exchange membrane fuel cells (LT-PEMFCs) represent a significant challenge towards further lowering platinum loadings and simultaneously achieving a long cycle life. The elaborated physically based modeling of the degradation [...] Read more.
The detrimental effects of the catalyst degradation on the overall envisaged lifetime of low-temperature proton-exchange membrane fuel cells (LT-PEMFCs) represent a significant challenge towards further lowering platinum loadings and simultaneously achieving a long cycle life. The elaborated physically based modeling of the degradation processes is thus an invaluable step in elucidating causal interaction between fuel cell design, its operating conditions, and degradation phenomena. However, many parameters need to be determined based on experimental data to ensure plausible simulation results of the catalyst degradation models, which proves to be challenging with the in situ measurements. To fill this knowledge gap, this paper demonstrates the application of a mechanistically based PEMFC modeling framework, comprising real-time capable fuel cell performance, and platinum and carbon support degradation models, to model transient CO2 release rates in the LT-PEMFCs with the consistent calibration of reaction rate parameters under multiple different accelerated stress tests at once. The results confirm the credibility of the physical and chemical modeling basis of the proposed modeling framework, as well as its prediction and extrapolation capabilities. This is confirmed by an increase of only 29% of root mean square deviations values when using a model calibrated on all three data sets at once in comparison to a model calibrated on only one data set. Furthermore, the unique identifiability and interconnection of individual model calibration parameters are determined via Fisher information matrix analysis. This analysis enables optimal reduction of the set of calibration parameters, which results in the speed up of both the calibration process and the general simulation time while retaining the full extrapolation capabilities of the framework. Full article
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Article
Multidisciplinary Approaches for Assessing a High Temperature Borehole Thermal Energy Storage Facility at Linköping, Sweden
Energies 2021, 14(14), 4379; https://doi.org/10.3390/en14144379 - 20 Jul 2021
Viewed by 970
Abstract
Assessing the optimal placement and design of a large-scale high temperature energy storage system in crystalline bedrock is a challenging task. This study applies and evaluates various methods and strategies for pre-site investigation for a potential high temperature borehole thermal energy storage (HT-BTES) [...] Read more.
Assessing the optimal placement and design of a large-scale high temperature energy storage system in crystalline bedrock is a challenging task. This study applies and evaluates various methods and strategies for pre-site investigation for a potential high temperature borehole thermal energy storage (HT-BTES) system at Linköping in Sweden. The storage is required to shift approximately 70 GWh of excess heat generated from a waste incineration plant during the summer to the winter season. Ideally, the site for the HT-BTES system should be able to accommodate up to 1400 wells to 300 m depth. The presence of major fracture zones, high groundwater flow, anisotropic thermal properties, and thick Quaternary overburden are all factors that play an important role in the performance of an HT-BTES system. Inadequate input data to the modeling and design increases the risk of unsatisfactory performance, unwanted thermal impact on the surroundings, and suboptimal placement of the HT-BTES system, especially in a complex crystalline bedrock setting. Hence, it is crucial that the subsurface geological conditions and associated thermal properties are suitably characterized as part of pre-investigation work. In this study, we utilize a range of methods for pre-site investigation in the greater Distorp area, in the vicinity of Linköping. Ground geophysical methods, including magnetic and Very Low-Frequency (VLF) measurements, are collected across the study area together with outcrop observations and lab analysis on rock samples. Borehole investigations are conducted, including Thermal Response Test (TRT) and Distributed Thermal Response Test (DTRT) measurements, as well as geophysical wireline logging. Drone-based photogrammetry is also applied to characterize the fracture distribution and orientation in outcrops. In the case of the Distorp site, these methods have proven to give useful information to optimize the placement of the HT-BTES system and to inform design and modeling work. Furthermore, many of the methods applied in the study have proven to require only a fraction of the resources required to drill a single well, and hence, can be considered relatively efficient. Full article
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Article
Robust Multi-Step Predictor for Electricity Markets with Real-Time Pricing
Energies 2021, 14(14), 4378; https://doi.org/10.3390/en14144378 - 20 Jul 2021
Cited by 3 | Viewed by 723
Abstract
Real-time electricity pricing mechanisms are emerging as a key component of the smart grid. However, prior work has not fully addressed the challenges of multi-step prediction (Predicting multiple time steps into the future) that is accurate, robust and real-time. This paper proposes a [...] Read more.
Real-time electricity pricing mechanisms are emerging as a key component of the smart grid. However, prior work has not fully addressed the challenges of multi-step prediction (Predicting multiple time steps into the future) that is accurate, robust and real-time. This paper proposes a novel Artificial Intelligence-based approach, Robust Intelligent Price Prediction in Real-time (RIPPR), that overcomes these challenges. RIPPR utilizes Variational Mode Decomposition (VMD) to transform the spot price data stream into sub-series that are optimized for robustness using the particle swarm optimization (PSO) algorithm. These sub-series are inputted to a Random Vector Functional Link neural network algorithm for real-time multi-step prediction. A mirror extension removal of VMD, including continuous and discrete spaces in the PSO, is a further novel contribution that improves the effectiveness of RIPPR. The superiority of the proposed RIPPR is demonstrated using three empirical studies of multi-step price prediction of the Australian electricity market. Full article
(This article belongs to the Special Issue Energy Management of Prosumer Communities)
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Article
Enhancement of Induction Motor Dynamics Using a Novel Sensorless Predictive Control Algorithm
Energies 2021, 14(14), 4377; https://doi.org/10.3390/en14144377 - 20 Jul 2021
Viewed by 1094
Abstract
The paper introduces a novel predictive voltage control (PVC) procedure for a sensorless induction motor (IM) drive. In the constructed PVC scheme, the direct and quadrature (d-q) components of applied voltages are primarily managed instead of controlling the torque [...] Read more.
The paper introduces a novel predictive voltage control (PVC) procedure for a sensorless induction motor (IM) drive. In the constructed PVC scheme, the direct and quadrature (d-q) components of applied voltages are primarily managed instead of controlling the torque and flux as in the classic predictive torque control (PTC) technique. The theoretical basis of the designed PVC is presented and explained in detail, starting from the used cost-function with its relevant components. A comprehensive performance comparison is established between the two controllers, from which the superiorities of the designed PVC over the PTC approach can be easily investigated through the reduced ripples, reduced computation time, and faster dynamics. To sustain the system’s reliability, a combined Luenberger–sliding mode observer (L-SMO) is designed and verified for different operating speeds for the two controllers. The Luenberger component is concerned with estimating the stator current, rotor flux, and rotor speed. Meanwhile, the sliding mode term is used to ensure the system’s robustness against any disturbance. The verification of PVC’s validity is outlined through performing a performance analysis using the Matlab/Simulink software. The results illustrate that the IM dynamic is significantly improved when considering the constructed PVC compared with the IM dynamics under the PTC. In addition, the designed L-SMO observer has effectively proved its ability to achieve definite parameters and variable estimation. Full article
(This article belongs to the Special Issue Vehicle Dynamics and Control 2021)
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Article
Using ANN to Predict the Impact of Communication Factors on the Rework Cost in Construction Projects
Energies 2021, 14(14), 4376; https://doi.org/10.3390/en14144376 - 20 Jul 2021
Cited by 4 | Viewed by 669
Abstract
The construction sector has a large impact on the environment and available resources. Natural resources and energy consumption occurs not only during the operation of the facility, but also during its construction. In addition, this situation often occurs when work already completed requires [...] Read more.
The construction sector has a large impact on the environment and available resources. Natural resources and energy consumption occurs not only during the operation of the facility, but also during its construction. In addition, this situation often occurs when work already completed requires rework. In such cases, not only the reuse of resources and energy occurs but also generation of waste. Many studies support the relationship between communication and project efficiency, which is expressed in the cost of rework. At present there is no available tool to quantify the evaluation of this relationship. This study aims to fill this knowledge gap. The article purpose was to create ANNs (artificial neural networks) for assessing and predicting the impact of communication factors on rework costs in construction projects. During the data collection phase, 12 factors that influence communication were identified and assessed. The level of rework costs in 18 construction projects was also calculated. We used ANN, which is a two-layer feedforward network with a sigmoid transfer function in the hidden layer and a linear transfer function in the output layer. The network input layer consists of 12 neurons while the hidden layer consists of 10 neurons and one output neuron. The optimal results of the mean square error and correlation were shown by the Levenberg–Marquardt algorithm. The proposed model can be used by project management as the integration decision support tool aimed at decreasing the number of reworks and reducing energy and resource consumption in construction projects. Full article
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Article
An Innovative Strategy Allowing a Holistic System Change towards Circular Economy within Supply-Chains
Energies 2021, 14(14), 4375; https://doi.org/10.3390/en14144375 - 20 Jul 2021
Cited by 2 | Viewed by 1097
Abstract
The concept of the circular economy (CE) is receiving encouraging attention among scholars and practitioners, as a convenient solution to move away from the linear economy concept without neglecting the goals of sustainable development. The main goals of the CE are the closing [...] Read more.
The concept of the circular economy (CE) is receiving encouraging attention among scholars and practitioners, as a convenient solution to move away from the linear economy concept without neglecting the goals of sustainable development. The main goals of the CE are the closing of resource loops and the keeping of resources in the system for as long as possible at the highest utility level. However, as a result of the lack of internationally accepted definitions of the CE and several unsolved barriers, an excessive and inconsistent number of different CE applications exist. Most fields are mainly focusing on making a linear system circular instead of applying the CE principles in a holistic way. This paper presents a strategy to close the mentioned inconsistency gap, by contrasting currently discussed CE barriers and goals and thereof deriving two areas with a need for action (1. identifying the needed collection, sorting, and recovery infrastructure, and 2. developing circular product design guidelines). The strategy itself consists of connecting these two areas through an improved information exchange between the end-of-life (EOL) and beginning-of-life (BOL) of products. The result is CE design guidelines which are in accordance with the available or needed collection, sorting, and recovery infrastructure. The proposed strategy presents an innovative solution to apply CE principles in a holistic manner, based on EOL-driven product design. Full article
(This article belongs to the Special Issue Technology and Strategy for Sustainable Energy Systems)
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Article
Applicability Study of a Sunken Vessel as an Artificial Reef in a High Wave Energy Zone
Energies 2021, 14(14), 4374; https://doi.org/10.3390/en14144374 - 20 Jul 2021
Cited by 1 | Viewed by 534
Abstract
The purpose of this study is to analyze the applicability of a sunken vessel as an artificial reef in a high wave energy area in a shallow water zone. Artificial reefs in general shapes are unlikely to be installed and maintained stably in [...] Read more.
The purpose of this study is to analyze the applicability of a sunken vessel as an artificial reef in a high wave energy area in a shallow water zone. Artificial reefs in general shapes are unlikely to be installed and maintained stably in high-energy wave zones. To solve this problem, a method for using a large 2000-ton class sunken vessel as an artificial reef was proposed in this study. Accordingly, we analyzed the applicability, including stability, of the sunken vessel as an artificial reef on the east coast of South Korea, where high-energy waves and swells are observed frequently. In the analysis process, various methods, such as numerical simulation and a hydraulic model experiment, were utilized. 2D and 3D numerical simulations were conducted to simulate the wave energy in the area where the sunken vessel was installed as an artificial reef to identify wave force applied to the vessel. Moreover, a hydraulic model experiment using a sunken vessel model as an artificial reef was performed to compare the stability and motion properties of the vessel model. The experimental results indicated that the stability and motion properties of the sunken vessel differed depending on the water depth. Additionally, the water depth that ensured the stability of the sunken vessel was identified. Full article
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Article
Analysis and Adequacy Methodology for Voltage Violations in Distribution Power Grid
Energies 2021, 14(14), 4373; https://doi.org/10.3390/en14144373 - 20 Jul 2021
Cited by 1 | Viewed by 622
Abstract
This paper proposes a computational process development capable of filling the electric power sector shortage regarding voltage non-conformities identification in electric distribution power grid accounting for loads dynamic behavior at medium and low voltages. Actual distribution power grid data are used, with georeferencing [...] Read more.
This paper proposes a computational process development capable of filling the electric power sector shortage regarding voltage non-conformities identification in electric distribution power grid accounting for loads dynamic behavior at medium and low voltages. Actual distribution power grid data are used, with georeferencing to signal voltage transgressions locations, generate a report with voltage transgression indices and financial reimbursement values provided by legislation. The methodology compares regulatory requirements and makes available in software some possible actions in an attempt to adjust voltage levels, avoiding inconvenience and penalties for energy utilities providers. The method involves a data extractor construction for electricity provider company’s databases, computer simulations and comparison of obtained results with values established in electricity quality control standards. Thus, finding non-conformity locations and determining network adjustments to correct tension indexes in permanent regulation. The proposal features a reduction in electricity utilities operating costs, increasing efficiency in operation and energy quality available to consumers. Full article
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Article
A Family of Transformerless Quadratic Boost High Gain DC-DC Converters
Energies 2021, 14(14), 4372; https://doi.org/10.3390/en14144372 - 20 Jul 2021
Cited by 9 | Viewed by 709
Abstract
This paper presents three new and improved non-isolated topologies of quadratic boost converters (QBC). Reduced voltage stress across switching devices and high voltage gain with single switch operation are the main advantages of the proposed topologies. These topologies utilize voltage multiplier cells (VMC) [...] Read more.
This paper presents three new and improved non-isolated topologies of quadratic boost converters (QBC). Reduced voltage stress across switching devices and high voltage gain with single switch operation are the main advantages of the proposed topologies. These topologies utilize voltage multiplier cells (VMC) made of switched capacitors and switched inductors to increase the converter’s voltage gain. The analysis in continuous conduction mode is discussed in detail. The proposed converter’s voltage gain is higher than the conventional quadratic boost converter, and other recently introduced boost converters. The proposed topologies utilize only a single switch and have continuous input current and low voltage stress across switch, capacitors, and diodes, which leads to the selection of low voltage rating components. The converter’s non-ideal voltage gain is also determined by considering the parasitic capacitance and ON state resistances of switch and diodes. The efficiency analysis incorporating switching and conduction losses of the switching and passive elements is done using PLECS software (Plexim, Zurich, Switzerland). The hardware prototype of the proposed converters is developed and tested for verification. Full article
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Article
Modelling of Solar Irradiance Incident on Building Envelopes in Polish Climatic Conditions: The Impact on Energy Performance Indicators of Residential Buildings
Energies 2021, 14(14), 4371; https://doi.org/10.3390/en14144371 - 20 Jul 2021
Cited by 3 | Viewed by 946
Abstract
In this study, we use the data of Polish typical meteorological years and 15 transposition models to obtain global solar irradiance on sloped surfaces to calculate solar irradiance on external building partitions, solar gains, heating demands, and primary nonrenewable energy for heating and [...] Read more.
In this study, we use the data of Polish typical meteorological years and 15 transposition models to obtain global solar irradiance on sloped surfaces to calculate solar irradiance on external building partitions, solar gains, heating demands, and primary nonrenewable energy for heating and domestic hot water (EPH+W) of two typical Polish residential buildings, each for two variants in five locations. In relation to TMYs, annual solar gains were lower by −31% and −36% on average in a single and multifamily building, respectively, and the annual heating demands increased by 9% and 16%, respectively. Consequently, averaged EPH+W in relation to TMYs rose by 1.4 kWh/m2 and 4.5 kWh/m2, respectively. The mean differences between TMYs and the new method from the recently published EN-ISO 52010 standard for test Building 1 were 1.6 and 1.2 kWh/m2, for Variants 1 and 2, respectively. Similarly, for test Building 2, the mean differences were 5.1 kWh/m2 and 3.9 kWh/m2, respectively. This means that the simulation model that is chosen has a visible impact on a building’s energy performance indicators and its rating without any changes in the physical structure and use of the building. Full article
(This article belongs to the Special Issue Thermal Energy Management in Buildings)
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Article
Hydrodynamic Efficiency Analysis of a Flexible Hydrofoil Oscillating in a Moderate Reynolds Number Fluid Flow
Energies 2021, 14(14), 4370; https://doi.org/10.3390/en14144370 - 20 Jul 2021
Viewed by 534
Abstract
The paper focuses on the study of a semi-activated system, based on a combination of two movements of forced pitching and free-heaving motion. Therefore, quantifying with accuracy the hydrodynamic forces applied on the hydrofoil seems to be crucial. This is investigated throughout a [...] Read more.
The paper focuses on the study of a semi-activated system, based on a combination of two movements of forced pitching and free-heaving motion. Therefore, quantifying with accuracy the hydrodynamic forces applied on the hydrofoil seems to be crucial. This is investigated throughout a numerical analysis of the hydrofoil dynamics. The deformable structure is oscillating in a low-Reynolds number flow. In this study, a hydrofoil animated by a combined forced pitching and heaving movements is considered. Various materials of the hydrofoil structure are studied, from the rigid material to a more flexible one. A partitioned implicit coupling approach is applied in order to consider the Fluid-Structure Interaction (FSI) effects, while the Navier–Stokes equations are solved using the Arbitrary Lagrangian–Eulerian (ALE) method. Both the viscous incompressible Navier–Stokes equations and the elasticity equation are solved using finite volume method. The study is based on the analysis of the hydrodynamic loads acting on the structure. Therefore, the induced dynamics and the power coefficient of the structure are investigated. It is shown that the flexibility of the hydrofoil has an effect on its hydrodynamic behavior. Indeed it increases the load fluctuations and the horizontal mean force component. Furthermore, the unsteady vortices around the hydrofoil are highly impacted by its deformations. Finally, the structure deformations mostly improve the device energy efficiency. Full article
(This article belongs to the Special Issue Tidal Turbines)
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Article
Experimental Studies of the Effect of Design and Technological Solutions on the Intensification of an Underground Coal Gasification Process
Energies 2021, 14(14), 4369; https://doi.org/10.3390/en14144369 - 20 Jul 2021
Cited by 9 | Viewed by 692
Abstract
This paper represents the results of experimental studies of physical modeling of the underground coal gasification process in terms of implementation of design and technological solutions aimed at intensification of a gasification process of thin coal seams. A series of experimental studies were [...] Read more.
This paper represents the results of experimental studies of physical modeling of the underground coal gasification process in terms of implementation of design and technological solutions aimed at intensification of a gasification process of thin coal seams. A series of experimental studies were performed in terms of a stand unit with the provided criteria of similarity to field conditions as well as kinetics of thermochemical processes occurring within a gas generator. Hard coal (high volatile bituminous coal) was selected as the raw material to be gasified, as that coal grade prevails in Ukrainian energy balance since it is represented by rather great reserves. Five blow types were tested during the research (air, air–steam, oxygen–steam, oxygen–enriched, and carbon dioxide and oxygen). As a result, the effect of tightness of a gas generator on the quantitative and qualitative parameters of coal gasification while varying the blow by reagents and changing the pressure in a reaction channel has been identified. Special attention was paid to the design solutions involving blow supply immediately into the combustion face of a gas generator. The experimental results demonstrate maximum efficiency of the applied gas generator design involving flexible pipelines and activator in the reaction channel and a blow direction onto the reaction channel face combined with blow stream reversing which will make it possible to improve caloricity of the generator gas up to 18% (i.e., from 8.4 to 12.8 MJ/m3 depending upon a blow type). Consideration of the obtained results of physical modelling can be used with sufficient accuracy to establish modern enterprises based on the underground coal seam gasification; this will help develop more efficiently the substandard coal reserves to generate heat energy as well as power-producing and chemical raw material. The research conclusions can provide technical reference for developing a new generation of underground coal gasification technology. Full article
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Article
Capillary Desaturation Tendency of Hybrid Engineered Water-Based Chemical Enhanced Oil Recovery Methods
Energies 2021, 14(14), 4368; https://doi.org/10.3390/en14144368 - 20 Jul 2021
Cited by 4 | Viewed by 582
Abstract
Several studies have shown the synergetic benefits of combining various chemical enhanced oil recovery (CEOR) methods with engineered waterflooding (EWF) in both sandstones and carbonate formations. This paper compares the capillary desaturation tendency of various hybrid combinations of engineered water (EW) and CEOR [...] Read more.
Several studies have shown the synergetic benefits of combining various chemical enhanced oil recovery (CEOR) methods with engineered waterflooding (EWF) in both sandstones and carbonate formations. This paper compares the capillary desaturation tendency of various hybrid combinations of engineered water (EW) and CEOR methods with their conventional counterparts. Several coreflood experiments were conducted, including EW-surfactant flooding (EWSF), EW-polymer flooding (EWPF), EW-alkali-surfactant flooding (EWASF), EW-surfactant-polymer flooding (EWSPF), and EW-alkali-surfactant-polymer flooding (EWASP). Capillary numbers (Nc) and corresponding residual oil saturation (Sor) for each scenario are compared with capillary desaturation curves (CDC) of conventional CEOR methods from the literature. The results indicate that hybrid EW–CEOR methods have higher capillary desaturation tendency compared to conventional methods. The capillary numbers obtained by standalone polymer flooding (PF) are usually in the range from 10−6 to 10−5, which are not sufficient to cause a significant reduction in Sor. However, the hybrid EW-polymer flooding approach considerably reduced the Sor for the same Nc values, proving the effectiveness of the investigated method. The hybrid EWASP flooding caused the highest reduction in Sor (23%) against Nc values of 8 × 10−2, while conventional ASP flooding reduced the Sor for relatively higher Nc values (3 × 10−3 to 8 × 10−1). Overall, the hybrid methods are 30–70% more efficient in terms of recovering residual oil, compared to standalone EWF and CEOR methods. This can be attributed to the combination of different mechanisms such as wettability modification by EW, ultralow interfacial tension by alkali and surfactant, reduced surfactant adsorption by alkali addition, and favorable mobility ratio by polymer. Based on the promising results, these hybrid techniques can be effectively implemented to carbonate formations with harsh reservoir conditions such as high salinity and high temperature. Full article
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Article
A Novel Method for Structural Lightweight Design with Topology Optimization
Energies 2021, 14(14), 4367; https://doi.org/10.3390/en14144367 - 20 Jul 2021
Viewed by 680
Abstract
Topological optimization is an innovative method to realize the lightweight design. This paper proposes a hybrid topology optimization method that combines the SIMP (solid isotropic material with penalization) method and genetic algorithm (GA), called the SIMP-GA method. In the method, SIMP is used [...] Read more.
Topological optimization is an innovative method to realize the lightweight design. This paper proposes a hybrid topology optimization method that combines the SIMP (solid isotropic material with penalization) method and genetic algorithm (GA), called the SIMP-GA method. In the method, SIMP is used to update the chromosomes, which can accelerate convergence. The filtering scheme in the SIMP method can filter unconnected elements to ensure the connectivity of the structure. We studied the influence of varying the filtering radius on the optimized structure. Simultaneously, in the SIMP-GA method, each element is regarded as a gene, which controls the population number to a certain extent, reduces the amount of calculation, and improves the calculation efficiency. The calculation of some typical examples proves that the SIMP-GA method can obtain a better solution than the gradient-based method. Compared with the conventional genetic algorithm and GA-BESO (Bi-directional Evolutionary Structural Optimization) method, the calculation efficiency of the proposed method is higher and similar results are obtained. The innovative topology optimization method could be an effective way for structural lightweight design. Full article
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Review
Positioning Bio-Based Energy Systems in a Hypercomplex Decision Space—A Case Study
Energies 2021, 14(14), 4366; https://doi.org/10.3390/en14144366 - 20 Jul 2021
Cited by 4 | Viewed by 652
Abstract
The optimization of the energy portfolio for a small, open, landlocked economy with rather limited fossil resources is a complex task because it must find a long-range, sustainable balance between the various goals of society under the constant pressure of different interest groups. [...] Read more.
The optimization of the energy portfolio for a small, open, landlocked economy with rather limited fossil resources is a complex task because it must find a long-range, sustainable balance between the various goals of society under the constant pressure of different interest groups. The opinions of independent, informed experts could be an essential input in the decision-making process. The goal of this research was to determine the relative importance of the values and goals potentially accompanying projects, based on the utilization of bioenergy. The current research is based on a wide-ranging survey of 65 non-partisan experts, applying the Pareto analytic hierarchy process to ensure the unbiased prioritization of project segments. The results of the survey put a spotlight on the importance of the economic role of bioenergy projects. Contrary to previous expectations and considerations, the social functions of these projects have hitherto been given relatively little importance. The results highlight the importance of bioenergy in increasing the income-generating capacity of agricultural producers by optimal utilization of natural resources for agricultural production. This can be achieved without considerable deterioration of the natural environment. Modern agricultural production is characterized by high levels of mechanization and automatization. Under these conditions, the social role of bioenergy projects (job creation) is rather limited. Full article
(This article belongs to the Special Issue Management and Technology for Energy Efficiency Development)
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Article
An Improved Method Based on Deep Learning for Insulator Fault Detection in Diverse Aerial Images
Energies 2021, 14(14), 4365; https://doi.org/10.3390/en14144365 - 20 Jul 2021
Cited by 2 | Viewed by 755
Abstract
Insulators play a significant role in high-voltage transmission lines, and detecting insulator faults timely and accurately is important for the safe and stable operation of power grids. Since insulator faults are extremely small and the backgrounds of aerial images are complex, insulator fault [...] Read more.
Insulators play a significant role in high-voltage transmission lines, and detecting insulator faults timely and accurately is important for the safe and stable operation of power grids. Since insulator faults are extremely small and the backgrounds of aerial images are complex, insulator fault detection is a challenging task for automatically inspecting transmission lines. In this paper, a method based on deep learning is proposed for insulator fault detection in diverse aerial images. Firstly, to provide sufficient insulator fault images for training, a novel insulator fault dataset named “InSF-detection” is constructed. Secondly, an improved YOLOv3 model is proposed to reuse features and prevent feature loss. To improve the accuracy of insulator fault detection, SPP-networks and a multi-scale prediction network are employed for the improved YOLOv3 model. Finally, the improved YOLOv3 model and the compared models are trained and tested on the “InSF-detection”. The average precision (AP) of the improved YOLOv3 model is superior to YOLOv3 and YOLOv3-dense models, and just a little (1.2%) lower than that of CSPD-YOLO model; more importantly, the memory usage of the improved YOLOv3 model is 225 MB, which is the smallest between the four compared models. The experimental results and analysis validate that the improved YOLOv3 model achieves good performance for insulator fault detection in aerial images with diverse backgrounds. Full article
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Article
Towards Better Wind Resource Modeling in Complex Terrain: A k-Nearest Neighbors Approach
Energies 2021, 14(14), 4364; https://doi.org/10.3390/en14144364 - 20 Jul 2021
Cited by 2 | Viewed by 1256
Abstract
Wind turbines are often placed in complex terrains, where benefits from orography-related speed up can be capitalized. However, accurately modeling the wind resource over the extended areas covered by a typical wind farm is still challenging over a flat terrain, and over a [...] Read more.
Wind turbines are often placed in complex terrains, where benefits from orography-related speed up can be capitalized. However, accurately modeling the wind resource over the extended areas covered by a typical wind farm is still challenging over a flat terrain, and over a complex terrain, the challenge can be even be greater. Here, a novel approach for wind resource modeling is proposed, where a linearized flow model is combined with a machine learning approach based on the k-nearest neighbor (k-NN) method. Model predictors include combinations of distance, vertical shear exponent, a measure of the terrain complexity and speedup. The method was tested by performing cross-validations on a complex site using the measurements of five tall meteorological towers. All versions of the k-NN approach yield significant improvements over the predictions obtained using the linearized model alone; they also outperform the predictions of non-linear flow models. The new method improves the capabilities of current wind resource modeling approaches, and it is easily implemented. Full article
(This article belongs to the Section B2: Wind, Wave and Tidal Energy)
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Article
Trade, Climate and Energy: A New Study on Climate Action through Free Trade Agreements
Energies 2021, 14(14), 4363; https://doi.org/10.3390/en14144363 - 20 Jul 2021
Viewed by 1063
Abstract
Efforts to tackle climate change are taking place on multiple fronts. This includes trade, an increasingly important defining feature of the global economy. In recent years, free trade agreements (FTAs) have become the primary mechanism of trade policy and diplomacy. This study examines [...] Read more.
Efforts to tackle climate change are taking place on multiple fronts. This includes trade, an increasingly important defining feature of the global economy. In recent years, free trade agreements (FTAs) have become the primary mechanism of trade policy and diplomacy. This study examines the development of climate action measures in FTAs and discusses what difference they can make to tackling climate change. Its primary source research is based on an in-depth examination of FTAs in force up to 2020. This paper is structured around a number of research questions forming around three main inter-related areas of enquiry. Firstly, to what extent are these provisions in FTAs essentially derivative of energy’s connections with climate change, and thus part of a wider trade–climate–energy nexus? Secondly, what kinds of climate action are FTAs specifically promoting, and how effective a potential positive impact may we expect these to have? Thirdly, are certain climate action norms being promoted by trade partners in FTAs and if so, then who are the norm leaders, what is motivating them, and to what extent are they extending their influence over other trade partners? In addressing these questions, this study offers new insights and analysis regarding a potentially important emerging trend in the trade–climate–energy nexus. Its international political economy approach and latest empirical research also provide a further distinctive contribution to knowledge in this inter-disciplinary area, developing new comprehensions of the relationship between trade, climate action and energy. Full article
(This article belongs to the Special Issue Economic Development and Energy Policy)
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Article
Transforming Access to Clean Energy Technologies in the Global South: Learning from Lighting Africa in Kenya
Energies 2021, 14(14), 4362; https://doi.org/10.3390/en14144362 - 20 Jul 2021
Cited by 2 | Viewed by 876
Abstract
As SDG7-related interventions seek to transform access to clean energy, this paper presents an analysis of both a previous transformative intervention (Lighting Africa) and a theoretical approach to understanding how such transformations can be achieved in the Global South (socio-technical innovation system, STIS, [...] Read more.
As SDG7-related interventions seek to transform access to clean energy, this paper presents an analysis of both a previous transformative intervention (Lighting Africa) and a theoretical approach to understanding how such transformations can be achieved in the Global South (socio-technical innovation system, STIS, building). The paper makes four contributions. First, it tests the extent to which the STIS-building concept is useful in understanding and conceptualising how Lighting Africa transformed the market for solar lanterns in Kenya from an estimated market size of 29,000 lamps in 2009 to one where 680,000 Lighting Africa certified lamps were sold in Kenya by the end of the Programme in 2013. Second, it presents the most in-depth analysis of Lighting Africa that we are aware of to date. Third, it presents a conceptual framework that illustrates the Lighting Africa approach, providing a framework for future policy interventions aiming to transform access to clean energy technologies in the Global South. Fourth, it reflects on weaknesses in the STIS approach. In particular, these include a need to better attend to: the gendered implications of interventions (and social justice more broadly); implications of different scales of technologies; value accumulation and the extent to which interventions benefit indigenous actors and local economies; and the political and economic implications of any intervention and its distribution of benefits. Full article
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Article
Active Distribution Networks Planning Considering Multi-DG Configurations and Contingency Analysis
Energies 2021, 14(14), 4361; https://doi.org/10.3390/en14144361 - 19 Jul 2021
Cited by 1 | Viewed by 842
Abstract
This paper proposes a novel method for planning active distribution networks (ADNs) with the integration of an active network management (ANM) scheme using coordinated voltage control (CVC) through on-load tap changer (OLTC) transformers. The method was formulated as a security-constrained optimal power flow [...] Read more.
This paper proposes a novel method for planning active distribution networks (ADNs) with the integration of an active network management (ANM) scheme using coordinated voltage control (CVC) through on-load tap changer (OLTC) transformers. The method was formulated as a security-constrained optimal power flow (SCOPF) problem to minimize total operational costs, which maximizes the utilization of renewable distributed generators (DGs) over a planning horizon. The ANM scheme was applied using OLTC to ensure safe operation and reduce voltage violations in the network. To analyse the impact of ANM, the planning problem was examined both with and without the ANM scheme. Moreover, SCOPF, considering the N-1 line contingency analysis and multi-DG configuration, was implemented to analyse the feasibility of the proposed method and the advantages of ANM under contingency situations. The method was validated on a weakly-meshed 16-bus UK generic distribution system (UKGDS). The results showed that ANM can lower operational costs and maintain network voltage for operation in feasible conditions even in the case of a contingency. Moreover, the ANM scheme mitigated the voltage rise effect caused by DGs and maximized their utilization. Full article
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Review
Overview of Control Algorithm Verification Methods in Power Electronics Systems
Energies 2021, 14(14), 4360; https://doi.org/10.3390/en14144360 - 19 Jul 2021
Cited by 1 | Viewed by 743
Abstract
The paper presents the existing verification methods for control algorithms in power electronics systems, including the application of model checking techniques. In the industry, the most frequently used verification methods are simulations and experiments; however, they have to be performed manually and do [...] Read more.
The paper presents the existing verification methods for control algorithms in power electronics systems, including the application of model checking techniques. In the industry, the most frequently used verification methods are simulations and experiments; however, they have to be performed manually and do not give a 100% confidence that the system will operate correctly in all situations. Here we show the recent advancements in verification and performance assessment of power electronics systems with the usage of formal methods. Symbolic model checking can be used to achieve a guarantee that the system satisfies user-defined requirements, while statistical model checking combines simulation and statistical methods to gain statistically valid results that predict the behavior with high confidence. Both methods can be applied automatically before physical realization of the power electronics systems, so that any errors, incorrect assumptions or unforeseen situations are detected as early as possible. An additional functionality of verification with the use of formal methods is to check the converter operation in terms of reliability in various system operating conditions. It is possible to verify the distribution and uniformity of occurrence in time of the number of transistor switching, transistor conduction times for various current levels, etc. The information obtained in this way can be used to optimize control algorithms in terms of reliability in power electronics. The article provides an overview of various verification methods with an emphasis on statistical model checking. The basic functionalities of the methods, their construction, and their properties are indicated. Full article
(This article belongs to the Special Issue Reliability of Power Electronic Systems)
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Article
Multiparameter Optimization of Thrust Vector Control with Transverse Injection of a Supersonic Underexpanded Gas Jet into a Convergent Divergent Nozzle
Energies 2021, 14(14), 4359; https://doi.org/10.3390/en14144359 - 19 Jul 2021
Cited by 4 | Viewed by 708
Abstract
The optimal design of the thrust vector control system of solid rocket motors (SRMs) is discussed. The injection of a supersonic underexpanded gas jet into the diverging part of the rocket engine nozzle is considered, and multiparameter optimization of the geometric shape of [...] Read more.
The optimal design of the thrust vector control system of solid rocket motors (SRMs) is discussed. The injection of a supersonic underexpanded gas jet into the diverging part of the rocket engine nozzle is considered, and multiparameter optimization of the geometric shape of the injection nozzle and the parameters of jet injection into a supersonic flow is developed. The turbulent flow of viscous compressible gas in the main nozzle and injection system is simulated with the Reynolds-averaged Navier–Stokes (RANS) equations and shear stress transport (SST) turbulence model. An optimization procedure with the automatic generation of a block-structured mesh and conjugate gradient method is applied to find the optimal parameters of the problem of interest. Optimization parameters include the pressure ratio of the injected jet, the angle of inclination of the injection nozzle to the axis of the main nozzle, the distance of the injection nozzle from the throat of the main nozzle and the shape of the outlet section of the injection nozzle. The location of injection nozzle varies from 0.1 to 0.9 with respect to the length of the supersonic part of the nozzle; the angle of injection varies from 30 to 160 degrees; and the shape of the outlet section of the injection nozzle is an ellipse with an aspect ratio that varies from 0.1 to 1. The computed fluid flow in the combustion chamber is compared with experimental and computational results. The dependence of the thrust as a function of the injection parameters is obtained, and conclusions are made about the effects of the input parameters of the problem on the thrust coefficient. Full article
(This article belongs to the Special Issue Advanced Cyber-Physical System for Engines and Power System)
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Article
Proportional Usage of Low-Level Actions in Model Predictive Control for Six-Phase Electric Drives
Energies 2021, 14(14), 4358; https://doi.org/10.3390/en14144358 - 19 Jul 2021
Cited by 1 | Viewed by 580
Abstract
Finite Control-Set Model Predictive Control (FCS-MPC) appears as an interesting alternative to regulate multiphase electric drives, thanks to inherent advantages such as its capability to include new restrictions and fast-transient response. Nevertheless, in industrial applications, FCS-MPC is typically discarded to control multiphase motors [...] Read more.
Finite Control-Set Model Predictive Control (FCS-MPC) appears as an interesting alternative to regulate multiphase electric drives, thanks to inherent advantages such as its capability to include new restrictions and fast-transient response. Nevertheless, in industrial applications, FCS-MPC is typically discarded to control multiphase motors because the absence of a modulation stage produces a high harmonic content. In this regard, multi-vectorial approaches are an innovative solution to improve the electric drive performance taking advantage of the implicit modulator flexibility of Model Predictive Control (MPC) strategies. This work proposes the definition of a new multi-vectorial set of control actions formed by a couple of adjacent large voltage vectors and a null voltage vector with an adaptative application ratio. The combination of two large voltage vectors provides minimum x-y current injection whereas the application of a null voltage vector reduces the active voltage production. Moreover, the optimum selection of the null voltage vector for each couple of large voltage vectors permits reducing the switching frequency. On the other hand, the active application time for this couple is estimated through an analytic function based on the operating point. This procedure avoids the use of an iterative process to define the duty cycles, hence significatively decreasing the computational burden. Full article
(This article belongs to the Special Issue Control, Operation and Protection of Multiphase Machines and Drives)
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Article
Improvement of Stand-Alone Solar PV Systems in the Maputo Region by Adapting Necessary Parameters
Energies 2021, 14(14), 4357; https://doi.org/10.3390/en14144357 - 19 Jul 2021
Viewed by 600
Abstract
With the energy crisis and the constant blackout in the Mozambique Power Company grid, the option of applying solar photovoltaic (PV) systems has been one of the most used alternatives in the neighborhoods of the Maputo region. However, inefficient power delivery caused by [...] Read more.
With the energy crisis and the constant blackout in the Mozambique Power Company grid, the option of applying solar photovoltaic (PV) systems has been one of the most used alternatives in the neighborhoods of the Maputo region. However, inefficient power delivery caused by unproper sizing and installation of stand-alone solar PV systems has been contributing to the low utilization of solar energy potential in the Maputo region. The optimal sizing and installation of the solar PV system is addressed to evaluate the influence of installation and operation parameters on the power output of PV modules. In this topic, PV modules parameters such as cell temperature, the module’s slope and azimuth angles, the losses caused by excessive heating of the module cells, shadows and dust on the PV module and the cooling process at the back of the module are assessed in order to find out the consequence of inadequate installation and operation parameters of solar PV systems in the Maputo region. The proper sizing and installation of the stand-alone solar PV system is fundamental to guarantee the continuous and efficient supply of power and, thus, different tools and techniques have been applied. This study will deal with the hybrid optimization of multiple energy resources (HOMER) and system advisor model (SAM), to size and improve power generation of solar PV systems. This study concluded that for the Maputo region, the optimal tilt angle is 23 ± 2° and the azimuth angle is 11 ± 2°. In addition, for optimization of the tilt and azimuth angles, it also examined the effect of module backside ventilation and proved that the system’s power generation increases with the rise of spacing between the module and the wall, since the strategy prevents the decline of the module cells efficiency. However, the maximum recommended spacing between the PV module and the mounting wall is about 0.4 m, since an effort to increase the spacing up to this level results in an insignificant growth of power output. Full article
(This article belongs to the Special Issue Modelling New Trends in Photovoltaics)
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