Jitendra Kumar Yadav, B. Rani, Ajay Tiwari, Ambesh Dixit
The highly porous and binder-free flexible paper electrodes can enhance the specific capacitance of symmetric supercapacitors (SCs) due to their large surface and effective ion diffusion pathways. We synthesized the exfoliated graphite (ExG) by the thermal exfoliation method of chemically treated graphite flakes and compressed it into a paper-like thin sheet (binder-free) of ∼0.15 mm thickness. The coin cell SCs with copper (Cu) and stainless steel (SS) as current collectors have been fabricated for the electrochemical measurement. The cyclic voltammetry and galvanostatic charge/discharge measurements are investigated at various scan rates and current densities. The SCs with Cu foil as a current collector perform better than SS-based SCs. The Cu current collector-based SCs showed a specific capacitance of 37.08 mF cm−2, whereas it was ∼29.98 mF cm−2 for SS-based SCs at a 0.01 V s−1 scan rate across a 0–0.6 V potential window. Approximately no degradation in charge storage capacity for more than 15 000 cycles at 0.1 V s−1 shows the ultra-stability of the flexible ExG-based binder-free electrodes. A digital watch is powered using the fabricated pouch cell supercapacitor with copper-based current collectors to show the potential of SCs.
高多孔、无粘结剂的柔性纸电极因其大表面和有效的离子扩散途径，可提高对称超级电容器（SC）的比电容。我们采用热剥离法合成了经过化学处理的剥离石墨（ExG）薄片，并将其压制成厚度为 0.15 毫米的纸状薄片（无粘结剂）。以铜（Cu）和不锈钢（SS）为集流体的纽扣电池 SC 已制作完成，用于电化学测量。在不同的扫描速率和电流密度下进行了循环伏安法和电静态充放电测量。以铜箔为集流器的 SC 性能优于以 SS 为集流器的 SC。以 0.01 V s-1 的扫描速率扫描 0-0.6 V 电位窗口时，基于铜电流收集器的 SC 的比电容为 37.08 mF cm-2，而基于 SS 的 SC 的比电容为 29.98 mF cm-2。在 0.1 V s-1 的条件下，电荷存储容量在超过 15000 个循环后几乎没有下降，这表明基于 ExG 的柔性无粘结剂电极具有超强稳定性。为了展示超级电容器的潜力，我们利用制作的袋式电池超级电容器和铜基集流器为一块电子手表供电。
{"title":"High areal-capacitance based extremely stable flexible supercapacitors using binder-free exfoliated graphite paper electrode","authors":"Jitendra Kumar Yadav, B. Rani, Ajay Tiwari, Ambesh Dixit","doi":"10.1063/5.0184499","DOIUrl":"https://doi.org/10.1063/5.0184499","url":null,"abstract":"The highly porous and binder-free flexible paper electrodes can enhance the specific capacitance of symmetric supercapacitors (SCs) due to their large surface and effective ion diffusion pathways. We synthesized the exfoliated graphite (ExG) by the thermal exfoliation method of chemically treated graphite flakes and compressed it into a paper-like thin sheet (binder-free) of ∼0.15 mm thickness. The coin cell SCs with copper (Cu) and stainless steel (SS) as current collectors have been fabricated for the electrochemical measurement. The cyclic voltammetry and galvanostatic charge/discharge measurements are investigated at various scan rates and current densities. The SCs with Cu foil as a current collector perform better than SS-based SCs. The Cu current collector-based SCs showed a specific capacitance of 37.08 mF cm−2, whereas it was ∼29.98 mF cm−2 for SS-based SCs at a 0.01 V s−1 scan rate across a 0–0.6 V potential window. Approximately no degradation in charge storage capacity for more than 15 000 cycles at 0.1 V s−1 shows the ultra-stability of the flexible ExG-based binder-free electrodes. A digital watch is powered using the fabricated pouch cell supercapacitor with copper-based current collectors to show the potential of SCs.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139394788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Pichugina, R. Banta, E. J. Strobach, B. J. Carroll, W. A. Brewer, D. D. Turner, V. Wulfmeyer, E. James, T. R. Lee, S. Baidar, J. B. Olson, R. K. Newsom, H.-S. Bauer, R. Rai
The rapid change of wind speed and direction on 21 August 2017 is studied using Doppler lidar measurements at five sites of the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) facility in north-central Oklahoma. The Doppler lidar data were investigated along with meteorological variables such as temperature, humidity, and turbulence available from the large suite of instrumentation deployed at the SGP Central Facility (C1) during the Land-Atmosphere Feedback Experiment in August 2017. Lidar measurements at five sites, separated by 55–70 km, allowed us to document the development and evolution of the wind flow over the SGP area, examine synoptic conditions to understand the mechanism that leads to the ramp event, and estimate the ability of the High-Resolution Rapid Refresh model to reproduce this event. The flow feature in question is an atmospheric bore, a small-scale phenomenon that is challenging to represent in models, that was generated by a thunderstorm outflow northwest of the ARM SGP area. The small-scale nature of bores, its impact on power generation, and the modeling challenges associated with representing bores are discussed in this paper. The results also provide information about model errors between sites of different surface and vegetation types.
{"title":"Case study of a bore wind-ramp event from lidar measurements and HRRR simulations over ARM Southern Great Plains","authors":"Y. Pichugina, R. Banta, E. J. Strobach, B. J. Carroll, W. A. Brewer, D. D. Turner, V. Wulfmeyer, E. James, T. R. Lee, S. Baidar, J. B. Olson, R. K. Newsom, H.-S. Bauer, R. Rai","doi":"10.1063/5.0161905","DOIUrl":"https://doi.org/10.1063/5.0161905","url":null,"abstract":"The rapid change of wind speed and direction on 21 August 2017 is studied using Doppler lidar measurements at five sites of the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) facility in north-central Oklahoma. The Doppler lidar data were investigated along with meteorological variables such as temperature, humidity, and turbulence available from the large suite of instrumentation deployed at the SGP Central Facility (C1) during the Land-Atmosphere Feedback Experiment in August 2017. Lidar measurements at five sites, separated by 55–70 km, allowed us to document the development and evolution of the wind flow over the SGP area, examine synoptic conditions to understand the mechanism that leads to the ramp event, and estimate the ability of the High-Resolution Rapid Refresh model to reproduce this event. The flow feature in question is an atmospheric bore, a small-scale phenomenon that is challenging to represent in models, that was generated by a thunderstorm outflow northwest of the ARM SGP area. The small-scale nature of bores, its impact on power generation, and the modeling challenges associated with representing bores are discussed in this paper. The results also provide information about model errors between sites of different surface and vegetation types.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139395807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Min Chen, Jing Lou, Yang Zhang, Lu Li, Yan Li, Xin-an Xie
Tungstoborate heteropolyacid catalysts have good catalytic degradation performance, especially for selective cleavage of C–C bonds in biomass. In this paper, the product yield and component distribution of tungstoborate heteropolyacid (BW12)-catalyzed lignin liquefaction were investigated at different parameters, including temperatures (120, 140, 160, 180, and 200 °C), catalyst amount (0, 2.5, 5, 10, and 20 wt. %), and reaction time (0, 30, 60, 90, and 120 min). It was found that a higher conversion (72.16 wt. %) and bio-oil yield (68.41 wt. %) could be obtained under suitable reaction conditions (180 °C, 60 min, 5 wt. %). Bio-oil analysis showed that the BW12 catalyst had a significant effect on the distribution of bio-oil fractions, in which mono-aromatic components increased from 32.96% to 47.56% compared to those without the catalyst. In particular, carbonyl substances in the mono-aromatic components increased from 18.66% to 26.97%. Spectroscopic analysis (FT-IR) found that the absorption peaks of C–O and C–C bonds in the liquefied residue catalyzed by BW12 decreased compared to the raw lignin. Moreover, the mechanism of BW12-catalyzed lignin depolymerization was investigated by DFT simulations. The simulation results demonstrated that the shortening of Cα–O bond, the breaking of Cβ–Cγ and Cα–Cβ bonds in lignin promoted the formation of vanillin and benzaldehyde, 3-hydroxy-4-methoxy. Finally, based on the experimental data and simulation results, a possible reaction pathway for the BW12-catalyzed liquefaction of lignin into mono-aromatic substances was proposed.
{"title":"Tungstoborate heteropolyacid-catalyzed lignin liquefaction: Product yield and component distribution","authors":"Min Chen, Jing Lou, Yang Zhang, Lu Li, Yan Li, Xin-an Xie","doi":"10.1063/5.0176615","DOIUrl":"https://doi.org/10.1063/5.0176615","url":null,"abstract":"Tungstoborate heteropolyacid catalysts have good catalytic degradation performance, especially for selective cleavage of C–C bonds in biomass. In this paper, the product yield and component distribution of tungstoborate heteropolyacid (BW12)-catalyzed lignin liquefaction were investigated at different parameters, including temperatures (120, 140, 160, 180, and 200 °C), catalyst amount (0, 2.5, 5, 10, and 20 wt. %), and reaction time (0, 30, 60, 90, and 120 min). It was found that a higher conversion (72.16 wt. %) and bio-oil yield (68.41 wt. %) could be obtained under suitable reaction conditions (180 °C, 60 min, 5 wt. %). Bio-oil analysis showed that the BW12 catalyst had a significant effect on the distribution of bio-oil fractions, in which mono-aromatic components increased from 32.96% to 47.56% compared to those without the catalyst. In particular, carbonyl substances in the mono-aromatic components increased from 18.66% to 26.97%. Spectroscopic analysis (FT-IR) found that the absorption peaks of C–O and C–C bonds in the liquefied residue catalyzed by BW12 decreased compared to the raw lignin. Moreover, the mechanism of BW12-catalyzed lignin depolymerization was investigated by DFT simulations. The simulation results demonstrated that the shortening of Cα–O bond, the breaking of Cβ–Cγ and Cα–Cβ bonds in lignin promoted the formation of vanillin and benzaldehyde, 3-hydroxy-4-methoxy. Finally, based on the experimental data and simulation results, a possible reaction pathway for the BW12-catalyzed liquefaction of lignin into mono-aromatic substances was proposed.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140519854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to solve the problem of power exchange between areas of multi-area power systems under the power market, this paper designs a power trading contract based on the generation participation matrix, so as to simulate the specific process of power change in each area. With the integration of wind power into the large-scale power system, it is difficult to model the multi-area power system. For this situation, this paper designs a data-driven model-free adaptive load frequency control algorithm based on collecting input and output data, which gets rid of the dependence of the power system on the model. Along with the frequent transmission of input and output data in each area, the communication load of the power system also increases. Aiming at saving communication resources, this paper designs an event-triggered mechanism to reduce the communication bandwidth. The stability of the control algorithm is demonstrated theoretically. Finally, a three-area power system with wind penetration is used as an example to simulate and verify the effectiveness of the proposed algorithm in this paper.
{"title":"Event-triggered data-driven load frequency control for multi-area power system with wind penetration under deregulation environment","authors":"Xuhui Bu, Yiming Zeng, Y. Yin, Jiaqi Liang","doi":"10.1063/5.0168895","DOIUrl":"https://doi.org/10.1063/5.0168895","url":null,"abstract":"In order to solve the problem of power exchange between areas of multi-area power systems under the power market, this paper designs a power trading contract based on the generation participation matrix, so as to simulate the specific process of power change in each area. With the integration of wind power into the large-scale power system, it is difficult to model the multi-area power system. For this situation, this paper designs a data-driven model-free adaptive load frequency control algorithm based on collecting input and output data, which gets rid of the dependence of the power system on the model. Along with the frequent transmission of input and output data in each area, the communication load of the power system also increases. Aiming at saving communication resources, this paper designs an event-triggered mechanism to reduce the communication bandwidth. The stability of the control algorithm is demonstrated theoretically. Finally, a three-area power system with wind penetration is used as an example to simulate and verify the effectiveness of the proposed algorithm in this paper.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139636968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When the temperature of solar photovoltaic (PV) modules rises, efficiency drops and module degradation accelerates. Thus, it is beneficial to reduce module operating temperatures. Previous studies of solar power plants have illustrated that incoming flow characteristics, turbulent mixing, and array geometry can strongly impact convective cooling, as measured by the convective heat transfer coefficient h. In the fields of heat transfer and plant canopy flow, previous work has shown that system-scale arrangement modifications—e.g., variable spacing, barriers, or windbreaks—can passively alter the flow, enhance turbulent mixing, and influence convection. However, researchers have not yet explored how variable spacing or barriers might enhance convective cooling in solar power plants. Here, high-resolution large-eddy simulations model the air flow and heat transfer through solar power plant arrangements modified with missing modules and barrier walls. We then perform a control volume analysis to evaluate the net heat flux and compute h, which quantifies the influence of these spatial modifications on convective cooling and, thus, module temperature and power output. Installing barrier walls yields the greatest improvements, increasing h by 3.4%, reducing module temperature by an estimated 2.5 °C, and boosting power output by an estimated 1.4% on average. These findings indicate that incorporating variable spacing or barrier-type elements into PV plant designs can reduce module temperature and, thus, improve PV performance and service life.
{"title":"Barriers and variable spacing enhance convective cooling and increase power output in solar PV plants","authors":"B. Stanislawski, Todd Harman, R. B. Cal, M. Calaf","doi":"10.1063/5.0177420","DOIUrl":"https://doi.org/10.1063/5.0177420","url":null,"abstract":"When the temperature of solar photovoltaic (PV) modules rises, efficiency drops and module degradation accelerates. Thus, it is beneficial to reduce module operating temperatures. Previous studies of solar power plants have illustrated that incoming flow characteristics, turbulent mixing, and array geometry can strongly impact convective cooling, as measured by the convective heat transfer coefficient h. In the fields of heat transfer and plant canopy flow, previous work has shown that system-scale arrangement modifications—e.g., variable spacing, barriers, or windbreaks—can passively alter the flow, enhance turbulent mixing, and influence convection. However, researchers have not yet explored how variable spacing or barriers might enhance convective cooling in solar power plants. Here, high-resolution large-eddy simulations model the air flow and heat transfer through solar power plant arrangements modified with missing modules and barrier walls. We then perform a control volume analysis to evaluate the net heat flux and compute h, which quantifies the influence of these spatial modifications on convective cooling and, thus, module temperature and power output. Installing barrier walls yields the greatest improvements, increasing h by 3.4%, reducing module temperature by an estimated 2.5 °C, and boosting power output by an estimated 1.4% on average. These findings indicate that incorporating variable spacing or barrier-type elements into PV plant designs can reduce module temperature and, thus, improve PV performance and service life.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139454017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In many small wind turbine blades, the interior space between laminate skins is filled by a material core. The mechanical properties of the core are much less important than its density, which must be low to reduce the moment of inertia as high inertia increases both the starting time of the turbine and the gyroscopic loads on the blades. In this paper, we use, for the first time, the petiole of the miriti palm (PMP) as the core of four small blades, in order to analyze its effect on turbine starting performance. PMP is abundant in the Amazon region and harvesting it does not destroy the palm because the petiole regrows; therefore, harvesting is fully sustainable and may well have a major role in increasing the sustainability on wind turbine manufacturing. We consider the benefits of using the easily worked petiole for the core in terms of manufacturing, as demonstrated by the construction of a 0.598 m blade. PMP is less dense on average than alternative materials, such as expanded polystyrene and balsa wood. The starting performance is an important issue for small wind turbines. It is evaluated using a quasi-steady model, in which blade element momentum theory is coupled to Newton's Second Law. The low density of the small blade made using petiole of the miriti reduces the starting time by 10% when compared with expanded polystyrene and 42% when compared to balsa wood.
{"title":"Using the petiole of the miriti palm for the core of a small wind turbine blade","authors":"I. D. S. Gomes, J. R. P. Vaz, D. Wood","doi":"10.1063/5.0185573","DOIUrl":"https://doi.org/10.1063/5.0185573","url":null,"abstract":"In many small wind turbine blades, the interior space between laminate skins is filled by a material core. The mechanical properties of the core are much less important than its density, which must be low to reduce the moment of inertia as high inertia increases both the starting time of the turbine and the gyroscopic loads on the blades. In this paper, we use, for the first time, the petiole of the miriti palm (PMP) as the core of four small blades, in order to analyze its effect on turbine starting performance. PMP is abundant in the Amazon region and harvesting it does not destroy the palm because the petiole regrows; therefore, harvesting is fully sustainable and may well have a major role in increasing the sustainability on wind turbine manufacturing. We consider the benefits of using the easily worked petiole for the core in terms of manufacturing, as demonstrated by the construction of a 0.598 m blade. PMP is less dense on average than alternative materials, such as expanded polystyrene and balsa wood. The starting performance is an important issue for small wind turbines. It is evaluated using a quasi-steady model, in which blade element momentum theory is coupled to Newton's Second Law. The low density of the small blade made using petiole of the miriti reduces the starting time by 10% when compared with expanded polystyrene and 42% when compared to balsa wood.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139637847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aggravation of the problem of climate change, as well as the growth of carbon dioxide emissions, determines the increased interest of the scientific community in the development of effective methods to minimize the growing threats. The focus of scientists is China with its accelerated economic development, contributing to the growth of carbon dioxide emissions and other environmental problems. Global and regional trends are reflected in the strategies of China's largest energy companies, which confirm the relevance of the topic under study. The purpose of the article is to study the current performance of China's energy sector, their trends, and future forecasts, taking into account the strategies of the key players in the country's oilfield services market. The study used the following scientific methods: economic and statistical analysis, predictive methods, system-structural method, analysis, comparison method, observation, and description. As a result of the study, the key trends in the energy industry in China today were analyzed, and forecast values selected indicators by announced pledges scenario and stated policies scenario. The structure of supply and consumption by China of both energies from traditional sources and generated from renewable sources is studied. The regional structure of energy exports and imports by China is considered, and the country's main strategic partners are identified. The analysis of operating models and strategic directions of activity of the largest oilfield services companies in China—PetroChina and Sinopec—was carried out. Attention is paid to the problems of interaction between logistics and oilfield services companies, and ways to minimize such problems are proposed. The results of the study can be used by government representatives when planning further actions regarding the development of the energy industry.
{"title":"Strategy of Chinese energy companies in the world market of oilfield services and logistics services: Regional aspects","authors":"Mushfig Guliyev, Azer Agarzayev, Lamiya Huseynova, Orkhan Huseynli, Samira Rustamova","doi":"10.1063/5.0178771","DOIUrl":"https://doi.org/10.1063/5.0178771","url":null,"abstract":"The aggravation of the problem of climate change, as well as the growth of carbon dioxide emissions, determines the increased interest of the scientific community in the development of effective methods to minimize the growing threats. The focus of scientists is China with its accelerated economic development, contributing to the growth of carbon dioxide emissions and other environmental problems. Global and regional trends are reflected in the strategies of China's largest energy companies, which confirm the relevance of the topic under study. The purpose of the article is to study the current performance of China's energy sector, their trends, and future forecasts, taking into account the strategies of the key players in the country's oilfield services market. The study used the following scientific methods: economic and statistical analysis, predictive methods, system-structural method, analysis, comparison method, observation, and description. As a result of the study, the key trends in the energy industry in China today were analyzed, and forecast values selected indicators by announced pledges scenario and stated policies scenario. The structure of supply and consumption by China of both energies from traditional sources and generated from renewable sources is studied. The regional structure of energy exports and imports by China is considered, and the country's main strategic partners are identified. The analysis of operating models and strategic directions of activity of the largest oilfield services companies in China—PetroChina and Sinopec—was carried out. Attention is paid to the problems of interaction between logistics and oilfield services companies, and ways to minimize such problems are proposed. The results of the study can be used by government representatives when planning further actions regarding the development of the energy industry.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139638444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The involvement of wind turbines operating at load shedding levels in primary frequency regulation serves as a crucial technical solution to provide high levels of inertial response capability and frequency regulation capability in power systems with significant proportions of renewable energy. Load-shedding units' frequency regulation capacity is constrained by the optimal operating speed, which prevents the utilization of the rotor's full kinetic energy and consequently limits the system's ability to provide strong inertia support. Additionally, the units are restricted by the maximum speed in the medium wind speed range, resulting in a reduced reserve capacity. The control mechanism of virtual synchronous generator (VSG) can ensure voltage stability at the machine end, and enable real-time tracking of the grid frequency, thereby imparting to wind turbines the on-grid operation characteristics of synchronous generator sets. To achieve this goal, this paper proposes a coordinated frequency control method for variable-speed variable-pitch doubly fed induction generator units based on VSG. Differentiated control strategies are employed for varying wind speed ranges, while an additional frequency control module is utilized to realize frequency regulation functionality. In conjunction with VSG, this approach enhances the inertial response of the units and strengthens their ability to support grid frequency. Simulation results indicate that the proposed control method mitigates the rate of decline in grid frequency and reduces frequency deviation, ultimately promoting grid stability. Additionally, a simulation system was designed based on the conventional four-machine two-area model to verify the effectiveness of this approach.
{"title":"Coordinated frequency control study of variable speed variable pitch of DFIG load shedding unit based on VSG","authors":"Lei Liu, B. Yang Zhao, Juan Hu","doi":"10.1063/5.0168998","DOIUrl":"https://doi.org/10.1063/5.0168998","url":null,"abstract":"The involvement of wind turbines operating at load shedding levels in primary frequency regulation serves as a crucial technical solution to provide high levels of inertial response capability and frequency regulation capability in power systems with significant proportions of renewable energy. Load-shedding units' frequency regulation capacity is constrained by the optimal operating speed, which prevents the utilization of the rotor's full kinetic energy and consequently limits the system's ability to provide strong inertia support. Additionally, the units are restricted by the maximum speed in the medium wind speed range, resulting in a reduced reserve capacity. The control mechanism of virtual synchronous generator (VSG) can ensure voltage stability at the machine end, and enable real-time tracking of the grid frequency, thereby imparting to wind turbines the on-grid operation characteristics of synchronous generator sets. To achieve this goal, this paper proposes a coordinated frequency control method for variable-speed variable-pitch doubly fed induction generator units based on VSG. Differentiated control strategies are employed for varying wind speed ranges, while an additional frequency control module is utilized to realize frequency regulation functionality. In conjunction with VSG, this approach enhances the inertial response of the units and strengthens their ability to support grid frequency. Simulation results indicate that the proposed control method mitigates the rate of decline in grid frequency and reduces frequency deviation, ultimately promoting grid stability. Additionally, a simulation system was designed based on the conventional four-machine two-area model to verify the effectiveness of this approach.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139631489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As a kind of renewable energy enterprise, wind power enterprise plays an important role in the energy transformation. However, its financing problems are also widespread. The purpose of this paper is to study the financing mode selection in order to improve sustainable development and future benefits of wind power enterprises. First, an evaluation index system is constructed through literature research and expert interviews, and the weight of each index is determined comprehensively by G1 and information entropy methods. On this basis, a financing mode selection model of wind power enterprises is constructed by using the prospect theory and hesitant fuzzy set. Next, this framework is used for case study. Financing patterns are ranked according to the comprehensive prospect value. The results show that financial leasing is the most suitable financing mode. Finally, the applicability and optimization of the model are proved by sensitivity analysis and comparative analysis.
{"title":"A study on financing mode selection of wind power enterprises based on prospect theory: A case study in China","authors":"Huixin Liu, Simeng Wang, Yuqian Zhang","doi":"10.1063/5.0183269","DOIUrl":"https://doi.org/10.1063/5.0183269","url":null,"abstract":"As a kind of renewable energy enterprise, wind power enterprise plays an important role in the energy transformation. However, its financing problems are also widespread. The purpose of this paper is to study the financing mode selection in order to improve sustainable development and future benefits of wind power enterprises. First, an evaluation index system is constructed through literature research and expert interviews, and the weight of each index is determined comprehensively by G1 and information entropy methods. On this basis, a financing mode selection model of wind power enterprises is constructed by using the prospect theory and hesitant fuzzy set. Next, this framework is used for case study. Financing patterns are ranked according to the comprehensive prospect value. The results show that financial leasing is the most suitable financing mode. Finally, the applicability and optimization of the model are proved by sensitivity analysis and comparative analysis.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140520204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, an integrated forecasting model was developed by combining the ensemble empirical mode decomposition (EEMD) model and gated recurrent unit (GRU) neural network to accurately predict the rooftop solar power output at a specific power unit located in Tay Ninh province, Vietnam. The EEMD method was employed to decompose the solar power signals into multiple frequencies, allowing for a more comprehensive analysis. Subsequently, the GRU network, known for its ability to capture long-term dependencies, was utilized to forecast future values for each decomposition series. By merging the forecasted values obtained from the decomposition series, the final prediction for the solar power output was generated. To evaluate the efficacy of our proposed approach, a comparative analysis was undertaken against other forecasting models, including a single artificial neural network, long short-term memory network, and GRU, all of which solely considered the solar power series as input features. The experimental results provided compelling evidence of the superior performance of the EEMD-GRU model, especially when incorporating weather variables into the forecasting process, achieving the best results in all three forecasting scenarios (1-step, 2-step, and 3-step). For both forecasting targets, Inverter 155 and 156, the n-RMSE indices were 1.35%, 3.5%, and 4.8%, respectively, significantly lower than the compared single models. This integration of weather variables enhances the model's accuracy and reliability in predicting rooftop solar power output, establishing it as a valuable tool for efficient energy management in the region.
{"title":"Short-term multi-step forecasting of rooftop solar power generation using a combined data decomposition and deep learning model of EEMD-GRU","authors":"N. Nhat, D. N. Huu, Thu Thi Hoai Nguyen","doi":"10.1063/5.0176951","DOIUrl":"https://doi.org/10.1063/5.0176951","url":null,"abstract":"In this study, an integrated forecasting model was developed by combining the ensemble empirical mode decomposition (EEMD) model and gated recurrent unit (GRU) neural network to accurately predict the rooftop solar power output at a specific power unit located in Tay Ninh province, Vietnam. The EEMD method was employed to decompose the solar power signals into multiple frequencies, allowing for a more comprehensive analysis. Subsequently, the GRU network, known for its ability to capture long-term dependencies, was utilized to forecast future values for each decomposition series. By merging the forecasted values obtained from the decomposition series, the final prediction for the solar power output was generated. To evaluate the efficacy of our proposed approach, a comparative analysis was undertaken against other forecasting models, including a single artificial neural network, long short-term memory network, and GRU, all of which solely considered the solar power series as input features. The experimental results provided compelling evidence of the superior performance of the EEMD-GRU model, especially when incorporating weather variables into the forecasting process, achieving the best results in all three forecasting scenarios (1-step, 2-step, and 3-step). For both forecasting targets, Inverter 155 and 156, the n-RMSE indices were 1.35%, 3.5%, and 4.8%, respectively, significantly lower than the compared single models. This integration of weather variables enhances the model's accuracy and reliability in predicting rooftop solar power output, establishing it as a valuable tool for efficient energy management in the region.","PeriodicalId":16953,"journal":{"name":"Journal of Renewable and Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140526158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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