The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform
Shaoyang Huang - One of the best experts on this subject based on the ideXlab platform.
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hydraulic tomography for estimating the diffusivity of heterogeneous aquifers based on groundwater response to tidal fluctuation in an Artificial Island in taiwan
Geofluids, 2018Co-Authors: Jetchau Wen, Hongru Lin, Tian Chyi Jim Yeh, Yu Li Wang, Keng Li Lin, Shaoyang HuangAbstract:This study investigated the hydraulic properties of the heterogeneous aquifers of an Artificial Island (Yunlin Offshore Industrial Park) in Taiwan. The research was based on the groundwater level response affected by tidal fluctuation using the hydraulic tomography (HT) to analyze the hydraulic diffusivity (α). Specifically, the power spectrum ratio of groundwater and tidal fluctuations derived from the Gelhar solution was used to estimate α in homogeneous aquifers; this, however, could not be applied in the Artificial Island. Next, the spatial distribution of the groundwater level response affected by tidal fluctuation was analyzed and found to be irregular, proving the existence of hydrogeological heterogeneity in the Artificial Island. Furthermore, the results of the estimated α using the HT showed low error and high correlation, 0.41 m2/hr and 0.83, respectively, between the optimal estimated heterogeneous and reference α fields in the synthetic aquifer. Last, the HT was used in the real tested scenario. By comparing the predicted groundwater levels of the optimal estimated heterogeneous α field and the observed groundwater levels of the real aquifer, it was found that the correlation was higher than 0.99. Therefore, the HT can be used to obtain the optimal estimated heterogeneous α field in the Artificial Island.
Fuminori Abe - One of the best experts on this subject based on the ideXlab platform.
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evaluation of subsurface thermal environmental change caused by a ground coupled heat pump system
Current Applied Physics, 2010Co-Authors: Yasuhiro Fujimitsu, Koichiro Fukuoka, Sachio Ehara, Hiroto Takeshita, Fuminori AbeAbstract:Abstract The authors have been conducting demonstration and performance assessment of the ground-coupled heat pump (GCHP) system optimized for the air conditioning system of an experimental house in the Artificial Island in Fukuoka City, Japan, since 2005 to evaluate the subsurface thermal environmental changes caused by heat exchange with the ground. The authors monitored the underground temperature and groundwater level in some observation wells around the heat exchanging well, and performed numerical simulation of the underground temperature change with a groundwater simulator “FEFLOW”. The simulation result for a 20-year operation by using the numerical model, which had replicated the measured heat exchange rate during the 40-day heating operation from 15 December 2006, predicted that the cumulative increase or decrease of subsurface temperature will not be seen. Therefore, it is thought that there is little impact to the subsurface thermal environment around this GCHP system.
Chatzivasileiadis Spyros - One of the best experts on this subject based on the ideXlab platform.
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North Sea Energy Islands: Impact on National Markets and Grids
2021Co-Authors: Tosatto Andrea, Beseler, Xavier Martínez, Østergaard Jacob, Pinson Pierre, Chatzivasileiadis SpyrosAbstract:Taking concrete steps towards a carbon-free society, the Danish Parliament has recently made an agreement on the establishment of the world's first two offshore energy hubs, one on the Island of Bornholm and one on an Artificial Island in the North Sea. Being the two first-of-their-kind projects, several aspects related to the inclusion of these "energy Islands" in the current market setup are still under discussion. To this end, this paper presents the first large-scale impact analysis of offshore hubs on the whole European power system and electricity market. The detailed models used for such analysis are publicly released with the paper. Our study shows that energy hubs in the North Sea have a positive impact, and overall increase economic welfare in EU. However, when considering the impact on each country, benefits are not shared equally. In order to help the development of such projects, we focus on the identification of market challenges and system needs arising from the hubs. From a market perspective, we show how exporting countries are negatively affected by the lower electricity prices and we point at potential strategic behaviors induced by the large amount of new transmission capacity installed in the North Sea. From a system point of view, we show how the large amount of wind energy stresses conventional generators, which are required to become more flexible, and national grids, which cannot always accommodate large imports from the hubs.Comment: Submitted to Energy Policy on March 31, 202
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North Sea Wind Power Hub: System Configurations, Grid Implementation and Techno-economic Assessment
2020Co-Authors: Misyris Georgios, Chatzivasileiadis Spyros, Van Cutsem Thierry, Moller Jakob, Dijokas Matas, Renom Estragués Oma, Bastin Bertrand, Nielsen Arne, Weckesser Tilman, Ostergaard JakobAbstract:peer reviewedaudience: researcher, professional, studentIn 2017, Energinet and TenneT, the Danish and Dutch Transmission System Operators (TSOs), have announced the North Sea Wind Power Hub (NSWPH) project. The project aims at increasing by 36 GW the North Sea offshore wind capacity, with an Artificial Island collecting all the power produced by wind turbines and several HVDC links transmitting this power to the onshore grids. This project brings together new opportunities and new challenges, both from a technical and economic point of view. In this regard, this paper presents three analyses regarding the design and operation of such an offshore system. First, we perform a techno-economic assessment of different grid configurations for the collection of the power produced by wind farms and its transmission to the hub. In this analysis, two frequencies and two voltage levels for the operation of the offshore grid are investigated. Our findings show that the nominal-frequency high-voltage option is the more suitable, as low-frequency does not bring any advantage and low-voltage would results in higher costs. The second analysis is related to the differences in operating the system with low- or zero-inertia; different dynamic studies are performed for each configuration to identify proper control actions and their stability properties. Comparing the outcomes of the simulations, we observed that voltage and frequency oscillations are better damped in the zero-inertia system; however, the risk of propagating offshore faults in the connected onshore grids is mitigated with the inclusion of the synchronous condensers. Lastly, a comparison of ElectroMagnetic Transient (EMT) and phasor-mode (also known as RMS) models is presented, in order to understand their appropriateness of simulating low- and zero- inertia systems. The results show that phasor approximation modelling can be used, as long as eigen-frequencies in power network are well damped.multiD
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North Sea Wind Power Hub: System Configurations, Grid Implementation and Techno-economic Assessment
2020Co-Authors: Misyris Georgios, Chatzivasileiadis Spyros, Van Cutsem Thierry, Moller Jakob, Dijokas Matas, Renom Estragués Oma, Bastin Bertrand, Nielsen Arne, Weckesser Tilman, Ostergaard JakobAbstract:In 2017, Energinet and TenneT, the Danish and Dutch Transmission System Operators (TSOs), have announced the North Sea Wind Power Hub (NSWPH) project. The project aims at increasing by 36 GW the North Sea offshore wind capacity, with an Artificial Island collecting all the power produced by wind turbines and several HVDC links transmitting this power to the onshore grids. This project brings together new opportunities and new challenges, both from a technical and economic point of view. In this regard, this paper presents three analyses regarding the design and operation of such an offshore system. First, we perform a techno-economic assessment of different grid configurations for the collection of the power produced by wind farms and its transmission to the hub. In this analysis, two frequencies and two voltage levels for the operation of the offshore grid are investigated. Our findings show that the nominal-frequency high-voltage option is the more suitable, as low-frequency does not bring any advantage and low-voltage would results in higher costs. The second analysis is related to the differences in operating the system with low- or zero-inertia; different dynamic studies are performed for each configuration to identify proper control actions and their stability properties. Comparing the outcomes of the simulations, we observed that voltage and frequency oscillations are better damped in the zero-inertia system; however, the risk of propagating offshore faults in the connected onshore grids is mitigated with the inclusion of the synchronous condensers. Lastly, a comparison of ElectroMagnetic Transient (EMT) and phasor-mode (also known as RMS) models is presented, in order to understand their appropriateness of simulating low- and zero- inertia systems. The results show that phasor approximation modelling can be used, as long as eigen-frequencies in power network are well damped.Peer reviewe
D G Steyn - One of the best experts on this subject based on the ideXlab platform.
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dynamical analysis of sea breeze hodograph rotation in sardinia
Atmospheric Chemistry and Physics, 2014Co-Authors: Nadya Moisseeva, D G SteynAbstract:Abstract. This study investigates the diurnal evolution of sea-breeze (SB) rotation over an Island at the middle latitudes. Earlier research on sea breezes in Sardinia shows that the onshore winds around various coasts of the Island exhibit both the theoretically predicted clockwise rotation as well as seemingly anomalous anticlockwise rotation. A non-hydrostatic fully compressible numerical model (WRF) is used to simulate wind fields on and around the Island on previously studied sea-breeze days, and is shown to capture the circulation on all coasts accurately. Diurnal rotation of wind is examined, and patterns of clockwise and anticlockwise rotation are identified. A dynamical analysis is performed by extracting individual forcing terms from the horizontal momentum equations. Analysis of several regions around the Island shows that the direction of rotation is a result of a complex interaction between near-surface and synoptic pressure gradient, Coriolis and advection forcings. An idealized simulation is performed over an Artificial Island with dramatically simplified topography yet similar dimensions and latitude to Sardinia. Dynamical analysis of the idealized case reveals a rather different pattern of hodograph rotation to the real Sardinia, yet similar underlying dynamics. The research provides new insights into the dynamics underlying sea-breeze hodograph rotation, especially in coastal zones with a complex topography and/or coastline.
Ostergaard Jakob - One of the best experts on this subject based on the ideXlab platform.
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North Sea Wind Power Hub: System Configurations, Grid Implementation and Techno-economic Assessment
2020Co-Authors: Misyris Georgios, Chatzivasileiadis Spyros, Van Cutsem Thierry, Moller Jakob, Dijokas Matas, Renom Estragués Oma, Bastin Bertrand, Nielsen Arne, Weckesser Tilman, Ostergaard JakobAbstract:peer reviewedaudience: researcher, professional, studentIn 2017, Energinet and TenneT, the Danish and Dutch Transmission System Operators (TSOs), have announced the North Sea Wind Power Hub (NSWPH) project. The project aims at increasing by 36 GW the North Sea offshore wind capacity, with an Artificial Island collecting all the power produced by wind turbines and several HVDC links transmitting this power to the onshore grids. This project brings together new opportunities and new challenges, both from a technical and economic point of view. In this regard, this paper presents three analyses regarding the design and operation of such an offshore system. First, we perform a techno-economic assessment of different grid configurations for the collection of the power produced by wind farms and its transmission to the hub. In this analysis, two frequencies and two voltage levels for the operation of the offshore grid are investigated. Our findings show that the nominal-frequency high-voltage option is the more suitable, as low-frequency does not bring any advantage and low-voltage would results in higher costs. The second analysis is related to the differences in operating the system with low- or zero-inertia; different dynamic studies are performed for each configuration to identify proper control actions and their stability properties. Comparing the outcomes of the simulations, we observed that voltage and frequency oscillations are better damped in the zero-inertia system; however, the risk of propagating offshore faults in the connected onshore grids is mitigated with the inclusion of the synchronous condensers. Lastly, a comparison of ElectroMagnetic Transient (EMT) and phasor-mode (also known as RMS) models is presented, in order to understand their appropriateness of simulating low- and zero- inertia systems. The results show that phasor approximation modelling can be used, as long as eigen-frequencies in power network are well damped.multiD
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North Sea Wind Power Hub: System Configurations, Grid Implementation and Techno-economic Assessment
2020Co-Authors: Misyris Georgios, Chatzivasileiadis Spyros, Van Cutsem Thierry, Moller Jakob, Dijokas Matas, Renom Estragués Oma, Bastin Bertrand, Nielsen Arne, Weckesser Tilman, Ostergaard JakobAbstract:In 2017, Energinet and TenneT, the Danish and Dutch Transmission System Operators (TSOs), have announced the North Sea Wind Power Hub (NSWPH) project. The project aims at increasing by 36 GW the North Sea offshore wind capacity, with an Artificial Island collecting all the power produced by wind turbines and several HVDC links transmitting this power to the onshore grids. This project brings together new opportunities and new challenges, both from a technical and economic point of view. In this regard, this paper presents three analyses regarding the design and operation of such an offshore system. First, we perform a techno-economic assessment of different grid configurations for the collection of the power produced by wind farms and its transmission to the hub. In this analysis, two frequencies and two voltage levels for the operation of the offshore grid are investigated. Our findings show that the nominal-frequency high-voltage option is the more suitable, as low-frequency does not bring any advantage and low-voltage would results in higher costs. The second analysis is related to the differences in operating the system with low- or zero-inertia; different dynamic studies are performed for each configuration to identify proper control actions and their stability properties. Comparing the outcomes of the simulations, we observed that voltage and frequency oscillations are better damped in the zero-inertia system; however, the risk of propagating offshore faults in the connected onshore grids is mitigated with the inclusion of the synchronous condensers. Lastly, a comparison of ElectroMagnetic Transient (EMT) and phasor-mode (also known as RMS) models is presented, in order to understand their appropriateness of simulating low- and zero- inertia systems. The results show that phasor approximation modelling can be used, as long as eigen-frequencies in power network are well damped.Peer reviewe
