The purpose of this work is to assess wind potential on the Kanfarandé site (Guinea). The data used for this research covers a period of 6 years (2018 to 2023) and consists of in situ data (Boké meteorologic...The purpose of this work is to assess wind potential on the Kanfarandé site (Guinea). The data used for this research covers a period of 6 years (2018 to 2023) and consists of in situ data (Boké meteorological station) and satellite products via NASA Power Larc. The study is based on sorted hourly data (speed and direction). The treatments focus on the monthly, annual and seasonal average of speeds, by sector and their frequencies as well as the annual available powers. The obtained results made it possible, on the one hand, to assess wind potential and, on the other hand, to highlight the most favorable periods for wind energy exploitation. The analyzes show the months of July and August have the best average wind speeds with 5.01 m/s and 5.34 m/s respectively. Average wind speeds are higher during the day than at night with a peak observed at 6 p.m. The study also shows that the prevailing winds are oriented towards the South-West. The Weibull parameters determined for the site give an average of 4.5 m/s for the scale parameter and for the shape parameter 2.40 corresponding to an average power density of 65 w/m2 with an annual available power of 194.80 W/m2 and an annual available energy of 1706.45 kWh/m2.展开更多
Switched reluctance motor power converters are prone to open-circuit faults because it need to withstand large voltages and currents.Due to the small number of traditional asymmetrical half bridge topology switches,it...Switched reluctance motor power converters are prone to open-circuit faults because it need to withstand large voltages and currents.Due to the small number of traditional asymmetrical half bridge topology switches,it is difficult to carry out fault tolerant control when power converters has an open-circuit fault,resulting in larger output torque ripple.This paper presents a five-level power converter based on the traditional asymmetric half-bridge power converter.The five-level topology has more switching states and can work in multi-level mode.Based on the topology,different excitation and demagnetization voltages can be choose at different speeds.A fault-tolerance strategy is developed to decrease the influence of the open-circuit fault.The five-level power converter has four switches per phase,and two of them will be used in one of the operating mode.So the remaining two of the switches can be used for safe backup,enabling fault-tolerant control when an open-circuit occur.Since each phase of the five-level power converter proposed in this paper is independent of each other,a reasonable control strategy can be used to avoid the unbalance of the midpoint potential.Finally,the topology and fault-tolerant strategy proposed in this paper are verified by simulation and experiment.展开更多
Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentia...Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions.展开更多
Decarbonization of the energy system is the key to China’s goal of achieving carbon neutrality by 2060.However,the potential of wind and photovoltaic(PV)to power China remains unclear,hindering the holistic layout of...Decarbonization of the energy system is the key to China’s goal of achieving carbon neutrality by 2060.However,the potential of wind and photovoltaic(PV)to power China remains unclear,hindering the holistic layout of the renewable energy development plan.Here,we used the wind and PV power generation potential assessment system based on the Geographic Information Systems(GIS)method to investigate the wind and PV power generation potential in China.Firstly,the high spatial-temporal resolution climate data and the mainstream wind turbines and PV modules,were used to assess the theoretical wind and PV power generation.Then,the technical,policy and economic(i.e.,theoretical power generation)constraints for wind and PV energy development were comprehensively considered to evaluate the wind and solar PV power generation potential of China in 2020.The results showed that,under the current technological level,the wind and PV installed capacity potential of China is about 56.55 billion kW,which is approximately 9 times of those required under the carbon neutral scenario.The wind and PV power generation potential of China is about 95.84 PWh,which is approximately 13 times the electricity demand of China in 2020.The rich areas of wind power generation are mainly distributed in the western,northern,and coastal provinces of China.While the rich areas of PV power generation are mainly distributed in western and northern China.Besides,the degree of tapping wind and PV potential in China is not high,and the installed capacity of most provinces in China accounted for no more than 1%of the capacity potential,especially in the wind and PV potential-rich areas.展开更多
文摘The purpose of this work is to assess wind potential on the Kanfarandé site (Guinea). The data used for this research covers a period of 6 years (2018 to 2023) and consists of in situ data (Boké meteorological station) and satellite products via NASA Power Larc. The study is based on sorted hourly data (speed and direction). The treatments focus on the monthly, annual and seasonal average of speeds, by sector and their frequencies as well as the annual available powers. The obtained results made it possible, on the one hand, to assess wind potential and, on the other hand, to highlight the most favorable periods for wind energy exploitation. The analyzes show the months of July and August have the best average wind speeds with 5.01 m/s and 5.34 m/s respectively. Average wind speeds are higher during the day than at night with a peak observed at 6 p.m. The study also shows that the prevailing winds are oriented towards the South-West. The Weibull parameters determined for the site give an average of 4.5 m/s for the scale parameter and for the shape parameter 2.40 corresponding to an average power density of 65 w/m2 with an annual available power of 194.80 W/m2 and an annual available energy of 1706.45 kWh/m2.
文摘Switched reluctance motor power converters are prone to open-circuit faults because it need to withstand large voltages and currents.Due to the small number of traditional asymmetrical half bridge topology switches,it is difficult to carry out fault tolerant control when power converters has an open-circuit fault,resulting in larger output torque ripple.This paper presents a five-level power converter based on the traditional asymmetric half-bridge power converter.The five-level topology has more switching states and can work in multi-level mode.Based on the topology,different excitation and demagnetization voltages can be choose at different speeds.A fault-tolerance strategy is developed to decrease the influence of the open-circuit fault.The five-level power converter has four switches per phase,and two of them will be used in one of the operating mode.So the remaining two of the switches can be used for safe backup,enabling fault-tolerant control when an open-circuit occur.Since each phase of the five-level power converter proposed in this paper is independent of each other,a reasonable control strategy can be used to avoid the unbalance of the midpoint potential.Finally,the topology and fault-tolerant strategy proposed in this paper are verified by simulation and experiment.
基金financially supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Grant No.2022R1I1A1A01069442)the 2024 Hongik University Research Fund。
文摘Salter's duck,an asymmetrical wave energy converter(WEC)device,showed high efficiency in extracting energy from 2D regular waves in the past;yet,challenges remain for fluctuating wave conditions.These can potentially be addressed by adopting a negative stiffness mechanism(NSM)in WEC devices to enhance system efficiency,even in highly nonlinear and steep 3D waves.A weakly nonlinear model was developed which incorporated a nonlinear restoring moment and NSM into the linear formulations and was applied to an asymmetric WEC using a time domain potential flow model.The model was initially validated by comparing it with published experimental and numerical computational fluid dynamics results.The current results were in good agreement with the published results.It was found that the energy extraction increased in the range of 6%to 17%during the evaluation of the effectiveness of the NSM in regular waves.Under irregular wave conditions,specifically at the design wave conditions for the selected test site,the energy extraction increased by 2.4%,with annual energy production increments of approximately 0.8MWh.The findings highlight the potential of NSM in enhancing the performance of asymmetric WEC devices,indicating more efficient energy extraction under various wave conditions.
基金the research support of the National Key Research and Development Program of China(Grant No.2018YFC1509000)the National Natural Science Foundation of China(Grant No.42175191)the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK1001).
文摘Decarbonization of the energy system is the key to China’s goal of achieving carbon neutrality by 2060.However,the potential of wind and photovoltaic(PV)to power China remains unclear,hindering the holistic layout of the renewable energy development plan.Here,we used the wind and PV power generation potential assessment system based on the Geographic Information Systems(GIS)method to investigate the wind and PV power generation potential in China.Firstly,the high spatial-temporal resolution climate data and the mainstream wind turbines and PV modules,were used to assess the theoretical wind and PV power generation.Then,the technical,policy and economic(i.e.,theoretical power generation)constraints for wind and PV energy development were comprehensively considered to evaluate the wind and solar PV power generation potential of China in 2020.The results showed that,under the current technological level,the wind and PV installed capacity potential of China is about 56.55 billion kW,which is approximately 9 times of those required under the carbon neutral scenario.The wind and PV power generation potential of China is about 95.84 PWh,which is approximately 13 times the electricity demand of China in 2020.The rich areas of wind power generation are mainly distributed in the western,northern,and coastal provinces of China.While the rich areas of PV power generation are mainly distributed in western and northern China.Besides,the degree of tapping wind and PV potential in China is not high,and the installed capacity of most provinces in China accounted for no more than 1%of the capacity potential,especially in the wind and PV potential-rich areas.
