In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software Orca Flex. Hydrodyna...In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software Orca Flex. Hydrodynamics coefficients of the vessel are calculated by using a 3D diffraction/radiation panel program. First- and second-order wave forces are included in the calculations. Morison equation is used to compute the drag force on line elements representing the net. Drag coefficients are determined at every time step in the simulation considering the relative normal velocity between the structural elements and the fluid flow. The dynamic response of the coupled system is analyzed for various environments and net materials. The results of the study show the effects of solidity ratio of the net and vertical positions of the cage on the overall dynamic response of the system, confirming the viability of this type of configuration for future development of offshore aquaculture in deep waters.展开更多
This study is concerned with the feasibility of power generation using a pico-hydraulic turbine from sewage flowing in pipes. First, the sewage flow rate at two connection points to the Toyogawa River-Basin Sewerage, ...This study is concerned with the feasibility of power generation using a pico-hydraulic turbine from sewage flowing in pipes. First, the sewage flow rate at two connection points to the Toyogawa River-Basin Sewerage, Japan, was explored for over a year to elucidate the hydraulic energy potential of the sewage. Second, the performance of the pico-hydraulic turbine was investigated via laboratory experiments that supposed the turbine to be installed in the sewage pipe at the connection points. This study indicates that the connection points have hydraulic potential that can be used for power generation throughout the year. It also demonstrates that the pico-hydraulic turbine can be usefully employed for power generation from sewage flowing in the pipe at the connection points.展开更多
In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperatur...In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.展开更多
The site selection of converter stations for voltage source converter-based direct current(VSC-DC)interties can significantly impact their control performance,particularly when both grid-following control(GFL)and grid...The site selection of converter stations for voltage source converter-based direct current(VSC-DC)interties can significantly impact their control performance,particularly when both grid-following control(GFL)and grid-forming control(GFM)are configured.It is challenging to fully realise the maximum potential of both control modes at a single node within an urban power grid.This paper proposes a novel converter station site selection method to identify optimal connection points in urban grids,enabling efficient active power transfer while providing flexible active and reactive power support in inter-connected urban areas.First,a comprehensive index system is developed to quantitatively assess the impact of VSC-DC intertie converter station siting on urban grids under both GFL and GFM modes.The proposed method utilises voltage stability margins to quickly rank candidate nodes and combines Euclidean distance with grey relational analysis to determine the most advantageous locations.A case study demonstrates the effectiveness of the proposed approach.The results show that the novel site selection method ensures converter stations configured with both GFL and GFM are optimally sited,thereby maximising control performance,significantly enhancing power support capabilities,and improving resilience at the connected nodes.展开更多
基金Kampachi Farms LLC for their support to complete this work and for all the technical information provided to complete the numerical model
文摘In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software Orca Flex. Hydrodynamics coefficients of the vessel are calculated by using a 3D diffraction/radiation panel program. First- and second-order wave forces are included in the calculations. Morison equation is used to compute the drag force on line elements representing the net. Drag coefficients are determined at every time step in the simulation considering the relative normal velocity between the structural elements and the fluid flow. The dynamic response of the coupled system is analyzed for various environments and net materials. The results of the study show the effects of solidity ratio of the net and vertical positions of the cage on the overall dynamic response of the system, confirming the viability of this type of configuration for future development of offshore aquaculture in deep waters.
文摘This study is concerned with the feasibility of power generation using a pico-hydraulic turbine from sewage flowing in pipes. First, the sewage flow rate at two connection points to the Toyogawa River-Basin Sewerage, Japan, was explored for over a year to elucidate the hydraulic energy potential of the sewage. Second, the performance of the pico-hydraulic turbine was investigated via laboratory experiments that supposed the turbine to be installed in the sewage pipe at the connection points. This study indicates that the connection points have hydraulic potential that can be used for power generation throughout the year. It also demonstrates that the pico-hydraulic turbine can be usefully employed for power generation from sewage flowing in the pipe at the connection points.
基金supported by the National Natural Science Foundation of China(No.62271109)。
文摘In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.
基金National Natural Science Foundation of China,Grant/Award Number:52207119Young Elite Scientists Sponsorship Program by CAST,Grant/Award Number:2023QNRC001Shandong Provincial Natural Science Foundation,China,Grant/Award Number:ZR2024QE468。
文摘The site selection of converter stations for voltage source converter-based direct current(VSC-DC)interties can significantly impact their control performance,particularly when both grid-following control(GFL)and grid-forming control(GFM)are configured.It is challenging to fully realise the maximum potential of both control modes at a single node within an urban power grid.This paper proposes a novel converter station site selection method to identify optimal connection points in urban grids,enabling efficient active power transfer while providing flexible active and reactive power support in inter-connected urban areas.First,a comprehensive index system is developed to quantitatively assess the impact of VSC-DC intertie converter station siting on urban grids under both GFL and GFM modes.The proposed method utilises voltage stability margins to quickly rank candidate nodes and combines Euclidean distance with grey relational analysis to determine the most advantageous locations.A case study demonstrates the effectiveness of the proposed approach.The results show that the novel site selection method ensures converter stations configured with both GFL and GFM are optimally sited,thereby maximising control performance,significantly enhancing power support capabilities,and improving resilience at the connected nodes.
