This paper described the impact of the electrical vehicle（EV） charging on the grid harmonic. In view of the randomness of the EV charging process, the harmonic admittance matrix method and superposition method were ...This paper described the impact of the electrical vehicle（EV） charging on the grid harmonic. In view of the randomness of the EV charging process, the harmonic admittance matrix method and superposition method were used to build the single and multiple EVs charging simulation model. By using Matlab as a simulation tool, we analyzed harmonic currents of single and multiple EVs chargers. The results show that the harmonic ratio is beyond the scope of the national harmonic standard. Finally a parallel hybrid active filter（PHAPF） was introduced for governance of harmonic.The experimental results show that net side harmonic currents are significantly reduced by using the PHAPF and meet the national standard GB/Z17625.6-2003 regulations limit.展开更多
Lithium-sulfur （Li-S） batteries with intrinsic merits in high theoretical energy density are the most promising candidate as the next-generation power sources. The strategy to achieve a high utilization of active ma...Lithium-sulfur （Li-S） batteries with intrinsic merits in high theoretical energy density are the most promising candidate as the next-generation power sources. The strategy to achieve a high utilization of active materials with high energy efficiency is strongly requested for practical applications with less energy loss during repeated cycling. In this contribution, a metal/nanocarbon layer current collector is proposed to enhance the redox reactions of polysulfides in a working Li-S cell. Such a concept is demon- strated by coating graphene-carbon nanotube hybrids （GNHs） on routine aluminum （AI） foil current collectors. The interracial conductivity and adhesion between the current collector and active material are significantly enhanced. Such novel cell configuration with metal/nanocarbon layer current collectors affords abundant Li ions for rapid redox reactions with small overpotential. Consequently, the Li-S cells with nanostructured current collectors exhibit an initial discharge capacity of 1,113 mAh g-1 at 0.5 C, which is -300 mAh g-1 higher than those without a GNH coating layer. The capacity retention is 73% for cells with GNH after 300 cycles. A reduced voltage hysteresis and a high energy efficiency of ca. 90% are therefore achieved. Moreover, the AI/GNH layer current collectors are easily implanted into current cell assembly process for energy storage devices based on complex multi-electron redox reactions （e.g., Li-S batteries, Li-O2 batteries, fuel cells, and flow batteries）.展开更多
Safe and efficient operation of batteries is always desired but batteries with a high energy density pose a threat to the system causing thermal breakdown,reduced performance and rapid ageing.To reduce such vulnerabil...Safe and efficient operation of batteries is always desired but batteries with a high energy density pose a threat to the system causing thermal breakdown,reduced performance and rapid ageing.To reduce such vulnerabilities,an optimum environment with controlled parameters is required.Four parameters have been considered for analysis,i.e.state of charge,current,voltage and temperature.The module makes a detailed analysis of the above-mentioned parameters and suggests a microcontroller-based prototype that is capable of monitoring the external factors in real time and generating relevant warnings.展开更多
基金supported by the National Basic Research Program of China(973 Program)under Grant No.2013CB228202the National Natural Science Foundation of China under Grant No.51361130153
文摘This paper described the impact of the electrical vehicle（EV） charging on the grid harmonic. In view of the randomness of the EV charging process, the harmonic admittance matrix method and superposition method were used to build the single and multiple EVs charging simulation model. By using Matlab as a simulation tool, we analyzed harmonic currents of single and multiple EVs chargers. The results show that the harmonic ratio is beyond the scope of the national harmonic standard. Finally a parallel hybrid active filter（PHAPF） was introduced for governance of harmonic.The experimental results show that net side harmonic currents are significantly reduced by using the PHAPF and meet the national standard GB/Z17625.6-2003 regulations limit.
基金supported by National Key Research and Development Program of China (2016YFA0202500, 2015CB932500)the National Natural Science Foundation of China (21776019, 21422604)
文摘Lithium-sulfur （Li-S） batteries with intrinsic merits in high theoretical energy density are the most promising candidate as the next-generation power sources. The strategy to achieve a high utilization of active materials with high energy efficiency is strongly requested for practical applications with less energy loss during repeated cycling. In this contribution, a metal/nanocarbon layer current collector is proposed to enhance the redox reactions of polysulfides in a working Li-S cell. Such a concept is demon- strated by coating graphene-carbon nanotube hybrids （GNHs） on routine aluminum （AI） foil current collectors. The interracial conductivity and adhesion between the current collector and active material are significantly enhanced. Such novel cell configuration with metal/nanocarbon layer current collectors affords abundant Li ions for rapid redox reactions with small overpotential. Consequently, the Li-S cells with nanostructured current collectors exhibit an initial discharge capacity of 1,113 mAh g-1 at 0.5 C, which is -300 mAh g-1 higher than those without a GNH coating layer. The capacity retention is 73% for cells with GNH after 300 cycles. A reduced voltage hysteresis and a high energy efficiency of ca. 90% are therefore achieved. Moreover, the AI/GNH layer current collectors are easily implanted into current cell assembly process for energy storage devices based on complex multi-electron redox reactions （e.g., Li-S batteries, Li-O2 batteries, fuel cells, and flow batteries）.
文摘Safe and efficient operation of batteries is always desired but batteries with a high energy density pose a threat to the system causing thermal breakdown,reduced performance and rapid ageing.To reduce such vulnerabilities,an optimum environment with controlled parameters is required.Four parameters have been considered for analysis,i.e.state of charge,current,voltage and temperature.The module makes a detailed analysis of the above-mentioned parameters and suggests a microcontroller-based prototype that is capable of monitoring the external factors in real time and generating relevant warnings.
