The limited energy density of lithium-ion capacitors poses a significant obstacle to their widespread application,primarily stemming from the inability of the electrodes to simultaneously fulfill both high energy dens...The limited energy density of lithium-ion capacitors poses a significant obstacle to their widespread application,primarily stemming from the inability of the electrodes to simultaneously fulfill both high energy density and rapid charging requirements.Experimental data demonstrate that a directional particle configuration can enhance charging speed while maintaining high-capacity density,but it is rarely discussed.Here,we have developed a particle-level electrochemical model capable of reconstructing an electrode with a directional particle configuration.By employing this method,an investigation was conducted to explore how the spatial morphology characteristics of particle configuration impact the energy storage characteristics of electrodes.Results demonstrate that rational particle configuration can effectively enhance the transport of lithium ions and create additional space for lithium-ion storage.With the same particle size distribution,the best electrode can increase the discharge capacity by up to132.4% and increase the charging SOC by 11.3% compared to the ordinary electrode under the condition of 6 C.These findings provide a further understanding of the energy storage mechanism inside the anisotropic particle distribution electrode,which is important for developing high-performance lithium-ion capacitors.展开更多
With the growing popularity of electric vehicles(EV),there is an urgent demand to solve the stress placed on grids caused by the irregular and frequent access of EVs.The traditional direct current(DC)fast charging sta...With the growing popularity of electric vehicles(EV),there is an urgent demand to solve the stress placed on grids caused by the irregular and frequent access of EVs.The traditional direct current(DC)fast charging station(FCS)based on a photovoltaic(PV)system can effectively alleviate the stress of the grid and carbon emission,but the high cost of the energy storage system(ESS)and the under utilization of the grid-connected interlinking converters(GIC)are not very well addressed.In this paper,the DC FCS architecture based on a PV system and ESS-free is first proposed and employed to reduce the cost.Moreover,the proposed smart charging algorithm(SCA)can fully coordinate the source/load properties of the grid and EVs to achieve the maximum power output of the PV system and high utilization rate of GICs in the absence of ESS support for FCS.SCA contains a self-regulated algorithm(SRA)for EVs and a grid-regulated algorithm(GRA)for GICs.While the DC bus voltage change caused by power fluctuations does not exceed the set threshold,SRA readjusts the charging power of each EV through the status of the charging(SOC)feedback of the EV,which can ensure the power rebalancing of the FCS.The GRA would participate in the adjustment process once the DC bus voltage is beyond the set threshold range.Under the condition of ensuring the charging power of all EVs,a GRA based on adaptive droop control can improve the utilization rate of GICs.At last,the simulation and experimental results are provided to verify the effectiveness of the proposed SCA.展开更多
为解决配电网、社区、充换电站3个利益主体之间难以保障能量最优交换和信息安全问题,提出一种主动配电网充换电站群智慧社区群的分层优化调度策略。首先,结合用户侧的储能需求和电动汽车充换电站的运行优化需求,在满足配电网经济运行的...为解决配电网、社区、充换电站3个利益主体之间难以保障能量最优交换和信息安全问题,提出一种主动配电网充换电站群智慧社区群的分层优化调度策略。首先,结合用户侧的储能需求和电动汽车充换电站的运行优化需求,在满足配电网经济运行的前提下建立电动汽车充换电站、配电网和社区共同参与的共享储能模式,上层为主动配电网运行模型,下层为社区和充换电站运行模型;其次,考虑各储能充换电站之间的交通流、能量流的时空特性,利用卡车对各电动汽车充换电站间的电池进行灵活调度,建立基于移动式储能车的电池时空共享模型;然后,为解决多主体(即充换电站、配电网、社区)参与的调度框架难以实现总体最优的问题,引入交替方向乘子法(alternating direction method of multipliers,ADMM)设计了社区充换电站配电网的3层能量共享模型;最后使用MATLAB对模型仿真编码求解。仿真结果表明:所提出的策略能够保障共享储能系统中各个主体隐私的安全性和用能的经济性,使能量共享形式更加多样化;可提高储能电池的使用效率和用能经济性,系统总成本降低了18%。展开更多
随着可再生能源比例增加,电网新建储能电站成为提升系统频率稳定性的重要手段。针对电网中分布式储能电站(distributedenergystoragestations,DESS)参与一次调频面临的荷电状态均衡问题,提出了一种考虑荷电状态(state of charge,SOC)一...随着可再生能源比例增加,电网新建储能电站成为提升系统频率稳定性的重要手段。针对电网中分布式储能电站(distributedenergystoragestations,DESS)参与一次调频面临的荷电状态均衡问题,提出了一种考虑荷电状态(state of charge,SOC)一致性的DESS协同控制策略。首先,构建了含分布式储能电站的区域电网调频模型,分析了传统调频控制方法的特点,并讨论了储能在高渗透率新能源电网中的调频及一致性控制需求;其次,分析了电网调频需求与DESS的SOC一致性调整需求之间的耦合关系,设计了基于一致性原理的SOC分布式控制策略,进而构建了兼顾两种需求的DESS一次调频协同控制方法,详细分析了关键控制参数的设计原则与取值方法。最后,搭建典型区域电网模型,结合不同频率波动工况进行了仿真验证,结果表明:所提控制策略可以有效改善电网频率质量,在不增加系统调频负担的前提下实现多个储能电站的SOC一致性调节,减小了DESS集群的SOC越限风险,增强了其聚合控制效果。展开更多
基金This work is supported by the National Key R&D Program of China(2021YFB2400400).
文摘The limited energy density of lithium-ion capacitors poses a significant obstacle to their widespread application,primarily stemming from the inability of the electrodes to simultaneously fulfill both high energy density and rapid charging requirements.Experimental data demonstrate that a directional particle configuration can enhance charging speed while maintaining high-capacity density,but it is rarely discussed.Here,we have developed a particle-level electrochemical model capable of reconstructing an electrode with a directional particle configuration.By employing this method,an investigation was conducted to explore how the spatial morphology characteristics of particle configuration impact the energy storage characteristics of electrodes.Results demonstrate that rational particle configuration can effectively enhance the transport of lithium ions and create additional space for lithium-ion storage.With the same particle size distribution,the best electrode can increase the discharge capacity by up to132.4% and increase the charging SOC by 11.3% compared to the ordinary electrode under the condition of 6 C.These findings provide a further understanding of the energy storage mechanism inside the anisotropic particle distribution electrode,which is important for developing high-performance lithium-ion capacitors.
基金supported in part by the National Key Research and Development Program of China under Grant No.2017YFF0108800in part by the National Natural Science Foundation of China under Grant No.61773109in part by the Major Program of National Natural Foundation of China under Grant No.61573094。
文摘With the growing popularity of electric vehicles(EV),there is an urgent demand to solve the stress placed on grids caused by the irregular and frequent access of EVs.The traditional direct current(DC)fast charging station(FCS)based on a photovoltaic(PV)system can effectively alleviate the stress of the grid and carbon emission,but the high cost of the energy storage system(ESS)and the under utilization of the grid-connected interlinking converters(GIC)are not very well addressed.In this paper,the DC FCS architecture based on a PV system and ESS-free is first proposed and employed to reduce the cost.Moreover,the proposed smart charging algorithm(SCA)can fully coordinate the source/load properties of the grid and EVs to achieve the maximum power output of the PV system and high utilization rate of GICs in the absence of ESS support for FCS.SCA contains a self-regulated algorithm(SRA)for EVs and a grid-regulated algorithm(GRA)for GICs.While the DC bus voltage change caused by power fluctuations does not exceed the set threshold,SRA readjusts the charging power of each EV through the status of the charging(SOC)feedback of the EV,which can ensure the power rebalancing of the FCS.The GRA would participate in the adjustment process once the DC bus voltage is beyond the set threshold range.Under the condition of ensuring the charging power of all EVs,a GRA based on adaptive droop control can improve the utilization rate of GICs.At last,the simulation and experimental results are provided to verify the effectiveness of the proposed SCA.
文摘为解决配电网、社区、充换电站3个利益主体之间难以保障能量最优交换和信息安全问题,提出一种主动配电网充换电站群智慧社区群的分层优化调度策略。首先,结合用户侧的储能需求和电动汽车充换电站的运行优化需求,在满足配电网经济运行的前提下建立电动汽车充换电站、配电网和社区共同参与的共享储能模式,上层为主动配电网运行模型,下层为社区和充换电站运行模型;其次,考虑各储能充换电站之间的交通流、能量流的时空特性,利用卡车对各电动汽车充换电站间的电池进行灵活调度,建立基于移动式储能车的电池时空共享模型;然后,为解决多主体(即充换电站、配电网、社区)参与的调度框架难以实现总体最优的问题,引入交替方向乘子法(alternating direction method of multipliers,ADMM)设计了社区充换电站配电网的3层能量共享模型;最后使用MATLAB对模型仿真编码求解。仿真结果表明:所提出的策略能够保障共享储能系统中各个主体隐私的安全性和用能的经济性,使能量共享形式更加多样化;可提高储能电池的使用效率和用能经济性,系统总成本降低了18%。
文摘随着可再生能源比例增加,电网新建储能电站成为提升系统频率稳定性的重要手段。针对电网中分布式储能电站(distributedenergystoragestations,DESS)参与一次调频面临的荷电状态均衡问题,提出了一种考虑荷电状态(state of charge,SOC)一致性的DESS协同控制策略。首先,构建了含分布式储能电站的区域电网调频模型,分析了传统调频控制方法的特点,并讨论了储能在高渗透率新能源电网中的调频及一致性控制需求;其次,分析了电网调频需求与DESS的SOC一致性调整需求之间的耦合关系,设计了基于一致性原理的SOC分布式控制策略,进而构建了兼顾两种需求的DESS一次调频协同控制方法,详细分析了关键控制参数的设计原则与取值方法。最后,搭建典型区域电网模型,结合不同频率波动工况进行了仿真验证,结果表明:所提控制策略可以有效改善电网频率质量,在不增加系统调频负担的前提下实现多个储能电站的SOC一致性调节,减小了DESS集群的SOC越限风险,增强了其聚合控制效果。
