DQ impedance-based method has been widely used to study the stability of three-phase converter systems.As the dq impedance model of each converter depends on its local dq reference frame,the dq impedance modeling of c...DQ impedance-based method has been widely used to study the stability of three-phase converter systems.As the dq impedance model of each converter depends on its local dq reference frame,the dq impedance modeling of complex converter networks gets complicated.Because the reference frames of different converters might not fully align,depending on the structure.Thus,in order to find an accurate impedance model of a complex network for stability analysis,converting the impedances of different converters into a common reference frame is required.This paper presents a comprehensive investigation on the transformation of dq impedances to a common reference frame in complex converter networks.Four different methods are introduced and analyzed in a systematic way.Moreover,a rigorous comparison among these approaches is carried out,where the method with the simplest transformation procedure is finally suggested for the modeling of complex converter networks.The performed analysis is verified by injecting two independent small-signal perturbations into the d and the q axis,and doing a point-by-point impedance measurement.展开更多
In traditional networks,enabling new network functions often needs to add new proprietary middleboxes.However,finding the space and power to accommodate these middleboxes is becoming increasingly difficult,along with ...In traditional networks,enabling new network functions often needs to add new proprietary middleboxes.However,finding the space and power to accommodate these middleboxes is becoming increasingly difficult,along with the increasing costs of energy and capital in-vestment.Due to the heterogeneous nature of hardware middleboxes,they suffer from long development and up-grading cycles and are hard to scale at peak load.展开更多
利用低压直流智能软开关(low voltage DC soft open point,LVDC-SOP)可实现多个低压直流微电网可控的柔性互联,如何实现合理灵活的子网间功率交换是其需要解决的关键问题。为此,该文针对多端口LVDC-SOP提出了一种计及标幺化电压差值和...利用低压直流智能软开关(low voltage DC soft open point,LVDC-SOP)可实现多个低压直流微电网可控的柔性互联,如何实现合理灵活的子网间功率交换是其需要解决的关键问题。为此,该文针对多端口LVDC-SOP提出了一种计及标幺化电压差值和功率裕度的双向下垂控制策略。建立了基于标幺化直流母线电压差值的功率交换规则。在此基础上,提出了多端口LVDC-SOP双向下垂控制策略,并设计了子网功率裕度影响因子,下垂系数在工作范围内可平滑连续变化。所提策略可根据子网母线电压和功率裕度的变化,实时调节子网间交换功率,同时可兼顾LVDC-SOP的功率交换能力和稳定性。实验结果表明所提策略可实现子网间合理灵活的功率交换,提高了子网对不平衡功率的调节能力,降低了子网直流母线电压越限风险。展开更多
智能配电网的发展提升电网的自愈能力和恢复速度,然而,当系统遭遇大范围停电事故时,其恢复过程颇为复杂。因此,针对受损配电网供电中断问题,提出一种计及冷负荷效应的受损配电网两阶段恢复策略,用以生成含开关控制动作的配电网供电恢复...智能配电网的发展提升电网的自愈能力和恢复速度,然而,当系统遭遇大范围停电事故时,其恢复过程颇为复杂。因此,针对受损配电网供电中断问题,提出一种计及冷负荷效应的受损配电网两阶段恢复策略,用以生成含开关控制动作的配电网供电恢复策略。先生成支持馈线重配的传统恢复和分布式电源辅助的孤岛供电恢复计划。然后,生成最优开关切换操作序列,将其转化为混合整数线性规划(mix integer linear programming,MILP)问题,使受损配电网快速恢复到最终配置。最后,使用多馈线1069节点电力系统中模拟单线与多线故障时的配电网恢复策略。研究结果表明,所提策略能有效生成开关切换动作序列,合理利用所有资源快速恢复配电网,提高受损配电网的恢复速度与容量。展开更多
基金The support of the first and fourth authors is given by National Key R&D Program of China,2018YFB0905200.The support for the second and third authors is coming from BIRD171227/17 project of the University of Padova.
文摘DQ impedance-based method has been widely used to study the stability of three-phase converter systems.As the dq impedance model of each converter depends on its local dq reference frame,the dq impedance modeling of complex converter networks gets complicated.Because the reference frames of different converters might not fully align,depending on the structure.Thus,in order to find an accurate impedance model of a complex network for stability analysis,converting the impedances of different converters into a common reference frame is required.This paper presents a comprehensive investigation on the transformation of dq impedances to a common reference frame in complex converter networks.Four different methods are introduced and analyzed in a systematic way.Moreover,a rigorous comparison among these approaches is carried out,where the method with the simplest transformation procedure is finally suggested for the modeling of complex converter networks.The performed analysis is verified by injecting two independent small-signal perturbations into the d and the q axis,and doing a point-by-point impedance measurement.
基金Acknowledgements： This work is supported by grants from the National Natural Science Foundation of China （No. 60203044, 90412010） and 242 program #（242）2007A07.
文摘In traditional networks,enabling new network functions often needs to add new proprietary middleboxes.However,finding the space and power to accommodate these middleboxes is becoming increasingly difficult,along with the increasing costs of energy and capital in-vestment.Due to the heterogeneous nature of hardware middleboxes,they suffer from long development and up-grading cycles and are hard to scale at peak load.
文摘利用低压直流智能软开关(low voltage DC soft open point,LVDC-SOP)可实现多个低压直流微电网可控的柔性互联,如何实现合理灵活的子网间功率交换是其需要解决的关键问题。为此,该文针对多端口LVDC-SOP提出了一种计及标幺化电压差值和功率裕度的双向下垂控制策略。建立了基于标幺化直流母线电压差值的功率交换规则。在此基础上,提出了多端口LVDC-SOP双向下垂控制策略,并设计了子网功率裕度影响因子,下垂系数在工作范围内可平滑连续变化。所提策略可根据子网母线电压和功率裕度的变化,实时调节子网间交换功率,同时可兼顾LVDC-SOP的功率交换能力和稳定性。实验结果表明所提策略可实现子网间合理灵活的功率交换,提高了子网对不平衡功率的调节能力,降低了子网直流母线电压越限风险。
文摘智能配电网的发展提升电网的自愈能力和恢复速度,然而,当系统遭遇大范围停电事故时,其恢复过程颇为复杂。因此,针对受损配电网供电中断问题,提出一种计及冷负荷效应的受损配电网两阶段恢复策略,用以生成含开关控制动作的配电网供电恢复策略。先生成支持馈线重配的传统恢复和分布式电源辅助的孤岛供电恢复计划。然后,生成最优开关切换操作序列,将其转化为混合整数线性规划(mix integer linear programming,MILP)问题,使受损配电网快速恢复到最终配置。最后,使用多馈线1069节点电力系统中模拟单线与多线故障时的配电网恢复策略。研究结果表明,所提策略能有效生成开关切换动作序列,合理利用所有资源快速恢复配电网,提高受损配电网的恢复速度与容量。
