The FREEDM （future renewable electric energy delivery and management） system is a smart distribution system that facilitates seamless integration of high-penetration DRER （distributed renewable energy resources） a...The FREEDM （future renewable electric energy delivery and management） system is a smart distribution system that facilitates seamless integration of high-penetration DRER （distributed renewable energy resources） and DESD （distributed energy storage devices） with the existing distribution system. Protection schemes have been proposed to detect the overcurrent faults throughout the FREEDM system, according to its requirements. In this paper the time inverse directional over current protection coordination scheme is developed as a backup protection when the primary protection communication failed. The proposed scheme is applied to FREEDM network using conventional mathematical model. To speed up the fault clearing time without coordination loss, the settings of the proposed relays in the two directions are minimized using genetic algorithm. The developed methods are validated using ETAP software. The results ensure that the faults throughout the FREEDM system sections are detected and the relays tripping time are minimized.展开更多
在未来可再生电能传输和管理微网(future renewable electric energy delivery and management,FREEDM)中固态变压器间会因输出电压偏差及输出阻抗的不匹配而产生环流,孤岛模式下尤为严重,为此,在下垂控制器中引入固态变压器(solid stat...在未来可再生电能传输和管理微网(future renewable electric energy delivery and management,FREEDM)中固态变压器间会因输出电压偏差及输出阻抗的不匹配而产生环流,孤岛模式下尤为严重,为此,在下垂控制器中引入固态变压器(solid state transformer,SST)间输出电压偏差反馈调节,减小输出电压相角差和幅值差;采用基于模糊控制理论的瞬时环流反馈,进行动态虚拟阻抗调节,使得SST输出阻抗按额定功率精确匹配。仿真及分析表明,电压偏差反馈调节配合动态虚拟阻抗控制可以有效地抑制SST间环流,同时提高SST输出电压的稳定性。展开更多
针对新型微网系统FREEDM(Future Renewable Electric Energy Delivery and Management)中的快速开关系统,提出了一种新型的IGBT驱动控制电路。将IGBT应用于FREEDM的快速开关系统中,根据其在不同故障状态下的不同关断特性,利用集电极退...针对新型微网系统FREEDM(Future Renewable Electric Energy Delivery and Management)中的快速开关系统,提出了一种新型的IGBT驱动控制电路。将IGBT应用于FREEDM的快速开关系统中,根据其在不同故障状态下的不同关断特性,利用集电极退饱和原理,研究设计了具有双故障检测支路的IGBT驱动控制电路,从而保证IGBT在FREEDM中的可靠关断。最终通过Saber仿真和实验验证了驱动控制电路能够在各故障状态下可靠地关断IGBT。展开更多
Smart grid was proposed as a practical form of future power distribution system. Evaluating the reliability of smart grids was of great importance and significance. A revised fault tree model was proposed to distingui...Smart grid was proposed as a practical form of future power distribution system. Evaluating the reliability of smart grids was of great importance and significance. A revised fault tree model was proposed to distinguish and separate grid-connected operation mode and islanded operation mode of smart grids,focusing on the perspective of the consumers. A hierarchical Monte Carlo simulation method for reliability evaluation was also proposed based on the proposed fault tree model. A case of reliability evaluation for the future renewable electric energy delivery and management( FREEDM) system was carried out and analyzed. The proposed methods can be applicable to other forms of smart grids.展开更多
文摘The FREEDM （future renewable electric energy delivery and management） system is a smart distribution system that facilitates seamless integration of high-penetration DRER （distributed renewable energy resources） and DESD （distributed energy storage devices） with the existing distribution system. Protection schemes have been proposed to detect the overcurrent faults throughout the FREEDM system, according to its requirements. In this paper the time inverse directional over current protection coordination scheme is developed as a backup protection when the primary protection communication failed. The proposed scheme is applied to FREEDM network using conventional mathematical model. To speed up the fault clearing time without coordination loss, the settings of the proposed relays in the two directions are minimized using genetic algorithm. The developed methods are validated using ETAP software. The results ensure that the faults throughout the FREEDM system sections are detected and the relays tripping time are minimized.
文摘在未来可再生电能传输和管理微网(future renewable electric energy delivery and management,FREEDM)中固态变压器间会因输出电压偏差及输出阻抗的不匹配而产生环流,孤岛模式下尤为严重,为此,在下垂控制器中引入固态变压器(solid state transformer,SST)间输出电压偏差反馈调节,减小输出电压相角差和幅值差;采用基于模糊控制理论的瞬时环流反馈,进行动态虚拟阻抗调节,使得SST输出阻抗按额定功率精确匹配。仿真及分析表明,电压偏差反馈调节配合动态虚拟阻抗控制可以有效地抑制SST间环流,同时提高SST输出电压的稳定性。
文摘针对新型微网系统FREEDM(Future Renewable Electric Energy Delivery and Management)中的快速开关系统,提出了一种新型的IGBT驱动控制电路。将IGBT应用于FREEDM的快速开关系统中,根据其在不同故障状态下的不同关断特性,利用集电极退饱和原理,研究设计了具有双故障检测支路的IGBT驱动控制电路,从而保证IGBT在FREEDM中的可靠关断。最终通过Saber仿真和实验验证了驱动控制电路能够在各故障状态下可靠地关断IGBT。
文摘Smart grid was proposed as a practical form of future power distribution system. Evaluating the reliability of smart grids was of great importance and significance. A revised fault tree model was proposed to distinguish and separate grid-connected operation mode and islanded operation mode of smart grids,focusing on the perspective of the consumers. A hierarchical Monte Carlo simulation method for reliability evaluation was also proposed based on the proposed fault tree model. A case of reliability evaluation for the future renewable electric energy delivery and management( FREEDM) system was carried out and analyzed. The proposed methods can be applicable to other forms of smart grids.
