| The distribution network is at the end of the power grid.The nodes have short distances,difficult operation and limited control effects,which leads to insufficient flexibility of the distribution network to cope with “customized power demand” and “source and load random fluctuations.” Applying traditional regulation Means will not be able to achieve unbalanced feeder load,distributed energy consumption,fast fault isolation,and difficult to realize custom power.Soft Normally Open Point as a full-featured flexible device can effectively avoid the limitations of traditional control methods.Soft Normally Open Point was first proposed by Imperial College of Technology in 2010 and is often referred to as Soft Normally Open Point(SNOP).The flexible multi-state switch topology is based on back-toback voltage source converters,which can be adjusted for inverters.The amplitude,phase and waveform of the output voltage.The Soft Normally Open Point can control the power flow transmitted between multiple feeders,can also realize flexible on-off switching control,and can provide power quality management function.The flexible multi-state switch is connected to the distribution network and is the primary problem for Smart distribution.In this paper,the IEEE33 node system is taken as an example to analyze the characteristics of open-loop operation of the closed-loop design of the distribution network topology.The distribution network nodes are layered according to the characteristics of the adjacency matrix in the graph theory,and the layer-by-layer search is performed between any two nodes based on this hierarchical structure.The shortest connection path.Introduces the community structure of the network in the graph theory,and weights the corresponding side of the branch with reference to the electrical distance.Based on this weight,the edge number of each edge is calculated.The reference value is compared to delete the edge whose median is greater than the given value,and the network topology is divided into several regions.Combined with the flexibility evaluation index,the distribution network is divided into community structures with the same flexible attributes.After dividing the distribution network into several areas,it is the next step of the research to connect the Soft Normally Open Point with which node in the partition.Therefore,the load center search method based on load moment is introduced,based on the load moment.The selection method of the dominant nodes of each community structure is considered,and the power distribution of the distribution network is modified correspondingly in different scenarios.The selection method of the partition dominant nodes considering multiple time scales is established,which is the connection of the subsequent flexible multi-state switches.The method establishment provides a reference,which effectively reduces the combination method and reduces the calculation difficulty.After dividing the distribution network into several regions and selecting the dominant node,the connection method can effectively improve the flexibility of each node of the system.This is the next research work in this paper.Finally,based on the above method,the flexible multi-state is given.The full connection mode of the switch determines the number of ports of the Soft Normally Open Point through the flexibility combination between different areas,establishes a flexible multi-state switch connection method for determining the number of ports,and combines the physical distance,the limit of the number of contact switches per checkpoint,and the contact capacity.The limitation and other restrictions on the set of connection modes are reduced,and the Soft Normally Open Point access mode set of the distribution network is given.Finally,an example analysis of the IEEE33 node power distribution system is given and given The set of access modes of the Soft Normally Open Point under the topology. |
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