Research On Structural Vulnerability Of Transmission Network Based On Complex Network Theory

The occurrence of frequent blackouts accentuates the vulnerability of the power system itself.Traditional methods of safety assessment based on reduction theory have not been able to analyze the vulnerability of power system and the propagation mechanism of cascading failures.The power network can be abstracted as a complex network with a large number of nodes and edges.Therefore,it is possible to study the power system vulnerability from the perspective of complex network theory.In this paper,further research is done,including the establishment of the complex network model,the identification of fragile components in the power network and the static analysis of the fragility of the power system structure.Specific research contents and achievements are as follows:In this paper,weighted and directed network model is constructed.The model considers both the flow characteristics of the power flow and the influence of the system and load capacity.In the weighted and directed model,the edge direction is the real active power direction and the edge weight is the apparent power flowing through the line.This model is more suitable than original model,in which the power flow in line by the shortest path.And the equivalent load power virtual nodes and equivalent load power virtual nodes are introduced to represent the effect of the system and load capacity on the transmission network.Based on this,the formulas of the static parameters of the network model are given.Based on the weighted and directed network model,the vulnerability index: node comprehensive importance degree index and the integrated weighted directed ed ge factor,is proposed,which can reflect the role of components in network structure and power flow.By comparing the results of the existing model with the simulation of IEEE30 node system,the feasibility and comprehensiveness of the model and the index is verified.Based on the static analysis method,this paper studies the structure fragility of the power grid.The operation state index of the power network-maximum connected domain and the loss-of-load ratio of the grid are used to represent the effect of the component failure on the operating state of the grid.Subsequently,the dynamic behavior of the power grid in the 4 fragile element removal strategies is analyzed.The results show that the power system is robust to random attacks,and the weak elements play a key role in the propagation of cascading failures.From the perspective of complex network theory,the existence of fragile link of power grid structure is proved.