Analysis And Evaluation Method Of Structural Vulnerability Of Power Grid

In recent years, a couple of large-scale blackouts occurred all over the world, whichbrought a devastating impact on social life. Traditional analysis methods based on reduc-tionism have shown some limitations in explaining the mechanisms of large-scale blackoutsand complex dynamics in power grid, while complex network theory provide an originalperspective in studying the structural vulnerability of power grid.At present, there are several problems generally existed in studying structural vulner a-bility of power grid based on complex network theory, such as abstract or simple model,incomplete failure indices and lack of evaluation methodology of structural vulnerability ofpower grid, etc. This paper studies structural vulnerability of power grid from three aspectsto settle the existing problem.Firstly, the electrical betweenness is improved. The electrical distance between gener-ator node and load node is added as a weight, which can make more accurate evaluation ofthe effect of power transmission between nodes on the whole power flow, and will makethe result conform to reality. The model used in this paper is compared with existing modelby simulation.Furthermore, structural overload index (SOI) is proposed to identify the critical nodesand lines that have strong possibility to cause cascading failures. The model of cascadingfailure is modified by adding power balance adjustment strategy, and a new index is definedto represent system failures. The index used in this paper has considered the dynamic im-pact of system after failures and can better identify the component with high possibility tocascading failures.Finally, a method of evaluating structural vulnerability of power grid based on struc-tural equilibrium degree is proposed. Based on the analysis on influencing factor of struc-tural vulnerability, structural equilibrium and structural equilibrium degree are defined inthis paper. Gini index is introduced as measuring indicators of structural equilibrium degree,and the relationship between structural equilibrium degree and structural vulnerability isutilized to evaluate power grid s structural vulnerability. Using the index, the impact onpower grid s structural vulnerability of changing grid structure and power source s positionis also analyzed.