Application Of Graph Calculation In Complex Power Grid Structure Analysis

Power grid is one of the most complex huge system in the world, the complexity of its structure makes graphical power system and topology modeling work is particularly becoming important. In recent years, a large area of power outages occur frequently in the world, experimental data analysis showed that the large area blackout is generally because of problems with power system in some key nodes and lines, then other components have been suspended to the occurrence of a chain reaction. Therefore, identification of complex grid structure in the key link have important significance to maintain the safety and reliability of the power grid, reduce the cascading failure occurrence probability.The identification of key links can be started from the node degree distribution and the number of lines. Based on the previous studies, this paper takes the IEEE node test system as an example, and makes a study on the vulnerability of the power grid on the basis of the characteristics of the power grid structure and the power operation.Firstly, based on the theory of graph theory, the network topology is simplified, and several different topology model are realized based on the complex network. In this paper, the characteristic parameters such as degree, clustering coefficient and average path length of the actual network and each complex network are calculated, and the results are compared. The results show that the average path length and clustering coefficient of the grid structure are similar to that of the small world network, which is more close to the small world network.Secondly, this paper on the structure of complex networks on the basis of the research on power grid vulnerability were analyzed, in addition to the degree and line weight as deliberate attacks outside. It also puts forward the line betweenness attack strategy, and identification of key nodes with node important degree function. The experimental results show that, in addition to the degree and the number of the nodes, the node importance function also has a great influence on the vulnerability of power grid. And three kinds of evaluation indexes are proposed, and the effective method to analyze the vulnerability of power grid is verified.Finally, the network characteristics and power characteristics are considered in this paper, and the characteristics of cascading failures are analyzed. The attack strategy was improved by using the line number index and the line load index, and the network transmission efficiency was used to evaluate the change of the transmission capacity after the fault attack.Based on IEEE 118 and IEEE 57 node system, the dynamic circuit fault attack simulation experiment is carried out, and the attack strategy is evaluated. The experimental results show that the line load induced the maximum number of lines of attack can make the network transmission efficiency decreased rapidly, decline rate is higher than the line betweenness, prove that the strategy in the discovery of the effectiveness of key line in a power grid.