Towards Optimal Topological Structure Entropy for Robustness of Smart Grid against Cascading Failures

In smart grid, the different adjacencies of its nodes have different local influences on the robustness of power supply service. Due to the interdependency between power grid and information network within smart grid, the local influences depend actually on the inter/intro-linking topological structure between the coupled power-information nodes. Hence, how to optimize the topological structure is crucial to reduce the risk of cascading failures occurred from the targeted attack to some critical nodes. Firstly, we define a topological structure entropy to measure the local influence of each node to its multi-hop neighbors, which exists obvious difference between the linking nodes, and can further reveal the distribution of critical nodes within smart grid. Then in order to avoid attackers to accurately identify critical nodes and to control the cascading failures propagating in a smaller range, we uniformly shape the distribution of the entropy through adjusting inter-linking adjacencies to optimize the interdependent structure between power grid and information network. Specifically, according to the entropy distribution type of each coupled node pair classified by the upper/lower of reasonable threshold and the upper/lower of fluctuant threshold, we appropriately adopt multiple coupling and random coupling mode to reshape the interdependent structure between power grid and information network. Finally, we intentionally attack the same node under different coupling strategy. After this, we employ the node survival rate to evaluate the robustness of interdependent structure. The result demonstrates that the node survival rate of smart grid is higher after optimizing topological structure which indicates that the optimal strategy proposed in this paper can suppress the propagation of cascading failures and improve the robustness of smart grid.