With the rapid development of smart grid

the interaction between power system and communication network is becoming more and more frequent

and it is developing towards the deep coupling of "power network + communication network". In order to reveal the interaction between power grid and communication system under cascading faults

this paper uses complex dependent network theory to build an interactive cascade model of power coupled communication system based on DC power flow redistribution and open shortest path first (OSPF) policy

and considers the influence of abnormal transmission behavior. In order to analyze the influence of different dependencies and structural characteristics of communication networks on grid chain faults

two kinds of communication network structures are proposed

and the dependency relationships are divided into four categories

and the method of quantifying the dependencies is given. Based on this

the coupling model of IEEE-118 node system and actual power grid in a certain region is established and simulated respectively

and the influence of network structure characteristics

dependency types

communication transmission efficiency and other factors on the cascading failures of power coupled communication system is explored. The simulation results show that choosing a reasonable communication network structure and dependence relationship can improve the robustness of power grid against cascading faults

and provide a reasonable reference for improving the security of complex power communication systems.