Active And Passive Defense Strategies Of Cyber Physical Power System Considering Vulnerability

The deep fusion and mutual coupling of power grid and cyber network make power grid develop into cyber physical power system.The cyber physical power system realizes the overall perception of power grid through the real-time monitoring and effective control of power grid.The rapid development of network technology and the malicious attack against the power grid have brought great security risks to the operation and maintenance of the power system.Therefore,it is of great significance to analyze the vulnerability of the cyber physical power system and establish a comprehensive defense system.In this thesis,the establishment of the cyber physical power system model,the active and passive defense strategy at the information level and the grid active disconnection section search are studied.Specific research contents are as follows:(1)The "partial one-to-one correspondence" cyber physical power system is established.The model of power grid and information network is established according to complex network theory and matrix knowledge.The model of cyber physical power system is established by coupling the nodes in the information network and the nodes in the power grid with the coupling method of "degree-betweeness".Kernighan-Lin algorithm will be used to partition the information network,seting a central control node in the information network,seting a distributed control node in each community structure.The establishment of scale-free network and small-world network provides theoretical basis for the subsequent defense strategy.(2)Put forward the active and passive defense strategy considering vulnerability at the information level.Firstly,the vulnerability is analyzed from the physical characteristics and topological structure.In terms of physical characteristics,the physical vulnerability index is obtained by calculating the load reduction of optimal power flow.In terms of topology structure,the vulnerability index of topology structure is obtained by cascade calculation of the number of survival nodes.By establishing the weight of CRITIC,the comprehensive vulnerability index is obtained.Based on the results of vulnerability analysis,a certain number of virtual nodes are deployed as the active defense strategy at the information level.Deploying distributed control nodes to correct and repair device nodes is a passive defense strategy at the information level.Therefore,the active and passive defense system of information level is established.Simulation results show that the proposed active and passive defense strategies can improve the robustness of the system.The comprehensive vulnerability index makes up for the deficiency of vulnerability analysis from a single aspect.The active and passive defense strategy combines the advantages of active defense and passive defense to establish a comprehensive defense system at the information level.(3)An active dissolving surface search method considering engine homology constraints is improved.As the defense means of power grid,active disassembly is the last line of defense of power grid.In this thesis,the traditional spectral clustering algorithm is improved on the basis of considering the homogeneity of units,and the minimum power flow impact is taken as the optimization objective.The NP-difficult problem is transformed into the eigenvalue problem.Finally,the improved K-means clustering algorithm is used to get the active decolumn section scheme.An IEEE 118 node is implemented to realize active uncolumn,and the effectiveness of the active uncolumn strategy is verified by simulation of attacks on scale-free networks and small-world networks.