Research On Immune Mechanism Of Power Cyber Physical Network Under Collaborative Attack

With the development of smart grids and the ubiquitous construction of power Internet of Things,power systems have gradually evolved into a Cyber Physical System(CPS)with deep coordination of cyber and physical systems.The stable operation of power physical systems is also increasing rely on the security of cyber systems.The information flow of the coupled system interacts with the energy flow more and more frequently.While improving the power perception,calculation,communication and control capabilities of the power grid,it also increases the security risk of the power CPS network.The network cooperative attack will cause the dual network cascade to fail and reduce the power CPS survivability.How to quantify the impact of network cooperative attacks on coupled power CPS and effectively suppress the spread of security risks is an urgent problem to be solved.Therefore,it is practical significant to establish a coupled model of power CPS,to quantify the survivability of network cooperative attacks,and to propose an immune method for brittle links.This paper studies the immune mechanism of collaborative attack of power cyber physical network.The main research work is as follows:(1)For the heterogeneity and coupling of power CPS nodes,it is difficult to characterize the information-energy flow interaction through the unweighted network model,and a weighted power information physical network model is constructed.Based on the analysis of topology and coupling relationship,the cyber network load optimization and physical network power flow distribution characteristics are integrated.The cyber network function and the physical network electrical media are defined as the weights of the connected edges in the network.The weighted correlation matrix and the initial load of the nodes are used.And capacity to achieve a formal representation of the coupled power CPS network,providing support for survivability assessment and immune methods.(2)Aiming at the problem that the power CPS scale is expanding and the existing cascade failure model ignores the information flow and the power flow transfer characteristics,making the survivability difficult to evaluate quickly and effectively,the power CPS survivability quantitative evaluation model under the network cooperative attack is designed.Taking into account the cascading failure load optimization redistribution process,the node load and capacity concept is introduced into the power CPS,starting from the two dimensions of the structural connectivity change and the risk propagation range of the coupled system cascading failure,based on the node load capacity limitation and information flow.The survivability evaluation model was designed based on the constraints of optimal allocation strategy,power flow optimization equation and system safety operation.The chaotic Lévy search firefly algorithm was used to solve the evaluation model efficiently.The example analysis shows that the model effectively quantifies the survivability of power CPS under network cooperative attack and improves the evaluation efficiency of large-scale coupled systems.(3)The security risk spread under the network cooperative attack is fast and spreads widely.It is difficult to improve the survivability of CPS by suppressing the risk outbreak by a small number of key nodes.The power CPS target immunity method based on high fragile information cell protection is proposed.Firstly,the cellular automaton theory is introduced to define the cellular CPS nodes,and the high-brittle cells are identified by considering the coupling network topology,functional attributes and interactions.Then,the high-brittle protection method is used to immunize the information cells,and the risk propagation probability is introduced.The target immune model is designed by cell recovery probability and immune probability.Finally,the immune model is solved by particle swarm optimization algorithm to improve the survivability of power CPS to network cooperative attack.The example analysis shows that the proposed high-brittle target immune model can improve the survivability of power CPS and effectively suppress the security risks caused by different types of network cooperative attacks.