Analysis Of Cascading Failure Of Power Cyber-physical System Based On Complex Network Theory

As the core system of Energy Internet,modern power system has gradually developed into a power cyber physical system(CPS)formed by the deep integration of the cyber network(communication information system and monitoring/control system)and the power network(Primary power system).However,the deep integration of the cyber network and the power network makes the primary power system have the advantages of flexibility,autonomy,and high efficiency,which can better serve the Energy Internet,but it also brings new vulnerabilities.Therefore,it is significance for the reliable and safe operation of power system to study the interaction mechanism between cyber network and power network,analyze the influence of cyber attack on cascading failure,and complete the vulnerability assessment of nodes.Power CPS is the research object in this paper,the problem of cascading failure is studied from different perspectives,and vulnerability assessment of the system is performed.The main research work of this paper is as follows:The model of power cyber-physical system is established.The power flow characteristics of the power network and the monitoring and control functions of the cyber network are considered comprehensively to model the power cyber-physical system.First of all,the Newton-Raphson method is used to solve the AC power flow distribution of the power grid,and the power grid is characterized by combining the information of grid structure and power flow;Then,the cyber network model is established for the monitoring and control functions of the cyber network,which uses the optimal economic dispatching algorithm to regulate the power of each generator and decides the opening and closing state of the circuit breakers of each line of the power network.according to the power situation of the line;Thus,the multi-characteristic correlation power information physical system model is established to characterize the quantitative correlation relationship between the power network and the information network.The cascading analysis of power cyber-physical systems is researched based on complex network theory.Firstly,the importance assessment index of nodes is defined based on the complex network theory,and the important nodes are evaluated without the push-out of cascading failures;Secondly,based on the established power CPS model,the cascading failure analysis process is given according to the functional characteristics of power network and cyber network,and the node vulnerability assessment index is defined;Finally,the importance of nodes based on the complex network theory is verified through the push-out analysis of cascading failures;Finally,the accuracy of the node importance assessment index based on complex network theory is verified through the extrapolation analysis of cascading failures.The cascading failure analysis of power CPS considering network attacks is performed.First,the direct and indirect effects of network attacks on the system are analyzed theoretically;Then,the formulaic expression of the false data injection attack is given in conjunction with the established power CPS model,and the cascading failure analysis method considering the false data injection attack is proposed;Finally,the impact of data injection attacks on cascading failures is derived by comparing the scale of cascading failures when the system communication is normal and the upstream/downstream communication process is injected to false data injection attacks.