Risk Assessment And Vulnerability Identification Of Cyber-Physical Power System Based On Interdependent Network

With the continuous development of smart grids,traditional power systems with physical devices as the core gradually integrate with cyber systems and communication networks,thus developing into Cyber Physical Power System(CPPS).In the fusion process of cyber-physics,various security risks in cyber system may be introduced into the power system and affect the stable operation of the power grid across domains.There is a complex coupling mechanism between cyber systems and physical systems,and power systems may cause serious failure accidents due to cyber-attacks.Considering the impact of cyberattacks on distribution automation systems,it is assumed that the targets of cyber-attacks can be divided into two types.The first type is an attack on the load circuit breaker,resulting in a reduction in bus load.This attack against bus loads has a certain degree of randomness,which will result in equal reduction of bus loads in a certain area.The second type is the attack on the generator circuit breaker,causing a single generator to cut off.This attack has a strong purpose and only targets the generator bus.In view of this,this article studies the modeling techniques of CPPS and CPPS model based on the theory of interdependent networks.On this basis,risk assessment and vulnerability identification are conducted on the CPPS.Firstly,this article analyzes the modeling method of CPPS.Based on the IEC61850 structure of the distribution automation system,a CPPS interdependent network model considering node heterogeneity is constructed.Three standard examples of CPPS interdependent network models,IEEE-14 bus system,IEEE-30 bus system,and IEEE-118 bus system,are established to provide a topological structure model for risk assessment and vulnerability identification in the following text.Then,this article establishes a risk assessment of the CPPS under the first type of cyber-attacks.Calculate the risk probability of distribution stations in the cyber layer based on Bayesian Attack Graph(BAG),Common Vulnerability Scoring System(CVSS),Maximum Likelihood Estimation(MLE),and Junction Tree(JT)algorithms.And combined with the active and reactive power losses caused by the cross-domain impact on all corresponding bus nodes when the cyber node fails,a risk assessment is conducted on the cyber layer.Finally,considering the second type of cyber-attack that may lead to forced generator disconnection,it is necessary to analyze the vulnerability of the CPPS from the perspective of eliminating cascading failure and ensuring stable operation of the power grid.Subsequently,a cascading failure model was cited,combined with the Bayesian attack graph model established earlier,and its overload protection process was optimized to form an improved cascading failure model.Analyze the scenario of generator tripping caused by cyber-attacks,in order to analyze the vulnerability of the CPPS and identify vulnerable nodes in the generator bus.And in this strategy,the factors that affect the vulnerability of CPPS nodes are analyzed and validated through the method of indicator decomposition.