Research On Modeling And Vulnerability Analysis Of Cyber-physical Power System

The smart grid is a typical Cyber-physical System in nature.The cyber-physical integrating has deeply affected the process of power energy’s generating,transmitting and distributing.The functions such as monitoring,acquisition,calculation and control for power grid provided by cyber system improves the automation of Power Grid.The traditional power grid is gradually developing into the Cyber-physical Power System(CPPS).In recent years,the research on blackouts shows that cyber-physical integrating brings new security risks and the failure of cyber system is one of the main blackouts’ causes.In the future,with the development of Energy Internet,the integrating of cyber system and physical system is bound to be deepened.Therefore,it’s of great significance to carry out security assessment relating to CPPS.Based on this background,starting from the Interdependent Network(IN),this paper focuses on unified modeling,cascading failures and vulnerability analysis of CPPS.The details are shown as follows:In order to carry out unified modeling of CPPS,the relevant knowledge of IN is expounded,and the cascading failure process of interdependent networks is summarized.From three aspects of power grid,cyber network and interdependency,a CPPS interdependent network model is established in which the station-level modeling accuracy and partial one-to-one correspondence model are adopted.Using this method,two cases are proposed including IEEE-30-CPPS and IEEE-118-node-CPPS.The interdependency of IEEE-30-node-CPPS is built according to the reality and that of IEEE-118-CPPS is established through degree-betweenness coupling strategy.In order to analyze the structural vulnerability of CPPS and the impact on vulnerability of different topological cyber n etwork,the double-star and mesh models of cyber network are built through the generation method of cyber network.A CPPS comprehensive importance index of interdependent node-pair is proposed.According to this index,the importance of interdependent node-pair can be measured to much extent.From the perspective of attack,this paper presents a dynamic analytical method of structural vulnerability for CPPS,in which randomly attacking and deliberately attacking are both considered.This method is adopted in the comparative analysis of two CPPS which has two different topological structure.Finally,IEEE-118-node-CPPS test system is used to verify the proposed method.In order to consider the influence of electrical parameters on cascading failure and establish a more realistic cascading failure model of CPPS,the survival conditions of dependent network cascading failure model are expanded.Vector of Observable Vertex(VOV),Vector of Controllable Vertex(VCV),Vector of Observable Branch(VOB)and Vector of Controllable Branch(VCB)are introduced to analog the functions of supervision,acquisition and control of cyber system.The economic dispatching by Optimal power flow is adopted.An improved interdependent network cascading failure model is established,in which the electrical parameters and topology are both considered.In order to resolve the vulnerability of CPPS from the view of attack,based on the improved interdependent network cascading failure model,t he CPPS vulnerability index are proposed to reflect the power supply capability,topological integrity and the level of supervision and control,including Ratio of Survival Vertex in Power Grid(RSVPG),Ratio of Survival Branch in Power Grid(RSBPG),Ratio of Survival Observable Vertex(RSOV)and Ratio of Survival Controllable Branch(RSCB).The vulnerability of CPPS is analyzed under three different attack scenarios: single-branch attack,relay protection setting value attack and coordinated attack.Finally,the IEEE-118-node-system is used to verify the proposed method.