Modeling Technique And Vulnerability Assessment Of Electrical Cyber Physical Systems Considering Cyber Attacks

With the development of smart grids,lots of communication devices such as sensors and actuators are equipped into power grids.The modern power system has developed into an electrical cyber physical system(ECPS)based on the deep integration of power grids and communication networks.However,the extensive use of advanced information technology and intelligent equipments may also bring potentially negative effects to the modern power system.Many security risks in communication networks may be introduced into power grids after the integrations.A small fault in power grids can lead to serious cascading failures owing to the complex interaction mechanism of ECPSs.Given these backgrounds,this dissertation explores the modeling technology,the propagation mechanism of cyber risks,and the vulnerability assessment issue in electrical cyber physical systems considering cyber attacks.The main technical contributions of this dissertation are as follows:(1)The modeling approach of electrical cyber physical systems based on DC power flow model.In this dissertation,we propose a double-layer framework of ECPSs considering communication transmission.Firstly,we model power grids based on DC power flow model with generators,loads and breakers as power nodes.Secondly,models of communication uplinks and downlinks in ECPSs for monitoring function and control function are proposed with sensors and actuators as interface nodes of power grids and communication networks.Finally,a multiple characteristic association approach is introduced for modeling ECPSs,quantitative analyses of the interrelationships between power grids and communication networks are also studied based on the ECPS model.(2)The risk propagation mechanism of cyber attacks in ECPSs.Firstly,we propose the detailed attack patterns based on measuring and controlling devices or uplinks and downlinks of communication transmission and a parameterized expression method for the risk propagation mechanism in ECPSs.Secondly,by defining attack matrix and updating model parameters,we propose a formulaic expression method for the impacts of three common attacks:destructive attacks,denial of service(DoS)attacks,and false data injection(FDI)attacks,based on the unified ECPS model.This study provides solutions for quantitatively analyzing impacts of different attacks on ECPSs.(3)Vulnerability assessment of Electrical cyber physical systems considering cascading failures in cyber attack environment.Combining the unified mathematic ECPS model and the parameterized expression of risk propagation mechanism,firstly,we propose an analysis method of system states during cascading failures considering cyber attacks.Secondly,based on the attack effects of ECPSs,we present the'Model-Calculation-Assessment' vulnerability assessment method with economic costs,the degree of damage and trip point as indicators.The rationality of the proposed model and the effectiveness of the vulnerability assessment method are proved based on qualitative and quantitative comparisons with other related studies.