Reliability Analysis Method Of Security And Stability Control Services In Cyber Physical Power System

With the continuous development of communication technology,computing technology and control technology in the power system,the physical system and the information system are more and more closely linked,and the modern power system has already reflected the typical cyber physical system(CPS)characteristics.As an important line of defense to ensure the reliable operation of the power grid,the security and stability control system(SSCS)is located on the information side.Due to the large number of control nodes and the long control chain,if it encounters communication failures or cyber attacks,the security and stability control services will fail,which may cause cascading failure of the power system and cause huge operational risks to the power grid.Therefore,it is of great significance to study the reliability analysis method of the security and stability control services in the cyber physical power system(CPPS).This paper takes the load control business in the stability control system as an example,and studies the communication faults,cyber attacks and cascading failures involved in the reliability of the security and stability control services for CPPS.On the basis of the analysis and conclusions of the existing research in communication fault modeling,cyber attack modeling and cascading failure analysis,the research is carried out in four aspects: component reliability modeling,communication failures,cyber attacks and cascading failure of power system.The main contents of the article are listed as follows:(1)On the basis of analyzing the hierarchical structure,operation mode and communication technology of SSCS,a reliability modeling method for the components of the SSCS with the power optical transmission network as a typical architecture is proposed.Based on the fault tree analysis method,the reliability model of the safety and stability control device and communication equipment is established,and the reliability model of the network protection unit is established based on the Petri net method,which lays the groundwork for the following research.(2)Aiming at the problem that the current power grid cyber-physical system lacks a rapid reliability analysis method,the influence of communication interruption and communication delay on the stability control service is analyzed.Based on the complete transmission path of the security and stability control services and the reliability model of the stability control system components,a reliability modeling method for the security and stability control services considering the communication failure is firstly proposed,and then a reliability model for the stability control service based on the improved state space segmentation method is proposed.Finally,the method is quickly evaluated and verified by simulation in the standard system.The results show that the proposed method has significant advantages in terms of computational efficiency and computational speed.(3)In order to quantitatively evaluate the impact of cyber attacks on security and stability control services,a reliability assessment method for security and stability control services considering the vulnerability of cyber attacks is proposed.Firstly,the weak points of the stability control device body and the communication between the stations of the stability control devices are analyzed from the perspectives of attack objects,attack methods and attack consequences.Secondly,considering the characteristics of cyber attacks,the susceptibility of cyber attacks is quantified based on the fuzzy analytic hierarchy process.Combined with the cyber attack protection unit model established based on Petri net,the success probability model of cyber attacks is established.finally,the validity of the proposed reliability method is verified by standard system and actual system examples.(4)In order to study the influence of stability control services on the evolution process of cascading failure of power system,a cascading failure analysis method considering the security and stability control services is proposed.Firstly,considering the characteristics of cascading failure of power system,the probability index of cascading failure of power system is established based on the method of Markov chain.Four cascading failure evaluation indexes of power system are established based on the severity function: the severity of generator output fluctuation,the severity of power flow fluctuation,the severity of voltage fluctuation and the severity of loss of load fluctuation.Then,the comprehensive consequence index of cascading failure is established based on the fuzzy analytic hierarchy process.Finally,based on the failure probability of power line and deterministic method in the reliability evaluation,a cascading failure analysis method for power systems considering the reliability of security and stability control services is proposed,and the feasibility and rationality of the proposed method are verified in the standard system.