Research On Communication-based System Reliability Under The Framework Of Cyber-physical Power System

With the massive access of intermittent power supply,flexible load related to real-time pricing and power electronics technology,the operation and control of the future power grid will depend heavily on information feedback and decision-making,and information flow will become an indispensable link in the closed loop of energy flow in the power system.Therefore,the future power grid will develop into a complex network in which the physical energy systems and information systems are composited,namely the Cyber-Physical Power System(CPPS).Network transmission can achieve brilliant information sharing,but the uncertainties of information systems and potential network faults may lead to operational risks of physical systems.This paper focuses on the smart substation relay protection system based on communication network architecture and the smart distribution network based on the mix of the information and the physic,and carries out reliability analysis and evaluation under the framework of information physics system.Firstly,this paper analyses the characteristics of information flow in smart substation and its application problems,and studies the influencing factors of the realization of protection function in smart substation.Taking current differential protection which is most seriously affected by information flow as the research object,this paper quantitatively presents how information transmission quality affects misoperation and maloperation of relay protection,which lays a foundation for reliability analysis of intelligent substation protection system based on information flow.Secondly,the reliability of smart substation protection system is evaluated from the perspective of information physics fusion.According to the information flow characteristics and protection structure of smart substation,the reliability of mart substation protection system is studied with fault tree analysis method.This method builds a fault tree with the protection function failure as the top-level event,establishes the reliability analysis model of the intelligent substation protection system,and calculates the probability of occurrence of each fault event and the system reliability.Further analyzing the constraints of the process layer message transmission on the protection function implementation,the state space is divided into protected components,protection units,SV channels and GOOSE channels.A Markov model for evaluating the reliability of relay protection in intelligent substations is established.The corresponding state transition matrix is listed.The state space method is used to calculate the reliability of relay protection in intelligent substations.Finally,the reliability of distribution network with distributed power supply is studied from the perspective of information physical integration.This paper analyses the influence of distributed generation access on the reliability of load supply in distribution system,describes the relationship between the information of power supply load status and the accessibility of control decision,and constructs a fault tree analysis model of load supply reliability in distribution network considering the influence of information system.The reliability evaluation of distribution network considering information network faults is realized through the index of load out-of-control rate.