Research On Cyber Attacks And Failure Mitigation Strategies Of Cyber-Physical Power System

Modern power system contains a large number of cyber equipment,the main function of these network equipment is to monitor,control and protect the physical network.The interdependence of cyber and physical network makes the modern power system become a typical information physical system,namely the cyber physical power system(CPPS).However,the cyber layer in CPPS brings new uncertainty while improving the quality of power supply.The unexpected failure of cyber layer may lead to the loss of observability and control of physical layer,which makes CPPS face great risk.Therefore,this paper mainly studies the vulnerability of CPPS when the cyber layer is attacked,and adopts some strategies to alleviate the cascading failure of CPPS.Consider the interdependence model to construct CPPS,convert the fault of the cyber layer into the change of the power flow of the grid layer,propose power vulnerability index and voltage vulnerability index based on the change of power flow,and study the change of the vulnerability index of CPPS after attacking the cyber node law.It is found that the disturbance of power and voltage can affect the vulnerability of CPPS.Attacking cyber nodes can cause CPPS to produce cascading failures,causing fluctuations in power vulnerability indicators and voltage vulnerability indicators,and reducing the proportion of remaining load and the rate of surviving nodes.Three mitigation strategies are proposed,one is the optimal DC power flow mitigation strategy which optimizes the traditional DC power flow model,the second is the load reduction mitigation strategy,the third is the load control mitigation strategy which can keep the residual load ratio close to the maximum possible value.The changes of residual load proportion are tested under different load factors,cyber network interdependence degree and power grid interdependence degree.Research shows that load control mitigation strategies can alleviate cascading faults to the greatest extent,and the load factor has a greater impact on the proportion of remaining load.The change in the degree of interdependence of the cyber network has a greater impact on the vulnerability of CPPS than the change in the degree of interdependence of the power grid has a greater impact on the vulnerability of CPPS.