| With the development of smart grids,the traditional power systems is gradually shifting from a single power network to a cyber physical power system(CPPS)that combines a power information network with a physical power grid.The introduction of the power information network has improved the level of power automation,reduced manual operation errors and improved social productivity.The introduction of the power information network,while improving the level of power automation,reducing manual operation errors,and improving social productivity,also threatens the security of the smart grid.The original fragile factors in the power information network may also introduced into the cyber physical power system.After investigating a number of accidents,it was found that attackers can break through the CPPS defense through email or USB flash drives,directly attack the power information network,and steal commercial confidential information,and interfere with the normal operation of the power information physical system,leading to major power outages.It can be seen that information system failures will pose a serious threat to the safety of power operations and become one of the main reasons for major power outages.In addition,the faults of the physical power grid may spread to the power information network and cause the propagation of cascading failure among them,thereby affecting the safe operation of the cyber physical power system.Based on the above background,it is of great practical significance to study the vulnerability of cyber physical power systems under cascading failures.This article from the perspective of complex networks,based on the power flow model,proposes a method to identify the crucial nodes of the information network,and quantitatively evaluates the risk of the power information system.The main research work of this paper is as follows:(1)Firstly,it summarizes the current research status of power information physics systems at home and abroad.The research and application of the cyber physical power system vulnerability,crucial node identification and risk assessment are comprehensively introduced.The basic theories of complex network theory,system modeling and failure mechanism,power flow calculation and collaborative information attack are explained in detail,which provides theoretical basis for later research.(2)Aiming at the problem of cyber network failure in cyber physical power system,based on the network model of the cyber physical power system,the three indicators of power flow transfer index,fault power flow distribution index,and impact on system safety are comprehensively considered based on the power characteristics to evaluate crucial bus in the power grid.The criticality index of the power line is converted into the criticality of the node as a functional attribute of the information network monitoring system.Combined with the functional attributes of the coupling nodes of the information network,the comprehensive criticality of the information nodes is defined.By evaluating the vulnerability of the IEEE57-node system,it is found that the failure of a highly integrated critical information node will cause greater load loss to the system.Therefore,comprehensive crucial indicators can effectively identify the crucial links of the information network.This conclusion has certain significance for the power system in defense resource allocation and protection.(3)The implementation of collaborative information attacks on the power information network will seriously threaten the security of the power information physical system.It is of practical significance to propose a CPPS risk assessment method for collaborative information attacks.Based on the analysis of the damage mechanism of the information attack on the physical grid and the weak link of the attacker’s choice of attack,the probability expression of cooperative information attack is proposed from the perspective of the attacker’s attack probability.Considering the success rate of information attacks and the system losses caused by the attacks,a CPPS risk calculation formula based on collaborative information attacks is given,assessing system risks and determining the vulnerability of CPPS. |
