Risk Assessment Of Power Cyber Physical System Considering Power Flow

As the scale of the power grid continues to expand,in order to ensure the reliability of the social demand for electricity,the modern power system has evolved into a power cyber physical based on the deep integration of power grids and cyber networks.The trend of gradual complexity of the system has been inevitable,the emergence of new network attacks makes the system security face a more severe test.How to locate the nodes and lines that may cause cascading failures in network attack environment,so as to reduce the occurrence of large-scale blackouts,has become a key problem.Therefore,the risk assessment of power cyber physical systems has practical significance.Given these backgrounds,this dissertation mainly analyzes the modeling method,the mechanism of risk propagation,and the risk assessment of the system under network attacks.The main research contents are as follows:(1)According to the internal operation mechanism of power cyber physical systems,a theoretical model is established.Among them,power grids are mainly based on DC power flow calculation,and cyber networks are mainly based on the uplink of power data and the downlink of control instructions.Power grids model and cyber networks model are combined through the matrix,and then the integrated model of power cyber physical systems is established.(2)According to the location of network attacks,the influence of different network attack modes on the system operation state is analyzed,and a parameterized representation of risk propagation mechanism of network attacks is proposed.Because the attackers have different knowledge of the basic information of the target,this dissertation takes two typical cyber-attack modes as examples to quantitatively analyze the impact of their attack matrix on the system operation state.Taking IEEE9-bus system as an example,the impact of cyber networks on power grids topology and energy transmission under different operation states is analyzed.(3)Starting from the system topology and energy transmission,a hierarchical risk assessment index system is established.Taking IEEE39-bus system as an example,this dissertation first analyzes the process of cascading failure in network attack environment,then counts the risk index of the system at the end of cascading failure,and finally obtains the risk level of the system nodes and transmission lines.In the research process,it is found that increasing the overload capacity of some transformers will reduce the risk level of most nodes and lines,and then improve the system topology and energy transmission.