| With the application of advanced information and communication technologies,the modern power system has developed into a power cyber physical system(CPS),which is deeply coupled by the cyber networks and the power grids.Frequent information interaction between networks improves the observability and controllability of the system,but the network attacks under the deliberate behavior also threatens the safe operation of the system at any time.Moreover,under the implementation of the electricity saving policy,the increasingly severe load uncertainty makes the operation and control of the system more difficult.It is of great significance to deeply analyze the cyber-physical coupling mechanism and accurately evaluate the system vulnerability to ensure the reliable and economic operation of power CPS.The existing vulnerability research is often based on the normal or abnormal state of cyber network monitoring,ignoring the impact of cyber network monitoring in different level;Moreover,there is a lack of consideration about load uncertainty.In view of the above background,the main works in this thesis are as follows:The power CPS model is established by fully considering the information interaction process of two-layer network.Taking the information flow as the main perspective,combined with the power flow calculation equation,the state matrix integrating multi-information is taken as the power network model;Taking into account the monitoring and control functions of the cyber network,the corresponding information characteristic matrix and regulatory function are established as the cyber network model according to the information transmission process;Then the fusion dual network model is calculated by matrix mixing.Based on the model,the information transmission process of network attack is quantified.Taking IEEE 9 bus power CPS as an example,the working process of the model and the information transmission process of network attack are analyzed briefly,and the correctness of the model is verified.Considering the difference of information network monitoring level under coordinated cyber-physical attack,the system vulnerability assessment is carried out.According to the amount of information obtained by attackers,the cyber network is divided into three operating states: fully observable and controllable,partially observable and controllable,and no observable and controllable,so as to establish different evaluation scenarios.Taking IEEE 30 bus power CPS as an example,the influence of the information asymmetry of the two-layer network on the system vulnerability is quantitatively evaluated,and the vulnerable components of the system are identified from the perspective of multiple scenarios.The simulation results show that the more power information the attacker obtains,the poorer the monitoring and adjustment ability of the cyber network,and the more vulnerable the system is.In addition,the power nodes and lines with heavy power load,large power flow and high topological correlation and their information elements in the system are highly vulnerable,so they need to be protected in actual operation.The impact mechanism of load uncertainty on system vulnerability is thoroughly explored and the system vulnerability assessment is carried out.By analyzing the influence of uncertainty on actual monitoring process,the load uncertainty model and system fault model are established.On the foundation of deterministic evaluation and combined with Monte Carlo stochastic power flow calculation,the vulnerability assessment process is established.Taking IEEE 30 bus power CPS as an example,the influence of load uncertainty level and load demand level on system vulnerability under deliberate attack of information network is quantitatively evaluated.The results indicate that with the increase of load uncertainty degree and load demand level,the vulnerability of the system is higher,and the uncertainty of heavy load nodes has a greater impact on the system,which needs to be protected. |
PDF Full Text Request