Secure State Estimation And Attack Defense For Cyber-physical Power Systems Via Observer

In the modern power system,the connection between the network part and the physical part is more and more close and the coupling is more and more deep.The Cyber-Physical Power Systems(Cyber-Physical Power Systems,CPPS)can accurately describe the dynamic process of the modern power grid.As a special network of power industry control system,power communication network has the characteristics of security partition,network specificity,horizontal isolation and vertical authentication.However,in CPPS,the network part and the physical part are deeply coupled and interact with each other,making them vulnerable to internal failures and external attacks.Attackers can easily take advantage of these characteristics to attack CPPS and thus control or even destroy the entire power grid,which is now widely observed.Based on the comprehensive analysis of the above problems,the security solutions are proposed,such as the CPPS model,the security state estimation of the CPPS based on the observer,the attack reconstruction and the attack defense strategy.Firstly,based on the classical small signal model of power system,and using the operating parameters of generator rotor Angle,frequency and so on,the CPPS system model is established.The false data attack is injected into the normal operating system,and the generator parameters are tampered with pertinently,then the operating state of the system is disturbed.On this basis,the actual influence of the attack on the whole power grid system is analyzed.Secondly,based on the above attacked CPPS model,the security state estimation and attack reconstruction methods of attacked CPPS are proposed based on robust sliding mode observer and intermediate observer theory.By establishing appropriate Lyapunov function,stability analysis is carried out to prove the validity of the observer theory.Therefore,the security state estimation and attack reconstruction of the attacked CPPS are realized through the observer.Finally,on the basis of the previously completed attacked CPPS modeling and the security state estimation data obtained from observer theory,an attack defense strategy satisfying the optimal economic scheduling is proposed.By adjusting the active power of the unattacked generator,the system can restore the power supply and demand balance,and complete the new power flow distribution.All the above theories are verified by IEEE 9-bus power system simulation.