Event-triggered Secure Control For Multi-area Power System Under Cyber Attacks

Nowadays,the modern power system brings extensive new functionalities e.g.monitoring,sensing,control technologies,and protection.In the multi-area power system,the load frequency control(LFC)problem has been received adequate attention recently due to maintaining stable power system frequency and net interchange of power with its area neighbors.However,cyber attacks caused by open communication infrastructure may adversely affect the LFC system dynamics and stability.Thus,it is significant and meaningful to study how to secure the LFC in the multi-area power system from the perspective of control theory and control engineering.At present,security control of the multi-area power system mainly includes security modeling,state estimation,defense,and control strategies for different cyber-attacks.False data injection(FDI)attacks,denial of service(DoS)attacks,delay attacks,and deception attacks are the most dangerous types of cyber-attacks,where DoS attacks and FDI attacks being the most common form.Although some excellent results have been achieved on security control,there are still exist some insufficiencies,for example,security state estimation is imprecise,probabilistic assumptions to attacks are unsecured,new security control methods are absent,etc.In the presence of DoS attacks and FDI attacks,security analysis and control of the multiarea power system with electric vehicles(EVs)are studied in this dissertation.In fact,there are the following shortcomings on security and control under DoS attacks and FDI attacks:(i)Generally,a real attacker launches cyber-attacks without any specific rules but energy and frequency constraints.It is unreasonable to characterize DoS attacks and FDI attacks.(ii)There are some limitations on the current security design method which compensate packet dropouts only by adjusting the sampling rate,however,the controller should be given in advance.Based on the above two facts,the following are the significant contributions of this dissertation:· Long-duration DoS attacks are demonstrated for the EV connected multi-area power systems,where DoS duration is the length of the communication disruption intervals.The control architecture establishes the LFC issue as a disturbance attenuation issue in the context of both long-duration DoS attacks and external disturbances.An observerbased predictive event-triggered control mechanism is used to solve the issue.Then,utilizing the Lyapunov theory and the linear matrix inequality(LMI)technique,asymptotic stability,and controller design are carried out,taking into consideration of longduration DoS attacks.· To deal with energy-limited DoS attacks,a redundant event-triggering load frequency control has been devised for the multi-area power system including EV.A model-based redundant event-triggering communication strategy is presented for decreasing transmitted packet losses by separating the time period into DoS free-interval and DoSinterval.Using the switched Lyapunov function and the LMI technique,the asymptotic stability criterion and H∞disturbance attenuation performance are then calculated.Then,at the same time,the explicit representation of feedback gain and the parameters of the redundant event-triggered mechanism are established.· For the analysis/synthesis of the multi-area power system under DoS attacks,a logicbased event-triggered control approach has been devised.A secure handshake protocol is used in order to identify DoS attacks.By combining a handshake logic and an eventtriggered communication system,the proposed controller can save network resources while ensuring system performance.Then,while considering DoS attacks,the stability requirements and control design are developed.Meanwhile,it should be noted that the suggested strategy is less conservative when lengthy inter-execution intervals or less sophisticated attackers are present.· To deal with hybrid cyber-attacks(e.g.,DoS attacks and FDI attacks),a bandwidth allocation-based distributed event-triggering load frequency control has been established for the multi-area power system.For distributed LFC systems,a bandwidth allocation-based distributed event-triggering control technique is presented in the face of hybrid cyber-attacks and global bandwidth limits.The control mechanism is more efficient than the pre-selected sampling method in managing the various flows of DoS attack packets and FDI attacks.The exponential stability conditions are then defined using the Lyapunov theory.Moreover,throughout the control process,the exclusion of Zeno behavior is demonstrated.Finally,simulation results support the validity of the suggested control strategy.