Research On Security Control Issues Of Distributed Microgrid Systems Under Denial Of Service Attack

With the development of network control technology and the continuous improvement of control theory,the smart grid composed of multiple distributed generators(DGs)has gradually replaced the traditional power grid,called microgrid systems.Meanwhile,the control strategy of network systems has gradually evolved from centralized to distributed control,but the designed distributed controller depends on global topology information and not suitable for actual systems,which is not the real distributed.That makes the fully distributed control strategy attracted wide attention.Considering the vulnerability of network links in practice,it is easy to be destroyed by network attacks,which leads to the failure of voltage tracking control task in microgrid systems.Therefore,it is of great significance to study various control tasks under the safe operation of microgrid systems.This paper studies the secondary voltage resilient tracking control of microgrid systems subject to denial of service attacks under the fully distributed control framework.Its main research contents are as follows:(1)Considering the condition of the system destroyed by denial of service attacks,this paper studies the event-triggered secondary voltage tracking control problem of microgrid systems with undirected network topology.By introducing time-varying coupling weights to designed the fully distributed controller to get rid of the limitation of global information,that is,the Laplacian matrix minimum nonzero eigenvalues positive real parts.By designing a dynamic event-triggered strategy,the problem of continuous communication among distributed generators is solved,the waste of network resources is reduced,and the risk of network attack being attacked is cut down to a certain extent,which ensure the completion of the secondary voltage tracking control task of distributed generators.The event-triggered mechanism can work normally by proving that the Zeno behavior is excluded.Finally,a simulation example is given to verify the effectiveness of the proposed control strategy.(2)For the conditions of unknown system dynamics and the system destroyed by denial of service attacks,this paper uses reinforcement learning technology to study the problem of secondary voltage event-triggered resilient tracking control in microgrids with undirected communication topology.Under the assumption of the system matrix and the input matrix are unknown,the controller gain is obtained by solving the Riccati equation using the input/output data set with the reinforcement learning algorithm.According to the feature that its own generator cannot receive the state information transmitted by the neighbor generators when the denial of service attack occurs,the state information of the last successful transmission of the neighbor generator obtained by its own generator is used as the compensation item to design the fully distributed controller and the eventtriggered strategy.This strategy can reduce the influence of network attack on the control effect,and reduce the frequency of communication among distributed generators when the control task of voltage tracking is finished.In addition,this paper proves that the designed event-triggered mechanism does not exist Zeno behavior.Finally,a simulation example is given to verify the validity of the designed control scheme.(3)Considering the conditions of the unmeasured states and the system destroyed by denial of service attacks,this paper solves the problem of event-triggered secondary voltage resilient output feedback tracking control for microgrid systems with undirected communication topology.In practical engineering applications,the system states are often unmeasurable due to the external interference.Thus,the estimated voltage states of distributed generators can be obtained by designing an observer.Aiming at aperiodic denial of service attacks,a security controller is designed to finish the secondary voltage tracking control task.Meanwhile,considering the limitation of communication resources,a reasonable event-triggered scheme is designed to reduce the communication times among distributed generators and save communication resources.In addition,the Zeno behavior of the designed event-triggered mechanism is excluded by strict theoretical demonstration.Finally,the simulation experiment is conducted to verify the effectiveness of the observer-based fully distributed event-triggered voltage resilient control strategy.