Research On Distributed Secondary Control Method Of AC Microgrid Based On Event-triggered

With the continuous advancement of energy structure transformation and the growth of renewable energy integration,microgrid has received extensive attention in the industry as a key technology for effectively consuming renewable energy and building new power system.Since there are various types of distributed energy sources with different characteristics.To balance the supply relationship between distributed generation(DG)units and load demands,designing flexible and efficient control schemes is the key to improve the multi-source coordination ability and optimize power quality of microgrids system.Hierarchical control can effectively realize stable system frequency output while ensuring accurate active power sharing,its operation control methods have become a research hotspot for maintaining the stable operation of microgrids.In the distributed secondary control layer,an event-triggered consensus control technique has been developed to alleviate the communication burden because of the large amount of redundant data generated by the information interaction between DGs.However,in practical applications of the microgrid,the bounded disturbances of the physical layer and the network security problem of the information layer can cause the system to deviate from the standard operating point,and even cause the system to be paralyzed.Therefore,it is urgent to further study the distributed secondary control methods based on event-triggered to improve the dynamic characteristics of the microgrids system.In this paper,the islanded AC microgrid with a wide range of existence is taken as the research object.Under different environmental conditions,the secondary control of AC microgrids is deeply studied through system modeling,control method,performance analysis,and simulation verification.The specific work and research include:Firstly,aiming at the hierarchical control structure of islanded AC microgrids,the control methods and function realization of each layer are analyzed.A multi-loop controller in the primary control layer,including power outer loop,as well as voltage and current inner loop is designed based on the droop control characteristics.Considering the communication burden between DGs,the design of an event-triggered consensus controller is studied in the secondary control layer,which lays the foundation for later research.Secondly,aiming at the problems of bounded disturbances in the physical layer and the limited communication resources in the information layer of AC microgrids,a distributed robust secondary control method based on event-triggered is studied to address.This method only exchanges information between DGs at the event-triggered time instants,which effectively saves communication resources and improves the anti-jamming ability of AC microgrids in the process of frequency recovery and active power sharing.Based on the Lyapunov theory,the stability of the system and the effectiveness of the event-triggered mechanism are analyzed in detail.The relationship between the feedback gains and the exponential convergence rate is established,and the Zeno phenomenon is excluded.Then,aiming at the network security problem of the AC microgrids information layer under false data injection(FDI)attack,an integrated design method of distributed adaptive observer and resilient controller is studied based on the event-triggered mechanism.This method does not need to isolate the infringed DG unit.Still,it estimates the FDI attack signal transmitted in the communication network through the fully distributed observer,further using the resilient controller to eliminate the adverse effects in the system.At the same time,the number of communication samples of the DGs is reduced under event-triggered control,which decreases the risk of attacker intrusion.Using the Lyapunov method,the consensus global convergence property of the AC microgrids utilizing the method is demonstrated,while the absence of the Zeno phenomenon in the system is proved.Finally,aiming at the above-studied secondary control method of AC microgrid,the simulation models are built in MATLAB/Simulink environment under different operating conditions.The load variation test and plug-and-play effectiveness test of the two control methods are carried out,respectively.The results show that the AC microgrids can quickly recover to the stable working point with good dynamic performance.Furthermore,compared with the conventional periodic sampling method,the occupancy of communication resources under the event-triggered mechanism is analyzed,and the effectiveness of the proposed control method is verified simultaneously.