| Frequency serves as a crucial metric for evaluating the stable operation of a power system.Load frequency control(LFC)stands out as a potent method to maintain the fre-quency within the normal operating range.The principle is to capture the data of frequency and tie-line power through the sensor,and transmit it to the control centra via communica-tion media to achieve the frequency feedback control.The advent of network communica-tion technology and intelligent control equipment has propelled the evolution of the smart grid into a cyber-physical power system,seamlessly integrating communication networks and power systems.While the application of network communication platform provides convenience for the huge and complex data interaction of power system,it also introduces novel challenges to LFC:x imited network communication resources inevitably lead to challenges such as communication congestion,data transmission delays,and control data packet losses.How to address these issues?y Communication networks are bound to suf-fer cyber attacks.How to design LFC methods to achieve efficient frequency regulation of power system under cyber attacks?Targeting cyber attacks,how to design active detection and defense methods to ensure the safe and reliable operation of power system?z The output power of renewable energy generation is significantly impacted by environmental factors,exhibiting strong intermittency and randomness,leading to power imbalance in microgrid systems and increasing the demand for system frequency regulation.This work focuses on optimizing the existing communication mechanisms,developing cyber-attack detection and defense methodologies,and exploring frequency security control within the cyber-physical power system.The primary contributions are summarized as follows:(1)The non-fragile LFC method is investigated for multi-area power systems un-der adaptive event-triggered communication scheme.Firstly,a nonlinear function as-sociated with the valve deviation state is introduced considering the limitation of valve regulation,and a nonlinear multi-area LFC model is established.Secondly,aiming at the excess of network communication caused by periodic data transmission,an adaptive ad-justment algorithm of event-triggered threshold parameters is designed,and an adaptive event-triggered communication scheme is proposed.Then,a non-fragile output feedback LFC method is designed to improve the reliability of the controller with disturbance.Fi-nally,the Lyapunov direct method is used to analyze the asymptotic stability and H_∞performance of LFC system by selecting the quadratic form with time-varying matrix and two-side looped Lyapunov-Krasovskii functional(LKF).Using linear matrix inequality(LMI)technique,the design methods of non-fragile control feedback gains and adaptive event-triggerred weight matrix are presented.(2)The distributed fault-tolerant control method is studied for power system under stochastic event-triggered frame.Firstly,a multi-dimension actuator fault model is pro-posed,and the LFC model of multi-area power system is established.Secondly,con-sidering the uncertainty of the sampling period,the random sampling mode is presented based on the traditional periodic sampling,and a stochastic event-triggered transmission scheme is proposed.Then,a distributed fault-tolerant LFC method is designed to solve the problem of control performance degradation or even failure caused by actuator faults.Finally,the asymptotic stability criterion of LFC system is established by using the Lya-punov method and inequality boundary technique.Applying LMI technique,an equiv-alent LMI-based stability condition is proposed,and the design methods of distributed fault-tolerant control gain and stochastic event-triggered weight matrix are provided.(3)The fault diagnosis and dynamic event-triggered LFC method is investigated for wind power system under Denial of service(Do S)attack.Firstly,the dynamic character-istics of wind power system are analyzed,and the LFC model of multi-area wind power system is established.Secondly,considering the actuator fault of power system,the fault residual signal accumulation function and fault warning threshold function are designed,and the observer-based actuator fault diagnosis method is proposed.Then,the model of dual Do S attack is proposed by analyzing the influence of Do S attack on the network control system,and the observer-based dynamic event-triggered LFC method is designed through optimizing the traditional static event-triggered threshold condition.Finally,the polynomial LKF is constructed based on the Lyapunov stability theory,the asymptotic stability criterion of LFC system with an H_∞performance index is established,and LMI-based methods of LFC gain and dynamic event-triggered weight matrix are proposed.(4)The Do S attack detection and compensation LFC method is addressed based on event-triggered communication framework.Firstly,the LFC model of multi-area inter-connected power systems is established by utilizing algebraic graph theory.Secondly,the Do S attack detection algorithm is designed by calculating the reception rate of the trans-mitted data,which realizes the warning of Do S attack and the determination of its active intervals.Then,the trigger compensation threshold condition of control data is proposed,and the joint algorithm of Do S attack detection and control data compensation is designed,and the distributed cooperative compensation LFC method is further designed.Finally,us-ing the Lyapunov method,the asymptotic stability criterion of power system is established by constructing suitable LKF,and the H_∞performance of power system is analyzed.The linear design of feedback control gain parameters is achieved by using LMI technology.(5)The dynamic-memory event-triggered LFC method is proposed for power sys-tem under hybrid cyber attacks.Firstly,the LFC model of power system is established considering the frequency fluctuation caused by large-scale grid-connected electric vehi-cles.Secondly,the dynamic triggered threshold condition including the past data trans-mission is designed,and the dynamic-memory event-triggered communication scheme is proposed.Then,a hybrid cyber-attack model is established by taking the influence of fault data injection attacks and Do S attacks into consideration,and the output feedback LFC method based on compenstion control data is designed for power system.Finally,by means of the Lyapunov direct method,a segmented LKF is constructed and an exponential stability criterion with H_∞performance index is established.Using LMI technology,an LMI-based equivalent exponential stability criterion is established,and a design method of feedback control gain and dynamic-memory event-triggered weight matrix is provided. |
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