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This paper is concerned with optimal security problem of cyber‐physical systems with state attacks. Consider a linear physical system, assuming that the control input signal of the network layer is vulnerable to state attack. For a system that cannot measure all states, by combining output integral sliding mode, robust observer, and adaptive methods, an adaptive output integral sliding mode control method is proposed to maintain the safe operation of cyber physical systems under state attacks. Moreover, by optimizing the linear control gain matrix, the control strategy the authors designed can use the minimum cost to compensate the impact on the CPS system. Different from the existing results, (1) It is assumed that the system information of the attack signal is not fully known, we assume that the attacker can only measure a small amount of state information. (2) Not only the stability of ideal sliding mode is proved, but also the upper bound of the augmented state composed of system states and the error dynamic is given. (3) The sliding mode compensator can eliminate the impact of state attack, on the one hand, the damage caused by the state attack has been eliminated by using the upper bound of error, and on the other hand, the cost is reduced by optimizing the linear control gain. Finally, a power system with 3 generators and 6 buses is used to prove the effectiveness of the adaptive output integral sliding mode control scheme. [ABSTRACT FROM AUTHOR]

This paper is concerned with the reliable operation of cyber‐physical systems under false data injection attacks. First of all, a robust adaptive sliding mode observer is designed to estimate the state of the power system; different from the traditional sliding mode observer, the observer we designed is not only robust to state errors but also can automatically adjust the parameter of attack identification. Secondly, a method of attack reconstruction has been given to estimate the actual attack signal. Finally, a reliable sliding mode control strategy is proposed to eliminate the impact of false data injection attacks; compared with the existing results, the designed defense strategy utilizes the reconstructed attack signal in the attack identification scheme and state error signal at the same time. Moreover, a power system with 3 generator buses and 6 load buses is taken as an simulation example to verify the availability of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Summary: The transient stability problem of a single‐machine infinite‐bus system with static var compensator is solved in this paper, where the static var compensator controller is designed by an improved backstepping method combining error compensation, adaptive backstepping control, and sliding mode variable structure control. Crucially, the error compensation term, which chooses in the step of virtual control by the adaptive backstepping method, is introduced to ensure that the system states are bounded, maintaining the nonlinearity of the power systems while also improving the speed of parameter identification. Meanwhile, the Lyapunov function is constituted step by step to achieve stability of the subsystem. In addition, a parameter updating law and a nonlinear control law are explicitly given to asymptotically stabilize the closed‐loop system. Finally, a simulation is used to illustrate the effectiveness and the practicality of the proposed control approach. [ABSTRACT FROM AUTHOR]

The stability of a single machine infinite bus system with a static var compensator is proposed by an improved adaptive backstepping algorithm, which includes error compensation, sliding mode control and a κ -class function. First, storage functions of the control system are constructed based on modified adaptive backstepping sliding mode control and Lyapunov methods. Then, adaptive backstepping method is used to obtain nonlinear controller and parameter adaptation rate for static var compensator system. The results of simulation show that the improved adaptive backstepping sliding mode variable control based on error compensation is effective. Finally, we get a conclusion that the improved method differs from the traditional adaptive backstepping method. The improved adaptive backstepping sliding mode variable control based on error compensation method preserves effective non-linearities and real-time estimation of parameters, and this method provides effective stability and convergence. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the robust fault diagnosis for switched systems is studied based on sliding mode observers, taking the DC–DC power electronic converter as an example. According to the switched system mode, a sliding mode observer is designed through linear matrix inequalities to detect the fault. The fault identification unit not only locates the faulty component, but also realizes the identification of the faulty component parameter. For different components of the system, a series of adaptive sliding mode observers are designed to determine the location of fault. At the same time, an appropriate adaptive law is selected to estimate the parameters of the components. Finally, the proposed method is proved to be effective by an example of power electronic DC-DC boost converter. [ABSTRACT FROM AUTHOR]

In recent years, many challenges have been faced in locating and identifying faulty components in inverter circuits. A variety of fault observers are used to monitor the fault state of the system. This paper studies the design of the sliding mode fault observer and identifier for closed-loop grid-connected inverter. First, the closed-loop grid-connected inverter system is mathematically modeled. Then the fault model of the system is analyzed. Thirdly, the fault detection sliding mode observer is designed by solving linear matrix inequalities, which has good robustness. By choosing a suitable adaptive law, sliding mode adaptive fault identifiers are designed for different circuit fault components. After the fault observer observes the circuit fault, the fault identifier can identify the specific location of the faulty component in the circuit. Finally, the effectiveness of the designed fault observer and identifier are verified in simulation platform. Compared with existing studies, the fault observer and identifier in this paper can accurately locate faulty components in the system without the influence of deforming load, and the output of the fault residual estimation function is more accurate. • The sliding mode fault observer and identifier for closed-loop grid-connected inverter is proposed. The fault observer and identifier can work normally without the influence of deforming loads. • We presented strict LMI conditions for solving fault observer and identifier gains. No matter how much the value of the component decreases after the fault, it can be observed and identified. • Compared with the PD learning observer used in article [11], the sliding mode fault observer in this paper has higher accuracy. [ABSTRACT FROM AUTHOR]