Smart grid (SG) represents a large-scale network system with the tight integration of a physical power network and an information network, which makes it more vulnerable to hybrid cyber attacks against different regional subsystems. First, an alternating direction method of multipliers-based distributed state estimation method is developed to overcome the limitation of conventional state estimation and performance analysis of SG against a single type of cyber attacks. Regional subsystems are partitioned via the K-means method. Second, a novel distributed state estimation method integrated with the characteristics of data deception attacks and denial of service (DoS) attacks is proposed to account for the simultaneous presence of different cyber attacks on individual regional subsystems. Third, the convergence of a distributed state estimation algorithm under hybrid cyber attacks is proved theoretically. Furthermore, the relationships between the convergence and algorithm parameters as well as the occurring probability of DoS attacks are established. Finally, the simulations on a modified IEEE 118-bus system are given to demonstrate the feasibility and effectiveness of the proposed method.

Aiming at the challenges of networked visual servo control systems, which rarely consider network communication duration and image processing computational cost simultaneously, we here propose a novel platform for networked inverted pendulum visual servo control using H∞ analysis. Unlike most of the existing methods that usually ignore computational costs involved in measuring, actuating, and controlling, we design a novel event-triggered sampling mechanism that applies a new closed-loop strategy to dealing with networked inverted pendulum visual servo systems of multiple time-varying delays and computational errors. Using the Lyapunov stability theory, we prove that the proposed system can achieve stability whilst compromising image-induced computational and network-induced delays and system performance. In the meantime, we use H∞ disturbance attenuation level ɣ for evaluating the computational errors, whereas the corresponding H∞ controller is implemented. Finally, simulation analysis and experimental results demonstrate the proposed system performance in reducing computational errors whilst maintaining system efficiency and robustness.

Persistent data packet losses induced by consecutive denial-of-service (DoS) attacks could fail traditional state estimation (SE) algorithms that highly rely on the completeness of dataset. To solve the problem, this article explores a novel SE algorithm with enhanced SE accuracy for power systems against consecutive DoS attacks. First, according to the characteristics of data packet losses induced by DoS attacks, we design a strategy by using the latest received measurement packet to compensate for consecutive data packet losses, and reconstruct the power system model. Second, by integrating Holt’s two-parameter exponential smoothing and extended Kalman filter techniques, a new enhanced SE algorithm is proposed, where the statistical properties of data packet losses are contained in the recursion formulas of the state prediction and state filtering processes. Third, the boundedness of estimation error covariance matrix and prediction error are proved. Finally, the proposed algorithm is compared with traditional SE algorithms via three IEEE testing systems and verified in a real power system. Simulation results illustrate the effectiveness and efficiency of the proposed algorithm under various data packet losses scenarios.

We here investigate the secure control of networked control systems developing a new dynamic watermarking (DW) scheme. First, the weaknesses of the conventional DW scheme are revealed, and the tradeoff between the effectiveness of false data injection attack (FDIA) detection and system performance loss is analyzed. Second, we propose a new DW scheme, and its attack detection capability is interrogated using the additive distortion power of a closed-loop system. Furthermore, the FDIA detection effectiveness of the closed-loop system is analyzed using auto/cross-covariance of the signals, where the positive correlation between the FDIA detection effectiveness and the watermarking intensity is measured. Third, the tolerance capacity of FDIA against the closed-loop system is investigated, and theoretical analysis shows that the system performance can be recovered from FDIA using our new DW scheme. Finally, the experimental results from a networked inverted pendulum system demonstrate the validity of our proposed scheme.

Dynamic watermarking schemes can enhance the cyberattack detection capability of networked control systems (NCSs). This article presents a linear event-triggered solution to conventional dynamic watermarking (CDW) schemes. First, the limitations of CDW schemes for event-triggered state estimation-based NCSs are investigated. Second, a new event-triggered dynamic watermarking (ETDW) scheme is designed by treating watermarking as symmetric key encryption, based on the limit convergence theorem in probability. Its security property against the generalized replay attacks (GRAs) is also discussed in the form of bounded asymptotic attack power. Third, finite sample ETDW tests are designed with matrix concentration inequalities. Finally, experimental results of a networked inverted pendulum system demonstrate the validity of our proposed scheme.

The existing identity security schemes (e.g., based on bilinear pairing) have high computation complexity and large bytes of variables, which result in high computation and communication costs and are difficult to apply to resource-constrained (i.e., computation and communication) devices. Moreover, most of these schemes adopt a fixed cycle key update strategy or dynamic (real-time) key update strategy with high computation cost, which could compromise the security of authentication schemes. To solve these issues, this paper explores a novel revocable lightweight authentication scheme for resource-constrained devices in cyber-physical power systems (CPPSs). First, a lightweight authentication scheme combined elliptic curve cryptography (ECC) and certificateless cryptography (CLC) is proposed to negotiate a secure session key, which can achieve mutual authentication with low computation and communication costs. Second, aiming at security problem caused by key leakage, a real-time key update strategy with low computation cost is designed to improve the security of identity authentication. Third, according to a hardness assumption of the elliptic curve discrete logarithm problem (ECDLP), theoretical analysis rigorously proves that the proposed authentication scheme ensures the security with respect to existential unforgeability against adaptively chosen message attacks (EUF-CMA). Finally, experimental results confirm the feasibility and effectiveness of the proposed authentication scheme.