Cooperative optimal preview tracking for linear descriptor multi-agent systems

© 2018 The Franklin Institute. In this paper, a cooperative optimal preview tracking problem is considered for continuous-time descriptor multi-agent systems with a directed topology containing a spanning tree. By the acyclic assumption and state augmentation technique, it is shown that the cooperative tracking problem is equivalent to local optimal regulation problems of a set of low-dimensional descriptor augmented subsystems. To design distributed optimal preview controllers, restricted system equivalent (r.s.e.) and preview control theory are first exploited to obtain optimal preview controllers for reduced-order normal subsystems. Then, by using the invertibility of restricted equivalent relations, a constructive method for designing distributed controller is presented which also yields an explicit admissible solution for the generalized algebraic Riccati equation. Sufficient conditions for achieving global cooperative preview tracking are proposed proving that the distributed controllers are able to stabilize the descriptor augmented subsystems asymptotically. Finally, the validity of the theoretical results is illustrated via numerical simulation

Resilient Output Consensus Control of Heterogeneous Multi-agent Systems against Byzantine Attacks: A Twin Layer Approach

This paper studies the problem of cooperative control of heterogeneous multi-agent systems (MASs) against Byzantine attacks. The agent affected by Byzantine attacks sends different wrong values to all neighbors while applying wrong input signals for itself, which is aggressive and difficult to be defended. Inspired by the concept of Digital Twin, a new hierarchical protocol equipped with a virtual twin layer (TL) is proposed, which decouples the above problems into the defense scheme against Byzantine edge attacks on the TL and the defense scheme against Byzantine node attacks on the cyber-physical layer (CPL). On the TL, we propose a resilient topology reconfiguration strategy by adding a minimum number of key edges to improve network resilience. It is strictly proved that the control strategy is sufficient to achieve asymptotic consensus in finite time with the topology on the TL satisfying strongly $(2f+1)$-robustness. On the CPL, decentralized chattering-free controllers are proposed to guarantee the resilient output consensus for the heterogeneous MASs against Byzantine node attacks. Moreover, the obtained controller shows exponential convergence. The effectiveness and practicality of the theoretical results are verified by numerical examples

Delay-robust distributed secondary frequency control for next-generation power systems: Stability analysis and controller synthesis

Power systems worldwide are undergoing major transformation to enable a low-carbon future. These developments require new procedures for advanced control to ensure a stable and efficient system operation. Consensus-based distributed secondary frequency control schemes have the potential to ensure real-time frequency restoration and economic dispatch simultaneously in future power systems with significant contribution of renewable energy sources. However, owing to their distributed nature, these control schemes critically depend on communication between different controlled units. Thus, robustness against communication uncertainty is crucial for their reliable operation. In this work, control design and stability analysis of delay-robust secondary frequency control in next-generation power systems are studied. The main contributions of the present thesis can be summarised as follows: (i) A design procedure for a consensus-based secondary frequency controller in microgrids is proposed that ensures robustness with respect to heterogeneous fast-varying communication delays and simultaneously provides the option to trade off the L2-gain performance against the number of required communication links; (ii) The conditions for robust stability of a consensus-based frequency control scheme applied to a power system model with second-order turbine-governor dynamics in the presence of heterogeneous time-varying communication delays and dynamic communication topology are derived; (iii) The performance of the proposed consensus-based secondary frequency controller is analysed in a detailed model capturing the dynamic behaviour of a real system. The results provide insights to the robustness of the closed-loop system with respect to unmodelled (voltage and higher-order generator) dynamics as well as communication delays

Computational intelligence approaches to robotics, automation, and control [Volume guest editors]

No abstract available

Systems Structure and Control

The title of the book System, Structure and Control encompasses broad field of theory and applications of many different control approaches applied on different classes of dynamic systems. Output and state feedback control include among others robust control, optimal control or intelligent control methods such as fuzzy or neural network approach, dynamic systems are e.g. linear or nonlinear with or without time delay, fixed or uncertain, onedimensional or multidimensional. The applications cover all branches of human activities including any kind of industry, economics, biology, social sciences etc