Hybrid networked control for cyber-physical network systems with applications to interconnected power grids
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This dissertation addresses the question of stability for some types of cyber-physical network systems. In particular, we apply the hybrid control technique to some cyber-physical network systems to construct some hybrid network controller design framework. We also apply the hybrid network control techniques to power network system to test the effi cacy of proposed designs. In Chapter 2, the notation and definitions are first introduced. Then some mathematical preliminaries and results of impulsive dynamical systems, hybrid control techniques, and di fferential inclusions with Filippov solutions are presented. In Chapter 3, we develop three novel hybrid stabilization techniques with distributed feedbacks and supervisory resetting laws to address fast energy equipartition for a class of cyber-physical network systems. The hybrid network control techniques are constructed to achieve the robust performance of geospatial physical networks by mimicking the dynamic behavior of thermodynamic systems. The proposed stabilization architectures are constructed in such a way that each stabilizer has a one-directional energy transfer from a plant to itself, and exchanges energy with its neighboring stabilizers. The hybrid stabilization techniques are applied to power network systems to conduct the simulation test. In Chapter 4, we describe the notions of partial cluster stability and partial cascade stability of a class of cyber-physical network systems, develop distributed hybrid network control techniques to achieve partial cluster stabilization and partial cascade stabilization, and apply the proposed approach to an 8-bus, 5-machine transmission and distribution power network system. Partial cluster stability is the property that every subsystem in a cyber-physical network system is partially convergent, and at least one subsystem is partially semistable. Partial cascade stability is the property of damping disturbance propagation of the cyber-physical network system. To achieve the effects of partial cluster stability and partial cascade stability, distributed hybrid network controller architectures are proposed in such a way that each plant is connected to a controller node with one communication link, and the controller nodes form a connected controller graph which collects information from plants and returns feedback information. To show the efficacy of the proposed approach, the proposed hybrid control techniques are applied to the 8-bus, 5-machine transmission and distribution power network system. In Chapter 5, an event-based switching hybrid network stabilizer for cyber-physical network systems is proposed. A hybrid automaton model for a class of hybrid dynamical systems are presented, and the invariant set results are proved. Furthermore, network hybrid automata are proposed to represent the cyber-physical network systems with hybrid controllers, the stability result is analyzed and proved. Finally, the hybrid controller is implemented in simulink and applied to the Kundur's two-area four-machine power system model.