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1. Asynchronous Periodic Distributed Event-Triggered Voltage and Frequency Control of Microgrids

   https://doi.org/10.1109/tpwrs.2021.3059158  

   Mohammadi, Keywan; Azizi, Elnaz; Choi, Jeewon; Hamidi Beheshti, Mohammad Taghi; Bidram, Ali; Bolouki, Sadegh (February 2021, IEEE Transactions on Power Systems)

   null (Ed.)

   In this paper, we introduce a distributed secondary voltage and frequency control scheme for an islanded ac microgrid under event-triggered communication. An integral type event-triggered mechanism is proposed by which each distributed generator (DG) periodically checks its triggering condition and determines whether to update its control inputs and broadcast its states to neighboring DGs. In contrast to existing event-triggered strategies on secondary control of microgrids, the proposed event-triggered mechanism is able to handle the consensus problem in case of asynchronous communication. Under the proposed sampled-data based event-triggered mechanism, DGs do not need to be synchronized to a common clock and each individual DG checks its triggering condition periodically, relying on its own clock. Furthermore, the proposed method efficiently reduces communication rate. We provide sufficient conditions under which microgrid's frequency and a critical bus voltage asymptotically converge to the nominal frequency and voltage, respectively. Finally, effectiveness of our proposed method is verified by testing different scenarios on an islanded ac microgrid benchmark in the MATLAB/Simulink environment as well as a hardware-in-the-loop (HIL) platform, where the physical system is modeled in the Opal-RT and the cyber system is realized in Raspberry Pis. 

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2. Distributed Finite-Time Event-Triggered Frequency and Voltage Control of AC Microgrids

   https://doi.org/10.1109/TPWRS.2021.3110263  

   Choi, Jeewon; Habibi, Seyed Iman; Bidram, Ali (September 2021, IEEE Transactions on Power Systems)

   null (Ed.)

   This paper proposes a finite-time event-triggered secondary frequency and voltage control for islanded AC microgrids (MGs) in a distributed fashion. The proposed control strategy can effectively perform frequency restoration and voltage regulations, while sharing the active and reactive power among the distributed generators (DGs) based on their power ratings. The finite-time control enables a system to reach consensus in a finite period of time enhanced from the asymptotic convergence. The event-triggered communication is utilized to reduce the communication burden among the DG controllers by transmitting data among DGs if an event-triggering condition is satisfied. The performance of the proposed finite-time event-triggered frequency control is verified utilizing a hardware-in-the-loop experimental testbed which simulates an AC MG in Opal-RT. 

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3. Application of Distributed Linear Multi-Agent Containment Control to Robotic Systems

   https://doi.org/10.1016/j.ifacol.2022.11.240  

   Tauchnitz, S.; Yuan, C.; Stegagno, P. (October 2022, IFACPapersOnLine)

   This article proposes the application of a distributed containment control algorithm to a team of mobile robots. This paper builds on the containment controller developed by Yuan et al. (2019) for generic linear multi-agent system and tested in simulation only. In this article, we particularize the controller for the case of multiple mobile robots by including it into a two-layer control scheme. The high-level controller computes a desired position for the mobile robots, that is then used as reference trajectory for the low-level controller. The resulting control system is implemented as a fully distributed system on a team of mobile robots and validated in simulations and experiments. 

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4. Dynamic Intermittent Feedback Design for H∞ Containment Control on a Directed Graph

   https://doi.org/10.1109/TCYB.2019.2933736  

   Yang, Yongliang; Modares, Hamidreza; Vamvoudakis, Kyriakos G.; Yin, Yixin; Wunsch, Donald C. (October 2019, IEEE Transactions on Cybernetics)

   This article develops a novel distributed intermittent control framework with the ultimate goal of reducing the communication burden in containment control of multiagent systems communicating via a directed graph. Agents are assumed to be under disturbance and communicate on a directed graph. Both static and dynamic intermittent protocols are proposed. Intermittent H∞ containment control design is considered to attenuate the effect of the disturbance and the game algebraic Riccati equation (GARE) is employed to design the coupling and feedback gains for both static and dynamic intermittent feedback. A novel scheme is then used to unify continuous, static, and dynamic intermittent containment protocols. Finally, simulation results verify the efficacy of the proposed approach. 

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5. Regulation‐triggered adaptive control of a hyperbolic PDE‐ODE model with boundary interconnections

   https://doi.org/10.1002/acs.3279  

   Wang, Ji; Krstic, Miroslav (May 2021, International Journal of Adaptive Control and Signal Processing)

   Summary We present a certainty equivalence‐based adaptive boundary control scheme with a regulation‐triggered batch least‐squares identifier, for a heterodirectional transport partial differential equation‐ordinary differential equation (PDE‐ODE) system where the transport speeds of both transport PDEs are unknown. We use a nominal controller which is fed piecewise‐constant parameter estimates from an event‐triggered parameter update law that applies a least‐squares estimator to data “batches” collected over time intervals between the triggers. A parameter update is triggered by an observed growth in the norm of the PDE state. The proposed triggering‐based adaptive control guarantees: (1) the absence of a Zeno phenomenon; (2) parameter estimates are convergent to the true values in finite time (from most initial conditions); (3) exponential regulation of the plant states to zero. The effectiveness of the proposed design is verified by a numerical example. 

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