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1. Joint Frequency Regulation and Economic Dispatch Using Limited Communication

   Jianan Zhang, Eytan Modiano (October 2018, IEEE SmartGridComm)

   We study the performance of a decentralized integral control scheme for joint power grid frequency regulation and economic dispatch. We show that by properly designing the controller gains, after a power flow perturbation, the control achieves near-optimal economic dispatch while recovering the nominal frequency, without requiring any communication. We quantify the gap between the controllable power generation cost under the decentralized control scheme and the optimal cost, based on the DC power flow model. Moreover, we study the tradeoff between the cost and the convergence time, by adjusting parameters of the control scheme. Communication between generators reduces the convergence time. We identify key communication links whose failures have more significant impacts on the performance of a distributed power grid control scheme that requires information exchange between neighbors. 

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2. Experiments on a Real-Time Energy Management System for Islanded Prosumer Microgrids

   https://doi.org/10.3390/electronics8090925  

   Macana, Carlos A.; Pota, Hemanshu R.; Zhu, Quanyan; Guerrero, Josep M.; Vasquez, Juan C. (September 2019, Electronics)

   This paper presents an experimental demonstration of a novel real-time Energy Management System (EMS) for inverter-based microgrids to achieve optimal economic operation using a simple dynamic algorithm without offline optimization process requirements. The dynamic algorithm solves the economic dispatch problem offering an adequate stability performance and an optimal power reference tracking under sudden load and generation changes. Convergence, optimality and frequency regulation properties of the real-time EMS are shown, and the effectiveness and compatibility with inner and primary controllers are validated in experiments, showing better performance on optimal power tracking and frequency regulation than conventional droop control power sharing techniques. 

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3. Evaluating Coupling Models for Cloud Datacenters and Power Grids

   https://doi.org/10.1145/3447555.3464868  

   Lin, Liuzixuan; Zavala, Victor M.; Chien, Andrew A. (June 2021, InThe TwelfthACM International Conference on Future Energy Systems (e-Energy ’21),)

   Ardakanian, Omid; Niesse, Astrid (Ed.)

   The rapid growth of datacenter (DC) loads can be leveraged to help meet renewable portfolio standard (RPS, renewable fraction)targets in power grids. The ability to manipulate DC loads over time(shifting) provides a mechanism to deal with temporal mismatch between non-dispatchable renewable generation (e.g. wind and solar) and overall grid loads, and this flexibility ultimately facilitates the absorption of renewables and grid decarbonization. To this end, we study DC-grid coupling models, exploring their impact on grid dispatch, renewable absorption, power prices, and carbon emissions.With a detailed model of grid dispatch, generation, topology, and loads, we consider three coupling approaches: fixed, datacenter-local optimization (online dynamic programming), and grid-wide optimization (optimal power flow). Results show that understanding the effects of dynamic DC load management requires studies that model the dynamics of both load and power grid. Dynamic DC-grid coupling can produce large improvements: (1) reduce grid dispatch cost (-3%), (2) increase grid renewable fraction (+1.58%), and (3) reduce DC power cost (-16.9%).It also has negative effects: (1) increase cost for both DCs and non-DC customers, (2) differentially increase prices for non-DC customers, and (3) create large power-level changes that may harm DC productivity. 

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4. Robust Decentralized Secondary Frequency Control in Power Systems: Merits and Trade-Offs

   https://doi.org/10.1109/TAC.2018.2884650  

   Weitenberg, Erik; Jiang, Yan; Zhao, Changhong; Mallada, Enrique; De Persis, Claudio; Dorfler, Florian (December 2018, IEEE Transactions on Automatic Control)

   Frequency restoration in power systems is conventionally performed by broadcasting a centralized signal to local controllers. As a result of the energy transition, technological advances, and the scientific interest in distributed control and optimization methods, a plethora of distributed frequency control strategies have been proposed recently that rely on communication amongst local controllers. In this paper, we propose a fully decentralized leaky integral controller for frequency restoration that is derived from a classic lag element. We study steady-state, asymptotic optimality, nominal stability, input-to-state stability, noise rejection, transient performance, and robustness properties of this controller in closed loop with a nonlinear and multivariable power system model. We demonstrate that the leaky integral controller can strike an acceptable trade-off between performance and robustness as well as between asymptotic disturbance rejection and transient convergence rate by tuning its DC gain and time constant. We compare our findings to conventional decentralized integral control and distributed- averaging-based integral control in theory and simulations. 

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5. Operating Power Grids during Natural Disasters

   https://doi.org/10.1109/PTC.2019.8810777  

   Oner, Ahmet; Abur, Ali (June 2019, 2019 IEEE Milan PowerTech)

   Optimal dispatch and network reconfiguration have so far been used effectively to improve power grid reliability and economic operation. This paper presents a linearized optimization formulation of best load shedding and topology control strategies under extreme events such as hurricanes. In addition, the algorithm analyzes voltage stability after each optimization cycle and iteratively tightens the constraints until a stable solution is found. The proposed method relies on the hurricane's trajectory forecast and available fragility curves for civil engineering structures to predict those power grid facilities most likely to be damaged or taken out in the next monitoring period. The developed algorithm also considers the requirements of other interdependent networks such as mobile communication and emergency services to prioritize load shedding for associated load centers 

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