Breaking the Hierarchy: Distributed Control and Economic Optimality in Microgrids

By Florian Dörfler, John William Simpson-Porco, Francesco Bullo. IEEE Transactions on Control of Network Systems, 2014

520 citations recorded by the source corpus.

Modeled after the hierarchical control architecture of power transmission systems, a layering of primary, secondary, and tertiary control has become the standard operation paradigm for islanded microgrids. Despite this superficial similarity, the control objectives in microgrids across these three layers are varied and ambitious, and they must be achieved while allowing for robust plug-and-play operation and maximal flexibility, without hierarchical decision making and time-scale separations. In this paper, we explore control strategies for these three layers and illuminate some possibly unexpected connections and dependencies among them. Building from a first-principle analysis of decentralized primary droop control, we study centralized, decentralized, and distributed architectures for secondary frequency regulation. We find that averaging-based distributed controllers using communication among the generation units offer the best combination of flexibility and performance. We further leverage these results to study constrained ac economic dispatch in a tertiary control layer. Surprisingly, we show that the minimizers of the economic dispatch problem are in one-to-one correspondence with the set of steady states reachable by droop control. In other words, the adoption of droop control is necessary and sufficient to achieve economic optimization. This equivalence results in simple guidelines to select the droop coefficients, which include the known criteria for power sharing. We illustrate the performance and robustness of our designs through simulations.

Subfields: Control and Systems Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/437023106098f96f1a15803300c2888eef823ec2

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Citations in the corpus

Resilient Disaster Recovery Logistics of Distribution Systems: Co-Optimize Service Restoration With Repair Crew and Mobile Power Source Dispatch (2018, unknown): “Second, intelligent control schemes enabling the system’s plug-and-play operation are required [79].”
Foundations and Challenges of Low-Inertia Systems (Invited Paper) (2018, background): “Results on frequency stabilization via decentralized nonlinear droop control are presented [67], [69], [71].”
Distributed Control Strategies for Microgrids: An Overview (2020, methodology): “Inspired by techniques from the cooperative control of MAS, other works proposed secondary control algorithms that ensure asymptotic convergence of the controlled variables [63], [128], [147], [239], [240].”
On the Secondary Control Architectures of AC Microgrids: An Overview (2020, methodology): “techniques, the following distributed protocol is used [14], [55], [88], [166], [167]:”
State of the Art in Research on Microgrids: A Review (2015, background): “…Secondary control that compensates the steady state deviations in voltage and frequency caused by the primary control, and Tertiary control that takes into account economic considerations and determines power flow between the microgrid and utility grid to achieve the optimal operation [210]–[212].”
A Survey on Model-Based Distributed Control and Filtering for Industrial Cyber-Physical Systems (2019, methodology): “This distributed controller is employed in [132] to offer the best combination of ﬂexibility and performance by using communication among generation units.”