Title
Online Optimization as a Feedback Controller: Stability and Tracking
Abstract
This paper develops and analyzes feedback-based online optimization methods to regulate the output of a linear time invariant (LTI) dynamical system to the optimal solution of a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">time-varying</italic> convex optimization problem. The design of the algorithm is based on continuous-time primal-dual dynamics, properly modified to incorporate feedback from the LTI dynamical system, applied to a proximal augmented Lagrangian function. The resultant closed-loop algorithm tracks the solution of the time-varying optimization problem without requiring knowledge of (time varying) disturbances in the dynamical system. The analysis leverages integral quadratic constraints to provide linear matrix inequality (LMI) conditions that guarantee global exponential stability and bounded tracking error. Analytical results show that under a sufficient time-scale separation between the dynamics of the LTI dynamical system and the algorithm, the LMI conditions can be always satisfied. This paper further proposes a modified algorithm that can track an approximate solution trajectory of the constrained optimization problem under less restrictive assumptions. As an illustrative example, the proposed algorithms are showcased for power transmission systems, to compress the time scales between secondary and tertiary control, and allow to simultaneously power rebalancing and tracking of the DC optimal power flow points.
Year
DOI
Venue
2020
10.1109/TCNS.2019.2906916
IEEE Transactions on Control of Network Systems
Keywords
Field
DocType
Optimization,Heuristic algorithms,Time-varying systems,Linear systems,Control systems,Steady-state,Power system stability
Mathematical optimization,Control theory,Augmented Lagrangian method,Exponential stability,Optimization problem,Convex optimization,Linear matrix inequality,Dynamical system,Trajectory,Mathematics,Tracking error
Journal
Volume
Issue
ISSN
7
1
2325-5870
Citations 
PageRank 
References 
6
0.48
0
Authors
3
Name
Order
Citations
PageRank
marcello colombino1516.70
Emiliano Dall'Anese236038.11
Andrey Bernstein3298.99