Constructing convex inner approximations of steady-state security regions

We propose a scalable optimization framework for estimating convex inner approximations of the steady-state security sets. The framework is based on Brouwer fixed point theorem applied to a fixed-point form of the power flow equations. It establishes a certificate for the self-mapping of a polytop...

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Κύριοι συγγραφείς: Nguyen, Hung D., Dvijotham, Krishnamurthy, Turitsyn, Konstantin
Άλλοι συγγραφείς: School of Electrical and Electronic Engineering
Μορφή: Journal Article
Γλώσσα:English
Έκδοση: 2020
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Διαθέσιμο Online:https://hdl.handle.net/10356/143661
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author Nguyen, Hung D.
Dvijotham, Krishnamurthy
Turitsyn, Konstantin
author2 School of Electrical and Electronic Engineering
author_facet School of Electrical and Electronic Engineering
Nguyen, Hung D.
Dvijotham, Krishnamurthy
Turitsyn, Konstantin
author_sort Nguyen, Hung D.
collection NTU
description We propose a scalable optimization framework for estimating convex inner approximations of the steady-state security sets. The framework is based on Brouwer fixed point theorem applied to a fixed-point form of the power flow equations. It establishes a certificate for the self-mapping of a polytope region constructed around a given feasible operating point. This certificate is based on the explicit bounds on the nonlinear terms that hold within the self-mapped polytope. The shape of the polytope is adapted to find the largest approximation of the steady-state security region. While the corresponding optimization problem is nonlinear and non-convex, every feasible solution found by local search defines a valid inner approximation. The number of variables scales linearly with the system size, and the general framework can naturally be applied to other nonlinear equations with affine dependence on inputs. Test cases, with the system sizes up to 1354 buses, are used to illustrate the scalability of the approach. The results show that the approximated regions are not unreasonably conservative and that they cover substantial fractions of the true steady-state security regions for most medium-sized test cases.
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spelling ntu-10356/1436612020-09-15T08:47:13Z Constructing convex inner approximations of steady-state security regions Nguyen, Hung D. Dvijotham, Krishnamurthy Turitsyn, Konstantin School of Electrical and Electronic Engineering Engineering::Electrical and electronic engineering Feasibility Inner Approximation We propose a scalable optimization framework for estimating convex inner approximations of the steady-state security sets. The framework is based on Brouwer fixed point theorem applied to a fixed-point form of the power flow equations. It establishes a certificate for the self-mapping of a polytope region constructed around a given feasible operating point. This certificate is based on the explicit bounds on the nonlinear terms that hold within the self-mapped polytope. The shape of the polytope is adapted to find the largest approximation of the steady-state security region. While the corresponding optimization problem is nonlinear and non-convex, every feasible solution found by local search defines a valid inner approximation. The number of variables scales linearly with the system size, and the general framework can naturally be applied to other nonlinear equations with affine dependence on inputs. Test cases, with the system sizes up to 1354 buses, are used to illustrate the scalability of the approach. The results show that the approximated regions are not unreasonably conservative and that they cover substantial fractions of the true steady-state security regions for most medium-sized test cases. Nanyang Technological University Accepted version 2020-09-15T08:47:13Z 2020-09-15T08:47:13Z 2018 Journal Article Nguyen, H. D., Dvijotham, K., & Turitsyn, K. (2019). Constructing convex inner approximations of steady-state security regions. IEEE Transactions on Power Systems, 34(1), 257-267. doi:10.1109/TPWRS.2018.2868752 0885-8950 https://hdl.handle.net/10356/143661 10.1109/TPWRS.2018.2868752 1 34 257 267 en IEEE Transactions on Power Systems © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. The published version is available at: https://doi.org/10.1109/TPWRS.2018.2868752 application/pdf
spellingShingle Engineering::Electrical and electronic engineering
Feasibility
Inner Approximation
Nguyen, Hung D.
Dvijotham, Krishnamurthy
Turitsyn, Konstantin
Constructing convex inner approximations of steady-state security regions
title Constructing convex inner approximations of steady-state security regions
title_full Constructing convex inner approximations of steady-state security regions
title_fullStr Constructing convex inner approximations of steady-state security regions
title_full_unstemmed Constructing convex inner approximations of steady-state security regions
title_short Constructing convex inner approximations of steady-state security regions
title_sort constructing convex inner approximations of steady state security regions
topic Engineering::Electrical and electronic engineering
Feasibility
Inner Approximation
url https://hdl.handle.net/10356/143661
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