A new algorithm for improving the numerical stability of power system state estimation

Hatim G. Abood, Victor Sreeram, Yateendra Mishra

Research output: Contribution to journalArticle

Abstract

State estimation (SE) is based on an iterative process for solving weighted least squares (WLS) via the so-called normal equations (NE). This process is prone to numerical instability and may lead to an ill-conditioned state estimator in many cases. Although several methods have been proposed in the past to deal with the ill-conditioning problem in high-voltage transmission systems, the SE stability of low-voltage distribution systems remains a challenge due to fewer measurements and high R/X ratios. This paper highlights the main reasons for the ill-conditioning problem and focuses on the impact of the R/X ratio of the distribution systems. NE-based SE uses a comparatively simple algorithm with much lower storage size. Hence, this paper proposes a regularized version of the WLS state estimator to solve the problem of ill-conditioning using an adjustable regularization parameter. Simulation results on U.K. 18-bus and radial 33-bus distribution systems show improved performance in terms of reducing the computational complexity, measurements redundancy, the impact of high R/X ratios and improving the accuracy and numerical stability of the SE solution. (c) 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Original languageEnglish
Pages (from-to)358-365
Number of pages8
JournalIEEJ Transactions on Electrical and Electronic Engineering
Volume14
Issue number3
DOIs
Publication statusPublished - Mar 2019

Cite this

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title = "A new algorithm for improving the numerical stability of power system state estimation",
abstract = "State estimation (SE) is based on an iterative process for solving weighted least squares (WLS) via the so-called normal equations (NE). This process is prone to numerical instability and may lead to an ill-conditioned state estimator in many cases. Although several methods have been proposed in the past to deal with the ill-conditioning problem in high-voltage transmission systems, the SE stability of low-voltage distribution systems remains a challenge due to fewer measurements and high R/X ratios. This paper highlights the main reasons for the ill-conditioning problem and focuses on the impact of the R/X ratio of the distribution systems. NE-based SE uses a comparatively simple algorithm with much lower storage size. Hence, this paper proposes a regularized version of the WLS state estimator to solve the problem of ill-conditioning using an adjustable regularization parameter. Simulation results on U.K. 18-bus and radial 33-bus distribution systems show improved performance in terms of reducing the computational complexity, measurements redundancy, the impact of high R/X ratios and improving the accuracy and numerical stability of the SE solution. (c) 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.",
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A new algorithm for improving the numerical stability of power system state estimation. / Abood, Hatim G.; Sreeram, Victor; Mishra, Yateendra.

In: IEEJ Transactions on Electrical and Electronic Engineering, Vol. 14, No. 3, 03.2019, p. 358-365.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A new algorithm for improving the numerical stability of power system state estimation

AU - Abood, Hatim G.

AU - Sreeram, Victor

AU - Mishra, Yateendra

PY - 2019/3

Y1 - 2019/3

N2 - State estimation (SE) is based on an iterative process for solving weighted least squares (WLS) via the so-called normal equations (NE). This process is prone to numerical instability and may lead to an ill-conditioned state estimator in many cases. Although several methods have been proposed in the past to deal with the ill-conditioning problem in high-voltage transmission systems, the SE stability of low-voltage distribution systems remains a challenge due to fewer measurements and high R/X ratios. This paper highlights the main reasons for the ill-conditioning problem and focuses on the impact of the R/X ratio of the distribution systems. NE-based SE uses a comparatively simple algorithm with much lower storage size. Hence, this paper proposes a regularized version of the WLS state estimator to solve the problem of ill-conditioning using an adjustable regularization parameter. Simulation results on U.K. 18-bus and radial 33-bus distribution systems show improved performance in terms of reducing the computational complexity, measurements redundancy, the impact of high R/X ratios and improving the accuracy and numerical stability of the SE solution. (c) 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

AB - State estimation (SE) is based on an iterative process for solving weighted least squares (WLS) via the so-called normal equations (NE). This process is prone to numerical instability and may lead to an ill-conditioned state estimator in many cases. Although several methods have been proposed in the past to deal with the ill-conditioning problem in high-voltage transmission systems, the SE stability of low-voltage distribution systems remains a challenge due to fewer measurements and high R/X ratios. This paper highlights the main reasons for the ill-conditioning problem and focuses on the impact of the R/X ratio of the distribution systems. NE-based SE uses a comparatively simple algorithm with much lower storage size. Hence, this paper proposes a regularized version of the WLS state estimator to solve the problem of ill-conditioning using an adjustable regularization parameter. Simulation results on U.K. 18-bus and radial 33-bus distribution systems show improved performance in terms of reducing the computational complexity, measurements redundancy, the impact of high R/X ratios and improving the accuracy and numerical stability of the SE solution. (c) 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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KW - regularization

KW - singular value decomposition (SVD)

KW - MATRIX

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