A numerically stable decomposition based power system state estimation algorithm

Pandian, A and Parthasarathy, K and Thukaram, D and Soman, SA (1998) A numerically stable decomposition based power system state estimation algorithm. In: International Journal of Electrical Power & Energy Systems, 20 (1). pp. 17-23.

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Abstract

This paper proposes a new approach for solving the equality constrained power system state estimation (PSSE) problem. The proposed approach decomposes the linear least squares with the linear equality constraints (LSE) problem encountered at each PSSE iteration into two unconstrained linear least squares (LS) problems. The solution of the LSE problem is the sum of the solutions of the individual LS problems. The proposed approach avoids giving large weights to equality constraints and hence results in a more stable formulation, that can be solved within the framework of unconstrained least squares. Based on the proposed decomposition, a Givens rotations based PSSE algorithm is proposed and developed. It is shown that the proposed implementation is numerically more stable than the conventional NE, normal equations with constraints (NE/C), Givens rotations and Hachtel's methods for PSSE. The first LS problem to be solved in the proposed implementation is identical to that encountered in conventional constrained weighting approaches like NE approach and Givens rotations approach, except for the fact that equality constraints (zero injection constraints) are not assigned large weights. The resulting error due to the lack of large weights for equality constraints is corrected by the solution obtained from the second LS problem. Simulation results on 23, 89 and 319 node systems show the desirable stability characteristics of the proposed implementation in comparison with NE, Givens rotations, NE/C, Hachtel's approach and NE.

Item Type:	Journal Article
Publication:	International Journal of Electrical Power & Energy Systems
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier.
Keywords:	Last Squares;Euality constraints;State estimation;Numerical stability;Decomposition
Department/Centre:	Division of Electrical Sciences > Electrical Engineering
Date Deposited:	18 Jan 2007
Last Modified:	19 Sep 2010 04:34
URI:	http://eprints.iisc.ac.in/id/eprint/9520

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