A NEW ROBUST ALGORITHM FOR ESTIMATING THE STATE OF A POWER SYSTEM

Abstract

The paper presents a new algorithm to estimate the state of a power system. It is essentially an improved version of the Weighted Least Squares (WLS) which is widely used in practice. In order to obtain an optimal estimate, the weighting matrix is to be chosen as the error covariance matrix in the WLS algorithm. In practice the error covariance is largely unknown and the weighting matrix is suitably tuned. There are problems of convergence if the weighting matrix is chosen as the inverse of E [ VV' 1. The new algorithm overcomes such problems and is found to have good convergence characteristics. Although it is essentially an improvement of the WLS algorithm, it differes from it in the method of implementation. .It is based upon a technique used to obtain the pseudo-inverse of a non-square matrix and is an extension of it to include weighting factors. The new algorithm does not call for any type of tuning of the weighting matrix and the number of iterations to converge do not depend upon the mix of measurements or size of the system. This is the main contribution of the paper.