Power system state estimation using weighted least trimmed sum of absolute deviation

Abstract

Power system state estimation (PSSE) is one of the vital components in energy management system. Owing to high computational efficiency of weighted least squares (WLS) estimator, it is generally utilized to estimate the state of the power system. However, WLS is a non-robust estimator, i.e. estimated states are highly distorted even in the presence of single bad data measurement. Hence, a high breakdown estimator that is insensitive to bad measurements is essential. This paper suggests the application of one such robust estimator known as weighted least trimmed sum of absolute (WLTA) deviation estimator to PSSE. The main principle of WLTA estimator is to optimize the weighted sum of the absolute residuals of rank υ. In the present work, the PSSE problem is solved as an optimization problem using orthogonal crossover based differential evolution algorithm. The proposed method has been demonstrated on IEEE 14-bus and IEEE 30-bus systems under normal and bad data conditions. The results thus obtained validate that WLTA is an attractive substitute to WLS estimator especially in the presence of bad data measurements. Further, it is shown that the proposed WLTA estimator is statistically robust compared to WLS technique.