An equivalent pi network model for power system state estimation with network parameter errors

Summary form only given. With the role of state estimation in energy management systems gaining weight every day, the demand for its accountability is an imperative, to say the least. The reliability of the network database is thus a key factor. This paper employs the two bus π equivalent model for every line in the power network to approach the network parameter estimation problem. The network π model is known to combine the effect of fixed tap transformers in the equivalent´s line impedance and line charging admittances. The method aims to correct the equivalent line parameters of the suspicious branch rather than evaluating every network component individually based on whether there is a transformer or not. The suspicious branch is determined by ranking the branches in order of their respective branch indices obtained in a particular way, from normalized residuals of measurements involved. The technique employs the state vector augmentation approach to correct and store the updated equivalent parameters of the erroneous branch, which is sufficient for an accurate state estimation. Besides this, the correct value of the parameters can always be estimated from the equivalent network if needed. Illustrations on the IEEE 14 and 30 bus systems have been furnished to validate the approach for different cases of parameter errors on any single branch.