Probabilistic constrained load flow for optimizing generator reactive power resources

The generator reactive capability curve normally used in operation planning overestimates the reactive supply or absorption capabilities of the unit b ecause it does not consider the operating conditions of the generator plant and of the electric power system. These are determined by the tap position s on the generator step-up and on the auxiliary unit transformer. This pape r presents the application of probabilistic constrained load flow to optima l selection of these taps. It is shown that the technique proposed provides tap settings satisfying the reactive requirements for a whole range of ope rating conditions taking into account their probabilities of occurrence.