Modeling zero impedance branches in power system state estimation

The authors discuss the modeling of branches with zero impedances in power system state estimation. A new modeling approach is introduced by means of which zero impedance branches can be modeled exactly. An overview of the state estimation problem is presented using two formulations: the standard normal equations and the extended form of the normal equations in which zero injections are represented as equality constraints. Next, the modeling of the zero impedance series branches is introduced. Thus the new modeling procedure is illustrated by two examples. Finally test results based on real life systems are discussed.>