Numerical experiments for three-phase state estimation performance and evaluation

Relatively poor performance of state estimators is a well documented experience. Yet, control and operation of electric power system requires reliable state estimators. The poor performance is attributed to implementation simplifications that use single phase asynchronous measurements and the positive sequence model of the system. These simplifications have generated practical problems. The experience is that the state estimation problem does not have 100% performance, i.e. there are cases and time periods that the SE algorithm will not converge. There are practical and theoretical reasons for this and they are explained in the paper. The paper also demonstrates that these problems are correctable by using a three phase asymmetric model of the system and precise modeling of three phase and/or single phase measurements. This approach leads to an enhanced hybrid SE approach that combines the current SCADA type data with three phase phasor measurements. The performance of the hybrid state estimator is demonstrated with visualization techniques that clearly demonstrate the superiority of the three phase modeling and hybrid data sets. The performance is demonstrated with data from an actual electric power network. Numerical experiments on this system have quantified the performance gains of the three phase hybrid state estimator.