Blocked Delayed Elimination in the Power System State Estimator

Grouping of the state estimator gain matrices into a blocked structure resembling the sparse Y-bus matrix is well accepted in the state estimation. However, features like the estimation of transformer tap position and zero impedance line flows may result in pivot failures when the blocked delayed elimination is used. Two types of enhancements are implemented to overcome these issues: enhance the pivot selection criterion in the delayed elimination and selectively apply the concept of an unknown measurement in the formulation of equations. These enhancements have improved the availability and quality of state estimation solution without the need for orthogonalization.