A Robust Method for Equality Constrained State Estimation

This paper presents a robust method for the solution of the equality constrained state estimation problem. The problem is formulated as a weighted least squares (WLS) problem with equality constraints. Traditionally the problem is solved iteratively by the normal equations with equality constraints (NE/C). One problem of NE/C is that the gain matrices are not positive definite and extra logic is required to process the zero pivots during Gaussian elimination. In this paper positive definite gain matrices are formulated and triangularization is performed symbolically using sparsity techniques. The method is illustrated with a six-bus system and the IEEE 14-bus system.