A Nonlinearity-Retaining State Estimation for Three-Phase Distribution System

A three-phase distribution system state estimation algorithm is proposed in this paper based on the retaining of nonlinearity. It takes advantage of the characteristics of the radial feeder and is suitable for systems with high R/X ratios. Considering the imbalance of a three-phase distribution system, this method is suitable for the observed system which involves real-time measurements and some power and voltage metered information treated as pseudo measurements. Because the method retains the nonlinear second order terms, the Jacobian matrix is constant and the second order terms are easier to compute and computing time is faster. Theoretical analysis and digital simulations are carried out and the results show that the method is reliable, efficient and requires less memory, suits on-line application for radial distribution systems.