Comparison of estimation methods for compensating the saturation effects in secondary current of Current Transformers

This work presents a comparative study of Least Squares Filter, Kalman Filter and Unscented Kalman Filter for estimating the secondary current phasor distorted due to saturation of Current Transformers (CTs). Several distorted current signals were generated in a Real Time Digital Simulator (RTDS) and embedded in noise. Then, these signals were segmented in two kinds of regions, named saturated and unsaturated regions, with the aid of an auxiliary saturation detecting method. The estimations were performed by the three filters only in the unsaturated regions, where there is no distortion in the signals. The mean estimation errors and its standard deviations were computed, the convergence times were analyzed and a comparative performance evaluation was made. The results obtained have the purpose to assist in choosing the most appropriated estimation method for compensating CT saturation effects.