CT Saturation Detection Based on the Distance Between Consecutive Points in the Plans Formed by the Secondary Current Samples and Their Difference-Functions

This paper proposes a novel method to detect the saturation intervals where the secondary current of current transformers for protection purposes becomes distorted. The method is based on the analysis of plans formed by the secondary current samples (i₂) and their difference-functions (del[n]). The distance between consecutive points in these plans has a significant increase when saturation occurs, bucking the trend of the intervals without saturation. Two plans are considered: del[2] versus del[1] and del[3] versus del[2]. Besides the ease of implementation, the results indicate the effectiveness of the method to detect saturation intervals.