Saturation detection of current transformers for protection blocking based on waveform symmetry using morphological skeleton

This paper proposes a novel scheme to detect the saturation of current transformers (CTs) for protection blocking. The scheme modifies the morphological skeleton method and applies it to analyze the shape information of CT secondary current. Afterwards, two indices are introduced to determine the existence of saturation. Simulation studies under a variety of fault conditions have been conducted using PSCAD/EMTDC to evaluate the performance of the proposed scheme. The results have shown that the proposed scheme is able to detect CT saturation accurately, and is robust to noise and sensitive to mild saturation.