Detection of Partial Saturation and Waveform Compensation of Current Transformers

Derivative-based approaches have been widely used for detecting current-transformer (CT) saturation. This letter proposes an efficient approach for detecting CT saturation with a generic discrimination index without the need for setting definition. For this aim, the simultaneous samples-based multiplication of the secondary current by its derivative is only used to differentiate between saturated and unsaturated wave portions. Reconstructing the detected saturated secondary current is performed by using Kalman filtering to efficiently extract the phasor quantities of the unsaturated current portion. The results provide evidence of the efficacy of the proposed detector and of the Kalman-based waveform reconstruction.