A Solution to CT Saturation by Gregory Newton's Backward Interpolation

Saturation problem in steel core Current Transformers (CTs) causes dreadful effects in protection systems as true replica of the primary current is not always reflected in CT secondary side under abnormal operating conditions. This is why detection and production of exact replica of primary current in the CT secondary side is very crucial. This paper presents a discrete wavelet transform based application using 'Daubechies3’ as mother wavelet for the detection of saturation. The compensation of saturated signal is done by Gregory Newton's Backward Interpolation (GNBI). The whole scheme of detection of CT saturation and compensation of saturated CT secondary current has been successfully tested on various saturated signals simulated in MATLAB/SIMULINK with various case studies. Finally, the scheme is validated in real time using DS1104 controller board of dSPACE. The results obtained are very encouraging.