A discrete dynamic filter for detecting and compensating CT saturation

Current transformers (CTs) are used in electric power systems for protection and measurement purposes. The current signals in the secondary side of a CT should be exact reproductions of the corresponding current signals on its primary side. CTs are susceptible to the saturation phenomenon which leads to inaccurate current measurement and therefore, may cause malfunction of the protective relays. This paper presents an approach to the correct the distorted waveforms caused by CT saturation. A dynamic filter based on weighted least absolute value minimization is used to produce compensated secondary current samples from the distorted ones. The proposed technique is independent of CT parameters/characteristics or secondary burdens. Various test results indicate that the proposed technique can successfully detect CT saturation and accurately compensate the distorted secondary currents.