Analysis of Mathematical Methods for Decreasing the Saturated Current Transformer Error
At different times, different devices were used as current sensors at electric power systems. However, the instrumental electromagnetic current transformers (CTs) proved more suitable and have been the most commonly adopted. The wide application of the CTs can also be justified by their reliability, subject to the operation rules. Accuracy and reliability of measured information sent from instrumental CTs are one of the important components for the correct operation of power system protection, data acquisition and telemetry systems, process control systems at electrical power facilities. There have been developed a lot of numerical methods for compensation of current transformer (CT) saturation. The article provides the comparison of several mathematical methods for secondary current restoration. The accuracy of different methods was analyzed under various conditions, namely, remaining flux, initial phase of short circuit current and noise presence. Linear combination of sine wave and aperiodic function was used as a test primary signal along with real short circuit current scope. Based on the performed analysis some recommendations and further development directions are stressed.