Integration of a Protection/Measurement Current Transformer based on Compensation Algorithm

Abstract

In this paper, a compensation algorithm for the integration of a protection/measurement current transformer is proposed, which can realize the accurate measurement of the grid current in both normal and fault situations. According to a real CT data and its hysteresis curve, two hyperbolic models can be established. In this way, the compensation algorithm can properly describe the exciting current by secondary current. It can improve the primary current measurement by secondary current and the calculated exciting current. The results indicate the proposed method can improve the accuracy of the CT and the measurement error meet the IEC standard, both in small load currents and large fault current scenarios. As a result, a CT not only can be used for power system protection at fault condition, but also for current measurement at normal operation situation.