A PSCAD/EMTDC Current Transformer Simulation Model Considering Nonlinear Core Saturation and Loss Characteristics

In power systems, current transformers (CTs) step down high currents, enabling accurate measurement and protection critical for system stability. Protection CTs require high accuracy to avoid relay malfunctions caused by distorted currents. While iron cores enhance flux linkage, their nonlinear hysteresis can introduce measurement errors. This paper proposes a CT simulation model for PSCAD/EMTDC, employing RMS-based excitation curve data provided by manufacturers. The model utilizes the Dommel algorithm for nodal analysis to simulate nonlinear core behavior and core losses without extensive experimental data. Based on a secondary equivalent circuit, it includes magnetizing inductance, hysteresis losses, secondary winding impedance, and burden impedance. Manufacturer‘s excitation curves are incorporated directly using 10 data points, with ‘Loop-width(%)’ quantifying loss currents and simplifying data processing. It’s accuracy was validated via open-circuit tests, capturing saturation characteristics, and verified through comparisons with built-in 'Saturable Reactor' and 'MOV' components, demonstrating the precision of the proposed method in time-domain simulations.