Research On Modeling Of High-voltage Current Transformer And Effect Of Its Saturation On Differential Protection

At present, the electromagnetic current transformer (CT) is still widely used in electric power relay protection. However, the saturation problem caused by CT core's nonlinearity often leads to differential protection's mal-operation. To have a better knowledge of CT's transient properties, two CT models based on EMTP-ATP and Matlab are set up respectively for steady and transient analysis. And these two models are mainly for project use. Then, another CT model with much more accuracy is built with Preisach theory, which could simulate CT's hysteresis and remanence. Last but not the least, operation situation of differential protection based on sampled values is simulated based on above models and also, some measures to ease saturation effect are put forward.