基于U-I象空间分布的CT饱和识别及畸变电流重构方法OA

Current transformers(CTs)are core components of various differential protection,but they are prone to saturation under complex fault current characteristics and significantly increased current amplitudes.First,voltage information provided by potential transformers(PTs)at measurement points is integrated,and a voltage-current coupling relationship is established to plot trajectory curves in a two-dimensional image space,with current on the horizontal axis and voltage on the vertical axis.This approach mitigates the interference of single-signal distortion caused by CT saturation on state identification.Based on the deviation of the degree of trajectory from a standard ellipse,saturation states are identified and the severity of saturation is graded.Finally,sampling points within the linear transmission interval are selected,and an improved ellipse-fitting algorithm is applied to integrate the image space and reconstruct the distortion current.A 220 kV transmission line model with new energy integration is constructed on the PSCAD/EMTDC platform.Simulation results show that the proposed method can efficiently and accurately identify CT saturation and reconstruct secondary distorted currents under different types and severities of CT saturation.