Prevention of Misoperation Caused by Magnetizing Inrush and CT Saturation Identification in Transformer-Adjacent Line Differential Protection

With the advancement of power grid construction, the saturation characteristics of current transformers pose challenges to the reliability of line differential protection. To address the issue of maloperation in adjacent line differential protection caused by CT saturation, it is necessary to develop fast identification algorithms based on multi-source information fusion. Firstly, aiming at the problem of false operation of differential protection caused by CT saturation due to inrush current, a protection strategy based on voltage characteristics is proposed. By using open criteria to accurately identify false differential current, the reliability of protection is improved. Secondly, a CT saturation identification method based on nonlinear dynamic criteria of phase trajectory is proposed. By utilizing the fractal dimension of the secondary current phase trajectory, CT saturation can be effectively identified. Simulation results show that this method has high accuracy and low computational complexity, making it suitable for real-time monitoring under complex operating conditions.