基于特定频率方波激励的保护用电流互感器剩磁检测研究OA

Accurate detection of residual magnetism in protection current transformer(CT)cores is essential for ef-fective demagnetization and for preventing protection misoperations caused by CT saturation.To address this issue,a residual-magnetism detection method based on square-wave excitation at a specific frequency is proposed.A single-phase inverter applies a square-wave voltage at a predefined frequency and amplitude to the CT secondary cir-cuit,driving the core into bidirectional deep saturation.The magnetizing current is analyzed to extract the detection signal and calculate the residual magnetism.CT core residual-magnetism detection and error analysis are conducted on the EMTP-RV platform under square-wave excitation with different frequencies,amplitudes,and combined amplitude-frequency settings.Simulation results demonstrate that the proposed method can rapidly and accurately detect residual magnetism.Increasing the excitation voltage amplitude and reducing the frequency further reduce the error.After testing,the core residual magnetism returns to its initial state,providing a foundation for subsequent rapid demagnetization studies based on known residual magnetism.