Assessment of saturated current transformer primary current by multi resolution analysis of its secondary current

This paper presents an approach for detection of Current Transformer (CT) saturation and assessment of Root Mean Square (RMS) value of primary current during saturation by Multi Resolution Analysis (MRA). This has been achieved by capturing voltage across secondary of CT and decomposing it by Discrete Wavelet Transform (DWT) for different primary currents. MRA is performed on secondary voltage. MRA shows oscillatory notches during saturation; positive peak of the notch is measured wherefrom saturation is detected. Then wavelet decomposition is performed and RMS value of approximate coefficients is measured for different primary currents. Then interpolation and extrapolation methods are applied for assessment of RMS value of primary current during saturation. Simulated results show very optimistic result in assessment of primary current at saturation.