Performance Analysis of Empirical Fourier Transform based Power Transformer Differential Protection

This paper investigates the performance of empirical Fourier transform (EFT) based differential protection algorithm (DPA) for power transformer protection. The performance indices such as sensitivity, specificity and accuracy are evaluated for EFT-DPA using confusion matrix analysis. The performance indices of the EFT-DPA are also compared with the existing conventional Discrete Fourier transform (DFT) DPA. Though DFT-DPA is well accepted in power utilities, the limitations such as maloperation for typical cases of simultaneous occurrences of inrush current, current transformer saturation, internal/external fault and cross country fault need to be addressed. Therefore, the recently developed EFT-DPA has to be thoroughly validated. Here, transformer modeling and DPA implementation is carried using PSCAD and MATLAB code, respectively. The performance analysis is statistically assessed for an existing real time power auto transformer in Tamil Nadu Transmission Corporation Limited (TANTRANSCO), Tamilnadu, India and two other power transformer systems available in the literature.