An Intelligent Protection Algorithm for Unsymmetrical Phase Shifting Transformers

This abstract illustrates differential protection philosophy for indirect unsymmetrical phase shifting transformer (IUPST) by using combined wavelet transform principal component analysis (PCA) and support vector machine (SVM). Discrimination between interval fault and magnetizing inrush condition is a very challenging task in IUPST differential protection scheme. Therefore, discrete wavelet transform is used to extract the feature from the relaying signal (i.e. differential current) and the features of the relaying signal is used to train and test the SVM. The IUPST is modelled in PSCAD/EMTDC software to obtain the relaying under different operating conditions. The proposed algorithm is evaluated in MATLAB under forward and backward mode of PST operation and the tested data is simulated in PSCAD/EMTDC by varying inception angle, fault position, tap positions, loading conditions of IUPST. Results shows that the proposed algorithm is stable, reliable and selective under different operating conditions of IUPST.