An EMD-DT Assisted Intelligent Protection Scheme for TCSC Compensated Transmission Lines

The dynamic variation of impedance during different operating modes of Thyristor Controlled Series Capacitor (TCSC) compensated transmission lines impose protection challenges to the conventional distance relays. The use of nonlinear metal oxide varistor for protection of the TCSC makes the impedance variation further complex during fault. This paper proposes a two criteria based improved fault detection and classification scheme for such networks. The method employs the sign of the change in the magnitude of positive-sequence current at both ends of the line for fault detection and an intelligent hybrid scheme based on empirical mode decomposition-decision tree for fault classification. The proposed approach is evaluated on 10,800 fault data generated on the modified WSCC 9-bus power system using EMTDC/PSCAD. The fault detection and classification accuracies are found to be 100% and 99.60%, respectively. The low computational burden with comparatively higher accuracies in the detection and classification faults compared to the available intelligent training based approaches justify the efficacy of the proposed protection scheme.