Implementation of an Improved Phasor Approximation Technique for Compensating the CCTV Transient Effect

This paper proposes an improved phasor estimation technique based on intrinsic time decomposition which enhances the distance relay performance during coupling capacitor voltage transformer (CCVT) subsidence transient. The proposed logic utilizes voltage and current signals at relay point and decomposes it’s in to corresponding baseline and residual signals. Then, the decaying dc component is calculated and removed from the signals. Finally, the phasor of corresponding signals are evaluated using discrete Fourier transform to evaluate the performance of the distance relay. The proposed integrated phasor estimation based distance relaying algorithm is tested for different worst scenarios such as different source impedance ratio and different CCVT burden. The simulation has been performed on 60 Hz, 500 kV CCVT power system modeled using EMTDC/PSCAD. Results obtained using proposed phasor estimation scheme enhances the distance relay for correctly discriminating the in-zone faults from out-zone faults. Finally, assessment of transient estimation technique proves the superiority of the proposed method in distance relaying application.