A New Adaptive Distance Relaying Scheme for Mutually Coupled Series-Compensated Parallel Transmission Lines During Intercircuit Faults

The presence of various types of intercircuit faults on a series-compensated parallel transmission line combined with the effect of mutual coupling and fault resistance makes the protection system quite complicated. In this paper, the authors have proposed a new adaptive digital distance relaying scheme which takes care of all such abnormalities of the conventional ground distance relays and measures the correct value of impedance during phase-to-phase and phase-to-phase-to-ground intercircuit faults. The proposed adaptive scheme is based on the derivation of the compensated value of impedance using symmetrical component theory. Furthermore, it does not require remote-end data. To validate the proposed scheme, numerous computer simulations have been carried out on an existing part of the Indian 400-kV, 300-km-long series-compensated parallel transmission line using MATLAB/SIMULINK software. Simulation results demonstrate the effectiveness of the proposed scheme since the maximum percentage error is within ±5%.