Series capacitor-compensated double-circuit transmission line directional relay system using a fuzzy expert system with a Haar wavelet

There has been no perfect methodology for directional relaying in a series capacitor-compensated double-circuit transmission (SCCDCT) line until now. As it is crucial to protect the SCCDCT line from inevitable fault consequences, intelligent techniques must be employed for immediate fault directional relaying. In this work, a fuzzy expert system (FES) is developed for non-unit protection in the SCCDCT line, due to its capacity for efficient handling of linguistic data. The validity of the proposed methodology is tested by simulating a 400 kV existing Indian SCCDCT network in MATLAB software. The suitable fault zones/sections, phase, and location are identified using a phase angle component, zero sequence component, and Haar wavelet transform currents. The simulations indicate that the proposed methodology is able to correctly detect the faulty section. Also, it precisely estimates the fault distance and classification, as the maximum recorded error and accuracy for faults remain within ± 0.232% and above 99.98%, respectively. Finally, a comparison of the proposed methodology with related protection methodologies clearly demonstrates its superiority. This routine protection methodology is sufficiently rapid, discriminative, enormously reliable, robust, and incredibly responsive for isolating the targeted fault.