Distance and User-defined Overcurrent Relay Coordination for IEEE-14 Bus Test System

The transmission and sub-transmission faults are predominantly sensed by zone-1 distance relays (DRs) and primary directional overcurrent relays (DOCRs) based on the corresponding fault location. In most of the research articles using traditional DOCRs, the relay characteristic coefficients are fixed according to IEEE or IEC standards. Due to this, the minimization of total relay operating time cannot be achieved significantly. However, in user-defined DOCRs, the relay characteristic coefficients can be optimized along with the time multiplier setting (TMS) and plug setting (PS). Therefore, this paper proposes user-defined DOCR coordination with DRs having flexible zone-2 settings to reduce the total relay operating time. The incorporation of a novel objective function (NOF) also adds a remarkable reduction in backup and primary relay operating times. The feasibility of the proposed protection scheme is validated on standard test systems, namely the IEEE-14 bus system. The efficacy of the proposed work is evaluated in terms of the total relay operating time and the number of miscoordination relay pairs. The comparative analysis intensifies a significant reduction in total relay operating time using user-defined DOCRs. The simulation results reveal that the proposed protection scheme can be effectively implemented on any power network.