Parameter-Less Fault Locator for Double-Circuit Transmission Line Using Two-Terminal Unsynchronized Measurements

This paper develops a parameter-free fault location (FL) method for double-circuit transmission lines utilizing pre- and post-fault unsynchronized current and voltage measurements. Firstly, the FL equation is deduced for normal-shunt and non-identical inter-circuit faults (involving different phases in both circuits). The FL equation relies on equating the voltage phasors' difference between identical phases in the two circuits at the FL without utilizing the line parameters and synchronization angle between both line terminals. Next, the FL equation is deduced for identical inter-circuit faults (involving identical phases in both circuits) utilizing pre- and post-fault measurements, where a new method is introduced to obtain the pre-fault synchronization angle and line shunt-admittance relying on pre-fault data. Besides, it considers different synchronism mismatch in the pre- and post-fault data. To distinguish identical inter-circuit faults from other fault types, the absolute difference, between post-fault currents of identical phases in both circuits at each line terminal, is employed. PSCAD/EMTDC software is used for modeling the IEEE 39-bus system to evaluate the proposed method for various fault resistances, locations, fault types, and measurement errors. In addition, the developed method offers solid performance against evolving faults and different loading conditions. Moreover, it remains applicable when one of the two circuits is out-of-service.