New fault detection and localisation technique for double‐circuit three‐terminal transmission line

This study proposes a new technique which detects fault on the line, identifies faulty circuit/line‐section and estimates location of fault (fault localisation) on the double‐circuit three‐terminal transmission line. The fault detection and faulty circuit/line‐section identification has been carried out by estimating the superimposed components of current at remote end with reference to all the three terminals. Subsequently, the estimation of fault distance is performed by utilising phase angle of voltage and current at the fault point. The performance of the proposed technique has been evaluated by simulating 400 kV double‐circuit three‐terminal transmission line network using PSCAD/EMTDC software package. The results indicate that the presented technique is able to detect as well as recognise the faulty circuit/line‐section correctly even in case of occurrence of a high resistance ground fault near the tap point. At the same time, it is also capable of estimating the precise value of fault location as the percentage error remains within ±1.3%, even under wide variation in system and fault parameters. The proposed technique is also valid for cross‐country faults and its accuracy remains consistent even with considerable errors in the measurement of current transformers and capacitive voltage transformers.