Fast & adaptive fault location technique for three-terminal lines

•Extraction of the phasor of voltage and current signals over a half-cycle via improved half-cycle Fourier method with recognition of decaying DC parameters and removal of its effect from the final phasor.•Adaptively determination of the parameters of three-terminal transmission line in a way that the values are estimated correctly while the environmental and operating conditions change.•Recognition of fault occurrence and faulty section with the calculation of the voltage at branch point using the voltage and current data of three terminal nodes.•Determining the precise location of fault on the faulty section with implementing the nodal current unbalance method for three-terminal lines. This paper presents a fast and adaptive method to locate faults in three-terminal transmission lines, based on the synchronized measurements within the half-cycle data window. First, the voltage and current data are processed by two sets of half-cycle Fourier filters at three terminals in order to extract the main component of the voltage and current phasors quickly and with a high accuracy using a novel method. The proposed algorithm uses the calculated phasors and works without any need to transmission line’s data or the Thevenin equivalent of the system at each terminal. For making sure of considering the real operation conditions of the network, transmission line’s parameters are determined adaptively using the calculated phasors. The voltage at the tapping point is calculated separately using three-terminal data and consequently the faulty section is identified and then, the precise location of fault in the faulty section is accurately calculated using the nodal current unbalance method. Performance of the proposed algorithm is evaluated under different fault conditions. The simulation results show the high convergence speed and the excellent accuracy of the proposed method under various operating conditions and various fault types.