An adaptive fault locator system for transmission lines

This paper presents an adaptive fault locator system which utilizes two-terminal Global Positioning System (GPS) based synchronized phasor measurements for on-line estimation of line parameters in steady-state and calculation of fault location in the occurrence of faults. Uncertainty about the line parameters, which usually results in a significant error in the calculated fault location, can be resolved in the proposed parameter estimation algorithm. A novel fault location index in terms of Clarke components of the synchronized voltage and current phasors is also proposed to calculate the fault location in the accuracy of up to 99.9%. This paper also proposes a new discrete Fourier transform (termed as smart discrete Fourier transform, SDFT) based algorithm to eliminate system noise and measurement errors. The field tests of two GPS based phasor measurement prototypes demonstrate that a synchronization error between two remotely spaced prototypes is small enough for a fault locator. The performance of the parameter estimation algorithm and index is illustrated with simulation results from EMTP.