State estimation based enhanced one-terminal algorithm for fault location in a transmission network

This paper proposes an enhanced one-terminal fault-location algorithm in which its salient performance is to combine the advantage of minimal fault data requirement for standard IEEE one-terminal algorithm with the advantage of superior accuracy for two-terminal algorithm. Assuming that voltage phasor at any bus can be easily obtained, and that fault impedance can be treated with resistive characteristic, an optimization problem is then formulated, and solved by a well-known SQP routine, to estimate the fault current contribution from the other terminal with no measuring device such as digital fault recorder. Performance of the proposed technique has been validated by comparing against respective performances of the two aforementioned IEEE standard algorithms as well as another enhanced one-terminal proposed by Takagi, et. al, testing on an IEEE 14-bus network for three-phase and single-phase-to-ground short-circuits with fault resistance varying from 0.1-5 ohm and fault position varying over the entire line length. Test results show impressive accuracy performance, especially for the cases with fault resistance above 1 ohm and fault position within 0.7 per-unit line length. The optimization formulation will be further refined in the future, in an attempt to even improve the accuracy closer to the level obtained from the two-terminal algorithm.