Precise impedance based fault location algorithm with fault resistance separation

The reactance method with fault resistance separation has been developed in order to determine as precisely as possible the impedance of a fault loop in a transmission or distribution power system line. This method has commonly been used for impedance calculation in case of a single phase-to-earth fault in diverse power system protection applications. New developments in this area have shown that the extension of the method to multi-phase faults is not only possible but also of practical relevance. However, all previous investigations focused on impedance calculation using data from one single side of the power system line. Due to missing data from the remote end, the determined impedance value can deviate from its real value. This research consists in an improvement of this calculation method using data from both the own and the remote line end. This approach uses communication between two measurement units e.g. protection relays, which have the advantage of not requiring a precise synchronization with each other. The additional time invariant parameters of the power system, acquired by each device and transferred to the remote end, allow an exact computation of the fault reactance and fault resistance. In this paper, the derivation of this novel approach as well as experimental results in a fault location application are presented.