Accurate impedance based fault location algorithm using communication between protective relays

The reactance method with fault resistance separation has been developed in order to determine the impedance of a fault loop as precisely as possible in a transmission or distribution power system line. This method has commonly been used for impedance calculation in the 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. This research consists of an improvement in the calculation method using data from both the own and the remote end of the line. This approach uses a communication link 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 for an exact computation of the fault reactance and fault resistance. In this paper, the derivation of this novel approach, as well as the experimental results in a fault location application are presented.