Michael Claus

Novel impedance determination method for phase-to-phase loops

In this paper a novel impedance determination method for the phase-to-phase loops is described. This approach promises a better accuracy of the reactance calculation of the faulty loops. Thus, better selectivity and security in operation of the distance element applied for the protection of transmission and distribution lines is guaranteed. Moreover, with this new method the separation of the fault resistance from load condition is achieved. Due to this fact, special measures for load encroachment are not necessary. It contributes to simplification of distance protection settings.

Precise distance to fault locator with two end phasor measurement transmitted via serial protection data interface

Fault locator functionality is a standard feature in modern numerical feeder protection devices for transmission systems. It is common practice to calculate the fault location via an impedance measurement separately at each line end. All calculation techniques used to date in this ldquosingle endedrdquo fault location exhibit limited accuracy. The accuracy that can be obtained is limited by natural constraints. The common factors that influence the accuracy are described below. Hereafter, the fundamental improvement provided by the ldquotwo endedrdquo fault locator, which in addition uses the measured values from the opposite line end, are described.