A New Two-Port Network Model-Based Pilot Protection for AC Transmission Lines

Conventional pilot protections used for EHV/UHV ac transmission lines require data synchronization between the two terminals of transmission line, and their performances are affected by the line capacitive charging current and load conditions. To tackle these problems, this paper proposes a new pilot protection scheme based on two-port network model of ac transmission lines. The new protection scheme calculates the two-port network parameters from the online measurements via the sequence components method, and then compares the solved parameters with their setting values to distinguish the internal and external faults. It does not require the data synchronization between two terminals of the transmission line. Moreover, its performance is not affected by the line capacitive charging current and load conditions. The applicability of the proposed scheme for series compensated lines is also analyzed. Effectiveness and accuracy of the proposed protection scheme have been verified by simulation tests.