Faulted Phase Selection for Half-Wavelength Power Transmission Lines

In this paper, a novel faulted phase selection algorithm is proposed to he used for distance protection applied to half-wavelength power transmission lines. These lines represent an alternating current solution for very-long point-to-point interconnections as an alternative to HVDC. However, no such lines are currently in operation, and if this type of line is to be constructed, it will require its own protection philosophy because of its peculiar characteristics. This paper shows that the fault selection algorithms used in conventional relays do not work properly when applied to half-wavelength lines. The algorithm proposed herein is initially studied in the steady state and ultimately implemented in a programmable protective relay that is tested using a real-time simulator.