Asynchronous fault location scheme for half-wavelength transmission lines based on propagation characteristics of voltage travelling waves

Due to prominent attenuation of travelling waves, double-end fault location method produces considerable errors when applied to ultra-high voltage AC half-wavelength transmission (UAHT) lines. In order to address this problem, this study presents a novel fault location scheme based on the attenuation, refraction and reflection principles of aerial-mode voltage travelling waves (AVTWs). In the scheme, the faulted section of an UAHT line is first determined according to the accumulated amplitude ratio of the pre-determined frequency components of AVTWs asynchronously sampled at both terminals of the line. Then, the Teager energy of the first two wavefronts of the AVTW - measured at the terminal in the faulted section - is used to define two factors for selecting the appropriate accurate fault location method. Finally, the single-end travelling wave method is adopted for locating the faults near the line terminal. The presented double-end method utilises the amplitude ratio of AVTWs to locate the faults far from the line terminal. A 1000 kV UAHT line model is considered with various fault conditions in PSCAD/EMTDC simulations. The simulation results and analysis demonstrate that the proposed fault location scheme is accurate and immune to fault distances, fault types, fault impedances and fault inception angles.