Analysis of half-wavelength transmission line under critical balanced faults: Voltage response and overvoltage mitigation procedure

This paper presents a detailed study of half-wavelength (HWL) transmission line system under critical fault conditions. This non-conventional ultra high voltage alternating current (UHVAC) transmission line has excellent properties in steady-state operation condition and economic advantage when compared to conventional UHVAC system and even high voltage direct current (HVDC) transmission systems for similar power capacity. This technology has been studied for many decades and its response under condition fault is an important topic. First, the point of fault and the type of fault conditions are evaluated to confirm that balanced faults in specific regions are critical. Then the main characteristics of voltage response of HWL transmission system under balanced fault are presented and critical regions that produce severe overvoltage are identified and main transient characteristics are described. Finally, a preliminary mitigation procedure is shown and its performance is evaluated.