Overvoltages due to line faults on a HWL transmission line: Corona effect and mitigation techniques

In half-wavelength (HWL) transmission lines, severe temporary overvoltages are usually observed during the occurrence of line-to-line faults in specific critical locations, and it is unrealistic to ignore the impact of the corona phenomenon. To represent the corona effect, an accurate Suliciu corona model was adopted and implemented in PSCAD software, and a new technique based on the genetic algorithm (GA) was proposed to fit the model parameters. Furthermore, the paper evaluated the performance of the overvoltage mitigation method based on the installation of two spark gaps (SGs) at strategic points to detune the resonance condition. As shown, the SGs turn the HWL line overvoltage levels similar to those observed in conventional AC lines, and the corona modelling further reduces the severity of the overvoltages. (AU)