Comparative Analysis of 500 kV Double-Circuit Transmission Line Electric Field Intensity: Ethiopian Lines Compliance With ICNIRP

The high-intensity electric fields, which are in the vicinity of power transmission lines, have adverse effects on human and other living beings if they are not within the specified limits. The International Commission on Non-ionizing Radiation Protection (INCIRP) specifies guidelines for these E-fields from the perspective of public exposure at the ground level and sets it to 5 kV/m at 50 Hz. Thus, this study was aimed at analyzing and comparing the E-fields intensity of differently configured double-circuit 500 kV transmission lines at a height of 1 m above the ground plane. Charge Simulation Method (CSM) using MATLAB as a programming platform is used for this study. Among the tower configurations studied, a configuration that provided minimum E-fields with minimum ground clearance was identified. From the actual built transmission lines included in the study, vertical lines configuration produces a minimum E-fields intensity of 4.565 kV/m root mean square and fulfills the INCIRP requirement. However, triangular line configuration is the preferable configuration for 500 kV double circuit transmission lines giving the least E-fields at the ground with minimum ground clearance using optimized phase sequence arrangements irrespective of other comparative parameters. Additionally, an evaluation of these line configurations based on the distribution of the conductor surface E-fields was conducted. The study reveals that the E-fields on the surface of the transmission line conductors included in the study remains significantly below the intrinsic breakdown strength of atmospheric air. Therefore, it was anticipated that the designs will remain free from corona discharge under fair weather conditions.