Study of the Impact of Weather Conditions on the Performance of HVDC Insulator String using Physics-Based System Model

Abstract

Electrical energy transmission over long distances using the High Voltage DC (HVDC) mechanism, instead of the standard High Voltage AC (HVAC), is beneficial as it introduces relatively lower power/line losses. However, compared to HVAC, HVDC is more susceptible to environmental conditions like humidity, wind, pollution, etc. Such conditions particularly impact the insulator strings and may degrade them over time resulting in increased line losses. Such surface effects of electric field and partial ionization, on the performance of HVDC transmission lines in extreme conditions, are usually characterized experimentally, however, numerical models are also used to understand experimental results. In this work, the impact of extreme weather conditions on the working of HVDC insulators and transmission lines is studied to identify key vulnerabilities in the system. For this purpose, a physics-based system model of the transmission line is developed and optimized. Using the developed model, weather conditions like atmospheric humidity is simulated to understand the impact of insulator string design, its materials, and construction on HVDC’s performance. Here, electric field and partial ionization insulator, flashover, and the stress distribution along the string are the pivot points of research. This study shows a significant variation from the original performance at 0% humidity once relative humidity reaches up to 60%. The developed model and performed analysis can assist in optimizing the choice of material and construction of insulator strings for HVDC applications based on prevalent weather conditions in the target area.