State Grid Corporation of China (SGCC) recently completed the annual inspection of the Qinghai-Tibet interconnection project, showing that the underground permafrost has been in a stable condition since the project was put into operation a decade ago.
Known as “the Grid’s Line in Heaven”, the project was one of the most difficult DC transmission line constructions in the world, with the highest altitude, the longest distance through the permafrost, and the largest construction area in the alpine region.
In order to ensure stable power supply to this region and to ensure that the fragile ecology is not damaged, SGCC conducts checks on the foundation of the project’s electricity pylons at various points throughout the year.
Staff working for SGCC Qinghai Maintenance Company are responsible for the inspection work. They need to detect and prevent problems such as the sinking, displacement, and tilting of pylons, as well as damage to the main structure.
They first conduct data measurement and permafrost monitoring of the transmission line pylons in the frozen soil section, and then compare and analyze the results with the original data to determine the foundation conditions.
In view of the characteristics of the Qinghai-Tibet Plateau, such as poor thermal stability and strong hydrothermal activities, the foundations of the pylons placed in the frozen soil have been specially designed, with heat conduction rods installed under them to minimize the influence of frost heaving and thaw on their foundations.
The concept of ecological protection is also constantly evolving. From driving birds away and preventing bird activities from causing damage to the power grid in the past, it has evolved into preventing the power grid from causing damage to wild animals, and placing artificial bird nests in the safe area of electricity pylons.