Braving wind and snow to keep the lights on

Heavy snow fell in Mianxian county in the hinterland at the southern foot of the Qinling Mountains on Feb 24. Not long after the team went up the mountain, biting cold pierced their heavy work clothes.

Liang Wenyi, a transmission line maintenance worker, had a red face and stiff hands from the cold. He rubbed his hands hard, took out a thermometer and pointed it at tower No. 2505 on the ±800 kV Qilian-Shaoshan line. It showed -10 C.

In the monitoring room of the Hanzhong base 150 km away, Zhang Zhen stared at real-time data pooled from more than 470 sets of online monitoring devices. At the ice-melting station in Chadian town, Mianxian, Yang Shuo carried out routine checks on power equipment and devices, ready at any time to respond to line icing emergencies.

At dusk, workers at three locations began coordinating efforts to protect the transmission line linking the Northwest China and Central China grids.

State Grid Shaanxi's Ultra-High Voltage Company, an important force safeguarding the security of the Shaanxi grid, said its operation and maintenance staff members were on duty on the front line to ensure uninterrupted power for the resumption of work and production after the holiday and for residents' daily life.

"This section is the most dangerous; I'll go first," said 50-year-old Liang at 17:30, as he put on his safety helmet and became the first to step onto an almost vertical gravel slope in the dangerous Changgou river section of the Qinling Mountains.

"Snow and thin ice cover the rocks. It is very slippery, so be extra careful," he told his colleagues over his shoulder, repeatedly striking the ground with a trekking pole.

The veteran, with 31 years of line-patrol experience, has walked 3,000 km since the Qilian-Shaoshan line was completed in 2017.

"Temperatures are low in the mountains; we cannot relax patrols at all." While recording data, Liang reminded his colleagues to focus on checking for hidden hazards on lines and corridors.

Over 31 Spring Festivals, he spent 28 on patrol routes. "The grid does not stop operating just because it is the New Year. We must remain at our posts at all times," Liang said.

In the monitoring room, Zhang had worked nearly 10 hours. A member of State Grid Shaanxi UHV Company's Hanzhong transmission operation and maintenance team, he is responsible for remote monitoring of five transmission corridors with a total length of more than 1,500 km. On the screen, images from 1,200 camera monitoring points rotated continuously.

"In rain and snow, monitoring intensity must be raised." He switched screens quickly with his mouse, and once abnormal information was found, he immediately entered it into the system.

"Patrols used to rely on feet; now electronic eyes give us more guarantees." Zhang said the company has built an integrated inspection system of online monitoring, drone patrol and manual patrol, making line conditions in remote areas visible in real time.

"But technology cannot replace people; workers still have to go to the site to verify," he said.

As he spoke, the screen showed suspected smoke in a forest. Zhang immediately enlarged the image to identify it and contacted a line-protection worker to check. After confirming it was water vapor rising, he breathed a sigh of relief.

At the ice-melting station in Chadian town, Mianxian county, China's first live ice-melting device for UHV ground wires and optical cables was running in an orderly manner. The station, put into operation in 2022, undertakes winter ice-melting tasks in sections prone to heavy icing and can switch among seven operating modes.

At 20:30, the online monitoring system sounded an alarm: ice thickness on the optical cable and ground wire at tower No. 2505 reached 6.4 mm and was still increasing.

Yang Shuo, deputy head of State Grid Shaanxi UHV Company's Hanzhong transmission operation and maintenance team, decisively ordered a Level IV emergency response, and the ice-melting station immediately entered an emergency state.

It was not his first night operation. During the 2023 Spring Festival, he started an ice-melting operation at midnight; by the time he finished, the New Year's Eve dumplings had frozen solid.

At 21:00, Yang pressed the start button. The screen showed an output current of 245 A and the line temperature was rising slowly. He watched the data closely and precisely controlled current changes — too small a current would fail to melt ice, while too large a current would damage the line. After 73 minutes, the ice was completely removed.

On the morning of Feb 25, sunlight lit the Qinling peaks. Liang headed to the next patrol section, Zhang completed a new round of monitoring, and Yang began equipment rechecks. Countless power workers, treating their posts as home, began a new day's work.

To ensure power supply during the Spring Festival holiday and for work resumption, State Grid Shaanxi UHV Company coordinated repair forces from its divisions and bases, gave full play to the advantages of integrated operation and maintenance of UHV AC and DC stations, optimized regional emergency repair resources, deployed emergency repair teams, improved production emergency command, and refined risk control measures, ensuring strong support for UHV and high-voltage grid equipment.

After the holiday, the Qinling Mountains were swept by biting cold wind, but the power lines operated steadily, delivering a steady stream of electricity. These ordinary power workers measure responsibility with their footsteps, safeguard safety with data, fend off the cold with technology, and silently guard the bright lights across the Sanqin land.