from：China Southern Power Griddate：2021-04-27
You may already have heard of the news that some areas in Texas have challenged by extensive power outages as a massive winter storm has engulfed a huge portion of the state.
China encounters cold waves each year charging southward from Siberia and in response, China Southern Power Grid has had to react by adopting measures to protect the valued power grids so that people can enjoy heating their homes and businesses as well as enjoying their modern conveniences, indoor Wi-Fi.
Year 2020 ended with China remitting combat against the cold, while the Year 2021 begins again with this same united offense against these sub-zero temperatures. With the cold wave sweeping across China and white snow covering the ground, instead of viewing the splendid snow view, the thousands-strong electrical staff from CSG rose to meet this cold wave head on … to deice transmission lines and ensure stable power supplies.
One thing needs to be stated at the outset: when these cold waves hits, it's the warmer regions of South China that is in more urgent need of protection efforts than the colder north.
It has to do with the related geographic position, landforms and special climate of Southern China.
During continuing rainy days at low temperatures, supercooled water droplets (droplets of rain and fog) in the air will freeze quickly the moment they fall on the surfaces of objects with temperatures below zero degree Celsius, then forming damaging ice claddding surfaces.
In southwest China's Guizhou Province, this is called “congelation”.
Congelation can cause dangerous ice coverage on power transmission lines and devices.
The congelation and ice accretions on transmission lines
The same power tower in summer (left) and winter (right) observed at the same perspective.
The congelation occurs in winter, mainly in South China's mountainous areas, particularly in the Yunnan-Guizhou Plateau. There are several conditions that allows for the congelation to form:
First - temperatures approaching zero or below zero degree Celsius.
Second - continuous freezing rain, drizzle, fog, or occasional sleet, and
Third - proper wind speeds.
On January 8, in Guizhou, Taijiang County, everything was frozen.
Congelation does not occur only in Guizhou, but is often seen in other areas in the southwest, as well as neighboring mountainous areas of Sichuan, Chongqing, Yunnan, Hunan and Guangxi provinces. Even some central and eastern mountainous areas of Hubei, Jiangxi, Anhui, Zhejiang and Fujian provinces have occasionally experienced these sub-zero temperatures.
In response to congelation, all the power grids in the southern area require deicing to ensure the stability of power supplies.
Huize, Yunnan. On January 8, staff of Kunming Power Grid were observing the conditions of the power lines and deicing at the temperature of negative 5.4 degrees Celsius, with a humidity of 99.9%.
Staff from State Grid are conducting observation of ice coverage on transmission lines in Fengdu, Chongqing.
Staff of the Shaoguan Power Supply Bureau, Guangdong Power Supply Company take precise measurements of the thickness of ice on simulated wires.
As mentioned, the special climate of southern mountainous areas can lead to potentially dangerous ice coverage on transmission lines and devices.
If the transmission lines are covered by ice, it may bring about icing flashover, short circuit, broken wires and even fallen power towers, thus leading to the failure of power systems.
In 2008, a power tower fell down due to extreme ice coverage.
During winter months, especially when cold waves require consistent deicing efforts that must be made in time to ensure safe operation of the power grid and stable supplies of electricity.
Facing a bitterly cold wave in early January, the engineering staff of China Southern Power Grid deiced several thousands of ice-covered lines of 10kV and above, with more than 6,000 staff involved each day in emergency response against the cold.
So, how to deice and protect the power grids?
Congelation and ice-coverage are unavoidable during the winter. Fortunately, with increasingly advanced technologies, high-tech have replaced the majority of valued manpower in deicing, marking a leapfrog progress as grid workers are getting more skilled on the job.
Ice-observing drone that can measure the accurate thickness of ice.
The work of ice-observing used to be done by the CSG engineering staff but today, it can be done by drones and online monitoring devices;
The work of deicing used to be done by hand but today can be done by DC (direct current).
What is DC ice-melting technology?
DC ice-melting refers to a method of melting ice by applying a DC voltage on the transmission lines and cause a short circuit at their terminals, heating the wires and then melting the ice.
It may sound simple, but considering such long transmission lines and the extremely complex operation of power grids, DC ice-melting is not as easy as connecting both ends of the lines to super large batteries. What lies behind are plenty of scientific research, development and applications.
Ice-melting with one click: Staff from the Zhaotong Power Supply Bureau, Yunnan Power Supply Company can start the ice-melting processing with a single click. The time ice-melting takes is shortened from four hours to just 10 minutes!
Flame-throwing drones are also applied.
There are some more incredible de-icers we'd like to share with you:
Apart from being used for removing obstacles, this laser de-icer can also be employed for ice-melting. It slice off an ice layer of 12 centimeters within eight minutes. (Note: the laser de-icer shown in the picture has been updated to the fifth generation, smaller but stronger.)
LIDAR (Laser Radar)
This worker from the Drone Inspection Center, Guangdong Power Grid, is scanning and observing transmission lines using LIDAR. He takes only 10 minutes to collect data on ice-covered earth wires of 561 meters, power towers and landforms.
The backpack LIDAR device can emit dense laser points, which can be used to measure accurate position of space. Then a detailed centimeter-accurate model is created, and on the digitalized transmission line, can be well applied in disaster prediction.
Rendering of backpack LIDAR scanning. Note: this technology has also been applied since early 2018.
The power systems in the southern mountainous area are challenging
particularly on the Yunnan-Guizhou Plateau that often suffer from cold waves. To avoid power failures caused by ice-coverage, CSG has devoted significant efforts to deicing and ensuring stable electric supplies, thus bringing people a continual flow of warmth and light.
As a proverb goes, "Rome was not built in a day." The same is true of the power grids, which also take years to grow strong. Each year, China Southern Power Grid has been making continuous progress while struggling with low temperatures and rainy and freezing days.
With CSG, the lights will always be on!
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