Study reveals mechanisms that promote icing responsible for power disruptions

November 26, 2018

Chinese scientists shed light on the meteorological conditions responsible for the rate of icing growth on electric power transmission lines. Having a clearer understanding of what promotes icing on transmission lines during cold surges can help us better forecast and mitigate against crippling power outages caused by these events.

Their findings were published on Nov 18, 2018 in Advances in Atmospheric Sciences. The journal is sponsored by the Institute of Atmospheric Physics of the Chinese Academy of Sciences and published by Springer.

"Wire icing can significantly impair the normal functioning of electric power transmission lines, negatively impacting productivity and everyday life," says Shengjie Niu, professor at the School of Atmospheric Physics, Nanjing University of Information Science & Technology, and corresponding author of the paper.

The impact of power outages resulting from transmission wire icing can disrupt business activity and have other negative spinoffs. For example, "from January to February in 2008, four large-scale freezing rain and snow weather events in southern China caused huge economic losses, causing widespread concern in the research community" explains Professor Niu.

Power disruptions and the resulting economic losses associated with icing have captured the attention of researchers around the world, and many scientists are now working on this issue, said Niu, noting that a clearer understanding of the mechanism responsible for icing accumulation can significantly help us improve forecasting that will in turn enable us to provide an early warning of freezing disasters.

For this study, the researchers monitored the icing process of agglomerate fog, an event where massive amounts of fog come together, at the Lushan Meteorological Bureau Observatory, in Southeast China during a cold surge that occurred from the 20th-25th January 2016, which lasted for 102 hours. Situated between Poyang Lake and the Yangtze River, Lushan has abundant moisture resources which contribute to the formation of ice during cold surges.

The duration, frequency and droplet spectrum distribution of agglomerate fog were analyzed, together with the effect that rain, snow and supercooled fog -- essentially a supercooled cloud containing water droplets in liquid form at temperatures below zero degrees celsius that forms just above the Earth's surface -- had on the rate of icing growth on wires laid out at two different heights: 10 meters (on an observation tower) and 1.5 meters (on an observation icing frame located underneath the tower).

They found that during this timeframe 218 agglomerate fogs, which lasted on average around 10 minutes, as well as snow and rain, contributed to the icing process. Ice accumulated on the wires rapidly during the freezing rain phase, but the rate of icing growth was much lower during the dry snow phase. However, certain meteorological conditions -- the presence of supercooled fog, lower temperatures and increased wind speed -- helped fuel the rate of icing growth during the dry snow phase.

The researchers observed significant differences in the thickness and density of the accumulated ice, as well as the mechanism that contributed to icing growth and the duration of the icing at the two different heights.

"The differences in temperature and wind speed were the main reasons for the differences in thickness, duration, density, and growth mechanism of icing at the two heights," said Niu, "which indicated that the icing thickness, duration, density, and growth mechanism were all closely related to height."

In order to make observation results closer to that of icing observed on actual high-voltage transmission lines, the authors suggest that the height of icing observation frames should be raised, and that more comparative observation studies of the relationship between different heights and icing growth should be conducted.

"Further observational results show that the sticking efficiency of snow particles has a significant impact on icing growth rate, which will be considered in the next wire-icing numerical simulation," said Professor Niu, who also hopes to establish methods to forecast wire icing in the future.
-end-


Institute of Atmospheric Physics, Chinese Academy of Sciences

Related Wind Speed Articles from Brightsurf:

Wind beneath their wings: Albatrosses fine-tuned to wind conditions
A new study of albatrosses has found that wind plays a bigger role in their decision to take flight than previously thought, and due to their differences in body size, males and females differ in their response to wind.

Simulating wind farm development
Engineers have devised a model to describe how, in the process of establishing wind farms, interactions between developers and landowners affect energy production costs.

Measuring the wind speed on a brown dwarf
Strong winds blow high in the atmosphere of the brown dwarf 2MASS J1047+21, according to a new study, which presents a simple method to deduce the windspeed in other brown dwarf atmospheres, too.

Astronomers measure wind speed on a brown dwarf
Using VLA and Spitzer observations, astronomers are able to determine wind speeds on a brown dwarf for the first time.

Supporting structures of wind turbines contribute to wind farm blockage effect
Much about the aerodynamic effects of larger wind farms remains poorly understood.

Wind and water
Damaging rains from hurricanes can be more intense after winds begin to subside, say UC Santa Barbara scientists.

Silverswords may be gone with the wind
In a new study in the Ecological Society of America's journal Ecological Monographs, researchers seek to understand recent population declines of Haleakalā silverswords and identify conservation strategies for the future.

Biodiversity and wind energy
The location and operation of wind energy plants are often in direct conflict with the legal protection of endangered species.

Boosting wind farmers, global winds reverse decades of slowing and pick up speed
In a boon to wind farms, average daily wind speeds are picking up across much of the globe after about 30 years of gradual slowing.

High-speed microscope illuminates biology at the speed of life
The Columbia team behind the revolutionary 3D SCAPE microscope announces today a new version of this high-speed imaging technology.

Read More: Wind Speed News and Wind Speed Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.