Icing destroys transmission lines

The last two winters the Norwegian transmission system operator Statnett has experienced heavier iceloads on parts of the transmission system than predicted.

One of the affected lines was an entirely new 420 kV transmission line crossing an exposed mountain area just north of the Hardanger Fjord in Norway. A ground wire broke due to heavy icing after only three weeks in operation.

Icing has also caused structural collapses of transmission towers.

– The icing challenges the security of supply, says Bjørn Egil Nygaard, advisor at Kjeller Vindtekikk, a Norweigan company that now is working to prevent similar failures in the future.


Icing can reach double the design load.

Iceloads drive the dimensioning of towers and foundations and hence it’s vital to Statnett to predict the level of ice.

The most severe problems are in the mountain areas and have been caused by in-cloud icing/rime icing, the same problem that you can find on wind turbines. This type of icing typically affects high structures that penetrate clouds.

The measured ice load on the 420 kV transmission line in mountain area north of the Hardanger Fjord was more than double the design load.

– That clearly indicates that the ice loads had been significantly underestimated in the pre-construction phase due to lack of suitable meteorological models, says Bjørn Egil Nygaard.

Is the heavy icing due to climate changes?

– Two years of heavy icing is a too short period to make that kind of conclusion, says Nygaard, but that has of course been discussed.

The design load on the 420 kV transmission line was estimated 2007, by applying the then best available meteorological expertise.

Today, an advanced local-scale meteorological model has been implemented as a tool to improve load estimation of the ice loads.

Bjorn Egil Nygaard

Bjørn Egil Nygaard.

The model used for simulations is the Weather Research and Forecasting model (WRF), developed by the National Center for Atmospheric Research (NCAR) in USA.

NCAR is federally funded and the WRF modeling system is possible to download free of charge. It has become an important tool of the trade and it has today grown to have a large worldwide community of users (over 20 000 in over 130 countries), and workshops and tutorials are held each year at NCAR.

Basically you apply the fastest computer you can find, and then use numerical weather prediction to simulate the local weather and icing conditions over the last decades to map the icing conditions on a local scale. With the same system we can do icing forecasts for the next few days and even simulate future icing based on climate change scenarios.

Bjørn Egil Nygaard:

– With modern meteorological models it will be easier to predict icing and also avoid building transmission lines in certain areas, or at least build them strong enough to cope with icing,

Another solution might be ice detectors. But current devices aren’t efficient enough and sometimes doesn’t work at all, says Nygaard. He and his colleagues are now working on a prototype that they hope will make proper measurements.

– There’s no quick fix for icing, but with better forecasts and measuring we might be able to prevent the kind of failures we have seen the last years, concludes, Bjørn Egil Nygaard.

Promising sensor

A new prototype of a atmospheric icing sensor promises to deliver more parameters on ice than current devices. Its set-up is modular so it can be modified for different users and climates 

– Presently, there is no ice sensor commercially available that can detect and measure all important icing parameters such as: icing rate, melting rate, load and type simultaneously, says Umair N. Mughal, researcher at Atmospheric Icing ResearchTeam of Narvik University College in Norway.

muvi_graphene_cold_room (2)

Experimentation of MuVi-Graphene at cold room chamber of Narvik University College.

Now Mr Mughal and collegue Muhammad S.Virk has designed and developed a new prototype modular hybrid atmospheric icing sensor.

– This sensory unit is potentially capable to deliver all of the described icing parameters and has successfully been tested at Cryospheric Environmental Simulator, Japan, in both icing and snow conditions.

MuVi-Graphene , as the device is called, is a modular atmospheric icing sensor, capable to:

* Measure Icing Load (Using Rotary/Torque Loading)

* Icing Rate (using Rotary/Torque Loading)

* Detect Icing Event (Using Mutual Charge Transfer Scheme)

* Determine Ice Type (Using Mutual Charge Transfer Scheme)

* Measure Melting Rate (Using Mutual Charge Transfer Scheme)

The sensor being modular means that the customers can decide which output parameters he or she wants (detecting ice, identify ice type, measure melting rate or measure icing load and icing rate) by doing minor design changes in the sensor configuration.

– Presently this sensor is suitable for onshore applications and stationary installations; however it also has adequate potential for offshore applications by introducing minor changes, says Mughal.

experimental_setup_icing_tunnel_4 (2)

Experimental Setup in Icing Tunnel at Cryospheric Environmental Simulator, Japan.

The device is an electromechanical rotating hexagon with six multi purpose plates mounted on it. It can be used by mounting on simple pole of designed dimensions. It can also be mounted on stationary structures in cold regions.

– Outputs from this sensor will be delivered to a data-logger, which can then be utilized in customized software solution for further applications like anti/deicing systems, says Mughal.

Among the potential users he mentions the wind energy industry, oil and gas, power network/distribution, road maintenance authorities and meteorological weather stations.

Things do at IWAIS 2015

In conjunction with IWAIS 2015 we organize visits to three different locations. Join our tours and learn more about Swedish science and one of Swedens most interesting R&D-centers. 

Explore the oldest university city in Sweden, Uppsala! This one hour city tour led by experienced guides will take you to the most interesting spots and beautiful views of Uppsala, giving you insights into the thousands of years of Uppsala’s history. Time: Wednesday July 1, 6 pm. Cost: 10 Euro. Included: One hour tour of Uppsala.


The main building of the university. Photo: David Naylor.

Study visit to STRI. STRI in Ludvika is an accredited laboratory specializing in high voltage testing and power system applications. They have operated for 25 years, and specialize in areas such as HVDC and UHVDC. The high voltage testing facility can perform tests of equipment rated up to 800 kV UHVDC and 1100 kV UHVAC. They also perform tests with low temperature, ice and snow.

Visit STRI for more information and an video about the company.

Departure time: Early Monday June 29. Return to Uppsala: Late Monday June 29. Cost: 20 Euro. Included: Bus trip to Ludvika. Guided tour of STRI. Lunch in Ludvika.

Visit Smart Grid Gotland. One of the smartest electricity networks in the world is being developed on the island of Gotland in the Baltic Sea, east of the Swedish mainland. The goals of the project is to increase the hosting capacity for wind power in the existing distribution system, create possibilities for demand side participation in the electricity market and to show that novel technology can improve the power quality in a rural grid. Visit Smart Grid Gotland for more information!

smart_grid_1205Gotland is one of the most beautiful places in Sweden. To get there, we will take a ferry from Nynäshamn, and arrive to Visby after three hours on the Baltic Sea. The Hanseactic city of Visby is the best-preserved medieval city in Scandinavia, and is on the UNESCO World Heritage Site list. One of the most notable remains is the 3,4 km long town wall encircling the town centre.

Included in the trip is travel to and from Gotland with bus and ferry, two nights in a hotel, the study visit to Smart Grid Gotland during Friday July 3rd as well as lunch and dinner during the Friday. The return trip arranged by IWAIS is scheduled on Saturday July 4th.

Cost: TBA

Included: Trip to and from Gotland, study visit Smart Grid Gotland, two nights at a hotel, lunch and dinner during Friday July 3rd. Departure time: Evening Thursday July 2nd. Return to Stockholm/Uppsala: Mid-day Saturday July 4th.


…and here are some more activities for you and your family:

Elton John concert in the Botanical garden in Uppsala. The artist behind hit songs such as “Candle In The Wind” and “Tiny Dancer” comes to Uppsala to play in the Botanical Garden on Wednesday July 1st. Tickets can be bought here. Price: 795 SEK


Linnaeus Garden. The first botanical garden in Sweden. Photo: Destination Uppsala.

The Linnaeus Garden. The first botanical garden in Sweden. It was founded in 1655 by Olof Rudbeck the elder. Approximately 1300 species are grown here. The garden is open Tuesday to Sunday from 11am to 5 pm. Entrance fee: 60 SEK.

Lennakatten – the railway museum in Uppland. Take a trip on the steam train departing from Uppsala railway station. The old train has been taken care of by the museum and is now open to the public. Various trips available. Tickets can be bought on Uppsala Railway station. The timetable can be found here. More information (in Swedish) found here. Price: 100 – 180 SEK


The Cathedral. Photo: Destination Uppsala.

Guided tours in the Cathedral. Experience Norden’s largest cathedral. Guided tours in English Monday to Friday at 10 am and 2 pm. Price: Free!

Old Uppsala Museum. Uppsala is one of the oldest cities in Sweden. Throughout history it has played an important role. The museum tells you about exciting archaeological finds and the history of civilization in Mälardalen. The museum is open every day from 11 am to 5 pm.

Get there: Bus 2 from Stadshuset, stop Kungshögarna. Price: 80 SEK

Activities in Stockholm

de081nznpprfea7gwmbtqVasa museum. The naval ship Vasa sank in 1628 on her maiden voyage. It sailed only 1300 m before it capsized and sank. The ship was salvaged in 1961, after 333 years below water. The Vasa ship was then preserve in a unique process and the Vasa museum was opened in 1990. Get there: Tram 7 from Stockholm Central to Vasamuseet. Price: 130 SEK.

Skansen. The world’s first open-air museum, founded in 1891. Here you can walk through five centuries of Swedish history, from north to south. A number of historical buildings have been preserved and renovated. There’s also a zoo with Swedish native species.

Price: 170 SEK. How to get there: Tram 7 from Stockholm Central to Vasamuseet.

Gamla Stan and the Castle. Visit the old town and the royal castle. It’s a unique part of the city with houses as old as 700 years. The Royal Castle is situated in Gamla Stan, tours are available daily. Price: 150 SEK

How to get to Stockholm: Take the commuter train from Uppsala Railway Station. You can buy your ticket in ticket machines at the station, or at the Information desk at the station. The trains leave every 10 to 30 minutes (every 60 min after 8 pm). The train will take you to Stockholm Central Station, from where you can change to subway or buses.

Minister hit by ice

Icing of structures creates problems – and can be dangerous, too, as Aleksandar Antić, Minister of Energy and Mining in Serbia, found out when he inspected power outages due to heavy icing.

– This was the best possible way to illustrate under which conditions people are working, Antić commented afterwards.

He was unharmed.

Registration is open – Early bird until 17 May

Registration to IWAIS 2015 is now open. Early bird is available until 17 May. More info.