Ice monitoring, forecasting, mapping, prevention and removal toolbox

Icing on power lines can cause major problems for the transmission network. This can lead to large repair and maintenance costs in addition to lost revenue. There is also a great risk for employees who have to carry out repairs and maintenance under harsh climatic conditions. Icing on power lines is a problem in most countries with power lines in high altitude, of which Norway has some of the highest ice loads that have been measured. In this project, we will develop a national icing map with design values based on historical weather, and we will also assess the effect of climate change. We will look at both wet snow and in-cloud icing in addition to the combination with high wind loads. The project aims to develop cost-effective instrumentation that gives us the opportunity to monitor the ice loads in exposed locations and also link this to icing forecasts. With an increased understanding of the errors related to icing, the project wants to investigate different methods to avoid large ice loads on existing facilities and design with higher accuracy when planning new power lines. WP1 Sensors and measuring stations Cost-effective and robust sensors that can measure ice loads in operational power lines have been developed. Through the development of smarter algorithms for heating sensors that enable fuel cells as a primary energy source, cost- and energy-efficient weather stations have also been developed for monitoring icing and weather conditions in particularly weather-exposed locations. Measurement data of icing and meteorological variables have also been obtained, which have been used for the development and validation of models for use in forecasts and climate maps. WP2 Monitoring In this work package, a prototype platform has been developed for monitoring ice loads on power lines. The monitoring system combines real-time data from the load sensors with short-term forecasts as well as information about the capacity of the specific power line mast. A web application shows measured and imminent ice loads and will also alert the user in case of increased load values. The system will contribute to efficient planning and operation of power lines in areas prone to icing, especially with regard to implementing mitigating measures in cases of increased loads. WP3 Modelling Through numerical modeling of meteorological conditions and atmospheric icing on structures, the model tools used in mapping, forecasting and climate projections of ice loads have been improved. Through the work, understanding has been increased and the uncertainty associated with modeling extreme ice loads in the high mountains has been reduced. As well as improving the weather forecasting model WRF with regard to forecasting icing as a result of wet snow. Work has been done to quantify possible changes in icing as a result of climate change. The climate data forms the basis for icing maps for future climate. Furthermore, a statistical model for ice shedding has been developed. WP4 Icing map The work has consisted of using a numerical weather forecast model to generate various model datasets that both cover a sufficiently long historical period and with sufficient horizontal resolution for the generation of icing maps and physical modeling of icing in combination with various statistical analyses. Results are icing maps that describe both the maximum expected ice load with a given return period, and reduction as a result of the horizontal orientation of a given power line. In addition, icing maps have been developed for future climate. The icing maps will be of great value both in planning and designing new power lines but will also be able to contribute to evaluating the reliability of existing lines. The ice maps will also be made digitally available to the public. The work also includes a study of the statistical relationship between extreme wind and ice loads, an important load case for power lines. WP5 Ice prevention WP 5 consisted of a literature study with 11 passive and active ice reduction technologies including a workshop where 85 participants from 15 countries and different industries took part. The knowledge, which sheds light on the technologies' applicability to different types of icing, maturity level and synergies that can be achieved through a combination of technologies, is useful for both the distribution and transmission networks. The solutions will be able to increase the reliability of power lines in Norway. WP6 Ice removal Here, literature research was carried out on activities related to the removal of ice from power lines such as e.g. heating of shield wires, robots for de-icing, increased load on lines for de-icing and mechanical methods. Mechanical methods of ice removal are proving to be effective, while robotics is still at the stage of laboratory testing. Heating systems are efficient as they do not require physical presence, but the challenge is to get the heat source close to the affected areas.

Deling av kunnskap og informasjon gjennom publikasjoner, vitenskapelige artikler og presentasjoner på relevante fora som f.eks. Iwais, Cigre, Winterwind samt workshop arrangert av Icebox prosjektet. WP1 Nye kosteffektive og robuste sensorer samt miljøvennlige målestasjoner gjør det mulig å innhente islast-data og meteorologiske variable på en effektiv måte som bidrar til overvåkning av utsatte kraftledninger samt nyttig input til forbedring av vær og isingsmodeller. WP2 Gjennom systemet for å overvåke islaster og formidle isingsprognoser vil man bidra til effektiv planlegging og drift av kraftledninger i isingsutsatte områder, spesielt med hensyn på å iverksette avbøtende tiltak i tilfeller med forhøyede laster. WP3 Isingsmodellene ligger bak blant annet dimensjonerende laster, isingsprognoser, isingskart. Gjennom økt forståelse og reduksjon av usikkerhet knyttet til modellering av ekstreme islaster i høyfjellet samt forbedring av værvarslingsmodellen (WRF) har man økt kvaliteten på alle disse produktene. WP4 Isingskartene vil ha stor nytteverdi både i planlegging og prosjektering av nye kraftledninger, men vil også kunne bidra til å evaluere påliteligheten til eksisterende ledninger. Iskartene vil også gjøres digitalt tilgjengelig for allmennheten gjennom en offentlig publiseringskanal. WP5 Prosjektet har gjennom workshopen «Ice reduction and removal techniques on structures and conductors» delt kunnskap og informasjon mellom 85 deltagere fra 15 forskjellige land og mange forskjellige bransjer. Forskningsaktiviteten, som belyser teknologienes anvendelighet til ulike isingstyper, modenhetsnivå og synergier som kan oppnås gjennom kombinasjon av teknologier, har fordeler både for distribusjonsselskaper som driver lav- og mellomspentlinjer samt Statnetts overføringsnett ettersom teknologiene ble vurdert for anvendelighet på ulike isingstyper. Hvis de implementeres, vil løsningene gi økt pålitelighet for kraftledninger i Norge. WP6 Kunnskapen som ble innhentet under litteraturforskningen økte kunnskapsbasen hos forskningspartnerne og bidro til å tilby en mer omfattende konsulenttjeneste til selskaper over hele verden. Forskningsaktiviteten, som belyser teknologienes anvendelighet til ulike isingstyper, modenhetsnivå og synergier som kan oppnås gjennom kombinasjon av teknologier, har fordeler både for distribusjonsselskaper som driver lav- og mellomspentlinjer samt Statnetts overføringsnett ettersom teknologiene ble vurdert for anvendelighet på ulike isingstyper. Hvis de implementeres, vil løsningene gi økt pålitelighet for kraftledninger i Norge.

Icing on power lines can cause major disruptions in electricity supply networks. These disruptions lead to excessive costs for repair as well as consequential losses. There is also a risk to human safety for employees tasked with the repair of power lines in harsh environmental conditions. Icing on power lines is a problem experienced in most high-latitude countries of which Norway has some of the highest recorded ice loads. In the project we will develop a national icing map containing design values based on historical weather, as well as taking future climate change into consideration. Both wet snow icing and in-cloud icing will be considered as well as their combination with high wind speeds. This will be important background information for the optimization and design of new power line routes. This project aims to develop cost effective instrumentation that allows for detailed, real-time monitoring of the ice loads at a large number of exposed locations and to develop methods for connecting all real time observations to a probabilistic icing forecasting system. With an increased awareness of possible failures due to climatic loads, the project will consequently investigate the most promising countermeasures for the removal or reduction of icing on the existing lines as well as the possibility to change the design to prevent the build up of large ice amounts on new lines. Examples of such methods that will be studied in the project are the use of anti torsional pendulums; super-hydrophobic or ice-phobic coatings; heating of the lines by controlling the electrical current; induction spirals; robot technologies.