Blade icing has a major impact on wind turbines but has historically been difficult to assess. Clir Renewables developed software to detect icing and reduce associated losses.

VANCOUVER, BC: Clir Renewables has released a new software feature which detects icing on turbine blades and measures its impact on performance. Weather is uncontrollable but assessable, and that’s what is required when mitigating icing impacts.

There are thousands of wind turbines located in cold and icing climates around the world and the estimated market potential for wind farms in cold and icing climate is over 200 GW*. Losses due to icing can range from a few percentage points all the way up to over 40% during the icing season. Blade icing furthermore causes increased loads and reduced aerodynamics, as well as health and safety concerns. Most of the time icing isn’t included in warranties or service contracts meaning the effects are difficult for owners to quantify. A simple SCADA data analysis often isn’t sufficient and it takes sophisticated analysis to pinpoint icing occurrences and quantify losses. Owners are looking for means to quantify losses and make the investment case for icing mitigation systems, but often don’t have the required information to do so.

Clir recognized this gap in information and developed a solution to automatically detect icing and quantify the associated losses. The algorithm uses a probability analysis approach to flag deviations from historical, turbine-specific power curves, based on site-specific climatic conditions and historical icing events. The icing events are automatically flagged to the user as a part of our standard system, including the losses related to the events, which enables the users to make informed decisions on how to proceed. The method is based on IEA Task 19’s standardized and widely approved method for ice loss calculations^ and has been further refined within the Clir system. Based on the results from the algorithm, Clir can make recommendations for optimization when the wind farm is experiencing icing. As part of this optimization work, an evaluation of any installed ice detection and mitigation system is undertaken, and the results are also useful for the evaluation of available third-party alternatives.

Rebecka Klintström, Data Scientist at Clir Renewables, says, “Significant losses are often experienced at wind farms in cold climates due to the impact of icing, but it is possible to regain some of this when there is a better understanding of the situation. With all the information, owners have the ability to take action and improve their output. One owner saw an increase of almost 5 % AEP after a manufacturer control update was implemented following assessment by Clir. While not all sites will see such an increase, it shows that icing is an issue that needs investigation.”

When it comes to decision making, knowledge is power and this what Clir’s software provides its users. The benefits to owners, operators and site managers of having this information are the quantification of the losses incurred, evidence for the manufacturer to optimize control algorithms, and decision-support for potential investment in a third-party ice mitigation system.

“Icing loss issues are compounded as they are excluded from the contractual obligations of the OEMs or the service providers under most service contracts. This has meant the issue has not been well managed in the turbine control design or operation phase of the assets, said Clir CEO, Gareth Brown.

“The Clir software has given owners actionable insights to increase output by reducing the number of false positive shutdowns inherent in the control assumptions for health and safety and loads on the blade. It also helps owners build the business case to change the control strategy of turbines and potentially shutdown turbines during icing conditions (freezing clouds) to minimize the build-up of ice on blades. The data model is set up specifically for renewables and Clir is the only platform in the market which can handle these types of issues,” he added.

* http://winterwind.se/wp-content/uploads/2015/08/9_1_24_Karlsson_IEA_Task_19_-_Cold_climate_wind_power_market_study_2015-2020_Pub_v1.pdf

^ https://community.ieawind.org/task19/t19icelossmethod

About Rebecka Klintström: Rebecka has over six years’ experience working in the wind industry, both as a consultant and for a utility. She has worked in all phases of a wind project, from pre-construction flow modeling, met mast installations and noise modeling to operational analysis, icing loss modeling, and optimizations, as well as managed research projects and project portfolios. Rebecka was a member of IEA’s task 19 for over five years and has an active role in developing the ice detection and loss algorithms. She’s been at Clir from the start and has worked with most turbine technologies, as well as starting up and heading Clir’s Inclusion and Diversity initiative.