Icing: Consequences for the operation and power production of wind turbines in the Jura Mountains, Switzerland

Introduction

The Swiss Federal Office of Energy has set focus points to investigate icing on wind turbines within their research programme "Wind Energy". This research project aimed at addressing the consequences for the operation and power production of wind turbines in the Jura Mountains under icing conditions.





Approach

Field studies were carried out from 2009 to 2015 in two wind parks in the Jura Mountains.

Main body of abstract

Investigations comprised the following five aspects:
1) Monitoring of the icing conditions on the nacelle and on the rotor blades with webcams.
2) Assessing the icing frequency as well as typical temperatures and wind conditions leading to icing.
3) Evaluation of different methods for ice detection on the rotor blades of the wind turbines:
- Comparison of the actual power production with the theoretical power curve
- Temperature and relative humidity
- Moog/Insensys rotor blade monitoring system
4) Assessing efficiency, cost and benefit of the Enercon blade heating based on the webcam images.
5) Field studies of ice throw at the two sites.

The main findings were:
1) Webcams are a very suitable tool to monitor icing on nacelle and rotor blades.
2) Instrumental icing occurs during approximately 60 days in the Jura Mountains
3) Icing detection:
- Comparison of the actual power production with the theoretical power curve showed to be a suitable tool to detect icing.
- Evaluation of temperature and relative humidity overestimated the periods of icing conditions.
- The performance of the Moog/Insensys rotor monitoring systems in detecting ice was generally positive. However, using the system without real-time operational data was not without difficulty.
4) The analysis of the data showed that the power production was higher when heating during operation, as opposed to heating at stand-still.
5) 75% of all ice particles collected were found within 0 to 0.6 x the tip height. No ice particles were found at distances larger than 1.4 x tip height.



Conclusion

Wind energy is increasingly being used in cold climates, and technology has to adapt to meet these challenges.


Learning objectives
The research project in the Jura Mountains was able to add valuables experiences for turbine manufacturers and project developers to overcome questions in planning and operating wind parks in cold climate.