Titel: Influence of Icing on the Power Performance of Seven NM82-1.5 MW Wind Turbines in Aapua, Elforsk rapport 09:59
Författare: Göran Ronsten
Utgivare: Elforsk, Vindforsk
Årtal: 2009
Ämnesord: Vindkraft i kallt klimat
Sökord/keywords:
Rapport
Sammanfattning/Abstract: The wind farm on Etu-Aapua, a hilltop in the Municipality of Övertorneå, was put into regular operation in Sep 2005. It is well known that icing has affected the power performance. The magnitude of this effect has not been investigated previously.
The energy production losses during the winter seasons have been found to be significantly higher compared to those during the summers. What is more alarming is the increase in downtime during the winters over the years due to a lower availability and a reduced energy production.
The average energy production losses, not including manual stops during 205 turbine days, are more than four times higher in the wintertime compared to those in the summertime. The average energy production loss, based on actual production, was 27.9% in the wintertime (t<+2C) and 6.6% in the summertime (t>+2C).
The method chosen, i.e. comparing the actual power for both summers and winters with the nominal power in each wind speed bin, enables the determination of when the power output is affected by low temperature related conditions. It is, based on a comparison of data from the summer time, assumed that icing, and not wakes, is causing this significant increase in losses.
Data for all turbines are missing during the start of the icing seasons in 2006 and 2007. Data from missing periods are not included in the evaluation. The most recent and frequent error codes are presented as are the power performances for each turbine during winters and summers. The increased spread in power performance data during the winters is obvious and significant.
The losses caused by iced-up wind turbine blades can be decreased by the use of de- or anti-icing systems. The hot air based de-icing systems on five E-70’s in Långå are found likely to be effective countermeasures in light icing conditions.
Consequently, the next step will be to install an anti-icing system on Aapua 7 to verify the findings in this report.