North offset: statistics & market trends
Illustration of a North offset reappearing 6 months after an on-site correction: the correction applied was lost after a software reboot
As presented in detail in our previous article (North Offset: an often forgotten issue), North offset is one of the most common and recurring issues we encounter when analysing wind farms. It is particularly important as it can significantly affect energy yield and even turbine lifespan—especially when Wind Sector Management or Acoustic Curtailments are present.
We at ExpertWind understand the importance of having reliable turbine information and we provide a clear and precise assessment of the north offset for all turbines on a daily basis, the only requirement being to have access to the SCADA data. Our method is based on a data coherence approach applied to the nacelle direction information from all turbines within a wind farm. By taking into account the effects of the local wind flow and the turbine’s relative position, we are able to provide calibrated north offset values without any external data source.
Statistics for North offset results: 43% of the turbines analysed presented a north offset of at least 10°
This approach allows not only for a simple and fast diagnosis but also to correct all previous historical data to validate, for example, curtailment plans or to precisely track turbine performance based on reliable wind sector information.
While working on wind farm analysis and optimisation, we encountered multiple causes that create North offsets on wind turbines: the most frequent being a wrong calibration during commissioning and turbines restarting after losing power connection to the grid. In addition, even after North offsets are corrected, software updates and reboots might make the issue reappear by losing the offset correction previously applied. This amplifies the need for close monitoring of this parameter over time.
From our experience, based on over 400MW of operating wind farms analysed, we identified over 40% of wind turbines with a north offset of at least 10°. And what surprises us the most, is the significant number of extreme north offsets (higher than 90°) detected (7%).
Turbines impacted by North offset for different OEMs
A noticeable pattern revealed in our statistics is the impact of the OEM on the results: for certain turbine brands, the number of turbines impacted is close to 80%, as in others it can be as low as 20%. In our interpretation, this variability does not seem related to the quality of the O&M performed but with the technologies used in both the nacelle direction sensor and the handling of previous corrections applied.
Are you looking for an efficient, reliable and cost-effective overall analysis of your wind farm including a precise and detailed north offset analysis? Feel free to Contact Us and learn more about our services and how your wind farms can benefit from them.