Yaw misalignment – The scourge of wind farm operators

Yaw misalignment

This is a short summary in English of an article published in the “Journal de l’Eolien”, the French reference magazine focusing on the Wind Industry. Access the full article in French by registering to the magazine here.

Yaw Misalignments are recurring errors on wind turbines, due to the lack of precision of the wind anemometers installed in the turbulent air flow behind the blades.

On wind farm La Renardière (6 Senvion MM92 in Western France), one of the turbines is now equipped with an innovative ultrasonic measurement device installed directly on the spinner; the iSpin, a technology developed by ROMO Wind.

This wind farm is one of seven operated in France by the customer, Zephyr Energies Renouvelables. On La Renardière, the turbine selected for the deployment of iSpin has been consistently the least productive in the wind farm since its commissioning seven years ago; without any apparent reason. The explanation for this underperformance was quickly identified by the iSpin technology: the turbine has a 17° yaw misalignment, corresponding to a potential AEP loss of 9.2% (according to the cos² rule commonly used in the industry). The real AEP gain from correcting yaw misalignment is currently being precisely evaluated, thanks to a “toggle algorithm”, where the correction of yaw misalignment by iSpin is turned on and off every other hour. According to Christian Briard (General Manager of Zephyr Energies Renouvelables), “5 to 6% additional AEP would already be a great success for this measurement campaign; this would bring an additional 20,000 € of yearly revenue for this turbine only”. Such an improvement would produce a simple payback of less than 6 months on the iSpin deployment, though 12-18 months is a more typical finding with such projects.

Additional applications of the iSpin technology include 360° turbulence assessments, power curve verifications, performance monitoring or the provision of the wind site conditions for the analysis of turbine life consumption.

With the iSpin technology, ROMO Wind intends to help its customers make the best out of their wind assets, in an industry where, in 2016, the wind resource was unusually low and remuneration schemes are converging towards pricing available on the electricity ‘spot’ markets.