DNV GL confirms: two percent higher yield when wind measured at the spinner

A yaw misalignment of more than four degrees was detected in 61 per cent of 152 turbines tested. The calculated increase in yield after correction: an average of two per cent. This has been confirmed by a current study by DNV GL (previously GL Garrad Hassan).

The spinner anemometer measures the wind where it first hits the wind turbine and thus delivers exact wind condition data. To date, wind direction and speed are usually measured behind the rotor on the wind turbine’s nacelle. The downside to this measuring technique: turbulence from the rotor can lead to inaccuracies.

A current DNV GL report confirms that iSpin technology has an advantage over conventional measuring techniques. ROMO Wind investigated the measurement data from 152 wind turbines fitted with iSpin technology. There were 24 different turbine types from ten manufacturers in performance classes from 0.6 to 3.4 megawatts. A nacelle misalignment of more than four degrees was detected in 93 (61 per cent) of these systems. Correcting the yaw misalignment means an average increased yield of two per cent for all 152 systems.

The DNV GL study confirms that:

• an average yield increase of two per cent could be achieved after correcting the detected yaw misalignment;
• the simple model for calculating increased yield after correcting yaw misalignment (cos² method) is a reliable procedure;
• the technology of the iSpin spinner anemometer is based on well-supported technical analysis and practical tests;
• fundamentally, there are many possible uses for data from a spinner anemometer in other wind park applications.

Søren Mouritsen, Co-CEO of ROMO Wind, says: “We are pleased that DNV GL has confirmed a significant yield increase from using iSpin technology. The system is setting new standards. It does not just recognise yaw misalignment; it also enables relative power curve measurement and reconciles actual wind conditions with the prognoses from wind assessments.”

Karl Fatrdla, Head of Sales at ROMO Wind Germany, expands: “Wind park operators are no longer willing to settle for inaccurate or computed wind data. With iSpin, they are now able to accurately measure, in front of the rotor, whether each wind turbine is properly aligned for the best possible yield. Another advantage is that the load is minimised through the corrected yaw misalignment. This reduces wear on the components, ensuring less down time and lower repair costs.”

ROMO Wind is the exclusive provider of the patented iSpin system, which uses proven ultrasound technology in an innovative way. The system was development by the Technical University of Denmark (DTU) and has been comprehensively tested since 2004. The product came onto market in 2013 and is listed in the international IEC 61400-12-2 norm as the standard for power curve measurement. The DNV GL report is available in full at www.romowind.com/knowledge-center.