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Conference programme 

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Poster session

Lead Session Chair:
Stephan Barth, Managing Director, ForWind - Center for Wind Energy Research, Germany
Matthias Henke SgurrEnergy, Germany
Co-authors:
Matthias Henke (1) F P
(1) SgurrEnergy, Hamburg, Germany

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Poster
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Presenter's biography

Biographies are supplied directly by presenters at OFFSHORE 2015 and are published here unedited

Matthias Henke is in charge of SgurrEnergy’s Hamburg office and working with his team on offshore and onshore wind projects in Europe. After starting working in wind energy in 1999 with the development of wind energy projects he worked as technical advisor to on- and offshore wind projects. His work experience includes a considerable number of independent engineering services for offshore and onshore wind energy projects around the world. Among his clients are international banks, investors, utilities and developers. Matthias Henke studied electrical engineering and got an additional degree in economics as well as an MBA in international management.

Abstract

Robust low cost offshore power curve tests with lidar

Introduction

Testing the power performance of offshore wind turbines is an important part of operating an offshore wind farm.

The key impediment to offshore power curve tests so far has been the high cost. Hitherto, it has been necessary to install an expensive offshore met mast to obtain the necessary measurements. The ability to install scanning lidar on the transition piece of an offshore wind turbine provides a valuable opportunity to eliminate the cost of the offshore met tower and make highly cost-effective measurements.

Approach

A scanning lidar can be installed on the access walkway of the transition piece. The lidar will be set up to implement scan geometries that allow wind data to be acquired at hub height 2.5 rotor diameters upwind of the test turbine.

This setup complies in most respects with the latest draft version of the revision of the IEC I61400-12-1 standard.

This set up has been used at turbine AV07 at Alpha Ventus Offshore Wind Farm. The accuracy of the data has been verified against the FINO 1 measurement platform.


Main body of abstract

A scanning lidar was installed on the transition piece of AV07 in Alpha Ventus Offshore Wind Farm on 18th February 2013.

One of the tasks scheduled for the lidar was the measurement of the wind turbine power curve.
The set up needed to be compliant with the draft 2nd edition of the power curve test standard IEC 61400-12-1. This requires “ground based” lidar methods. Nnacelle mounting is not compliant, but. Mounting on the transition piece satisfies this requirement. A further IEC requirement is measurement at hub height 2.5 rotor diameters upwind of the test turbine.

The measurement accuracy was verified against the FINO1 reference mast approximately 900m from AV07. The results showed excellent agreement, consistent with onshore tests, with both correlation coefficient R2 and regression slope m exceeding 0.98% acceptance criteria. The procedure has been independently reviewed.

The transition piece mounting of a lidar device at one turbine also allows power curve tests of multiple offshore wind turbines in the vicinity during a single test campaign, further reducing the costs associated with power curve tests


Conclusion

The methodology described for installing lidar on the transition piece of an offshore wind turbine complies with the draft 2nd edition of the power curve test standard IEC 61400-12-1 to the fullest extent possible without a met mast.

The results of measurements performed at Alpha Ventus confirm the suitability of this method. The measurements showed excellent agreement with reference anemometry, with both correlation coefficient R2 and regression slope m exceeding 0.98% acceptance criteria.

The cost of the power curve test undertaken using this lidar method is less than 1% of the cost of the equivalent met mast based test.



Learning objectives
The delegates will understand robust lidar method for offshore power curve tests which is cost effective and compliant with IEC standards.

A well-documented, independently reviewed and repeatable procedure for implementing this method will be presented.