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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
Gregor Giebel DTU Wind Energy, Denmark
Gregor Giebel (1) F P Tuhfe Göcmen Bozkurt (1) Poul Sørensen (1) Pierre-Elouan Rethore (1) Mahmood Mirzaei (1) Niels Kjølstad Poulsen (2) Mads Rajczyk Skjelmose (3) Jesper Runge Kristoffersen (3)
(1) DTU Wind Energy, Risø, Denmark (2) DTU Compute, Lyngby, Denmark (3) Vattenfall, Fredericia, Denmark

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Presenter's biography

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

Gregor Giebel is Senior Scientist at DTU Wind Energy at Risø. During the last 18 years, he worked with short-term prediction of wind power, wind power meteorology including measurements with drones, ancillary services, grid integration and condition monitoring.


Experimental verification of a real-time power curve for down-regulated offshore wind power plants


Available (or Possible) Power is the power that a turbine or a wind power plant would produce if it had not been down-regulated (or curtailed). While down-regulation, either mandated or to sell reserve power as ancillary service, is getting more frequent, Transmission System Operators have no real way to determine exactly the available power of a down-regulated wind farm. The PossPOW project is addressing that need, aiming to develop a verified method for the real-time estimation of the available power of a down-regulated offshore wind power plant (see


While the estimation of the available power for a single turbine is state of the art, the sum of those available powers from all turbines in a wind farm overestimates the power due to the reduced wake effects during down-regulation. In order to calculate that effect, the turbine wind speed is estimated from the produced power, the pitch angle and the rotor speed using the Cp curve. A real-time wake estimation of normal operation is then performed and advected to the next downstream turbine, and so on until the entire wind farm is calculated.

Main body of abstract

The estimation of the rotor equivalent wind speed, the parameterisation of the GCLarsen wake model for real-time use (i.e., 1-sec data from Horns Rev and Thanet) and the details of the advection are the topic of another paper in these proceedings by Göcmen et al. Here we describe the experiments using the Horns Rev wind farm and the verification of the algorithm.
Assuming similarity of the wind speeds between neighbouring rows of turbines, the power produced by the second turbines in the line can be compared when some of the front row turbines are down-regulated. To get a good signal, a trigger mechanism is employed which assures that the experiment is only started if the wind is blowing directly down the line of turbines, and in a strength which is below rated power. The experiments will run during autumn of 2014.
A verified algorithm could be employed by manufacturers and operators world-wide, both for the determination of compensation payments during mandated down-regulation as well as for the exact determination of reserve power for use in ancillary services markets.


The experimental verification of the algorithm of the wind farm scale available power estimation is presented. The experiments are run at the Horns Rev wind farm, down-regulating some turbines while leaving others as benchmark turbines.

Learning objectives
Available (or possible) power estimation
Real-time wake modelling
Real-time wind farm power curve