Nacelle power curve measurement with spinner anemometer and uncertainty evaluation

Giorgio Demurtas,Troels Friis Pedersen,Rozenn Wagner

doi:10.5194/wes-2-97-2017

Abstract

Abstract. The objective of this investigation was to verify the feasibility of using the spinner anemometer calibration and nacelle transfer function determined on one reference wind turbine, in order to assess the power performance of a second identical turbine. An experiment was set up with a met mast in a position suitable to measure the power curve of the two wind turbines, both equipped with a spinner anemometer. An IEC 61400-12-1-compliant power curve was then measured for both wind turbines using the met mast. The NTF (nacelle transfer function) was measured on the reference wind turbine and then applied to both turbines to calculate the free wind speed. For each of the two wind turbines, the power curve (PC) was measured with the met mast and the nacelle power curve (NPC) with the spinner anemometer. Four power curves (two PCs and two NPCs) were compared in terms of AEP (annual energy production) for a Rayleigh wind speed probability distribution. For each wind turbine, the NPC agreed with the corresponding PC within 0.10 % of AEP for the reference wind turbine and within 0.38 % for the second wind turbine, for a mean wind speed of 8 m s−1.

Highlights

Measuring the power performance of a wind turbine means establishing the relation between wind speed and electric power
The objective of this investigation was to verify the feasibility of using the spinner anemometer calibration and nacelle transfer function determined on one reference wind turbine, in order to assess the power performance of a second identical turbine
The nacelle power curve (NPC) agreed with the corresponding power curve (PC) within 0.10 % of annual energy production (AEP) for the reference wind turbine and within 0.38 % for the second wind turbine, for a mean wind speed of 8 m s−1

Summary

Introduction

Measuring the power performance of a wind turbine means establishing the relation between wind speed (input) and electric power (output). The IEC61400-12-1 standard describes the instrumentation requirements and the calculation procedures to determine the power curve with the method of bins, measuring the wind at hub height upstream of the wind turbine with a cup anemometer installed on a meteorological mast. While the use of the nacelle anemometer (mounted on the nacelle roof) for performance measurements is a well-established procedure, the spinner anemometer is an option to measure the wind turbine performance with which few engineers have experience. A spinner anemometer (Pedersen, 2007) consist of three onedimensional sonic wind speed sensors mounted on the spinner of the wind turbine. The three sonic sensor signals are converted to the horizontal wind speed Uhor, the yaw misalignment γ and the flow inclination angle β with a conversion algorithm (Pedersen et al, 2015). The advantage of a spinner anemometer over a nacelle anemometer is that it is measuring in front of the rotor rather than behind, where the flow is influenced by the wake of the blades and other elements present on the nacelle as described by Frandsen et al (2009)

Objectives

Results

Conclusion