Andreas Rettenmeier

Wind velocity measurements using a pulsed LIDAR system: first results

Wind velocity measurements were taken using a Leosphere Windcube LIDAR system, which operates as a pulsed laser Doppler anemometer. Here we report on first results, which show typical characteristics of atmospheric wind velocities.

Arrangements for enhanced measurements of a large turbine near-wake using LiDAR from the nacelle

New LiDAR techniques are being tested and developed to support the development of large offshore wind turbines. Our interest in this paper is concentrated in wake measurements; therefore, a pulsed standard LiDAR is adapted for fullscale wind field measurements from the nacelle of a large wind turbine. We show the conceptual framework for planned adaptations to a Windcube® LiDAR for operation at the nacelle of a 5 MW wind turbine. The standard scanning mode is to be modified to properly obtain downstream and also upstream wind speeds. The wind field measurements are intended for verification of models for near-wake wind speed, wake meandering and new predictive control estrategies.

Characterization of short time fluctuations in atmospheric wind speeds by LIDAR measurements

Wind velocity measurements were taken using a Leosphere Windcube LIDAR system, which operates as a pulsed laser Doppler anemometer. Here we report on first results, which show typical characteristics of atmospheric wind velocities. Especially pronounced intermittent (or heavy-tailed) probability density functions (PDF) of wind speed increments are present on all observed time scales. A transition for large time scales towards a more Gaussian shape is found if only ten minute intervals are selected which share the same mean wind speed. Both typical shapes of PDF are well described and modeled by two previously proposed models.

Power Performance Measurements of the NREL CART-2 Wind Turbine Using a Nacelle-Based Lidar Scanner

AbstractDifferent certification procedures in wind energy, such as power performance testing or load estimation, require measurements of the wind speed, which is set in relation to the electrical power output or the turbine loading. The wind shear affects the behavior of the turbine as hub heights and rotor diameters of modern wind turbines increase. Different measurement methods have been developed to take the wind shear into account. In this paper an approach is presented where the wind speed is measured from the nacelle of a wind turbine using a scanning lidar system.The measurement campaign was performed on the two-bladed Controls Advanced Research Turbine (CART-2) at the National Wind Technology Center in Colorado. The wind speed of the turbine inflow was measured and recalculated in three different ways: using an anemometer installed on a meteorological mast, using the nacelle-based lidar scanner, and using the wind turbine itself. Here, the wind speed was recalculated from turbine data using the wi...

Impact of Complex Orography on Wake Development: Simulation Results for the Planned WindForS Test Site

In Southern Germany a test site will be erected in complex terrain. The purpose is to enable detailed scientific studies of terrain impact on the characteristics of two research wind turbines and to demonstrate new technologies. Within preparatory studies an appropriate site was identified and examined by field tests and numerical studies in more detail. The present paper summarizes CFD analyses on the impact of the local test site orography on the wake development of a virtual wind turbine. The effects of the orography are identified by comparative simulations for the same turbine using comparative wind situation in flat terrain.