Sunday, 22 January 2012
Characterizing Wind Turbine Inflow and Wakes Through Comparison of SODAR and Met Tower Observations-- A Part of TWICS: The Turbine Wake Inflow Characterization Study
Hall E (New Orleans Convention Center )
Wind offers an inexhaustible domestic energy source with minimal greenhouse gas emissions. To maximize energy generation from wind turbines it is essential to understand the influence of inflow conditions and wakes on wind turbine energy production. In accordance with this goal, the TWICS field campaign was conducted in April and May 2011 at the National Renewable Energy Lab's (NREL) National Wind Technology Center (NWTC) in the complex terrain downwind of Colorado's Front Range mountains. TWICS employed meteorological monitoring towers and remote sensing systems to provide a three dimensional spatio-temporal illustration of the inflow to and wake from a 2.3 MW turbine with a 100 meter rotor diameter. An important step in analyzing the TWICS data was quantifying the performance of the different measurement devices that were used. This research compares simultaneous measurements taken during TWICS by a Second Wind Triton Sodar and from the NREL M2 80 meter meteorological tower, which were located one kilometer apart.
During the TWICS campaign, we found strong linear correlations between wind speed measurements at 50 and 80 meters from the sodar and met tower. The high correlation suggests that flow is usually homogenous across the NWTC at time scales of ten minutes, but that there are also occasional periods of inhomogeneous flow. Wind speed correlations were also found to vary with time of day. This diurnal variation could represent different conditions at the sodar and tower site because of localized heating and turbulent mixing, but may also be due to changes in sodar performance as atmospheric stability changes during the course of the day. Results from this research will feed into future analysis of data collected during TWICS and help improve our understanding of turbine performance in the atmospheric boundary layer.