WFIP2 • HILFLOWS

WFIP2 - Hill Flow Study (HilFlowS)

Overview

In 2015, the U.S. Department of Energy initiated the Second Wind Forecast Improvement Project (WFIP2), which aims to improve the accuracy of meteorological models that forecast wind speed in complex terrain for applications in wind energy. As a part of WFIP2, a dataset was collected in the Columbia River Basin region of Oregon and Washington.

In summer 2019 a secondary dataset for WFIP2 was collected at the Lawrence Livermore National Laboratory’s Site 300 Experimental Test Site. Site 300 is located in the Diablo Range adjacent to the Altamont Pass Wind Resource Area, which as of 2019, has a total rated capacity of 282 MW. The 2019 experiment was designated the Hill Flow Study or HilFlowS.

Three vertical profiling light detection and ranging (LIDAR) systems were deployed to measure wind profiles above the top of three hills ranging in elevation and slope. The LIDARs were aligned along parallel ridge lines with the predominant wind direction from the southwest. The exact angle of alignment was 237° (from point B to point A in Figure 1).

The data collection period was for approximately 11 weeks, from July 8 through September 23, 2019.

Primary points of contact for HilFlowS are:

Objective

Observations of wind direction and wind speed were used to capture and better understand how wind flow is modified over hills in complex terrain and to determine the optimal turbine hub height for new turbine installations in the region. HilFlowS provides a secondary location in complex terrain to validate and verify WFIP2 atmospheric model simulations.


Details

Three vertically profiling LIDAR were deployed. This included one WindCube v2 and two ZephIR300 LIDARs. All three instruments send infrared laser pulses into the atmosphere to derive wind speed and direction. Laser pulses are backscattered by aerosol particles in the air (dust, water droplets, aerosol, etc.) and the LIDAR assumes that the particles are moving at the same speed as the wind. The collected backscattered light allows the calculation of wind speed and direction using Doppler-induced laser wavelength shift.

The WindCube v2 is a pulsed LIDAR and uses four beams sent in succession in the four cardinal directions along a 28°scanning cone angle to measure horizontal velocity and wind direction. A fifth beam is sent in the vertical direction to measure vertical velocity. Measurement heights are user-programmed and range from 40 m to 200 m. During HilFlowS, the WindCube v2 was programmed to measure from 40 m to 150 m at 10 m intervals. The data sampling rate was 1 s, wind speed accuracy was 0.1 m/s, and direction accuracy was 1.5° for the instrument. The data were averaged across 10-min. averaging intervals.

The WindCube v2 was co-located with Site 300’s 52 m-tall meteorological tower so that measurements below 40 m also could be observed. The meteorological tower has three measurement levels: 10 m, 23 m, and 52 m. Wind speed was measured with a cup anemometer; wind direction was measured with a wind vane. Data are available as 15-min. averages.

The ZephIR300 is a continuous wave LIDAR with a range of 10 m to 300 m. During HilFlowS the ZephIR300 was programmed to measure from 10 m to 150 m. In addition, the ZephIR300 provided a measurement at 1 m height using an onboard meteorological sensor. The ZephIR300 had a 30° scanning cone angle, data sampling rate of approximately 15 s, wind speed accuracy of 0.5 percent, and direction accuracy of 0.5°.

Prior to HilFlowS all three LIDAR were deployed on the Lawrence Livermore National Laboratory campus adjacent to a 52 m-tall meteorological tower. The fetch contained no buildings or trees and the local terrain and terrain in the predominant fetch were flat. Excellent agreement between the LIDARs and meteorological tower was achieved (r-square values > 0.95 for all heights for both wind speed and direction).

Table 1: Measurement Locations during HilFlowS

LocationInstrumentInstanceLatitudeLongitudeElevation Measurment heights (m)
WOPZephIR300 - #773lidar.0337.66641-121.55810526 m 1, 10, 20, 30, 38, 50, 60, 70, 80, 90, 120, 150
MOPZephIR300 - #345lidar.0237.67060-121.54990448 m 1, 10, 20, 30, 38, 50, 60, 70, 80, 90, 120, 150
EOPWindCube V2 - #96lidar.0137.67515-121.54106394 m 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150
EOP52 m-tall meteorological tower with cup anemometers, wind vanesmet.0137.67526-121.54111394 m 10, 23, 52

Alt Text

Figure 1: Topographical map and LIDAR locations for HilFlowS (top). Terrain profile along line A-B with labeled LIDAR locations (bottom).

Alt Text

Figure 2: Google Earth image with LIDAR locations shown (left). LIDAR deployment of WOP, the ZephIR300 - #773 (right); the photograph was taken facing east-northeast.

Data Quality Control/Quality Assurance

The data period did not cover any significant rain events. The LIDARs have an internal data quality procedure and produce 9999 or NaN in the wind data fields if the LIDAR threshold criteria are not met. Each measurement height includes a data availability percentage. Data users are encouraged to use an additional data quality threshold based on this data availability field. For example, a user may to decide to remove wind observations if data availability is less than 50 percent during the averaging period.

Note that the LIDAR data were recorded in UTC and meteorological tower data were recorded in Pacific Standard Time.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

LLNL-WEB-794261