ZephIR Lidar’s turbine-mounted Dual Mode (DM) system has been deployed by developers Renewable Energy Systems Ltd. (RES) in a commercial investigation into lidar-generated turbine performance measurements.
This trial, which began in June 2013 and is expected to end in November 2013, uses a ZephIR DM installed on a Vestas V90 turbine. The ZephIR DM is capable of measuring upwind; wind speed, shear, turbulence and veer. The DM was chosen for its ability to provide absolute (traceable to IEC Standard 61400-12-1CD) and relative power curve assessments both hub-height and rotor-equivalent. In non-complex terrain, current industry guidelines require measuring the wind at distances of two to four rotor diameters upwind – minimising blade induction effects on the wind speed. Complex terrain causes the wind model to evolve as it moves over the landscape approaching the turbine, meaning that the wind and available energy at the turbine rotor can differ significantly from the measurement point. To combat this uncertainty, wind speed can be measured much closer to the turbine. Although these measurements are within the blade induction zone, their repeatability is higher and will be less influenced by the complex terrain. The ZephIR DM and ZephIR 300 are able to measure at distances as short as 10 metres, and out to 300 metres. With the ZephIR measuring at 135, 90, 45 and 10 metres ranges in its second phase, the trial exploits the DM’s ability to measure short distances upwind of the turbine within complex terrain to produce power curves.