ZephIR Lidar's industry-leading, turbine-mounted Dual Mode (DM) system has been deployed by developers Renewable Energy Systems Ltd. (RES) in a first-of-its-kind commercial investigation into lidar-generated turbine performance measurements.

This pioneering 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 uniquely 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 the only commercial lidar systems with the ability to measure at distances as short as 10m, and out to 300m.

With the ZephIR measuring at 135, 90, 45 and 10m ranges in its second phase, the trial exploits the DM's unique ability to measure short distances upwind of the turbine within complex terrain to produce power curves.

Ian Locker, ZephIR Lidar's Managing Director, said: "In this trial, the ZephIR Dual Mode is demonstrating its ability to take measurements that other lidars cannot. We are demonstrating with this trial that higher repeatability of turbine performance measurements can be made possible through deployment of the DM. Additionally, our system is helping RES, one of the most respected technical leaders in the wind industry, determine new and more reliable power curve measurement techniques for turbines, including those increasingly operating in complex terrain."

A spokesperson for RES said: "The ZephIR DM was the perfect choice for this trial. Traditional methodologies for measuring power curves have practical and technical challenges. This trial has the potential to change current methodologies, address existing challenges and improve commercial relationships between developers, operators and turbine suppliers by better understanding the relationship between wind and turbine performance. As well being able to measure upwind at extremely short distances, no other lidar system was able to incorporate shear, turbulence and veer in absolute and relative power curves. The ZephIR DM is the only wind lidar device that satisfied our requirements for this trial."