Wind energy is a key part of the global energy future, expanding rapidly throughout the world in onshore and offshore settings. But to be sustainable, large scale, multi-megawatt (multi-MW) wind farming’s economic efficiencies need to be maximized and knowing where to place the turbines within the wind farm is a first step.
Without proper and strategic placement of wind turbines, the low-speed wind behind turbines, called a wake, decreases the efficiency of the wind farm. Wind tunnel tests have been used to guide placement, but their conditions are not representative of the complex flow behaviours in the field conditions of actual wind farms. So the question is, how to overcome this?
“In wind farms, the power output of wind turbines can decrease by up to 40% if the wind turbines are in the wake of upstream wind turbines, so there are intensive efforts to develop simulation tools that can be used to optimize the placement of wind turbines within wind farms,” said lead researcher Ndaona Chokani, lead researcher of the study.
Bring on the drones. Moreover, design novel instrumented drones with a suite of sensors capable of gathering precise field data in the complex flow and terrain of an actual wind farm.
Team members with the Swiss Federal Institute of Technology Zurich have developed novel instrumented drones that made high-resolution measurements of wind speed, wind direction and turbulence encountered in actual wind farms. Results show detailed flow behaviours around the wind turbines, useful for developing simulation tools that can be used to optimize placement of wind turbines within the wind farms. This offers the turbines the most efficient use of the wind resource.
The team is the first to develop and field test an instrumented drone used to measure, in detail, the airflow and mixing near and downwind of the wind farm. Chokani said, “These measurements shall accelerate the development of simulation tools that can be used to optimize the placement of wind turbines in onshore and offshore wind farms.”
The key to the current work is a seven-sensor, fast-response, aerodynamic probe used to make the time-resolved wind measurements. The probe is based on measuring technology used in conventional power plants, which was developed over the past two decades at the Swiss Federal Institute of Technology Zurich.
The researchers are to present their findings at the November meeting 2016 of the American Physical Society’s Division of Fluid Dynamics in Portland, Oregon.