How to Accelerate Wind Turbine Technology

For decades, wind turbines have traditionally undergone extensive testing in the field to ensure they are ready to be actively integrated into a power grid. This approach involves simple testing equipment, but comes with several caveats.

“Field tests have the disadvantage of being dependent on favorable wind and weather conditions, and the tests conducted are only partially reproducible,” says Florian Hans, a research associate with the Power Electronics and Grid Integration Group at the Fraunhofer Institute for Wind Energy Systems (IWES) in Bremerhaven, Germany.

A nacelle test bench hall run by Fraunhofer IWES.Martina Buchholz/IWES

With so many different factors affecting wind turbines—including wind speeds, grid load, and grid voltage—testing them in a more controlled environment offers significant advantages.

Therefore, Hans and his colleagues at Fraunhofer IWES are creating new laboratory testing methods for wind turbines, which allow for more controlled variables and reproducible results. “These advantages result in shorter test campaigns and cost savings,” Hans says, also noting that, in the controlled conditions of a lab, various grid conditions can be simulated based on customer needs, such as changes in voltage, frequency, or grid strength.

The first method that Hans and his colleagues are proposing involves testing how the entire turbine functions in a simulated grid, including the electrical and mechanical parts and their interactions. To support this approach, Fraunhofer IWES is currently commissioning a new grid simulator, called Mobil-Grid, which will be capable of testing a wide range of turbines, onshore and offshore, with up to a power of 20 megawatts and voltages of 20, 33, or 66 kilovolts.

Although not new, a second approach, called nacelle testing,includes simulating wind fields, rotor blades, and the electrical grid, which collectively allows researchers to simulate various wind and grid conditions. As noted in the group’s paper, Fraunhofer IWES has been conducting this type of testing through its DyNaLab (Dynamic Nacelle Testing Laboratory) since 2015.