Scientific Planning and Design of the Southern German Wind Energy Test Site in Complex Terrain

Introduction

At present, WindForS, the Southern German Wind Energy Research Cluster, is comprised of twenty-five institutes from seven institutions of higher education and research institutes from Baden-Württemberg and Bavaria. They are pooling their competencies in the field of wind energy research and their complementary expertise covers the entire wind energy value chain – both onshore and offshore.

Demand for test site
Both industry and research institutions strive to reduce turbine costs, increase availability and energy yield and minimise technological risks. That is why there already exist a number of test sites where wind turbine manufacturers install either prototypes of wind turbines or standard turbines on defined test pads for testing. However, all of the test sites except one (Aláiz, Spain) are on flat terrain as they are used for certification measurements. The research wind turbines of NREL (USA), Sandia (USA) or DTU (Denmark) are located in flat terrain as well. This means that there is a lack of accessible research turbines in complex terrain. Several letters of support and expressions of interest we received from national and international research institutions and from companies in the field show that there is a need for such a test site.


Approach

Developing the site
The nationally funded research project “KonTest” (2013-2015) aimed to develop the design for a wind energy test site in complex terrain. One important feature of the project was the scientific monitoring of the planning stages of the test site so that the goals of the research institutions involved and the technological goals of wind turbine manufacturers and their suppliers could be taken into account. A catalogue of criteria for possible locations of the test site in terms of geographical, meteorological and landscape features was developed. Meteorological data such as wind speed, turbulence and wind profile were collected as well as information on soil consistency and on land use. The flow field around the area where the research turbines are planned to be installed was simulated. An important task after deciding where the test site will be was to define future research needs and to plan the equipment of the test site and the research turbines accordingly.


Main body of abstract

Test Site Description
The location for the research turbines is forest-free in the prevailing wind direction so that an undisturbed airflow is possible in the main wind direction behind the edge of the slope. The turbines will be erected side by side to have the possibility to directly compare the behaviours of the modified turbine and the reference turbine. The idea is to position a meteorological masts and further measurement sensors in front of and behind each research turbine.

Research objectives
The test site is intended to be used to prepare, test and validate new technologies in terms of turbine construction, aerodynamics, aero-acoustics, aero-elastics, manufacturing engineering, measurement tools and techniques and monitoring. Furthermore, investigations regarding the research foci storage, grid integration and operation management are planned to be carried out.

Conclusion

For the development and verification of simulation tools for designing wind turbines as overall systems, for designing wind turbine components and for modelling environmental influences (flow etc.) actual measurement data are essential. The measurement data obtained from the research turbines and the meteorological sensors will be stored in a research data archive.
On account of the topological and topographical location, basic research on meteorological conditions with a view to wind energy use in complex-mountainous terrain is also envisaged.


Learning objectives
The test site will enable research institutions and manufacturers of wind turbines and turbine components to test and validate new technologies on two accessible research turbines in complex terrain.






Acknowledgement
The project KonTest (No. 0325656) was funded by the German Federal Ministry for Economic Affairs and Energy (BMWi).