Opportunities and Challenges of Advanced Testing Approaches for Multi-Megawatt Wind Turbines

To safely integrate large numbers of wind turbines into the electric power grid, turbines must demonstrate compliance with grid codes and technical guidelines through rigorous testing. Such tests are traditionally performed using prototype turbines on designated measurement sites. So-called field tests offer little flexibility and repeatability, as factors such as wind and grid conditions cannot be adjusted at will. Recently, specialized laboratory test facilities were established to augment or completely replace conventional field tests. These facilities need to constantly grow in size, power, and functionality to keep up with wind turbine trends, while new and increasingly complex grid requirements necessitate more advanced testing methodologies. This paper presents four testing concepts and how they can be further integrated into the development and certification process of wind turbines using the laboratories of Fraunhofer IWES as an example. In particular, turbine, nacelle, subsystem, and component testing are reviewed and their advantages and anticipated challenges for evaluating grid code compliance are highlighted. Experiences gained over the past decade from testing wind turbines and constructing experimental testing facilities are shared, including key data and capabilities of the developed test benches. The authors expect the presented approach to be used for validating simulation models that can be embedded into larger interaction and stability studies of wind farms at a later stage. Such an integrated testing approach may lead to quicker and more flexible design and optimization of new generations of wind turbines, effectively increasing the speed of grid integration and ensuring safe and reliable grid operation.