Towards full electrical certification of wind turbines on test benches - experiences gained from the HiL-GridCoP project

In recent years, more and more wind turbine manufacturers have been using test benches, such as the Dynamic Nacelle Testing Laboratory at Fraunhofer IWES in Bremerhaven, to test and optimize their turbines. To further accelerate the test phases, Fraunhofer IWES, together with the project partners Nordex Energy SE & Co. KG and Vestas Wind Systems A/S, has built a new test bench for grid compliance testing of reduced systems, consisting of the generator, the converter, and the transformer plus control as well as protection system. The HiL-GridCoP project demonstrated the comparability of test bench measurements on a wind turbine equipped with a doubly-fed induction generator with field measurements performed using a fault ride-through container. The aim of this paper is to present some of the key findings related to the electrical commissioning and test execution. The focus is on the grid simulator and on its impedance simulation functionality. It is discussed which limitations may be caused by specific test bench components and which issues might affect the test results. Finally, some measurements of voltage dips are presented to verify the test bench's comparability with field tests so that the full electrical certification can be carried out next.