This paper presents measurement results of the world wide first successful certification the electrical properties of a wind turbine, solely based upon measurements obtained at a system test bench with HiL-System and grid emulator. For all certification relevant tests the results are compared to field measurements. The impact of the real-time models in the HiL-System as well as the converter-based grid emulator are discussed in this paper. For full converter wind turbine, different requirements for the model depth could be determined depending on the tests. Nevertheless, higher-quality models that reflect the plant behaviour better are recommended to reduce uncertainties within the certification process. This paper also shows that especially for grid failure events grid emulators require real-time impedance control, in order to emulate grid failures properly. Based on these findings, recommendations for the requirements on test bench components are formulated in this paper, in order to contribute to new certification guidelines. Overall, we conclude that based on the experiences made at two different system test benches, the vast majority of certification measurements can be carried out without limitation at such system test benches.

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This paper presents a converter topology for the realisation of high power grid simulators. This can be used for highly flexible simulation and testing of the grid compliance of renewable energy conversion systems, even for the certification procedure of the electrical characteristics

Advanced testing methods are becoming more and more prevalent to increase the reliability of wind turbines. In this field, dynamometers that allow for system level tests of full-scale nacelles will play an important role. Operating these test benches in a hardware-in-the-loop (HiL) set-up that emulates realistic drive train modes is challenging because of the relatively low stiffness of the load machines’ drive trains. This paper proposes a control method for enabling the said operation mode. It is based on the idea that the HiL-controller overrides the present unrealistic dynamics and directly imposes desired realistic dynamics on the test bench. A solution for the control problem is given and applied in a design study with a generic wind turbine and a test bench model obtained from construction data of a real test bench. In the design study, the HiL-controller robustly imposes desired drive train dynamics on the test bench model. Despite measurement noise, unmodelled parametric uncertainty, and unmodelled delays, the first drive train mode is correctly reproduced. This is confirmed by a comparison with simulation results from a full servo-aero-elastic code. Furthermore, an implementation of the test bench model on a programmable logic controller showed the real-time feasibility of the proposed method

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