CertBench: conclusions from the comparison of certification results derived on system test benches and in the field

Abstract

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.

Impact of Multi-Physics HiL Test Benches on Wind Turbine Certification

“…The experimental results showed that, with the given HiL systems, it is possible to conduct certification measurements at the test bench, which lead to results comparable to results from field measurements. As shown in [28], this is not only true for the few tests discussed in this paper, but also for many others and at other nacelle test benches. However, the analysis in this paper also illustrated in detail that a limited accuracy or errors of the HiL systems, their simulation models, and controls could easily compromise the quality of the certification result.…”

“…This project achieved the worldwide first wind turbine certification, solely based upon test bench measurements by means of the German FGW TR3 guideline. An overview of the results [28], and some results on MHiL- [29] and PHiL-specific [30] aspects have been published already.…”

Testing Requirements and Control Strategies of Next-Generation Grid Emulator: A Review

“…Typically, grid emulators using a fast voltage control with 1 kHz~3 kHz bandwidth can emulate 0%~130% of nominal voltage within 20 ms [7], [8]. However, the 130%~160% overvoltage and the multi-consecutive faults are not easy to achieve [7], [18]. Further, the impact of reactive current injection by DUT on the emulated voltage profile is overlooked in existing MMC-based grid emulators [4], [5].…”

Influences on the LVRT behavior of DFIG wind turbine systems

“…The concept of a certification process using a system test bench was investigated in the research project CertBench [7]. In this project the LVRT behavior of a WT on two different test bench setups are compared to field tests [8].…”